Waveguide structure, silicon photonic chip, detection apparatus, and terminal device

Abstract

A waveguide structure (400), a silicon photonic chip (2400), a detection apparatus (2500), and a terminal device (2600). The waveguide structure (400) comprises a grating coupler (411), a first connection portion (412), and an N-stage beam splitting unit (413). The cross-sectional area of an output end of the first connection portion (412) is greater than or equal to the cross-sectional area of an input end of the first connection portion (412). A first optical signal incident on the grating coupler (411) is transmitted through the first connection portion (412) and converted into an optical signal in a multimode waveguide, and is then split by the N-stage beam splitting unit (413) into at least two second optical signals, wherein the optical power of each second optical signal is less than that of the first optical signal. All optical power coupled into the grating coupler (411) is split and output in stages into at least two waveguides in the case of the multimode waveguide, rather than being concentrated in a single waveguide, such that high optical power density is not prone to occurring in each waveguide, and the TPA effect is likewise not prone to occurrence, thereby reducing optical transmission loss.

Description

A waveguide structure, a silicon photonics chip, a detection device, and a terminal equipment. Technical Field

[0001] This application relates to the field of sensor technology, and in particular to lidar, the waveguide structure of lidar and silicon photonic chip, which can be applied to, but is not limited to, the field of transportation control. Background Technology

[0002] Among silicon photonics chip manufacturing processes, silicon-on-insulator (SOI) technology is the most mature. This process achieves dielectric isolation between components in the chip by introducing a buried oxide layer (also known as an insulating layer) between the top silicon layer and the back substrate. Compared to silicon nitride (SiN) and planar lightwave circuits (PLCs), SOI silicon photonics chips have advantages such as small size, doping capability, support for active device integration such as photodiodes (PDs), high yield, and low cost.

[0003] Currently, the waveguides in SOI silicon photonics chips are called silicon optical waveguides. Due to silicon's high refractive index, it is generally transparent to light with wavelengths exceeding 1.1 μm. However, at high optical power densities, two photons with wavelengths exceeding 1.1 μm are absorbed, generating charge carriers. These charge carriers further absorb light, leading to increased transmission loss, higher temperature, and decreased reliability in the silicon optical waveguide. This phenomenon is called the two-photon absorption (TPA) effect in silicon optical waveguides. The TPA effect in silicon optical waveguides is positively correlated with the optical power density; the higher the optical power density, the stronger the TPA effect and the greater the transmission loss of the silicon optical waveguide.

[0004] Therefore, how to reduce the transmission loss caused by the TPA effect of waveguides at high optical power is a technical problem that urgently needs to be solved in the field of SOI silicon photonics chips. Summary of the Invention

[0005] This application provides a waveguide structure, a silicon photonics chip, a detection device, and a terminal device to reduce the transmission loss caused by the TPA effect of the waveguide under high optical power and increase the maximum optical power that the silicon photonics chip can withstand.

[0006] In a first aspect, this application provides a waveguide structure, including a grating coupler, a first connecting portion, and an N-stage beam splitter unit, where N is a positive integer; the input end of the N-stage beam splitter unit is connected to the output end of the first connecting portion, and the cross-sectional area of ​​the output end of the first connecting portion is greater than or equal to the cross-sectional area of ​​the input end of the first connecting portion; a first optical signal incident on the grating coupler is transmitted through the first connecting portion and becomes an optical signal in a multimode waveguide, and the optical signal in the multimode waveguide is split into at least two second optical signals by the N-stage beam splitter unit, wherein the optical power of each of the at least two second optical signals is less than the optical power of the first optical signal.

[0007] Based on the above waveguide structure, when the output of the N-stage beam splitter unit is connected to the waveguide, all optical power coupled into the GC will be output in stages and beams to at least two waveguides in the case of multimode waveguides. This avoids the situation where all optical power is concentrated in a single waveguide, reducing the optical power transmitted in each waveguide and making it less likely for high optical power density to occur in each waveguide. Thus, when the waveguide structure is applied to SOI silicon photonics chips, the TPA effect is less likely to occur in each waveguide, solving the problem of high transmission loss caused by the TPA effect under high optical power density in SOI silicon photonics chips. Furthermore, the above waveguide structure uses entirely passive components, therefore, it can be directly formed through a single exposure without additional semiconductor process steps, doping, power-on processes, or additional power consumption. It has advantages such as simple process, minimalist architecture, extremely low cost, extremely high performance, and extremely high reliability.

[0008] It should be noted that if the cross-sectional area of ​​the output end of the first connector is equal to the cross-sectional area of ​​the input end, then the mode size of the output end of the first connector is equal to the mode size of the input end. The first connector is responsible for converting the received optical signal into an optical signal for transmission in the multimode waveguide. Conversely, if the cross-sectional area of ​​the output end of the first connector is greater than the cross-sectional area of ​​the input end, then the mode size of the output end of the first connector is greater than the mode size of the input end. In addition to transmitting optical signals in the multimode waveguide, the first connector also has the effect of expanding the mode size. The expanded mode size results in a lower optical power density per unit area, which can further reduce the probability of the TPA effect.

[0009] In one possible design, the first connection can be implemented using one or more waveguide elements, which can be at least one of a multimode waveguide, a mode converter, a tapered structure with a gradually tapered cross-section (taper), or a tapered structure with a gradually thickened cross-section (reverse taper). For example, the first connection may include a mode converter, where the cross-sectional area of ​​the output end of the mode converter is greater than or equal to the cross-sectional area of ​​the input end of the mode converter; or, the first connection may include a multimode waveguide and a mode converter, where the output end of the multimode waveguide is connected to the input end of the mode converter, and the cross-sectional area of ​​the output end of the mode converter is greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide; or, the first connection may include a first mode converter and a second mode converter, where the input end of the second mode converter is connected to the output end of the first mode converter, and the cross-sectional area of ​​the output end of the second mode converter is greater than or equal to the cross-sectional area of ​​the input end of the first mode converter, and so on, and so on.

[0010] Based on the above design, the first connection can be realized by one or more waveguide elements. The structure of one or more waveguide elements is simple, the cost is low, they are easy to obtain, and they can be applied to various application scenarios, with high flexibility.

[0011] In one possible design, when N is 1, the N-level beam splitter includes a beam splitter with at least two branches. The inputs of the at least two branches are connected to the output of the first connection, and the outputs of the at least two branches serve as the outputs of the N-level beam splitter.

[0012] Based on the above design, the optical signal output from the first connector can be divided into at least two beams through at least two branches. The optical power density of each of the at least two optical signals is lower than the optical power of the optical signal output from the first connector, thus realizing the beam-splitting output of optical power.

[0013] In one possible design, when N is greater than or equal to 2, the first-level beam splitter includes a beam splitter with at least two branches. The inputs of the at least two branches are connected to the output of the first connection, and the outputs of the at least two branches are connected to the input of the second-level beam splitter through at least two second connections. Each beam splitter from the second-level to the Nth-level beam splitter includes one or more beam splitters. Each of the one or more beam splitters includes at least two branches. The inputs of the one or more beam splitters are connected to the output of the previous-level beam splitter through the second connection, and the outputs of the one or more beam splitters are connected to the input of the next-level beam splitter through the second connection, or serve as the output of the Nth-level beam splitter.

[0014] Based on the above design, as long as each beam-splitting unit contains at least one beam splitter, enabling further beam splitting compared to the output of the previous stage, the specific number of branches and sub-branches is not limited. With this structural design, an N-stage beam-splitting unit can progressively split a first optical signal into two or more arbitrary numbers of second optical signals. For example, if each beam splitter is a 1-to-2 splitter, the final stage beam-splitting unit will have 2... N One output terminal, output 2 N For each second optical signal, under the same optical power, the larger the value of N, the smaller the optical power density of each second optical signal, and the better the effect of reducing the TPA effect.

[0015] In one example of the above design, for each branch, in the direction from the input end to the output end of the branch, the cross-sectional shape of the branch remains unchanged; or, the cross-sectional height of the branch remains unchanged, but the cross-sectional width of the branch tends to increase or decrease.

[0016] Based on the above examples, the cross-sectional area of ​​the output end of each branch can be the same as, smaller than, or larger than the cross-sectional area of ​​the input end. If the cross-sectional area is the same, the output and input ends of the branch have the same pattern size, and the branch is only used to transmit optical signals. If the cross-sectional area is smaller, the branch can reduce the pattern size while transmitting optical signals, allowing the optical signal to adapt to the required pattern size more quickly, reducing the number of stages or beams in the N-stage beam splitting unit. If the cross-sectional area is larger, the branch can expand the pattern size while transmitting optical signals. Expanding the pattern size through the branch eliminates the need for the first or second connecting part; for example, the first and second connecting parts can be designed with the same cross-sectional area, reducing the design difficulty of the first and second connecting parts. Based on this, by designing branches to support both constant and increasing / decreasing cross-sectional areas, the branch structure can be flexibly designed according to requirements to adapt to different application needs.

[0017] In one example of the design above, the branch includes a curved structure. For instance, the branch could be curved from input to output, or the input and output could both be straight, with a curved transition in between. Alternatively, the input could be straight and the output curved, or vice versa. The possibilities are not limited to these variations.

[0018] Based on the above example, by designing branches including curved structures, the branches can smoothly connect with the two end regions through the curved structures. The slope of the curved structure at the connection point with the two end regions is the same, and the mode spot size matches each other. Therefore, there will be no large mode spot loss during optical signal transmission, which can ensure a better signal transmission effect.

[0019] In one example of the above design, the cross-sectional area of ​​the output end of the second connector is greater than or equal to the cross-sectional area of ​​the input end. For instance, if the mode-expanding effect of the first connector is sufficient to make the optical power density after mode expansion sufficiently low to avoid the TPA effect, the output end of the second connector can be designed to have the same cross-sectional area as the input end, so that the optical signal with lower optical power density can be transmitted to the next stage beam splitting unit through the second connector. However, if the mode-expanding effect of the first connector is insufficient, the optical signal after mode expansion may be output to the subsequent waveguide after one or two beam splits, and the optical power density may not be reduced significantly. In this case, the output end of the second connector can be designed to have a larger cross-sectional area than the input end. The second connector expands the mode while transmitting the signal, and the expanded mode further reduces the optical power density per unit area, thereby further reducing the probability of the TPA effect.

[0020] In further examples, similar to the first connection, the second connection can also be implemented using one or more waveguide elements. For instance, the second connection may include a mode converter, where the cross-sectional area of ​​the output of the mode converter is greater than or equal to the cross-sectional area of ​​the input of the mode converter; or, the second connection may include a multimode waveguide and a mode converter, where the output of the multimode waveguide is connected to the input of the mode converter, and the cross-sectional area of ​​the output of the mode converter is greater than or equal to the cross-sectional area of ​​the input of the multimode waveguide; or, the second connection may include a first mode converter and a second mode converter, where the input of the second mode converter is connected to the output of the first mode converter, and the cross-sectional area of ​​the output of the second mode converter is greater than or equal to the cross-sectional area of ​​the input of the first mode converter, and so on, and so on.

[0021] Based on the above examples, the second connection can be implemented using one or more waveguide elements. These waveguide elements are simple in structure, low in cost, readily available, and suitable for various application scenarios, offering high flexibility.

[0022] In a further example, when N is greater than or equal to 2, the cross-sectional area of ​​the output end of all second connections between N-level beam splitters can be greater than the cross-sectional area of ​​the input end; alternatively, the cross-sectional area of ​​the output end of all second connections between N-level beam splitters can be equal to the cross-sectional area of ​​the input end; or, the cross-sectional area of ​​the output end of some second connections between N-level beam splitters can be greater than the cross-sectional area of ​​the input end, while the cross-sectional area of ​​the output end of the remaining second connections can be equal to the cross-sectional area of ​​the input end. For example, the cross-sectional area of ​​the output end of the second connection between the first to T-level beam splitters can be greater than the cross-sectional area of ​​the input end, and the cross-sectional area of ​​the output end of the second connection between the T-level to N-level beam splitters can be equal to the cross-sectional area of ​​the input end, where T is a positive integer less than N.

[0023] Based on the above example, the mode-expanding spot can be added to the T-level beam splitting through the front T-level beam splitting unit and the second connecting part between them, and then the optical signal in the multimode waveguide can be converted into a single-mode waveguide or a multimode waveguide through the subsequent NT-level beam splitting unit. This achieves the effect of expanding the mode spot first and then splitting the beam for output.

[0024] In one possible design, some or all of the first connecting part and the N-level beam splitter unit are subwavelength grating structures.

[0025] Based on the above design, the mode size of the first connecting part and the N-level beam splitter unit in the first direction can be improved by using a subwavelength grating structure. The first direction is the input direction of the optical signal. Based on the improved mode size, under the same optical power input, the optical power per unit area is further reduced compared to the scheme without improving the mode size, thereby further reducing the probability of the TPA effect.

[0026] In one example of the above design, when the first connecting part and the N-level beam splitter are both subwavelength grating structures, the first connecting part and the N-level beam splitter include periodic regions. A periodic region refers to a region with periodic variations, such as the first connecting part and the N-level beam splitter being divided into independent sections, or a thin section at the bottom connected to an independent section at the top, etc., as long as the period and duty cycle are stable.

[0027] In one example of the above design, when the first connecting part and part of the N-level beam splitter are subwavelength grating structures, the first connecting part and the N-level beam splitter include a periodic region, a transition region and a continuous region, which are arranged along the direction from the first connecting part to the N-level beam splitter.

[0028] Based on the above examples, the transition region can realize the transition of optical signals from the periodic region to the continuous region, avoid reflection caused by abrupt changes in refractive index, and reduce the transmission loss of optical signals.

[0029] In a further possible example, the periodic region includes multiple short blocks, and the continuous region includes long blocks that connect to the middle part of the multiple short blocks to form a transition region.

[0030] Based on the above examples, continuous regions and periodic regions can form a transition region at the connection point without the need to set up an additional transition region, resulting in lower process costs.

[0031] In one possible design, the waveguide structure further includes at least two first waveguides connected to at least two first output terminals of the N-level beam splitter unit for receiving at least two second optical signals output by the N-level beam splitter unit.

[0032] Based on the above design, the N-level beam splitter unit can be connected to other components through at least two first waveguides, or can realize the output transmission of optical signals.

[0033] In one example of the above design, at least two first waveguides are single-mode waveguides, and the mode spot size of at least two first output terminals is the same as that of a single-mode waveguide. Single-mode waveguides have a smaller cross-sectional area and transmit only a single mode internally, avoiding the problems of multiple modes and collision interference between multiple modes, thus exhibiting better optical transmission performance.

[0034] In one possible design, the above-mentioned grating coupler, first connection part, N-level beam splitter unit and at least two first waveguides are located in the transmitting assembly. The transmitting assembly may also include other structures, mainly including the following structure one and structure two.

[0035] Structure 1: At least two first output terminals of the N-level beam splitter unit are connected to at least two transmitter terminals of the chip containing the waveguide structure. At least two second optical signals output from the at least two first output terminals serve as at least two transmitter signals of the chip. The at least two transmitter signals are scanned to the detection space by the scanning component for target detection.

[0036] Based on the above structure one, a transmitting component can be set in the waveguide structure. At least two first output terminals of the N-level beam splitter are directly connected to at least two transmitting terminals. Therefore, at least two second optical signals output by the N-level beam splitter can be directly used as at least two transmitted signals without further processing by beam splitters or combiners, thus saving the number of such components and reducing costs. Furthermore, at least two transmitted signals can be used to jointly measure targets in the detection space. For example, at least two transmitted signals can correspond to at least two detection channels. Thus, at least two regions can be detected in a single scan, increasing the scanning range and improving detection efficiency.

[0037] In one example of structure one, the waveguide structure further includes a receiving component for acquiring the local oscillator signal and the echo signal, and mixing the local oscillator signal and the echo signal to obtain an intermediate frequency (IF) signal. The IF signal is used to determine the velocity and / or distance of the target. The local oscillator signal is derived from the input signal, transmitted signal, or output signal of the first connection section, any first-stage beam splitter unit, or any first waveguide.

[0038] Based on the above example, when there is one transmitting component, there is also one receiving component. The local oscillator signal of the receiving component can be separated from the relevant signal of any element in the transmitting component, which has high flexibility and versatility and can be adapted to various detection occasions.

[0039] In the above example, the local oscillator signal in the receiving component can be output using either of the following methods:

[0040] In the first splitting method, the N-stage beam splitter also has a second output terminal, which outputs the local oscillator signal. The receiving component is connected between the second output terminal and the receiving terminal of the chip. Based on this splitting method, the local oscillator signal can be separated from the input signal of the N-stage beam splitter. The N-stage beam splitter directly splits the input optical signal into at least three optical signals, of which at least two optical signals are used as the transmitted signal, and the other optical signal is used as the local oscillator signal and mixed with the echo signal. In this way, the local oscillator signal and the transmitted signal are both separated from the same optical signal, resulting in the strongest signal correlation and the best subsequent mixing effect.

[0041] In the second separation method, the waveguide structure also includes a beam splitter element. This element is coupled between any of the first waveguides and the input of the receiving component. It is used to split the second optical signal transmitted through the coupled first waveguide into a local oscillator signal, and then output the local oscillator signal to the receiving component. Based on this second separation method, the local oscillator signal can be separated from the signal transmitted through the first waveguide using the beam splitter element. A portion of the optical signal transmitted in the first waveguide is separated as the local oscillator signal, while the remainder is directly used as the transmitted signal.

[0042] In one example of the above beam splitting method two, the beam splitting element can be a directional coupler or a beam splitter.

[0043] Based on the above examples, a directional coupler can couple the local oscillator signal from the first waveguide in a non-contact manner, while a beam splitter can be inserted into the first waveguide to directly split the local oscillator signal. Therefore, the waveguide structure can be applied to different beam splitting elements, improving flexibility and versatility.

[0044] Structure 2: A grating coupler, a first connecting part, an N-stage beam splitter unit, and at least two first waveguides are located in a transmitting assembly. There are K transmitting assemblies, where K is an integer greater than or equal to 2. In this case, the waveguide structure also includes M beam combiners / splitters. Each of the M beam combiners / splitters has K input terminals and at least two first output terminals. The K input terminals are respectively connected to the output terminals of the K first waveguides in the K transmitting assemblies, and the at least two first output terminals are connected to at least two transmitting terminals of the chip in which the waveguide structure is located. Each beam combiner / splitter is used to combine the K input optical signals into a beam and then split the beam into at least two transmitted signals. All transmitted signals split by the M beam combiners / splitters are scanned to the detection space by a scanning assembly for target detection.

[0045] Based on the above structure two, K transmitting components can be set in the waveguide structure. The optical signals emitted by the K transmitting components are combined and split by M beam combiners to form at least 2M transmitted signals. These at least 2M transmitted signals can be used to jointly measure and detect targets in the detection space. For example, at least 2M transmitted signals can correspond to at least 2M detection channels. In this way, at least 2M areas can be detected in a single scan, increasing the scanning range and improving detection efficiency.

[0046] In one example of structure two, optical signals from K emitting components have different wavelengths and / or different polarization states.

[0047] Based on the above examples, if different wavelengths are used, each transmitted signal has K wavelengths, and K wavelengths correspond to different detection distances. Therefore, each transmitted signal can detect a wider range and has a higher frequency. If different polarization states are used, multiple signals of the same wavelength can be used to detect the same distance, thereby improving ranging capability.

[0048] In one example of structure two, the waveguide structure further includes a receiving component for acquiring the local oscillator signal and the echo signal, and mixing the local oscillator signal and the echo signal to obtain an intermediate frequency signal, which is used to determine the velocity and / or distance of the target; wherein the local oscillator signal is separated from the input signal, transmitted signal, or output signal of the first connection part of any transmitting component, the N-level beam splitting unit of any transmitting component, the first waveguide of any transmitting component, or any beam combiner / splitter.

[0049] Based on the above examples, when there are multiple transmitting components, there may be one or more receiving components. The local oscillator signal of the one or more receiving components can be separated from the related signals of the elements of any of the multiple transmitting components. Therefore, the waveguide structure has high flexibility and versatility and can be adapted to various detection applications.

[0050] In the above example, the local oscillator signal in the receiving component can be separated using any of the following separation methods one to three:

[0051] In the first splitting method, there are K receiving components, each corresponding to one of the K transmitting components. Each transmitting component has an N-stage beam-splitting unit with a second output terminal, which outputs a local oscillator signal. Each receiving component is connected between the second output terminal of the N-stage beam-splitting unit in its corresponding transmitting component and a receiving terminal of the chip. Based on this splitting method, with K receiving components, the local oscillator signals of each of the K receiving components are derived from the input signals of the K transmitting components. These K local oscillator signals have different wavelengths, and each is a single-wavelength signal. Therefore, the mixing process also involves mixing single-wavelength signals. Furthermore, when the beam combiner and splitter distributes the optical signals equally, every two transmitting signals have equal power, and the light output from every two detection channels is uniform.

[0052] In the second separation method, the M beam combiners / splitters include a first beam combiner / splitter. The first beam combiner / splitter also has a second output terminal. The receiving component is connected between the second output terminal and the receiving terminal of the chip. The first beam combiner / splitter is also used to separate the local oscillator signal from the combined optical signal and output the local oscillator signal to the receiving component through the second output terminal. Based on this separation method, there can be only one receiving component. The local oscillator signal of this receiving component is separated from the input signal of any beam combiner / splitter. The local oscillator signal is a K-wavelength signal, and the mixing operation is a single mixing of the K-wavelength signal.

[0053] In the third separation method, there are K receiving components, and the waveguide structure also includes K beam splitters. These K beam splitters correspond one-to-one with the K transmitting components and K receiving components. Each beam splitter is coupled between a first waveguide of its corresponding transmitting component and the input terminal of its corresponding receiving component. The K beam splitters are used to separate the local oscillator signal from the optical signal transmitted through the coupled first waveguide and output the local oscillator signal to the coupled receiving component. Based on this third separation method, there are K receiving components, and the local oscillator signal of each receiving component can be separated from the signal transmitted through the waveguide of a transmitting component. The separation method can be through coupling via a directional coupler or beam splitting via a beam splitter. The local oscillator signals of the K receiving components are all single-wavelength signals with different wavelengths.

[0054] In one example of structure one or structure two above, the optical power of the local oscillator signal is less than the optical power of each of at least two second optical signals.

[0055] Based on this example, the local oscillator signal can have a smaller optical power to reduce the impact on the power of the transmitted signal and increase the detection range of the transmitted power.

[0056] In one example of Structure 1 or Structure 2 above, the receiving component includes a beam splitter and at least two mixers. The input of the beam splitter is used to receive the local oscillator signal, and the at least two outputs of the beam splitter are connected to the first inputs of the at least two mixers. The second inputs of the at least two mixers are connected to the at least two receiving ends of the chip. The beam splitter is used to split the local oscillator signal into at least two sub-local oscillator signals and output the at least two sub-local oscillator signals to the at least two mixers. The at least two mixers are used to perform a mixing operation on the at least two sub-local oscillator signals and the at least two echo signals received by the at least two receiving ends of the chip to obtain at least two intermediate frequency signals.

[0057] Based on the above examples, the reception range of the echo signal can be increased by using at least two receiving paths. Even if the echo signal is deviated from a certain distance, the probability of receiving the echo signal can be increased, thereby improving the reception efficiency.

[0058] In a further possible example, the receiving component also includes a detection element connected between the outputs of at least two mixers and the electrical output of the chip, for photoelectric detection of at least two intermediate frequency signals, obtaining an electrical signal and outputting it.

[0059] Based on the above examples, the conversion from optical signals to electrical signals can be realized, thereby enabling the transmission of silicon photonic signals to electrical chips.

[0060] Secondly, this application provides a silicon photonics chip, including the waveguide structure described in the first aspect, any of the designs or examples above.

[0061] In one possible design, the silicon photonics chip includes a silicon substrate layer, a buried oxide layer, and a waveguide layer stacked sequentially, with the waveguide structure located in the waveguide layer.

[0062] Based on the above design, silicon photonics chips can have advantages such as small size, doping capability, support for active device integration, high yield, and low cost.

[0063] In one example of the above design, the waveguide structure is exposed to air, where the refractive index is lower than that of the waveguide material.

[0064] Based on the above design, the thickness of the silicon photonics chip can be reduced, thus minimizing its footprint. Simultaneously, the low refractive index of air can reduce its impact on the transmission of optical signals through the waveguide structure.

[0065] In another example of the above design, the silicon photonics chip also includes an upper cladding layer, which is stacked on the waveguide layer. The waveguide structure is embedded in the upper cladding layer, and the refractive index of the material of the upper cladding layer is lower than that of the material of the waveguide structure.

[0066] Based on the above design, the upper cladding can protect the internal waveguide structure. At the same time, the low refractive index of the upper cladding material can reduce the impact on the transmission of optical signals in the waveguide structure.

[0067] Thirdly, this application provides a detection device, including the waveguide structure in the first aspect or any of the designs or examples of the first aspect, or including the silicon photonic chip in the second aspect or any of the designs of the second aspect.

[0068] In one possible design, the detection device also includes a light source assembly for emitting optical signals to the silicon photonic chip, which are coupled into the waveguide structure via an end-face coupler.

[0069] In one possible design, the detection device also includes a scanning component for scanning the optical signal emitted from the silicon photonics chip into the detection space.

[0070] In one possible design, the detection device also includes a processing component disposed on the electrical chip for determining the distance and / or velocity of the target based on the electrical signal output by the silicon photonics chip.

[0071] Fourthly, this application provides a terminal device that includes the waveguide structure in the first aspect or any of the designs or examples of the first aspect, or includes the silicon photonic chip in the second aspect or any of the designs of the second aspect, or includes the detection device in the third aspect or any of the designs of the third aspect.

[0072] The technical effects that can be achieved in the second to fourth aspects mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0073] Figure 1 illustrates a possible application scenario to which this application applies;

[0074] Figure 2 illustrates a schematic diagram of a mainstream FMCWLiDAR launch architecture.

[0075] Figure 3 illustrates an exemplary structural diagram of a solution to the TPA effect in silicon photonics chips provided by the industry.

[0076] Figure 4a illustrates a schematic diagram of a planar waveguide structure provided in this application;

[0077] Figure 4b illustrates a schematic diagram of another waveguide structure provided in this application;

[0078] Figure 5 illustrates a possible structural diagram of a first connector implemented using a waveguide element, as provided in this application.

[0079] Figure 6 illustrates a possible structural diagram of a first connector implemented using two waveguide elements, as provided in this application.

[0080] Figure 7 illustrates a schematic diagram of a waveguide structure provided in this application that contains only a first-level beam splitter unit.

[0081] Figure 8 illustrates a possible structural diagram of a branch in a beam splitter provided in this application;

[0082] Figure 9a illustrates a possible structural diagram of a branch in another beam splitter provided in this application;

[0083] Figure 9b illustrates a possible structural diagram of a branch in another type of beam splitter provided in this application;

[0084] Figure 10 illustrates a schematic diagram of a waveguide structure containing two-stage beam splitting units provided in this application.

[0085] Figure 11a illustrates a schematic diagram of a waveguide structure including a three-stage beam splitter unit provided in this application.

[0086] Figure 11b illustrates an exemplary schematic diagram of another waveguide structure provided in this application that includes a three-stage beam splitter unit.

[0087] Figure 12a illustrates a schematic diagram of a three-dimensional waveguide structure including a subwavelength grating structure provided in this application.

[0088] Figure 12b illustrates a schematic diagram of a planar waveguide structure including a subwavelength grating structure provided in this application.

[0089] Figure 13a illustrates an exemplary schematic diagram of another three-dimensional waveguide structure including a subwavelength grating structure provided in this application;

[0090] Figure 13b illustrates an exemplary schematic diagram of another planar waveguide structure including a subwavelength grating structure provided in this application;

[0091] Figure 14 illustrates a schematic diagram of a waveguide structure provided in this application;

[0092] Figure 15a illustrates a schematic diagram of another waveguide structure provided in this application;

[0093] Figure 15b illustrates a schematic diagram of another waveguide structure provided in this application;

[0094] Figure 15c illustrates a schematic diagram of another waveguide structure provided in this application;

[0095] Figure 16 illustrates a schematic diagram of a waveguide structure provided in Implementation Scheme 1.

[0096] Figure 17a illustrates an exemplary schematic diagram of a structure for separating a local oscillator signal from the input signal of a coupling component, provided in Embodiment 1.

[0097] Figure 17b is an exemplary schematic diagram of a structure for separating a local oscillator signal from a signal transmitted through a waveguide, provided in Embodiment 1.

[0098] Figure 17c exemplarily illustrates another structural schematic diagram of separating the local oscillator signal from the signal transmitted in the waveguide according to Embodiment 1;

[0099] Figure 18 illustrates a schematic diagram of the structure of a receiving component provided in Embodiment 1;

[0100] Figure 19 illustrates a schematic diagram of a waveguide structure provided in Scheme 2;

[0101] Figure 20a is an exemplary schematic diagram of a structure for separating a local oscillator signal from a signal transmitted by a beam combiner / splitter according to embodiment two;

[0102] Figure 20b illustrates an exemplary schematic diagram of a structure for separating a local oscillator signal from the input signal of a coupling component, provided in Embodiment 2.

[0103] Figure 20c exemplarily illustrates a schematic diagram of a structure for separating a local oscillator signal from a signal transmitted through a waveguide, according to Embodiment 2.

[0104] Figure 20d illustrates an exemplary schematic diagram of another structure for separating the local oscillator signal from the signal transmitted through the waveguide, provided by Implementation Scheme 2.

[0105] Figure 21a illustrates a schematic diagram of a receiving component provided in Embodiment 2;

[0106] Figure 21b illustrates a schematic diagram of another receiving component provided in Implementation Scheme 2;

[0107] Figure 22 illustrates a schematic diagram of a waveguide structure provided in Embodiment 3;

[0108] Figure 23a is an exemplary schematic diagram of a waveguide structure including a receiving component provided in Embodiment 3;

[0109] Figure 23b exemplarily illustrates a waveguide structure including K receiving components provided in Implementation Scheme 3;

[0110] Figure 23c exemplarily illustrates a schematic diagram of another waveguide structure provided in Scheme 3, which includes K receiving components;

[0111] Figure 24a illustrates a possible structural diagram of a silicon photonic chip provided in this application;

[0112] Figure 24b illustrates a possible structural diagram of another silicon photonic chip provided in this application;

[0113] Figure 25 illustrates a possible structural diagram of a detection device provided in this application;

[0114] Figure 26 illustrates a schematic diagram of the structure of a terminal device provided in this application. Detailed Implementation

[0115] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0116] The following provides explanations of some terms used in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0117] I. Silicon-on-insulator (SOI)

[0118] SOI is a technique for growing semiconductor thin films on an insulating substrate. It introduces a buried oxide layer between the top silicon layer and the back substrate, effectively isolating current leakage and mutual interference between different parts of the chip, thus improving device performance and reliability. Chips fabricated using SOI technology offer advantages such as high speed and low power consumption.

[0119] II. Two-photon absorption (TPA) effect

[0120] The two-photon absorption (TPA) effect refers to the phenomenon where a molecule absorbs two photons simultaneously, transitioning from its ground state to an excited state via a virtual energy level. The absorption intensity is proportional to the square of the light intensity. The TPA effect occurs only under strong light and is a type of third-order nonlinear effect. For example, in lidar, the TPA effect is mainly concentrated at the focal point of the ultra-intense laser generated by the laser, while the laser intensity elsewhere in the optical path is insufficient to produce two-photon absorption. Simply put, if the ultra-intense laser generated by the laser is focused onto the same single-mode waveguide of an SOI silicon photonics chip, that single-mode waveguide will exhibit a very strong TPA effect. A large amount of the optical signal in this single-mode waveguide will be absorbed, resulting in a reduced output signal and significant transmission loss.

[0121] III. Single-mode waveguide

[0122] A single-mode waveguide is a waveguide in which light can propagate in only one mode. This propagation mode is called the fundamental mode. Therefore, it can also be considered that only the fundamental mode of light is transmitted in a single-mode waveguide, while all higher-order modes of the light wave are cut off. Different types of waveguides can have different single-mode conditions. Achieving the single-mode condition can avoid multimode interference and signal distortion, making waveguide transmission more stable and reliable.

[0123] IV. Mold

[0124] A mode spot, also known as a mode field, refers to the electric field distribution that a waveguide cross-section can support. The parameter that measures this electric field distribution is the mode spot size. The mode spot size is related to the width of the waveguide cross-section, the refractive index distribution, and the operating wavelength.

[0125] V. Subwavelength grating

[0126] Subwavelength gratings, also known as sub-wavelength gratings, are a type of metamaterial and an optical element with a subwavelength periodic structure. Compared to ordinary gratings, the period length of a subwavelength grating is not only much smaller than the wavelength of the incident light, but also significantly smaller than the period wavelength of a Bragg grating. Methods for realizing this structure include periodic surface nanostructures and subwavelength optical waveguides.

[0127] VI. Periodic Regions, Transitional Regions, and Continuous Regions

[0128] A periodic region refers to a region that exhibits periodic changes, such as a region formed by a periodic arrangement of short blocks. A continuous region refers to a region that is continuous in the transmission direction without any breaks, such as a long block. A transition region can be understood as a region that facilitates the transition from a periodic region to a continuous region; one end of the transition region connects to the periodic region, and the other end connects to the continuous region. If the periodic region includes multiple short blocks, and the continuous region includes long blocks, then the long blocks connect to the middle part of the multiple short blocks, forming the transition region.

[0129] VII. Tapered Structure (Taper)

[0130] In the semiconductor industry, a taper refers to a shape on a wafer or chip that gradually decreases or tapers along the input-to-output direction. Flipping a taper 180 degrees creates an inverted taper, where the wafer or chip gradually increases or widens along the input-to-output direction.

[0131] VIII. Linear Polarization State

[0132] Linear polarization is a mode of light propagation. Light exhibiting linear polarization is called linearly polarized light, also known as plane-polarized light. In the direction of light propagation, the electric vector at each point lies within a defined plane. Since the trajectory of the endpoints of the electric vector is a straight line, it is called linearly polarized light. The plane of vibration of linearly polarized light is fixed and does not deflect. The plane of vibration refers to the plane formed by the direction of the light vector and the direction of light propagation.

[0133] Common linearly polarized light includes P-waves, S-waves, TE-waves, and TM-waves. P-waves and S-waves represent light with different polarization directions in space. Simply put, in space, the light vector is decomposed into two mutually perpendicular vibration directions. The vibration direction within the plane of incidence is called the parallel component of the light vector, or P-wave, and the vibration direction perpendicular to the plane of incidence is called the perpendicular component, or S-wave. TE-waves and TM-waves represent light with different polarization directions from a chip integration perspective, often used to describe the propagation characteristics of electromagnetic waves. TE-waves are also called transverse electric waves, where the electric field component is perpendicular to the propagation direction of the electromagnetic wave; that is, the electric field component is parallel to the plane of incidence. TM-waves are also called transverse magnetic waves, where the magnetic field component is perpendicular to the propagation direction of the electromagnetic wave; that is, the electric field direction is perpendicular to the plane of incidence.

[0134] 9. Frequency mixing.

[0135] Frequency mixing, also known as coherent demodulation, refers to the difference between the frequencies and phases of two signals. In frequency-modulated continuous wave (FMCW) lidar, the detection signal is typically a linear frequency modulated (LFM) signal. After this LFM signal interacts with the target object, the reflected echo signal (i.e., the received signal) also carries the same frequency variation characteristics. However, depending on the target distance, the echo signal will have a certain phase and frequency difference relative to the detection signal. Therefore, after receiving the echo signal, the echo signal and the detection signal can be mixed, that is, the frequency and phase of the detection signal and the echo signal are differed to obtain a low-frequency beat signal, also known as a beat frequency signal or intermediate frequency (IF) signal. The IF signal contains information about the frequency difference between the two signals, which is related to the target distance. For example, in a static state, the absolute value of the frequency difference is proportional to the target distance. In a dynamic state, the IF signal also contains information about the Doppler effect caused by target movement, and the target's velocity can be calculated based on this Doppler effect information.

[0136] The preceding text introduced some of the terms used in this application. The following text introduces the possible application scenarios of this application.

[0137] In one possible implementation, the waveguide structure provided in this application can be applied to a detection device installed on a vehicle, such as, but not limited to, vehicles, ships, airplanes, drones, trains, subways, automated guided vehicles (AGVs), or unmanned vehicles.

[0138] For example, please refer to Figure 1, which illustrates a possible application scenario of this application. In this scenario, the detection device is installed on the front bumper of a vehicle. This detection device can serve as an information source for path planning, assisting the driver in achieving or automatically achieving safe driving. It is understood that the detection device can also be installed in other locations on the vehicle, such as around the headlights, rearview mirrors, near the doors, the rear bumper, behind the windshield, or on the roof, to capture information about the vehicle's surrounding environment. When the detection device is installed behind the windshield, the requirement for no stone collision is lower, it does not affect the vehicle's appearance, and the windshield itself has window heating and defogging functions as well as wiper cleaning functions.

[0139] It should be understood that the above application scenarios are merely examples, and the detection device provided in this application can also be applied to other possible scenarios, and is not limited to those exemplified above. For example, the detection device can also be installed in a roadside unit (RSU) as a roadside traffic detection device to realize intelligent vehicle-road cooperative communication. For example, the detection device can also be installed in the cabin of a vehicle as a liveness detection device to detect and alert the user to children or pets left behind in the cabin. Furthermore, the detection device can also be applied to terminal devices or components installed in terminal devices, such as smartphones, smart home devices, smart manufacturing equipment, medical devices, industrial equipment, and robots. These will not be listed exhaustively here. It should be noted that the application scenarios described in this application are for the purpose of more clearly illustrating the technical solution of this application and do not constitute a limitation on the technical solution provided in this application.

[0140] In addition, the above-mentioned application scenarios can be applied to fields such as autonomous driving, assisted driving, intelligent driving, autonomous driving, connected vehicles, optical communication, security monitoring, biomedicine, surveying and mapping (such as 3D mapping and remote sensing mapping), meteorological research, biomass and vegetation research, air quality monitoring, and aviation and aerospace applications.

[0141] The detection devices mentioned above may include, but are not limited to, light detection and ranging (LiDAR), such as FMCWLiDAR. Before introducing the specific solution provided in this application, the relevant content of FMCW LiDAR will be introduced below.

[0142] Please refer to Figure 2, which shows a schematic diagram of a mainstream FMCWLiDAR transmission architecture. This architecture includes a laser, an SOI silicon photonics chip, and a scanning component. The laser and scanning component are located outside the SOI silicon photonics chip. The SOI silicon photonics chip contains a grating coupler (GC), a tapered structure Taper with a gradually tapering cross-section, beam splitter 1, beam splitter 21, and beam splitter 22, as well as waveguides connecting these components. For example, there is a multimode waveguide C1 connecting GC and Taper, a single-mode waveguide B1 connecting Taper and beam splitter 1, and a single-mode waveguide B connecting beam splitter 1 and beam splitter 21. 21 The single-mode waveguide B connecting beam splitter 1 and beam splitter 22 22 And the single-mode waveguide B connecting beam splitters 21 and 22 to the four transmitters of the SOI silicon photonics chip. 31 B 32 B 33 and B 34 The diagram only illustrates an SOI silicon photonics chip with four transmitters, but the actual number of transmitters can be any integer greater than or equal to two, and this application does not impose any specific limitation.

[0143] Optionally, in the actual layout diagram, the laser can be positioned above the SOI silicon photonic chip, either directly above or at an angle. The laser emits a laser signal S1, which is incident on the GC in a direction perpendicular or at an angle to the plane of the SOI silicon photonic chip. The GC converts this signal into a beam parallel to the SOI silicon photonic chip and then couples it into the multimode waveguide C1. The optical signal in the multimode waveguide C1 is transmitted through a taper to the single-mode waveguide B1, and then through the single-mode waveguide B1 to the beam splitter 1. The beam splitter 1 then splits the light into two sub-light signals. The two sub-light signals are then transmitted through the single-mode waveguide B1 and C1 respectively. 21 and B 22 The light is transmitted to beam splitters 21 and 22, where it is further split into four sub-optical signals. These four sub-optical signals then pass through four single-mode waveguides B. 31 ~B 34 The signal is transmitted to the four transmitters of the SOI silicon photonics chip and emitted to the outside of the SOI silicon photonics chip. After being scanned into the detection space by the scanning component, it is used to illuminate the target.

[0144] As shown in Figure 2, the optical signal input to the SOI silicon photonics chip is coupled to the single-mode waveguide B1 via GC, multimode waveguide C1, and Taper. The optical signal received by the single-mode waveguide B1 is related to the coupling loss of GC, multimode waveguide C1, and Taper. When the coupling loss is non-zero, the optical power of the optical signal received by the single-mode waveguide B1 is less than that of the optical signal input to the SOI silicon photonics chip. However, since the coupling loss of GC, multimode waveguide C1, and Taper is not significantly relevant to the scheme of this application, it can be assumed that all the optical power received by GC will enter the single-mode waveguide B1 without considering the coupling loss of GC, multimode waveguide C1, and Taper.

[0145] In SOI silicon photonics chips, the mode size of GC is larger than that of single-mode waveguide B1. At a constant optical power, the optical power density in the device is inversely related to the mode size. Therefore, the optical power density in GC is lower than that in single-mode waveguide B1. Single-mode waveguide B1 is the part of the SOI silicon photonics chip that withstands the highest optical power density and is most prone to the TPA effect. After passing through single-mode waveguide B1, the optical signal is split into two single-mode waveguides B1. 21 B 22 Above, each single-mode waveguide B 21 B 22 The optical power in the single-mode waveguide B1 is lower than that in the single-mode waveguide B1. Therefore, the single-mode waveguide B1... 21 B 22 The optical power density on the single-mode waveguide B1 is less than that on the single-mode waveguide B1. Similarly, the optical power density on the single-mode waveguide B1 is less than that on the single-mode waveguide B1. 31 ~B 34 The optical power density on the upper part is less than that of the single-mode waveguide B. 21 B 22 The optical power density on the first waveguide B1 is insufficient to produce the TPA effect. Therefore, the bottleneck of the TPA effect lies in the first waveguide B1.

[0146] As described in the background section, the TPA effect in silicon optical waveguides leads to problems such as increased transmission loss, higher temperature, and decreased reliability. Therefore, to mitigate these issues caused by the TPA effect in the first single-mode waveguide B1, an industry solution has been proposed, as shown in Figure 3. This solution designs the first single-mode waveguide B1 as a silicon ridge waveguide, adding P-doping and N-doping to its two sides respectively to form a PN junction. Simultaneously, a reverse bias voltage is applied to the PN junction. When a high-power optical signal passes through the first waveguide B1, the carriers generated by the TPA effect are extracted from the first waveguide B1 by the PN junction, maintaining a low carrier concentration in the first waveguide B1 and suppressing further absorption and heating of the optical signal by the carriers. In some scenarios, the extracted current can be measured to form an ammeter, allowing adjustment of the reverse bias voltage applied to the PN junction based on the real-time current signal to ensure that the first waveguide B1 maintains a low carrier concentration.

[0147] While the above solutions can remove carriers generated by the TPA effect through power application, they cannot prevent the TPA effect from occurring. Furthermore, they introduce other problems, primarily the following two: First, whether designing the first waveguide B1 as a silicon ridge waveguide or doping it with P and N ions on both sides, the manufacturing process is complex and costly; second, applying power to the PN junction introduces additional power consumption and generates current-induced heating, raising reliability issues. Due to these problems, the above solutions offered by the industry have limited usability in FMCW LiDARs.

[0148] In view of this, this application provides a waveguide structure that utilizes a connector with a constant or increasing cross-sectional area to convert an input optical signal into an optical signal in a multimode waveguide. In the case of a multimode waveguide, the optical power is output in stages and splits into at least two waveguides to reduce the optical power density in each waveguide and decrease the probability of TPA (Transient Power Allocation) effect. Compared to industry-provided solutions, this waveguide structure is entirely passive, requiring no additional semiconductor processing steps, doping, or electrical processes, thus eliminating the problems associated with existing industry solutions and offering advantages such as simple manufacturing process, low cost, low power consumption, and high reliability.

[0149] The waveguide structure and related schemes proposed in this application will be described in detail below with reference to Figures 4a to 26.

[0150] Please refer to Figure 4a or Figure 4b, which shows a schematic diagram of a waveguide structure provided in this application. The waveguide structure 400 includes a GC 411, a first connecting portion 412, and an N-stage beam splitter unit 413, where N is a positive integer; in the figures, N=2 is used as an example. The input end (left side) of the N-stage beam splitter unit 413 is connected to the output end (right side) of the first connecting portion 412. The cross-sectional area of ​​the output end of the first connecting portion 412 is greater than or equal to the cross-sectional area of ​​the input end of the first connecting portion 412. For example, Figure 4a shows a schematic diagram where the cross-sectional area of ​​the output end of the first connecting portion 412 is greater than the cross-sectional area of ​​the input end of the first connecting portion 412, and Figure 4b shows a schematic diagram where the cross-sectional area of ​​the output end of the first connecting portion 412 is equal to the cross-sectional area of ​​the input end of the first connecting portion 412.

[0151] As is understandable, Figures 4a and 4b both show planar views of the waveguide structure. The cross-sectional area refers to the area on a section perpendicular to the plane, including both height and width directions. The x-direction in the figures represents the width direction. The height direction will be shown in the later 3D views and will not be explained here. Generally, changes in cross-sectional area can be achieved through height and / or width. However, changes in width on a chip are easier to achieve than changes in height. Therefore, the height of devices on a chip is usually constant, and changes in cross-sectional area are equivalent to changes in width.

[0152] Based on this, in terms of cross-section, if the cross-sectional height of the first connecting part 412 from the input end to the output end remains unchanged, then: the cross-sectional area of ​​the output end is greater than the cross-sectional area of ​​the input end, that is, the cross-sectional width of the output end is greater than the cross-sectional width of the input end, as shown in Figure 4a, where the cross-sectional width of the output end is x2 and the cross-sectional width of the input end is x1, x2>x1; or, the cross-sectional area of ​​the output end is equal to the cross-sectional area of ​​the input end, that is, the cross-sectional width of the output end is equal to the cross-sectional width of the input end, as shown in Figure 4b, where the cross-sectional widths of both the output end and the input end are x1.

[0153] Alternatively, in other examples, the cross-sectional width of the output terminal may be equal to the cross-sectional width of the input terminal, while the cross-sectional height of the output terminal may be greater than or equal to the cross-sectional height of the input terminal; or the cross-sectional width of the output terminal may be greater than the cross-sectional width of the input terminal, while the cross-sectional height of the output terminal may also be greater than or equal to the cross-sectional height of the input terminal. Another possibility is that the cross-sectional width of the output terminal is greater than the cross-sectional width of the input terminal, while the cross-sectional height of the output terminal is less than the cross-sectional height of the input terminal; or the cross-sectional width of the output terminal is less than the cross-sectional width of the input terminal, while the cross-sectional height of the output terminal is greater than or equal to the cross-sectional width and height of the input terminal, and so on. These are not all listed here.

[0154] Regardless of whether the cross-sectional area of ​​the output end of the first connecting part 412 is greater than the cross-sectional area of ​​the input end, or whether the cross-sectional area of ​​the output end is equal to the cross-sectional area of ​​the input end, the first optical signal S incident on GC411 11 (The illustration shows an incident light perpendicular to the plane containing waveguide structure 400, but it can also be at a certain angle to this plane, without limitation.) After transmission through the first connecting part 412, the light becomes an optical signal in the multimode waveguide. Under the same optical power, the optical power density of the optical signal in the multimode waveguide is less than that in the single-mode waveguide. Therefore, compared to the prior art scheme shown in Figure 2, which couples all the optical power to a single-mode waveguide through a Taper, the optical power density of the optical signal in the multimode waveguide output by the first connecting part 412 is lower than that in the single-mode waveguide B1. After the optical signal in the multimode waveguide is split by the N-stage beam splitting unit 413, the optical power density will be further reduced, and the probability of the TPA effect will be further reduced.

[0155] For example, in a structure with a constant cross-sectional area, since the cross-sectional area of ​​the output end of the first connection part 412 is the same as that of the input end, the mode size of the output end of the first connection part 412 is the same as that of the input end. Therefore, with a constant optical power, the optical power density at the output end is the same as that at the input end. After beam splitting in the N-stage beam splitter 413, the optical power density further decreases. Based on this, the optical power density in GC411 is the highest in the entire waveguide structure 400. As mentioned earlier, the mode size of GC411 is larger than that of the single-mode waveguide. Therefore, the optical power density in GC411 is lower than that in the single-mode waveguide. The optical power density of the optical signal output by GC411 gradually decreases during subsequent transmission, making the TPA effect less likely to occur in the entire waveguide structure 400.

[0156] Alternatively, if the structure has a larger cross-sectional area, since the cross-sectional area of ​​the output end of the first connecting part 412 is larger than that of the input end, the mode spot size at the output end of the first connecting part 412 is larger than that at the input end. This is equivalent to the first connecting part 412 first expanding the mode spot of the optical signal output from GC411, and then outputting the expanded mode spot optical signal to the N-stage beam splitter 413. The larger the mode spot is expanded, the lower the optical power density of the optical signal output from the first connecting part 412. After the optical signal is split in the N-stage beam splitter 413, the optical power density will further decrease. Simultaneously, because the mode spot is expanded, if a certain size mode spot needs to be matched, the number of stages of the beam splitter, or the number of beams split in each stage, will be more, resulting in a lower optical power density of the final output optical signal, and making the waveguide structure 400 less prone to the TPA effect.

[0157] Based on this, whether the cross-sectional area of ​​the output end of the first connection part 412 is set to be greater than the cross-sectional area of ​​the input end, or the cross-sectional area of ​​the output end of the first connection part 412 is set to be equal to the cross-sectional area of ​​the input end, compared with the prior art shown in Figure 2, it is possible to reduce the optical power density in the subsequent transmission process and reduce the probability of TPA effect in the waveguide structure 400.

[0158] Optionally, the cross-sectional area of ​​the output terminal of the first connection part 412 is greater than or equal to the cross-sectional area of ​​the input terminal, and can be implemented in various ways, such as:

[0159] In one implementation, the first connection portion 412 includes a waveguide element, the cross-sectional area of ​​which at its output end is greater than or equal to the cross-sectional area at its input end. Alternatively, when the cross-sectional height of the waveguide element remains constant, the cross-sectional width at its output end is greater than or equal to the cross-sectional width at its input end. The waveguide element can be a multimode waveguide, a mode converter, a reverse taper, or other types of waveguide elements, without limitation.

[0160] For example, taking a pattern converter as an example, when the cross-sectional width of the output end is greater than the cross-sectional width of the input end, the cross-sectional width of the pattern converter can increase according to any pattern when viewed from the input end to the output end. For example, it can increase with a fixed slope as shown in Figure 5(A), or it can remain constant first and then increase with a fixed slope as shown in Figure 5(B), or it can increase with a fixed slope first and then remain constant as shown in Figure 5(C), or it can increase with a smaller slope first and then increase with a larger efficiency as shown in Figure 5(D), or it can increase smoothly in a curved form as shown in Figure 5(E), or it can increase with a fixed slope first, then decrease with a fixed slope, and then increase with a fixed slope as shown in Figure 5(F), and so on. There are many other possible implementation structures, which will not be listed here.

[0161] In the second implementation, the first connection portion 412 includes at least two waveguide elements, the cross-sectional area of ​​the output end of each of the at least two waveguide elements being greater than or equal to the cross-sectional area of ​​the input end. The at least two waveguide elements include at least one type of waveguide element selected from multimode waveguides, mode converters, tapers, reverse tapers, and other waveguide elements. For example, it could be a combination of at least two mode converters, a combination of at least one multimode waveguide and at least one mode converter, a combination of at least one multimode waveguide and at least one reverse taper, or a combination of at least three of the following waveguide elements: multimode waveguide, mode converter, taper, reverse taper, and other waveguide elements; the choice is not limited.

[0162] Taking a combination of a multimode waveguide and a mode converter as an example, assuming the output of the multimode waveguide is connected to the input of the mode converter, the beam passes through the multimode waveguide first and then the mode converter. Therefore, the cross-sectional area of ​​the output of the mode converter is greater than or equal to the cross-sectional area of ​​the input of the multimode waveguide. If the cross-sectional heights are the same, that is, the cross-sectional width of the output of the mode converter is greater than or equal to the cross-sectional width of the input of the multimode waveguide. Taking the example that the cross-sectional width of the output of the mode converter is greater than the cross-sectional width of the input of the multimode waveguide, there are several possible implementation shapes. For example, referring to Figure 6, the cross-sectional width of the multimode waveguide can remain unchanged while the cross-sectional width of the mode converter increases, as shown in Figure 6(A); or the cross-sectional width of the multimode waveguide can increase while the cross-sectional width of the mode converter remains unchanged, as shown in Figure 6(B); or the cross-sectional width of both the multimode waveguide and the mode converter can increase, as shown in Figure 6(C). The way to increase the cross-sectional width can be a fixed slope, a variable slope, a straight line, a curve, or a splicing of multiple straight lines or curves, as shown in Figure 5 above. This application does not limit this.

[0163] Understandably, if the cross-sectional area of ​​the output end of the first connecting part 412 is equal to the cross-sectional area of ​​the input end, the cross-sectional area can remain constant from the input end to the output end, or the cross-sectional area can first increase and then decrease, or fluctuate slightly. As long as the cross-sectional areas at both ends are the same, this application does not limit this.

[0164] The above content has introduced the implementation of the first connecting part 412. Next, we will explain the possible structure of the N-level beam splitting unit 413.

[0165] As shown in Figure 4a or Figure 4b, the N-level beam splitter 413 is connected to the output end of the first connection part 412. The optical signal in the multimode waveguide output by the first connection part 412 passes through the N-level beam splitter 413 and can be split into at least two second optical signals. The optical power of each of the at least two second optical signals is less than the optical power of the first optical signal.

[0166] For example, in Figures 4a and 4b, four second optical signals S are generated by splitting the beam. 121 S 122 S 123 S 124 For example, four second optical signals S 121 ~S 124 The optical power of both signals is less than that of the first optical signal S. 11The optical power of the first optical signal S is less than that of the second optical signal S. However, in the actual waveguide structure 400, it is possible to split the beam into two or more arbitrary numbers of second optical signals, such as 2, 3, 4, 5, 6, etc. Regardless of the number of second optical signals split, the optical power of these second optical signals is less than that of the first optical signal S. 11 The optical power will not be all output on a single waveguide. Therefore, the hierarchical beam splitting of the N-level beam splitter unit can also be used to reduce the probability of the TPA effect.

[0167] Understandably, the structure of the N-level beam splitter unit will be different when the value of N is different. The following will introduce the different cases.

[0168] Case 1, N=1.

[0169] Optionally, when N is 1, the N-level beam splitting unit 413 is specifically a first-level beam splitting unit. This level of beam splitting unit may include only one beam splitter, and the beam splitter includes at least two branches. The at least two branches can be 2 branches, 3 branches, 4 branches, 5 branches, etc., without limitation.

[0170] For example, taking two branches as an example, please refer to Figure 7, which shows a possible waveguide structure schematic diagram when N=1. Figure 7 uses the structure shown in Figure 4a as an example of the first connecting part 412. Figure 7(A) shows a three-dimensional view of the waveguide structure, and Figure 7(B) shows a planar view of the waveguide structure. Combining Figure 7 and Figure 4a above, when N=1, the N-level beam splitting unit 413 can specifically include a beam splitter, which includes two branches, namely branch 1 and branch 2. The input terminals of both branch 1 and branch 2 are connected to the output terminals of the first connecting part 412, and the output terminals of branch 1 and branch 2 serve as the two output terminals of the N-level beam splitting unit 413. Based on this, the optical signal output from the first connecting part 412 will be divided into two parts. One part is transmitted in branch 1 and becomes a second optical signal, and the other part is transmitted in branch 2 and becomes another second optical signal. The two second optical signals are output from the output terminals of the two branches respectively, serving as the two second optical signals output by the N-level beam splitting unit 413.

[0171] Optionally, the outputs of the two branches can also be connected to two waveguides, such as waveguides 31 and 32 shown in Figure 7(B). Waveguides 31 and 32 can be single-mode waveguides or multi-mode waveguides, depending on the application scenario. When waveguides 31 and 32 are multi-mode waveguides, the optical signal in the multi-mode waveguide output from the first connection part 412, after being split by the beam splitter, remains a multi-mode optical signal. This beam splitter is a multi-mode beam splitter. When waveguides 31 and 32 are single-mode waveguides, the optical signal in the multi-mode waveguide output from the first connection part 412, after being split by the beam splitter, becomes a single-mode optical signal. This beam splitter is a multi-mode to single-mode beam splitter, responsible for splitting the optical signal in the multi-mode waveguide input from the input end into a single-mode optical signal.

[0172] Optionally, the cross-sectional shapes of the two branches can be identical or different. When the cross-sectional shapes are identical, the modal sizes of the two branches are the same, resulting in identical power of the transmitted optical signals. The two second optical signals output by the two branches also have identical power, forming two channels with uniform power and improving subsequent detection performance. However, when the cross-sectional shapes are different, if one branch has a larger cross-sectional shape and the other a smaller one—for example, the cross-sectional area of ​​branch 1 is larger than that of branch 2, or the cross-sectional heights of branch 1 and branch 2 are the same but the cross-sectional width of branch 1 is greater than that of branch 2—then the modal size of branch 1 is larger than that of branch 2. The optical signal output from the first connecting part 412 is absorbed more by branch 1 and less by branch 2. Correspondingly, in the detection channel, the light intensity of the optical signal output by branch 1 is greater, which can be used to detect the region of interest, while the light intensity of the optical signal output by branch 2 is lower, which can be used to detect areas other than the region of interest, achieving the effect of zoned detection.

[0173] Optionally, for a branch, the cross-sectional shape of its output end can remain unchanged compared to the cross-sectional shape of its input end, or it can exhibit a changing trend. For example, the cross-sectional shape of the branch's output end may be exactly the same as the cross-sectional shape of its input end, or the cross-sectional shape of the output end may be larger than the cross-sectional shape of the input end, or the cross-sectional shape of the output end may be smaller than the cross-sectional shape of the input end. Here, cross-sectional shape can also be replaced by cross-sectional area. The cross-sectional shape or cross-sectional area is mainly determined by two parameters: cross-sectional width and cross-sectional height. The cross-sectional width refers to the dimension in the x-direction shown in Figure 7(A), and the cross-sectional height refers to the dimension in the y-direction shown in Figure 7(A).

[0174] Assuming the cross-sectional height remains constant from the input to the output of each branch, then:

[0175] In one example, as shown in Figure 8(A), the cross-sectional width of the output end of each branch is the same as the cross-sectional width of the input end, for example, both are x. 11This can also be understood as the branch's cross-sectional width remaining constant from its input to its output. In this case, the branch's mode size remains unchanged, the optical signal is transmitted in the branch with the same optical power density, and the TPA effect does not occur in the branch.

[0176] In another example, as shown in Figure 8(B), the cross-sectional width of the output end of each branch is greater than the cross-sectional width of the input end; for example, the cross-sectional width of the input end is x. 11 The cross-sectional width of the output terminal is x. 12 x 12 >x 11 This can also be understood as the branch's cross-sectional width increasing from its input to its output. In this case, the mode size of the branch gradually increases from its input to its output. Besides splitting the optical signal, the branch can also expand the mode area. Utilizing the branch to split the beam while simultaneously expanding the mode area can, on the one hand, expand the waveguide structure to a larger mode area, further reducing the optical power density in the waveguide structure and lowering the probability of the TPA effect. On the other hand, it also allows the first connection part 412 to no longer be configured as a mode-expanding structure; for example, it can be directly designed as a structure with a constant cross-sectional area as shown in Figure 4b, thereby reducing the design difficulty of the first connection part 412.

[0177] In another example, as shown in Figure 8(C), the cross-sectional width of the output end of each branch is smaller than the cross-sectional width of the input end; for example, the cross-sectional width of the input end is x. 11 The cross-sectional width of the output terminal is x. 13 x 13 <x 11 This can also be understood as the branch's cross-sectional width decreasing from its input to its output. In this case, the mode size of the branch gradually decreases from input to output. Besides splitting optical signals, the branch can also achieve mode reduction, allowing the smaller mode to adapt more quickly to the mode required at the output. For example, if the required mode at the output is a single-mode waveguide mode, a branch with a constant cross-sectional width would require two beam-splitting units to split the signal into the single-mode waveguide mode. However, by designing the branch with a smaller cross-sectional width, only one beam-splitting unit might be needed to directly split the signal into the single-mode waveguide mode, reducing the number of N-stage beam-splitting units required.

[0178] Alternatively, the cross-sectional shape, cross-sectional area, and cross-sectional width of each branch may also have other trends of change, such as first increasing and then remaining constant in the direction from the input end to the output end, or first decreasing and then remaining constant, or first increasing and then decreasing, or first decreasing and then increasing, or first decreasing and then remaining constant and then increasing, or the cross-sectional shape of one branch has a changing trend while the cross-sectional shape of another branch remains constant, and so on, which will not be listed here.

[0179] It should be noted that the above figures all use straight branches as examples, but in other examples, the branches can also include curved structures. For example, taking the branch shown in Figure 8(A) as an example, in one example, as shown in Figure 9a, the branch can be made into a curved structure from the input end to the output end, so that the branch presents an "S" shape as a whole. One end of the "S" shape is smoothly connected to the first connecting part 412, and the other end is smoothly connected to the rear-end element. The rear-end element can be the waveguide in Figure 9a, or it can be the second connecting part in a multi-stage beam splitting scenario, without limitation. Alternatively, in another example, as shown in Figure 9b, the input end of the branch can be made into a straight structure, and the output end can also be made into a straight structure. The two straight structures are connected by a curved structure, and the position where the curved structure connects with the straight structures on both sides is uniformly transitioned. Alternatively, in other examples, the input end of the branch can be made into a straight structure, and the output end can be made into a curved structure, or the output end of the branch can be made into a straight structure, and the input end can be made into a curved structure, etc., without limitation. Compared to a structure where the entire branch is straight, making all or part of the branch curved allows for smooth connection between the curved structure and the two end regions. The slope of the curved structure at the connection point with the two end regions is the same, and the modal size matches each other. Therefore, there will be no significant modal loss during optical signal transmission, ensuring better signal transmission performance.

[0180] Scenario 2, N = 2.

[0181] Optionally, when N is 2, the N-level beam splitting unit 413 is specifically a two-level beam splitting unit, wherein each level of beam splitting unit may include one or more beam splitters, and each beam splitter includes one or more branches. For example, the first-level beam splitting unit includes one beam splitter, which includes 2 branches, 3 branches, 4 branches, 5 branches, etc., and the second-level beam splitting unit includes one or two beam splitters, which include 2 branches, 3 branches, 4 branches, 5 branches, etc.

[0182] For example, taking a first-stage beam splitter unit comprising one beam splitter and a second-stage beam splitter unit comprising two beam splitters, each beam splitter comprising two branches, as an example, please refer to Figure 10, which shows a possible waveguide structure schematic diagram when N=2. Figure 10 shows an example where the first connection part 412 is the structure shown in Figure 4b. Figure 10(A) shows a three-dimensional view of the waveguide structure, and Figure 10(B) shows a planar view of the waveguide structure. As shown in Figure 10, in this example, the N-stage beam splitter unit 413 specifically includes a first-stage beam splitter unit 4131 and a second-stage beam splitter unit 4132. The first-stage beam splitter unit 4131 includes one beam splitter comprising two branches 11 and 12. The second-stage beam splitter unit 4132 includes two beam splitters, one of which comprises two branches 211 and 212, and the other beam splitter comprises two branches 221 and 222. In the first-stage beam splitter unit 4131, the input terminals of the two branches 11 and 12 are both connected to the output terminal of the first connection part 412. The output terminals of the two branches 11 and 12 are connected to the input terminals of the two beam splitters in the second-stage beam splitter unit 4132 through the two second connection parts 4141 and 4142. In the second-stage beam splitter unit 4132, the input terminals of the two branches 211 and 212 of one beam splitter are connected to the output terminal of branch 11 in the first-stage beam splitter unit 4131 through the second connection part 4141. The input terminals of the two branches 221 and 222 of the other beam splitter are connected to the output terminal of branch 12 in the first-stage beam splitter unit 4131 through the other second connection part 4142. The output terminals of the two branches 211 and 212, and the output terminals of the two branches 221 and 222 serve as the four output terminals of the N-stage beam splitter unit 413.

[0183] Based on this structure and connection, the optical signal in the multimode waveguide output from the first connection part 412 is divided into two parts. One part is transmitted through branch 11 to the second connection part 4141, and then further divided into two parts. One part is transmitted through branch 211 and becomes a second optical signal, while the other part is transmitted through branch 212 and becomes another second optical signal. The other part of the optical signal in the multimode waveguide output from the first connection part 412 is transmitted through branch 12 to the second connection part 4142, and is also divided into two parts. One part is transmitted through branch 221 and becomes a second optical signal, while the other part is transmitted through branch 222 and becomes another second optical signal. Thus, through a two-stage beam splitting unit, the optical signal in the multimode waveguide output from the first connection part 412 is split into two beams. 2 That is, four second optical signals are output from the output ends of the four branches 211, 212, 221 and 222 respectively, as the four second optical signals output by the N-level beam splitting unit 413.

[0184] Optionally, the outputs of the four branches 211, 212, 221, and 222 can also be connected to four waveguides, such as waveguides 311, 312, 313, and 314 shown in Figure 10. Waveguides 311 to 314 can be single-mode waveguides or multi-mode waveguides, depending on the application scenario. For example, when waveguides 311 to 314 are single-mode waveguides, the optical signal in the multi-mode waveguide output from the first connection 412, after being split by the beamsplitter in the first-stage beamsplitter unit 4131, remains a multi-mode optical signal. This multi-mode optical signal is further split by the beamsplitter in the second-stage beamsplitter unit 4132, becoming a single-mode optical signal. Therefore, the beamsplitter in the first-stage beamsplitter unit 4131 is a multi-mode beamsplitter, and the beamsplitter in the second-stage beamsplitter unit 4132 is a multi-mode to single-mode beamsplitter. When waveguides 311-314 are multimode waveguides, the optical signal output from the first connection 412 in the multimode waveguide, after being split by the beamsplitter in the first-stage beamsplitter unit 4131, remains a multimode waveguide optical signal. This multimode waveguide optical signal is further split by the beamsplitter in the second-stage beamsplitter unit 4132, and remains a multimode waveguide optical signal. Therefore, both the beamsplitter in the first-stage beamsplitter unit 4131 and the beamsplitter in the second-stage beamsplitter unit 4132 are multimode beamsplitters. Of course, waveguides 311-314 may also be partially single-mode waveguides and partially multimode waveguides; this is not a limitation.

[0185] Optionally, the cross-sectional area of ​​the output end of the second connector is greater than or equal to the cross-sectional area of ​​the input end. For example, the cross-sectional area of ​​the output end of the second connector 4141 is greater than or equal to the cross-sectional area of ​​the input end, and the cross-sectional area of ​​the output end of the second connector 4142 is also greater than or equal to the cross-sectional area of ​​the input end. For any second connector, if the cross-sectional area of ​​its output end is equal to the cross-sectional area of ​​its input end, then the second connector is only used to transmit optical signals. However, if the cross-sectional area of ​​its output end is greater than the cross-sectional area of ​​its input end, then the second connector can achieve the effect of expanding the mode area while transmitting optical signals. The latter structure is designed for accurate matching with back-end components. For example, if the mode spot size after the last-stage beam splitter is smaller than the mode spot size of the back-end component, such as the mode spot size of the single-mode waveguide, without mode expansion, then by setting the cross-sectional area of ​​the output end of the second connection part to be larger than the cross-sectional area of ​​the input end, the optical signal is expanded before being split by the last-stage beam splitter. After the expanded optical signal is split by the last-stage beam splitter, it is very likely to be exactly matched with the mode spot size of the single-mode waveguide, thus achieving accurate connection with the single-mode waveguide.

[0186] Optionally, similar to the first connection 412, the cross-sectional area of ​​the output end of the second connection is greater than or equal to the cross-sectional area of ​​the input end, and this can also be achieved using one or more waveguide elements. For example, the second connection may include only one multimode waveguide, or only one mode converter, or only one reverse taper, with the cross-sectional area of ​​the output end of the multimode waveguide, mode converter, or reverse taper being greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide, mode converter, or reverse taper. Alternatively, the second connection may include a multimode waveguide and a mode converter, with the input end of the mode converter connected to the output end of the multimode waveguide, and the cross-sectional area of ​​the output end of the mode converter being greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide. And so on. For details, please refer to the description of the first connection above; further details will not be repeated here.

[0187] Understandably, the same applies to scenario one. For example, in scenario two, the branches in each beam splitter can be straight or curved, the cross-sectional shape of each branch can remain constant or change, the cross-sectional shapes of different branches can be the same or different, and so on. These details will not be repeated here.

[0188] Case 3, N≥3.

[0189] Optionally, when N is an integer greater than or equal to 3, the N-level beam splitting unit 413 specifically comprises at least three levels of beam splitting units, wherein each level of beam splitting unit may include one or more beam splitters, and each beam splitter includes one or more branches. For example, the first-level beam splitting unit includes one beam splitter, which includes 2 branches, 3 branches, 4 branches, 5 branches, ...; the second-level beam splitting unit includes one or two beam splitters, where each beam splitter includes 2 branches, 3 branches, 4 branches, 5 branches, ...; the third-level beam splitting unit includes one or two beam splitters, where each beam splitter includes 2 branches, 3 branches, 4 branches, 5 branches, ..., and so on.

[0190] Taking N=3 as an example, please refer to Figure 11a, which shows a possible waveguide structure diagram when N=3. Figure 11a uses the structure shown in Figure 4a as an example, with the first connecting part 412 as shown. Figure 11a(A) shows a three-dimensional view of the waveguide structure, and Figure 11a(B) shows a planar view of the waveguide structure. Combining Figure 11a and Figure 4a above, when N=3, the N-level beam splitting unit 413 can specifically include a first-level beam splitting unit 4131, a second-level beam splitting unit 4132, and a third-level beam splitting unit 4133. The first-level beam splitting unit 4131 includes one beam splitter, the second-level beam splitting unit 4132 includes two beam splitters, and the third-level beam splitting unit 4133 includes four beam splitters. Similarly, if each beam splitter includes two branches, then the I-level beam splitting unit can include 2... I-1 There are 1 beam splitter, where I is a positive integer less than or equal to N.

[0191] As shown in Figure 11a, in the first-stage beam splitter unit 4131, the input terminals of both branches of the beam splitter are connected to the output terminal of the first connection part 412, and the output terminals of the two branches are connected to the input terminals of the two beam splitters in the second-stage beam splitter unit 4132 through two second connection parts. In the second-stage beam splitter unit 4132, the input terminals of the two branches of each beam splitter are connected to the output terminal of one branch of the first-stage beam splitter unit 4131 through the second connection part, and the output terminals of the two branches of each beam splitter are connected to the input terminals of the two beam splitters in the third-stage beam splitter unit 4133 through the second connection part. In the third-stage beam splitter unit 4133, the input terminals of the two branches of each beam splitter are connected to the output terminal of one branch of one beam splitter in the second-stage beam splitter unit 4132 through the second connection part, and the output terminals of the two branches of each beam splitter serve as the two output terminals of the N-stage beam splitter unit 413.

[0192] Based on this structure and connection, the optical signal in the multimode waveguide output from the first connection unit 412 enters the first-stage beam splitter unit 4131, where it is split into two parts by a beam splitter. These two parts are then transmitted through two branches to the second connection unit between the first-stage beam splitter unit 4131 and the second-stage beam splitter unit 4132, and subsequently enter the two beam splitters in the second-stage beam splitter unit 4132, where they are split into four parts. These four parts are then transmitted through four branches to the second connection unit between the second-stage beam splitter unit 4132 and the third-stage beam splitter unit 4133, and subsequently enter the four beam splitters in the third-stage beam splitter unit 4133, where they are split into eight parts. Thus, through the three-stage beam splitter unit, the optical signal output from the first connection unit 412 is split into 2... 3 That is, there are 8 second optical signals, which are output from the output ends of the eight branches respectively, serving as the 8 second optical signals output by the N-level beam splitting unit 413.

[0193] Optionally, the outputs of the eight branches can also be connected to eight waveguides, such as waveguides 311, 312, 313, 314, 315, 316, 317, and 318 shown in Figure 11a. Waveguides 311 to 318 can be single-mode waveguides or multi-mode waveguides, depending on the requirements of the application scenario. For example, when waveguides 311-318 are single-mode waveguides, the optical signal in the multimode waveguide output from the first connection 412, after being split by the beamsplitter in the first-stage beamsplitter unit 4131, remains a multimode waveguide optical signal. This multimode waveguide optical signal is further split by the beamsplitter in the second-stage beamsplitter unit 4132, still remaining a multimode waveguide optical signal. This multimode waveguide optical signal is further split by the beamsplitter in the third-stage beamsplitter unit 4133, becoming a single-mode waveguide optical signal. Therefore, the beamsplitters in the first-stage beamsplitter unit 4131 and the second-stage beamsplitter unit 4132 are multimode beamsplitters, and the beamsplitter in the third-stage beamsplitter unit 4133 is a multimode-to-single-mode beamsplitter. However, when waveguides 311-318 are multimode waveguides, the beamsplitters in the first-stage beamsplitter unit 4131 to the third-stage beamsplitter unit 4133 are all multimode beamsplitters. Of course, waveguides 311 to 318 may also be partially single-mode waveguides and partially multi-mode waveguides, without limitation.

[0194] Optionally, for any second connection between adjacent beam splitting units, the cross-sectional area of ​​its output end can be greater than or equal to the cross-sectional area of ​​its input end. For example, the cross-sectional area of ​​the output end of all second connection parts can be greater than the cross-sectional area of ​​the input end, so that the N-stage beam splitting unit expands the modal area before each beam splitting. Alternatively, the cross-sectional area of ​​the output end of all second connection parts can be equal to the cross-sectional area of ​​the input end, so that the N-stage beam splitting unit only splits the beam without expanding the modal area. Or, the cross-sectional area of ​​the output end of the second connection parts between some adjacent beam splitting units can be greater than the cross-sectional area of ​​the input end, while the cross-sectional area of ​​the output end of the second connection parts between the remaining adjacent beam splitting units can be equal to the cross-sectional area of ​​the input end, so that some of the N-stage beam splitting units expand the modal area before splitting the beam, while others split the beam directly, and so on, without limitation.

[0195] For example, in one design, the cross-sectional area of ​​the output end of the second connection between the first-level to the T-level beam splitter units can be designed to be larger than the cross-sectional area of ​​the input end, while the cross-sectional area of ​​the output end of the second connection between the T-level to the N-level beam splitter units can be equal to the cross-sectional area of ​​the input end, where T is a positive integer less than N. For instance, as shown in Figure 11b, when N is 3, the cross-sectional area of ​​the output end of the second connection between the first-level beam splitter unit 4131 and the second-level beam splitter unit 4132 can be designed to be larger than the cross-sectional area of ​​the input end, while the cross-sectional area of ​​the output end of the second connection between the second-level beam splitter unit 4132 and the third-level beam splitter unit 4133 can be equal to the cross-sectional area of ​​the input end. If the cross-sectional height remains constant, this translates to the cross-sectional width: the cross-sectional width of the output end of the second connection between the first-level beam splitter unit 4131 and the second-level beam splitter unit 4132 is larger than the cross-sectional width of the input end, while the cross-sectional width of the output end of the second connection between the second-level beam splitter unit 4132 and the third-level beam splitter unit 4133 is equal to the cross-sectional width of the input end.

[0196] Based on this design, the optical signal output from the first connector 412 first passes through the pre-T-stage beam splitter and the second connecting part between them for mode expansion and T-stage beam splitting, becoming 2 T The optical signal in the multimode waveguide is then split into NT-level beams by the T-th to N-th beam splitting units, becoming 2 N A second optical signal is generated and then output to back-end components, such as a single-mode waveguide. The second connection between the front T-stage beam splitters can expand the mode of the optical signal to a sufficiently large size, and the subsequent NT-stage beam splitters can split the expanded mode to the same size as the mode of the single-mode waveguide, so that the optical signal can be transmitted better into the single-mode waveguide.

[0197] It should be noted that Figure 11b only shows one possible structural design for the second connection between N-level beam splitters. In actual waveguide structures, the second connection can also have other structural designs. For example, the cross-sectional width of the second connection between the later beam splitters can be increased while the cross-sectional width of the second connection between the earlier beam splitters remains unchanged; or the cross-sectional width of the second connection between the middle beam splitters can be increased while the cross-sectional width of the second connection between the two outer beam splitters remains unchanged; or the cross-sectional width of the second connection between all beam splitters can be increased, but with different slopes, etc., which will not be listed here.

[0198] Optionally, similar to the first connection, the cross-sectional area of ​​the output end of the second connection is greater than or equal to the cross-sectional area of ​​the input end, and this can also be achieved using one or more waveguide elements. For example, the second connection may include only one multimode waveguide, or only one mode converter, or only one reverse taper, where the cross-sectional area of ​​the output end of the multimode waveguide, mode converter, or reverse taper is greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide, mode converter, or reverse taper. Alternatively, the second connection may include a multimode waveguide and a mode converter, with the input end of the mode converter connected to the output end of the multimode waveguide, and the cross-sectional area of ​​the output end of the mode converter being greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide. And so on. For details, please refer to the description of the first connection above; these will not be repeated here.

[0199] Furthermore, the relevant content of scenarios one and two above also applies to scenario three. For example, in scenario three, the branches in each beam splitter can be straight structures or include curved structures; the cross-sectional shape of each branch can remain unchanged or have a changing trend; the cross-sectional shapes of different branches can be the same or different, and so on.

[0200] Furthermore, when including multi-level beam-splitting units, as long as each level of beam-splitting unit has at least one beamsplitter, such that the output of that level of beam-splitting unit is further split compared to the output of the previous level of beam-splitting unit, this application does not specifically limit the number of branches that are split, or the number of sub-branches that are further split. For example, in the second-level beam-splitting unit, there may be only one beamsplitter, and the other branch may be a multimode waveguide directly connected to the third-level beam-splitting unit. Alternatively, in any level of beam-splitting unit from the second to the Nth level, one beamsplitter may have two branches, and another beamsplitter may have three branches. And so on, there are many other possible variations, which will not be listed here.

[0201] The above content describes the structure of the first connecting part 412 and the N-stage beam splitter 413. In addition to the first connecting part 412 and the N-stage beam splitter 413, the waveguide structure 400 also includes GC411. GC411 is an optoelectronic device based on the principles of diffraction and interference, typically having a periodic structure. This periodic structure can couple a beam of light incident obliquely or perpendicularly on the waveguide surface into the waveguide. This periodic structure can be of uniform period and uniform duty cycle, or it can be of uniform period and non-uniform duty cycle, or it can be of non-uniform period and uniform duty cycle, or it can be of non-uniform period and non-uniform duty cycle; the specific design can be tailored to the specific requirements of the application scenario and is not limited thereto.

[0202] Optionally, the first connecting portion 412 and the N-stage beam splitter 413 can be a homogeneous medium or a metamaterial. For example, taking the waveguide structure shown in Figure 11a above as an example, several possible implementations are given below.

[0203] In one possible implementation, the first connecting portion 412 and the N-level beam splitting unit 413 are both continuous structures, such as continuous blocks of the same height, as shown in Figure 11a above. In this case, the first connecting portion 412 and the N-level beam splitting unit 413 belong to a uniform medium with a uniform period and a uniform duty cycle.

[0204] In another possible implementation, the first connecting portion 412 and the N-stage beam splitter 413 contain subwavelength grating structures. For example, all or part of the first connecting portion 412 and the N-stage beam splitter 413 may be subwavelength grating structures. The subwavelength grating structure is a type of metamaterial and has two possible forms. One form, as shown in Figures 12a and 12b, contains subwavelength grating structures throughout the entire structure. The other form, as shown in Figures 13a and 13b, contains subwavelength grating structures only in the portion before the output end.

[0205] Optionally, in the first configuration, as shown in Figures 12a and 12b, the first connecting portion 412 and the N-level beam splitter 413 are both composed of periodic regions. A periodic region refers to a region with periodic variations; the period here needs to be sufficiently small, typically smaller than the period of a Bragg grating, to form a subwavelength grating structure. In detail, the first connecting portion 412 and the N-level beam splitter 413 include a series of short blocks, which together present the shape shown in Figure 11a, enabling the functions described above.

[0206] It should be noted that the individual short blocks can be discrete or non-discrete. Figures 12a and 12b illustrate the former. Discrete means that the different short blocks are completely disconnected, while non-discrete means that the different short blocks are not completely disconnected, such as having a portion connected at the bottom. This is equivalent to having many through slots cut into a single structure, forming rows of structures, but the bottoms of these rows are connected by relatively thin sections. Of course, there could be other structures, such as partially completely disconnected, partially connected at the bottom, or connected in the middle, etc., without any specific limitations.

[0207] Optionally, in the second configuration, as shown in Figures 13a and 13b, the first connecting portion 412 and the N-stage beam splitter 413 include a periodic region, a transition region, and a continuous region, arranged along the direction from the input end to the output end, i.e., from left to right. One end of the transition region is connected to the periodic region, and the other end is connected to the continuous region, used to achieve the transition of the optical signal from the periodic region to the continuous region. For example, in one possible implementation, as shown in Figure 13b, the periodic region includes multiple short blocks, and the continuous region includes long blocks. The long blocks connect to the middle portions of the multiple short blocks, forming the transition region. In this way, the continuous region and the periodic region themselves can form a transition region at the connection point, eliminating the need for an additional transition region and reducing manufacturing costs.

[0208] It should be noted that, in the second form, the periodic region can be completely disjointed blocks, meaning multiple short blocks are discretely separated, or it can be partially disjointed blocks, such as multiple short blocks having a thin section connected at the bottom (or center region or top, etc., without limitation), or some short blocks being connected while the remaining short blocks are completely disjointed, and so on. There are many possible structures, as long as they can form a subwavelength grating structure; this application does not impose specific limitations on this.

[0209] Furthermore, in the second configuration, the periodic region, transition region, and continuous region can typically be arranged sequentially adjacent to each other; the periodic region cannot be designed after the continuous region. Therefore, the periodic region must begin from the input end of the first connecting part 412, and the length of the periodic region can be designed according to actual needs. For example, the region from the input end of the first connecting part 412 to the end of the first-stage beam splitting unit can be designed as a periodic region, or the region from the input end of the first connecting part 412 to the end of the second-stage beam splitting unit can be designed as a periodic region, or the region from the input end of the first connecting part 412 to a short section before the end of the last-stage beam splitting unit can be designed as a periodic region, etc., without any specific limitation.

[0210] It should be noted that if the first connecting part 412 and the N-level beam splitting unit 413 are designed as a continuous block as shown in FIG11a, the first connecting part 412 and the N-level beam splitting unit 413 have a large pattern size in the x direction shown in FIG11a. Based on this large pattern size, under the same input optical signal power, the optical power transmitted per unit area by the first connecting part 412 and the N-level beam splitting unit 413 is smaller than that of the prior art, and the probability of TPA effect is also smaller. If designed as shown in Figures 12a, 12b, 13a, and 13b, the subwavelength grating structure can be used to increase the mode size of the first connecting part 412 and the N-level beam splitter 413 in the y-direction. In other words, the first connecting part 412 and the N-level beam splitter 413 not only have a large mode size in the x-direction, but also have a large mode size in the y-direction (compared to the structure shown in Figure 11a). The first connecting part 412 and the N-level beam splitter 413 support a large two-dimensional mode size. Based on this large mode size, under the same input optical signal power, the optical power transmitted per unit area by the first connecting part 412 and the N-level beam splitter 413 is further reduced, and the probability of TPA effect is further reduced.

[0211] Optionally, if the first connecting part 412 and the N-level beam splitter 413 are designed as a whole subwavelength grating structure as shown in Figures 12a and 12b, the output of the waveguide structure is also a subwavelength grating waveguide, meaning the back end needs to be connected to the subwavelength grating waveguide. However, if the first connecting part 412 and the N-level beam splitter 413 are designed as a partially subwavelength grating structure as shown in Figures 13a and 13b, the output of the waveguide structure will be converted from a subwavelength grating waveguide to a continuous waveguide, thus the back end can be connected to a continuous waveguide. For example, if the back end element is a single-mode waveguide, the mode spot size of the continuous region in the partially subwavelength grating structure can also be designed as the mode spot size of a single-mode waveguide. In this way, after the optical signal passes through the subwavelength grating structure, it directly transitions to the mode spot size of a single-mode waveguide and enters the single-mode waveguide element at the back end, making the waveguide structure directly applicable to scenarios where the back end is connected to a single-mode waveguide or other types of waveguides.

[0212] Based on the waveguide structure provided above, after the optical signal is coupled to the first connector via the GC, it is converted into an optical signal in a multimode waveguide. Then, it passes through an N-stage beam splitter unit to further divide the optical power into stages, outputting it to at least two waveguides. This prevents all the optical power from being concentrated in a single waveguide, reducing the optical power in a single waveguide and making it less prone to high optical power density. Thus, when the waveguide is a waveguide in an SOI silicon photonics chip (referred to as an SOI waveguide), it is less likely to experience the TPA effect, solving the problem caused by the TPA effect at high optical power densities. In other words, with the same optical power density in the SOI waveguide as in existing technologies, the SOI silicon photonics chip can support higher optical power input than existing technologies, increasing the maximum optical power that the SOI silicon photonics chip can withstand. In addition, the above structure adopts a passive waveguide structure, which can be directly formed by a single exposure without the need for additional semiconductor process steps, doping, or other additional processes and power consumption. It has the advantages of simple process, minimalist architecture, extremely low cost, extremely high performance, and extremely high reliability.

[0213] The above content provides a detailed description of the structure of GC, the first connecting part 412, and the N-level beam splitter unit in the waveguide structure. The following section will explain the other components in the waveguide structure.

[0214] For ease of understanding, the GC411, the first connecting part 412 and the N-stage beam splitter 413 in the waveguide structure 400 will be collectively referred to as the coupling component 410, and it is assumed that the N-stage beam splitter 413 outputs M second optical signals, where M is an integer greater than or equal to 2.

[0215] Please refer to Figure 14, which shows a schematic diagram of another waveguide structure provided in this application. In this example, the coupling component 410 may include M first output terminals, which are also the M output terminals of the N-stage beam splitter unit 413, i.e., a 121 a 122 ... a 12M After receiving a first optical signal incident perpendicular to or tilted to the plane of the waveguide structure 400, the coupling component 410 splits the first optical signal into M second optical signals, i.e., S 121 S 122 ... S 12M And through M first output terminals a 121 ~a 12M Output, M second optical signals S 121 ~S 12MThe optical power of each second optical signal is less than the optical power of the first optical signal. Based on this, the coupling component 410 can support the input of a large mode spot, which is divided into M smaller mode spots in the coupling component 410. In this way, the coupling component 410 can turn a large mode spot input into M smaller mode spot outputs. The coupling component 410 can also be called a large mode spot coupling component.

[0216] Optionally, as shown in Figure 14, the waveguide structure 400 may further include M first waveguides, namely 511, 512, ..., 51M, with each of the M first waveguides 511 to 51M connected to one of the M first output terminals a of the coupling component 410. 121 ~a 12M Used to receive M second optical signals S output by coupling component 410 121 ~S 12M .

[0217] The first waveguide 511–51M can be any type of waveguide, such as a single-mode waveguide or a multi-mode waveguide. For example, a single-mode waveguide can be chosen as the first waveguide. Single-mode waveguides have smaller cross-sectional dimensions and occupy less volume compared to multi-mode waveguides, which can reduce the size of the chip containing the waveguide structure. They are also suitable for scenarios requiring the transmission of a single-mode optical signal, such as the transmitting component in an FMCW lidar. Furthermore, since only a single mode is transmitted in a single-mode waveguide, there is no interference from multiple modes or collisions between modes, thus improving the transmission efficiency of the optical signal.

[0218] Understandably, when the first waveguides 511-51M are single-mode waveguides, since the M first waveguides 511-51M are connected to the M first output terminals a of the coupling component 410... 121 ~a 12M Therefore, the M first output terminals a of the coupling component 410 121 ~a 12M The mode size is equal to the mode size of the single-mode waveguide.

[0219] In other words, the output of the coupling component 410 can be an independent waveguide with a cross-sectional area greater than or equal to a specific value, where the specific value is greater than or equal to the cross-sectional area of ​​a single-mode waveguide. For example, it could be the cross-sectional area of ​​a single-mode waveguide or the cross-sectional area of ​​the fundamental mode of a multimode waveguide. When it is the cross-sectional area of ​​a single-mode waveguide, the M second optical signals S output by the N-stage beam splitter 413... 121 ~S 12M The optical signals are from M single-mode waveguides. When the cross-sectional area is the fundamental mode of a multimode waveguide, the M second optical signals S output by the N-stage beam splitter 413 are... 121 ~S 12M It consists of the fundamental mode signals of M multimode waveguides.

[0220] Optionally, the waveguide structure 400 can be located on a chip, such as an SOI silicon photonics chip. The chip includes at least one transmitter, which can be part of at least one first waveguide as described above, or it can be a new device, such as a spot size converter (SSC). In other words, in one example, the coupling component 410 is directly connected to the chip edge via the first waveguide, with the portion of the first waveguide at the chip edge serving as the chip's transmitter. Alternatively, in another example, an SSC is located at the chip edge, and the coupling component 410 is connected to the SSC via the first waveguide. The SSC is used to match the intra-chip mode pattern with the spatial mode pattern, reducing the loss of the optical signal during transmission from the chip to space.

[0221] There are several possible relationships between the number of at least one transmitter of the chip and the number M of the first output terminals of the coupling component 410, for example:

[0222] Scenario 1: The number of at least one transmitter is less than the number of M first output terminals. For example, as shown in Figure 15a, the chip has ML (L is an integer less than M) transmitters, namely b1, b2, ..., b... M-L The coupling component 410 has M first output terminals a 121 ~a 12M In this case, the waveguide structure 400 can also be equipped with a beam combiner / splitter (or beam combiner), which is connected to the M first output terminals a. 121 ~a 12M and ML transmitters b1~b M-L Between, used to connect M first output terminals a 121 ~a 12M The output of M second optical signals S 121 ~S 12M Mixing the components, for example, combining M second optical signals S 121 ~S 12M The components of each part are mixed into a single transmission signal, and ML transmission signals are obtained and output. These ML transmission signals are emitted from ML transmitting ends. The optical power of the ML transmission signals can be the same or different, without limitation. Optionally, other implementation methods are also possible. For example, the optical combining / splitting element (or optical combining element) can be connected to fewer than M first output ends to combine or split the second optical signals output from the connected first output ends into one or more transmission signals. Regardless of the implementation method, as long as ML transmission signals can be output through the coupling component 410 and the optical combining / splitting element, this application does not impose specific limitations on this.

[0223] Scenario 2: The number of at least one transmitter is greater than the number of M first output terminals. For example, as shown in Figure 15b, the chip has M+L transmitter terminals, namely b1, b2, ..., b... M ... b M+L The coupling component 410 has M first output terminals a 121 ~a 12M In this case, a beam splitter can also be provided in the waveguide structure 400, and the beam splitter is connected to the first output terminal a. 12M and L+1 transmitters b M ~b M+L Between, used to connect the first output terminal a 12M The output second optical signal S 12M It is divided into L+1 transmitted signals, and another M-1 first output terminals a 121 ~a 12M-1 It is then directly connected to M-1 transmitting terminals, so that the output of M-1 second optical signals S 121 ~S 12M-1 The signal can be directly transmitted as M-1 signals. Alternatively, other implementations are possible. For example, a beam splitter can be connected to each of the multiple first output terminals, and each beam splitter splits the second optical signal output from the connected first output terminal into at least two transmitted signals. Alternatively, a beam combiner / splitter can be connected to some or all of the first output terminals, and the components of some or all of the second optical signals can be mixed by the beam combiner / splitter to obtain more transmitted signals. Regardless of the implementation method, as long as M+L transmitted signals can be output through the coupling component 410 and the beam splitter, this application does not impose specific limitations on this.

[0224] Scenario 3: The number of at least one transmitter is equal to the number of M first output terminals. For example, as shown in Figure 15c, the chip has M transmitter terminals b1 to b2. M The coupling component 410 also has M first output terminals a 121 ~a 12M In this case, M first output terminals a 121 ~a 12M-1 It can be directly connected to M transmitters b1 to b M Above, so that the output M second optical signals S 121 ~S 12M It can be directly used as M transmitted signals. In this case, by using the coupling component 410 structure provided in this application, the conversion from the input end to the multiple transmitting end can be directly realized. There is no need to set up additional beam splitting elements or beam combining elements to split more transmitted beams or combine fewer transmitted beams. This can reduce the number of beam splitting elements or beam combining elements, reduce structural complexity, and save costs.

[0225] To facilitate the introduction of the scheme, the following uses scenario three as an example to further illustrate the other components in waveguide structure 400.

[0226] Optionally, in the waveguide structure 400 shown in Figure 15c, the coupling component 410 and the M first waveguides 511 to 51M can be located in the transmitting component. The waveguide structure 400 may include one transmitting component or multiple transmitting components. The following describes in detail the schemes including one or more transmitting components through embodiments one to three.

[0227] Implementation Plan 1: Includes a launch component.

[0228] Please refer to Figure 16, which shows a schematic diagram of a waveguide structure provided in Implementation Scheme 1. In this example, it is assumed that the chip has M transmitters b1 to b2. M The coupling component 410 has M first output terminals a 121 ~a 12M Then there are M first output terminals a 121 ~a 12M M first waveguides 511 to 51M can be directly connected to M transmitters b1 to b M Above. Based on this connection, the M first output terminals a of the coupling component 410 121 ~a 12M The output of M second optical signals S 121 ~S 12M It will be transmitted to M transmitters b1 to b through M first waveguides 511 to 51M. M The signals are transmitted as M signals to the scanning component, and then scanned by the scanning component into the detection space.

[0229] Optionally, M transmitted signals are used to measure the target. For example, M transmitted signals can correspond to M detection channels, and the M transmitted signals are scanned into M regions by subsequent scanning components. In this way, M regions can be detected in a single scan, increasing the scanning range and improving detection efficiency. Each region can be a point, line, or surface, etc., without limitation.

[0230] Optionally, when each beamsplitter in the coupling assembly 410 comprises axisymmetric beams and each beamsplitter has the same branching structure, the M second optical signals S output by the coupling assembly 410... 121 ~S 12M The optical power is the same, and there are M second optical signals S 121 ~S 12M The M signals are directly transmitted, ensuring that the optical power of the M detection channels is the same, allowing them to reach the same distance in the detection space and achieve consistent ranging capabilities.

[0231] Optionally, as shown in Figure 16, the waveguide structure 400 may further include a receiving component 610, which is used to acquire the local oscillator signal S. 13 and echo signal S 14 And the local oscillator signal S 13 and echo signal S 14 Frequency mixing is performed to obtain an intermediate frequency (IF) signal, which is used to determine the target's velocity and / or distance. The receiving component 610 can receive the echo signal S from the receiving terminal c1 of the chip. 14 For example, one input terminal of the receiving component 610 can be connected to the receiving terminal c1 of the chip via a waveguide, optical fiber, or other means capable of transmitting optical signals. The transmitted signal is reflected by the target and becomes an echo signal S. 14 The signal is then transmitted back to the receiving terminal c1 of the chip, allowing the receiving component 610 to receive the echo signal S from the receiving terminal c1. 14 .

[0232] In addition, the local oscillator signal S 13 It can be separated from the input signal, transmitted signal, or output signal of any of the devices in the coupling component 410 and the first waveguides 511 to 51M. Here, being separated from the coupling component 410 can be understood as being separated from the input signal, transmitted signal, or output signal of any of the devices in the GC411, the first connector 412, and the N-stage beam splitter 413.

[0233] For ease of understanding, two possible examples are given below.

[0234] Example 1, see Figure 17a, which shows the local oscillator signal S. 13 A possible structural diagram derived from the input signal of the coupling component 410. In this structure, the coupling component 410 also has a second output terminal a. 13 One input terminal of the receiving component 610 is connected to the receiving terminal c1 of the chip, and the other input terminal is connected to the second output terminal a of the coupling component 410. 13 Above. After receiving the first optical signal, the coupling component 410 splits the first optical signal into M first output terminals a in stages. 121 ~a 12M Second output terminal a 13 Above, where M are first output terminals a 121 ~a 12M Output M second optical signals S 121 ~S 12M Second output terminal a 13 Then output the local oscillator signal S 13 The receiving component 610 receives data from the second output terminal a. 12 Received local oscillator signal S 13 .

[0235] Optionally, the local oscillator signal S 13 The optical power is less than M second optical signals S 121 ~S 12M The optical power of each second optical signal in the first optical signal. For example, coupling component 410 couples the lower power optical signal in the first optical signal to the second output terminal a. 13 The remaining high-power optical signal is coupled to the M first output terminals a through power sharing or uneven distribution. 121 ~a 12M Up. In this way, the M transmitted signals will have relatively high transmission power, while the local oscillator signal S... 13 It has relatively low power consumption, which reduces the amount of local oscillator signal S separated from the coupling component 410. 13 The impact on the transmitted signal.

[0236] Optionally, the second output terminal a of the coupling component 410 13 There are many ways to implement this. For example, the output of one branch of a beam splitter in the coupling component 410 can be used as the second output a. 13 Alternatively, a signal channel can be directionally coupled from one of the elements or waveguides in the coupling assembly 410 in a non-contact manner as a second output terminal a. 13 Alternatively, another beam splitter can be inserted on one branch of a beam splitter to create a channel as a second output terminal a. 13 ...etc., no specific limitations are made here.

[0237] For example, if the second output terminal a 13 This is achieved through one branch of the beam splitter. Therefore, to make the local oscillator signal S... 13 Since the optical power is relatively low, the cross-sectional area of ​​this branch at the input end can be designed to be smaller than that of other branches at the input end, and / or, if the cross-sectional height is the same, the cross-sectional width of this branch at the input end can be designed to be smaller than that of other branches at the input end. In this way, the optical power received at the input end of this branch is less than that at the input ends of other branches, and the optical signal is transmitted to the second output end a of the coupling component 410. 13 Then, the output is the local oscillator signal S. 13 Local oscillator signal S 13 The optical power is also relatively small.

[0238] In the above description, the receiving component 610 can be connected to the second output terminal a via a waveguide, optical fiber, or other means capable of transmitting optical signals. 13 Above. For example, Figure 17a shows a waveguide connection, in which case the second output terminal a of the coupling component 410 is... 13It can have a first mode size; when the waveguide is a single-mode waveguide, the first mode size is also the mode size of the single-mode waveguide. If the second output terminal a 13 If the beam splitter is used to achieve this, then the mode size of the branch at the output end is equal to the mode size of the single-mode waveguide, and the cross-sectional area of ​​the branch at the output end is equal to the cross-sectional area of ​​the single-mode waveguide.

[0239] Example 2, please refer to Figures 17b and 17c, which show the local oscillator signal S. 13 Two possible structural diagrams can be derived from the signal transmitted by the first waveguide 51M. The first waveguide 51M can also be replaced by any other first waveguide, without limitation. In this structure, the waveguide structure 400 further includes a beam splitter 710, which is coupled or connected between the first waveguide 51M and one input terminal of the receiving component 610, for transmitting the second optical signal S from the first waveguide 51M. 12M The split beam is the local oscillator signal S 13 and the local oscillator signal S 13 The output is sent to the receiving component 610. In this case, the output is sent to the transmitting end b. M The optical power of the optical signal is less than that of the first output terminal a of the coupling component 410. 12M The output second optical signal S 12M Optical power. Optionally, the local oscillator signal S 13 The optical power is less than the output to the transmitter b M The optical power of the optical signal. For example, the beam splitter 710 receives the optical power of the second optical signal S. 12M The lower-power optical signal is separated and output to the receiving component 610, while the remaining high-power optical signal is output to the transmitting end b. M .

[0240] The beam splitter 710 can be a directional coupler, as shown in Figure 17b. This directional coupler does not contact the first waveguide 51M, but is relatively close to it. In other words, a directional coupler can be placed sufficiently close to the first waveguide 51M, allowing the directional coupler to transmit the second optical signal S from the first waveguide 51M. 12M The local oscillator signal S is split into two signals with unequal power. 13 Alternatively, the beam splitter 710 can also be a beam splitter, as shown in Figure 17c. This beam splitter is directly inserted in the middle of the first waveguide 51M, splitting the second optical signal S transmitted in the first waveguide 51M. 12M The spectral dispersion is the local oscillator signal S. 13 And transmit signals.

[0241] Understandably, the two examples above are only for illustrating how to extract the local oscillator signal S from the input signal. 13Several possible structures are given, and other branched structures can be deduced by analogy with the above structures, which will not be repeated here.

[0242] Optionally, the receiving component 610 can be any component or combination thereof capable of performing mixing. For example, taking the structure shown in Figure 17b as an example, please refer to Figure 18, which shows a specific structural schematic diagram of a receiving component provided in Embodiment 1. Referring to Figures 17b and 18, in this example, the receiving component 610 includes a beam splitter 611 and at least two mixers. Figure 18 uses M mixers as an example, namely mixers 6121, 6122, ..., 612M. The beam splitter 611 has one input terminal and M output terminals. The input terminal is the input terminal of the receiving component 610, used to acquire the local oscillator signal S. 13 The M output terminals are respectively connected to the M first input terminals of the M mixers 6121 to 612M, and the M second input terminals of the M mixers 6121 to 612M are connected to the M receiving terminals c of the chip. 11 c 12 ... c 1M Here, the connections between the various components can be achieved through waveguides, optical fibers, or other means that can transmit optical signals. Figure 18 shows a waveguide connection as an example.

[0243] It should be emphasized that if the first waveguide 511 to 51M is a single-mode waveguide, then the beam splitter 611 is also a single-mode beam splitter, while the beam splitter in the coupling component 410 is a multi-mode beam splitter or a multi-mode to single-mode beam splitter. These two types of beam splitters are different beam splitters with different structures.

[0244] Based on this structure and connection, the input of beam splitter 611 can receive the local oscillator signal S. 13 The beam splitter 611 splits the local oscillator signal S 13 Spectroscopy (e.g., equal power splitting) results in M ​​sub-local oscillator signals S. 131 S 132 ... S 13M And through its M output terminals, these M sub-local oscillator signals S 131 ~S 13M The outputs are distributed to M mixers 6121 to 612M. These M mixers 6121 to 612M can also receive signals from the chip's M receivers c. 11 ~c 1M Received M echo signals S 141 S 142 ... S 14MEach mixer performs a mixing operation on the received sub-local oscillator signal and echo signal to generate its own intermediate frequency signal. The M intermediate frequency signals generated by the M mixers 6121 to 612M are used to jointly determine the distance and / or velocity of the target; in other words, they jointly achieve target measurement.

[0245] Optionally, the M mixers 6121-612M, together with subsequent components, achieve target measurement. For example, as shown in Figures 17b and 18, the receiving component 610 may further include a detection element 613. The detection element 613 is connected between the output terminals of the M mixers 6121-612M and the electrical output terminal (d) of the chip, and is used to perform photoelectric detection on the M intermediate frequency signals generated by the M mixers 6121-612M to obtain and output electrical signals. This electrical signal is transmitted to subsequent components, such as an electrical chip, through the electrical output terminal d of the chip. In the electrical chip, the intermediate frequency signal is processed to obtain point cloud data and determine the distance and / or velocity of the target.

[0246] It should be noted that there can be only one detector element 613, or there can be M detector elements, with each of the M detector elements corresponding to one of the M mixers. Each mixer is connected to its corresponding detector element. In this case, each detector element only performs photoelectric detection on the intermediate frequency signal generated by the mixer it is connected to. Alternatively, there can be more than or equal to two but less than M detector elements; no specific limitation is made here.

[0247] Optionally, a transmitting component is used to transmit an optical signal of one wavelength. In embodiment one, since the waveguide structure 400 includes a transmitting component, the M transmitted signals have the same wavelength, and the M sub-local oscillator signals S 131 ~S 13M The wavelengths are also the same. Each mixer can mix the signal with the same wavelength as the sub-local oscillator signal in the received echo signal, while other wavelength signals are treated as noise signals and are not used. Therefore, the M intermediate frequency signals are all signals with the same wavelength as the transmitted signal. Based on these M intermediate frequency signals, the measurement accuracy can be improved.

[0248] Based on the above implementation scheme one, a transmitting component and a receiving component can be set in the waveguide structure, and the local oscillator signal of the receiving component can be separated from the correlation signal of any element in the transmitting component. Therefore, the waveguide structure has high flexibility and versatility and can be adapted to various detection occasions.

[0249] Implementation Plan 2: Includes two launch components.

[0250] Please refer to Figure 19, which shows a schematic diagram of a waveguide structure provided in Embodiment 2. In this example, the waveguide structure 400 includes two transmitting components. Each of the two transmitting components includes the coupling component described above and M first waveguides. For example, as shown in Figure 19, one transmitting component includes a coupling component 410 and M first waveguides 511 to 51M, and the other transmitting component includes a coupling component 420 and M first waveguides 521, 522, ..., 52M. In this case, the waveguide structure 400 also includes M beam combiners and splitters, namely beam combiners and splitters 810, 820, ..., 8M0. The chip containing the waveguide structure 400 may include one or more transmitting ends. Figure 19 uses 2M transmitting ends as an example, i.e., transmitting end b. 11 b 12 b 21 b 22 ... b M1 b M2 Each of the M beam combiners / splitters 810 to 8M0 has two input terminals and two output terminals. The two input terminals of each beam combiner / splitter are connected to the output terminals of any two first waveguides in the two transmitting components, and the two output terminals of each beam combiner / splitter are connected to the two transmitting terminals of the chip. For example, the two input terminals of beam combiner / splitter 810 are connected to the output terminals of first waveguide 511 and first waveguide 521, respectively, and the two output terminals are connected to the transmitting terminal b of the chip. 11 b 12 The two input terminals of the beam combiner / splitter 820 are connected to the output terminals of the first waveguide 512 and the first waveguide 522, respectively, and the two output terminals are connected to the transmitter b of the chip. 21 b 22 The two input terminals of the beam combiner / splitter 8M0 are connected to the output terminals of the first waveguide 51M and the first waveguide 52M, respectively. The two output terminals are connected to the transmitter terminal b of the chip. M1 b M2 .

[0251] Based on this structure and connection, in the transmitting component above, after the coupling component 410 receives the first optical signal that is perpendicular to or tilted to the waveguide structure plane, it splits it into M second optical signals S. 121 S 122 ... S 12M The second optical signal S 121 The second optical signal S is transmitted through the first waveguide 511 to the beam combiner / splitter 810. 122 After being transmitted through the first waveguide 512 to the beam combiner / splitter 820, ..., the second optical signal S 12MThe signal is transmitted through the first waveguide 51M to the beam combiner / splitter 8M0. In the lower transmitting assembly, the coupling component 420 receives the first optical signal, which is perpendicular to or tilted to the plane of the waveguide structure, and then splits it into M second optical signals S. 221 S 222 ... S 22M The second optical signal S 221 The second optical signal S is transmitted through the first waveguide 521 to the beam combiner / splitter 810. 222 After being transmitted through the first waveguide 522 to the beam combiner / splitter 820, ..., the second optical signal S 22M The signal is transmitted through the first waveguide 52M to the beam combiner / splitter 8M0.

[0252] Furthermore, the beam combiner / splitter 810 takes the two incoming second optical signals S 121 and S 221 The light is split into two transmission signals, which are then output through its two output terminals, allowing these two transmission signals to be transmitted to the two transmitter terminals b of the chip. 11 b 12 The beam combiner / splitter 820 receives two second optical signals S from the input. 122 and S 222 The light is split into two transmission signals, which are then output through its two output terminals, allowing these two transmission signals to be transmitted to the two transmitter terminals b of the chip. 21 b 22 ...The beam combiner / splitter 8M0 receives two second optical signals S from the input... 12M and S 22M The light is split into two transmission signals, which are then output through its two output terminals, allowing these two transmission signals to be transmitted to the two transmitter terminals b of the chip. M1 b M2 Based on this, a total of 2M transmission signals will be emitted from the chip's 2M transmitters and enter the scanning component. These 2M transmission signals are then scanned by the scanning component into the detection space to measure targets within that space. For example, the 2M transmission signals correspond to 2M detection channels, and the 2M transmission signals are scanned into 2M areas. Thus, a single scan can detect 2M areas, increasing the scanning range, the number of detection channels, and the frequency.

[0253] In one example, each beam combiner / splitter is a power-type beam combiner / splitter. Each beam combiner / splitter mixes components of the two input second optical signals, for example, mixing 50% of each component to obtain two transmitted signals, and then outputs two transmitted signals. Based on this method, each pair of transmitted signals will have the same optical power, and these two transmitted signals can reach the same distance in different directions, making the ranging capability identical in different directions.

[0254] In one example, the two first optical signals from the two transmitting components have different wavelengths; therefore, M second optical signals S are split from the first optical signal of the upper transmitting component. 121 ~S 12M and M second optical signals S split from the first optical signal of the lower transmitting component 221 ~S 22M Therefore, they have different wavelengths. Each beam combiner / splitter receives two input signals of different wavelengths. After processing the two input signals of different wavelengths, each beam combiner / splitter obtains two dual-wavelength transmission signals and outputs them. Therefore, each transmission signal is a dual-wavelength signal. Although the ranging capability of each transmission signal is the same, it has two wavelengths, which can obtain a higher point frequency.

[0255] Alternatively, in another example, the two first optical signals from the two transmitting components have the same wavelength but different polarization states; in other words, the two first optical signals are light with different linear polarization states. For example, one first optical signal is TE light while the other is TM light, or one first optical signal is P light while the other is S light. In this case, the waveguide structure 400 also needs to be equipped with polarization elements, such as a polarization beam splitter (PBS) or a polarization beam splitter rotator (PSR). The polarization elements, based on different linear polarization states, split the echo signals corresponding to different transmitting components to perform frequency mixing on the echo signals corresponding to each transmitting component.

[0256] Alternatively, in another example, the two first optical signals in the two transmitting components have the same wavelength and the same linear polarization state, but the waveguide structure 400 is provided with a polarization element, which is used to polarize and split the echo signal, thereby separating the echo signal corresponding to each of the different transmitting components, so as to mix the echo signal corresponding to each transmitting component.

[0257] It should be noted that the implementation methods of the echo signals corresponding to different transmitting components of the polarization element beam splitting can be found in existing solutions, and will not be described in detail here.

[0258] Optionally, in the example of Figure 19, the target detection is combined by generating 2M dual-wavelength transmit signals using M beam combiners / splitters; this is just one possible implementation. In another implementation, one or more beam combiners / splitters can also split the transmit signals into three or more beams. In this case, the chip includes more than 2M transmitters. Alternatively, in yet another implementation, the M beam combiners can be replaced with M beam combiners, each combining two received input signals into a single transmit signal. In this case, the chip only needs M transmitters, each of which emits a dual-wavelength optical signal. Alternatively, in another implementation, one or more second optical signals output from coupling component 410 and / or one or more second optical signals output from coupling component 420 can be directly used as one or more single-wavelength transmission signals. Other second optical signals output from coupling component 410 and / or coupling component 420 can be combined or split using a beam combiner or beam splitter to produce one or more single-wavelength or dual-wavelength transmission signals. These single-wavelength and dual-wavelength transmission signals can then be used together to detect the target. Many other possible implementations exist, and they will not be listed here.

[0259] Optionally, as shown in Figure 19, the waveguide structure 400 may further include a receiving component. This receiving component acquires the local oscillator signal and the echo signal, and mixes them to obtain an intermediate frequency (IF) signal. This IF signal is used to determine the target's velocity and / or distance. The receiving component can receive the echo signal from the chip's receiving end c. For example, one input terminal of the receiving component can be connected to the chip's receiving end c via a waveguide, optical fiber, or other means capable of transmitting optical signals. The transmitted signal is reflected by the target and becomes an echo signal, returning to the chip's receiving end c, allowing the receiving component to receive the echo signal from that receiving end c.

[0260] In addition, there may be one or more receiving components, and the local oscillator signal of each receiving component may be separated from the input signal, transmitted signal or output signal of any device in the coupling component (i.e., coupling component 410 and coupling component 420), the first waveguide (i.e., M first waveguides 511 to 51M and M first waveguides 521 to 52M), the beam combiner / splitter (i.e., M beam combiners / splitters 810 to 8M0) or the waveguide after the beam combiner / splitter.

[0261] For ease of understanding, four possible examples are given below.

[0262] Example 1, please refer to Figure 20a, which shows a possible structural diagram of the local oscillator signal being separated from the signal transmitted by the beam combiner / splitter 8M0. In this structure, there is only one receiving component, called receiving component 610. The beam combiner / splitter 8M0 also has a third output terminal. One input terminal of receiving component 610 is connected to the receiving terminal c of the chip, and the other input terminal is connected to the third output terminal of the beam combiner / splitter 8M0. The beam combiner / splitter 8M0 receives two second optical signals S. 12M S 22M Then, for the two second optical signals S 12M S 22M The components are mixed to obtain two transmitted signals and a local oscillator signal S3. The local oscillator signal S3 is output through the third output terminal and enters the receiving component 610, while the two transmitted signals are transmitted to the two transmitting terminals b. M1 and b M2 And it was launched into the exploration space.

[0263] Optionally, in the two second optical signals S 12M S 22M When the wavelengths are different, the two second optical signals S are mixed. 12M S 22M The local oscillator signal S3 obtained from the components is also dual-wavelength. The receiving component 610 can mix the signals of these two wavelengths in the echo signal and the signals of these two wavelengths in the local oscillator signal S3 based on these two wavelengths to directly obtain the intermediate frequency signals of these two wavelengths, while the signals of other wavelengths in the echo signal are treated as noise signals and are not used.

[0264] Optionally, the optical power of the local oscillator signal S3 is less than the optical power of any of the transmitted signals output by the beam combiner / splitter 8M0. For example, the beam combiner / splitter 8M0 separates a lower-power optical signal from the synthesized dual-wavelength optical signal and outputs it from its third output terminal, while the remaining high-power optical signal is output from its first two output terminals through power equalization. In this case, it can be guaranteed that the optical power of the two transmitted signals output by the beam combiner / splitter 8M0 is the same. If the coupling components 410 and 420 also equally divide the optical signals, then the optical power of the two transmitted signals output by the beam combiner / splitter 8M0 will be different from the optical power of the other transmitted signals; specifically, it will be less than the optical power of the other transmitted signals.

[0265] Example 2, please refer to Figure 20b, which shows a possible structural diagram of the local oscillator signal being separated from the input signals of coupling component 410 and coupling component 420. In this structure, there are two receiving components, referred to as receiving component 610 and receiving component 620. Receiving component 610 corresponds to the transmitting component where coupling component 410 is located, and receiving component 620 corresponds to the transmitting component where coupling component 420 is located.

[0266] For the receiving component 610, the coupling component 410 also has a second output terminal a 13 One input terminal of the receiving component 610 is connected to the receiving terminal c1 of the chip, and the other input terminal is connected to the second output terminal a of the coupling component 410. 13 Above. After receiving the first optical signal incident perpendicular to or tilted to the waveguide structure plane, the coupling component 410 splits the first optical signal into its M+1 output terminals a. 121 ~a 12M a 13 Above, where M are first output terminals a 121 ~a 12M Output M second optical signals S 121 ~S 12M Second output terminal a 13 Output local oscillator signal S 13 Assuming the first optical signal received by the coupling component 410 has a first wavelength, then the local oscillator signal S 13 It also has a first wavelength, and the receiving component 610 receives the second output terminal a of the coupling component 410. 13 Received local oscillator signal S of the first wavelength 13 And receive the echo signal S from the receiver C1 of the chip. 14 Using echo signal S 14 The signal of the first wavelength and the local oscillator signal S 13 The frequency is mixed to obtain the intermediate frequency signal of the first wavelength.

[0267] Similarly, for the receiving component 620, the coupling component 420 also has a second output terminal a 23 One input terminal of the receiving component 620 is connected to the receiving terminal c2 of the chip, and the other input terminal is connected to the second output terminal a of the coupling component 420. 23 Above. After receiving the first optical signal incident perpendicular to or tilted to the waveguide structure plane, the coupling component 420 splits the first optical signal into its M+1 output terminals a. 221 ~a 22M a 23 Above, where M are first output terminals a 221 ~a 22M Output M second optical signals S 221 ~S 22M Second output terminal a 23 Output local oscillator signal S 23 Assuming the first optical signal received by the coupling component 420 has a second wavelength, then the local oscillator signal S 23 It also has a second wavelength, and the receiving component 620 receives the second output terminal a of the coupling component 420. 23 Received local oscillator signal S of the second wavelength23 And receive the echo signal S from the receiver C2 of the chip. 24 Using echo signal S 24 The signal of the second wavelength and the local oscillator signal S 23 The frequency is mixed to obtain the intermediate frequency signal of the second wavelength.

[0268] Understandably, the local oscillator signal is single-wavelength, but the four transmitted signals are dual-wavelength. Therefore, each echo signal also has at least two wavelengths. When each echo signal performs a mixing operation in its corresponding receiving component, it is only mixed with a single wavelength of the current local oscillator signal, while other wavelengths are treated as noise signals and not used, in order to improve the quality of the intermediate frequency signal.

[0269] Optionally, for each coupling component, the optical power of the local oscillator signal it outputs is less than the optical power of the second optical signal it outputs. For example, coupling component 410 couples the lower-power optical signal from the received first optical signal to the second output terminal a. 13 The remaining high-power optical signal is coupled to the M first output terminals a through power sharing or uneven distribution. 121 ~a 12M Above. The coupling component 420 couples a similarly low-power optical signal from the received first optical signal to the second output terminal a. 23 The remaining high-power optical signal is coupled to the M first output terminals a through power sharing or uneven distribution. 221 ~a 22M Furthermore, optionally, the M beam combiners 810 to 8M0 can be power-sharing devices, so that the two transmission signals emitted by the two transmitters connected to each beam combiner will be of equal power, and the light output from each pair of detection channels will be uniform.

[0270] Example 3, please refer to Figure 20c, which shows a possible structural diagram of the local oscillator signal being separated from the signals transmitted in the first waveguide 511 and the first waveguide 52M. In this structure, there are also two receiving components, referred to as receiving component 610 and receiving component 620. Receiving component 610 corresponds to the transmitting component where the coupling component 410 is located, and receiving component 620 corresponds to the transmitting component where the coupling component 420 is located.

[0271] For the receiving component 610, the waveguide structure 400 also includes a directional coupler 710. The directional coupler 710 is coupled between the first waveguide 511 and one input terminal of the receiving component 610, and the other input terminal of the receiving component 610 is connected to the receiving terminal c1 of the chip. The directional coupler 710 does not contact the first waveguide 511, but is relatively close to it; therefore, it can transmit the second optical signal S from the first waveguide 511. 121 The local oscillator signal S is coupled out from the middle.13 and the local oscillator signal S 13 The output is sent to the receiving component 610. Assuming the first optical signal received by the coupling component 410 has a first wavelength, then the second optical signal S... 121 It also has a first wavelength, and the receiving component 610 receives the second optical signal S through the directional coupler 710. 121 The local oscillator signal S of the first wavelength is coupled out from the middle. 13 And receive the echo signal S from the receiver C1 of the chip. 14 Using echo signal S 14 The signal of the first wavelength and the local oscillator signal S 13 The frequency is mixed to obtain the intermediate frequency signal of the first wavelength.

[0272] Similarly, for the receiving component 620, the waveguide structure 400 also includes a directional coupler 720. The directional coupler 720 is coupled between the second waveguide 52M and one input terminal of the receiving component 620, and the other input terminal of the receiving component 620 is connected to the receiving terminal c2 of the chip. The directional coupler 720 does not contact the second waveguide 52M, but is relatively close to it; therefore, it can transmit the second optical signal S from the second waveguide 52M. 22M The local oscillator signal S is coupled out from the middle. 23 and the local oscillator signal S 23 The output is sent to the receiving component 620. Assuming the first optical signal received by the coupling component 420 has a second wavelength, then the second optical signal S... 22M It also has a second wavelength, and the receiving component 620 receives the second optical signal S through the directional coupler 720. 22M The second wavelength local oscillator signal S is coupled out from the middle. 23 And receive the echo signal S from the receiver C2 of the chip. 24 Using echo signal S 24 The signal of the second wavelength and the local oscillator signal S 23 The frequency is mixed to obtain the intermediate frequency signal of the second wavelength.

[0273] Based on the above beam splitting method, the optical power of the optical signal entering the beam combiner / splitter will be less than the optical power of the optical signal output from the coupling component to the split waveguide. For example, the optical power of the optical signal entering the beam combiner / splitter 810 is less than the second optical signal S output from the coupling component 410 to the first waveguide 511. 121 The optical power of the optical signal entering the beam combiner / splitter 8M0 is less than the optical signal S output from the coupling component 420 to the second waveguide 52M. 22M The optical power.

[0274] Optionally, the optical power of the local oscillator signal split from the beam-splitter is less than the optical power of the optical signal entering the subsequent beam combiner / splitter. For example, the directional coupler 710 receives the second optical signal S... 121 The lower-power optical signal is split from the first optical signal and output to the receiving component 610, while the remaining high-power optical signal is output to the beam combiner / splitter 810. The directional coupler 720 receives the second optical signal S... 22M A lower-power optical signal is split off and output to the receiving component 620, while the remaining high-power optical signal is output to the beam combiner / splitter 8M0. In this way, the higher-power beam can be used as the transmitted signal to improve the target detection effect.

[0275] Understandably, the directional coupler described above is a type of beam-splitting element. This directional coupler can also be replaced with other elements capable of beam splitting, such as a beam splitter. Taking a beam splitter as an example, the beam splitting method can also include the following example four:

[0276] Example 4, as shown in Figure 20d, illustrates another possible structural diagram for separating the local oscillator signal from the signals transmitted in the first waveguide 511 and the second waveguide 52M. This structure differs from that in Example 3 in that the directional coupler 710 in Example 3 is replaced by the beam splitter 730 in Example 4, and the directional coupler 720 in Example 3 is replaced by the beam splitter 740 in Example 4. The directional coupler couples the local oscillator signal from the waveguide in a non-contact but sufficiently close manner, while the beam splitter is directly inserted into the waveguide. It can be considered that the input end of the beam splitter is connected to the output end of the waveguide, and the two output ends of the beam splitter are then connected to subsequent components via the waveguide.

[0277] For example, as shown in Figure 20d, the input terminal of the beam splitter 730 is connected to the output terminal of the first waveguide 511, and the two output terminals are respectively connected to one input terminal of the beam combiner / splitter 810 and one input terminal of the receiving component 610. The beam splitter 730 splits the second optical signal S output from the first waveguide 511 into two optical signals. 121 The spectral splitting consists of the measurement optical signal and the local oscillator signal S. 13 The measurement optical signal is output to the beam combiner / splitter 810 to participate in the target measurement, and the local oscillator signal S is output to the beam combiner / splitter 810. 13 The output is sent to the receiving component 610 to complete the connection with the echo signal S. 14 The mixing is performed. Similarly, the input of beam splitter 740 is connected to the output of the second waveguide 52M, and the two outputs are respectively connected to one input of beam combiner / splitter 8M0 and one input of receiver 620. Beam splitter 740 converts the second optical signal S output from the second waveguide 52M into a frequency-mixing signal. 22M The spectral splitting consists of the measurement optical signal and the local oscillator signal S. 23 The measurement optical signal is output to the beam combiner / splitter 8M0 to participate in the target measurement, and the local oscillator signal S is output to the beam combiner / splitter 8M0. 23The output is sent to the receiving component 620 to complete the connection with the echo signal S. 24 Frequency mixing.

[0278] Understandably, the four examples above are just a few possible structures for extracting the local oscillator signal from the input signal. Other extraction structures can be deduced by analogy with the above structures, and will not be repeated here.

[0279] Optionally, the above receiving component can be any component or combination thereof capable of performing mixing. For example, taking the structure shown in Figure 20a as an example, please refer to Figure 21a, which shows a specific structural schematic diagram of a receiving component provided in Embodiment 2. Combining Figures 20a and 21a, in this example, the receiving component 610 includes a beam splitter 611 and M mixers, namely mixers 6121, 6122, ..., 612M. The beam splitter 611 has one input terminal and M output terminals. The input terminal is the input terminal of the receiving component 610, used to acquire the local oscillator signal S3. The M output terminals are respectively connected to the M first input terminals of the M mixers 6121 to 612M. The M second input terminals of the M mixers 6121 to 612M are connected to the M receiving terminals c1, c2, ..., c of the chip. M Here, the connections between the various components can be achieved through waveguides, optical fibers, or other means that can transmit optical signals. Figure 21a shows a waveguide connection as an example.

[0280] Based on this structure and connection, the input of beam splitter 611 can receive a dual-wavelength local oscillator signal S3. Beam splitter 611 splits the dual-wavelength local oscillator signal S3 (e.g., equally distributed with equal power) into M dual-wavelength sub-local oscillator signals S. 31 S 32 ... S 3M And through its M output terminals, these M dual-wavelength sub-local oscillator signals S 31 ~S 3M The outputs are distributed to M mixers 6121 to 612M. These M mixers 6121 to 612M can also receive signals from the chip's M receivers c1 to c2. M Received M echo signals S 41 S 42 ... S 4M Each mixer performs a mixing operation on the signal in the received echo signal that has the same wavelength as the dual-wavelength sub-local oscillator signal, generating its own intermediate frequency (IF) signal. The M IF signals generated by the M mixers 6121 to 612M together achieve the target measurement.

[0281] Optionally, the M mixers 6121-612M, together with subsequent components, achieve target measurement. For example, as shown in Figures 20a and 21a, the receiving component 610 may further include a detection element 613. The detection element 613 is connected between the output terminals of the M mixers 6121-612M and the electrical output terminal (d) of the chip, and is used to perform photoelectric detection on the M intermediate frequency signals generated by the M mixers 6121-612M to obtain and output electrical signals. This electrical signal is transmitted to subsequent components, such as an electrical chip, through the electrical output terminal d of the chip. In the electrical chip, the intermediate frequency signal is processed to obtain point cloud data and determine the distance and / or velocity of the target.

[0282] The structure of the receiving component 610 shown in Figure 21a above can be directly deduced from the receiving component 620. For example, referring to Figure 21b in conjunction with Figure 21a and Figure 20c above, the receiving component 610 includes a beam splitter 611 and M mixers 6121 to 612M. The input terminal of the beam splitter 611 is the input terminal of the receiving component 610, used to acquire the local oscillator signal S. 13 The M output terminals of beam splitter 611 are respectively connected to the M first input terminals of M mixers 6121 to 612M, and the M second input terminals of the M mixers 6121 to 612M are connected to the M receiving terminals c of the chip. 11 c 12 ... c 1M Similarly, the receiving component 620 includes a beam splitter 621 and M mixers, namely mixers 6221, 6222, ..., 622M. The input terminal of the beam splitter 621 is the input terminal of the receiving component 620, used to acquire the local oscillator signal S. 23 The four outputs of beam splitter 621 are respectively connected to the M first inputs of M mixers 6221 to 622M, and the M second inputs of the M mixers 6221 to 622M are connected to the other M receivers of the chip. 21 c 22 ... c 2M .

[0283] Based on this structure and connection, assuming the first optical signal received by the coupling component 410 is of the first wavelength, then, in the receiving component 610, the input terminal of the beam splitter 611 can receive the local oscillator signal S of the first wavelength. 13 The beam splitter 611 splits the local oscillator signal S of the first wavelength. 13 The light is split (e.g., evenly divided with equal power) into M sub-local oscillator signals S of the first wavelength. 131 S 132 ... S 13M And through its M output terminals, these M sub-local oscillator signals S of the first wavelength are... 131 ~S 13MThe outputs are distributed to M mixers 6121 to 612M. These M mixers 6121 to 612M can also receive signals from the chip's M receivers c. 11 ~c 1M Received M echo signals S 141 S 142 ... S 14M Each mixer performs a mixing operation on the first wavelength signal in the received echo signal and the sub-local oscillator signal to generate its own intermediate frequency (IF) signal. The four IF signals generated by the M mixers 6121 to 612M are all IF signals of the first wavelength. In other words, they can indicate relevant information about the target at the measurement distance corresponding to the first wavelength, such as distance and / or velocity.

[0284] Similarly, assuming the first optical signal received by the coupling component 420 is of the second wavelength, then in the receiving component 620, the input terminal of the beam splitter 621 can receive the local oscillator signal S of the second wavelength. 23 The beam splitter 621 splits the second wavelength local oscillator signal S 23 The light is split (e.g., evenly split with equal power) into M sub-local oscillator signals of the second wavelength S. 231 S 232 ... S 23M And through its M output terminals, these M second-wavelength sub-local oscillator signals S 231 ~S 23M The outputs are distributed to M mixers 6221 to 622M. These M mixers 6221 to 622M can also receive signals from the chip's additional M receivers. 21 ~c 2M Received M echo signals S 241 S 242 ... S 24M Each mixer performs a mixing operation on the second wavelength signal in the received echo signal and the sub-local oscillator signal to generate its own intermediate frequency (IF) signal. The M IF signals generated by the M mixers 6221 to 622M are all second wavelength IF signals. In other words, they can indicate relevant information about the target at the measurement distance corresponding to the second wavelength, such as distance and / or velocity.

[0285] Optionally, the 2M mixers 6121-612M and 6221-622M can be combined with subsequent components to achieve target measurement. For example, as shown in Figure 21b, the waveguide structure can also include a detection element 630. The detection element 630 is connected between the output terminals of the 2M mixers 6121-612M and 6221-622M and the electrical output terminal (d) of the chip. It is used to perform photoelectric detection on the 2M intermediate frequency signals generated by the 2M mixers 6121-612M and 6221-622M, obtain electrical signals, and output them. The electrical signals are transmitted to subsequent components, such as an electrical chip, through the electrical output terminal d of the chip. In the electrical chip, the intermediate frequency signals are processed to obtain point cloud data and determine the distance and / or velocity of the target.

[0286] Based on the above implementation scheme 2, two transmitting components and one or two receiving components can be set in the waveguide structure, and the local oscillator signal of any one of the receiving components can be separated from the correlation signal of any element in the transmitting component. Therefore, the waveguide structure has high flexibility and versatility and can be adapted to various detection occasions.

[0287] Implementation Plan 3: Includes K transmission components.

[0288] Please refer to Figure 22, which shows a schematic diagram of a waveguide structure provided in Implementation Scheme 3. In this example, the waveguide structure 400 includes K transmitting components, where K is an integer greater than or equal to 2. It is understood that Implementation Scheme 2 above is a special case of Implementation Scheme 3, specifically the structure when K = 2 in Implementation Scheme 3.

[0289] As shown in Figure 22, each of the K transmitting modules includes the coupling component described above and M first waveguides. For example, as shown in Figure 22, from top to bottom, the first transmitting module includes the coupling component 410 and M first waveguides 511 to 51M, the second transmitting module includes the coupling component 420 and M first waveguides 521 to 52M, ..., and the Kth transmitting module includes the coupling component 4K0 and M first waveguides 5K1 to 5KM. In this case, the waveguide structure 400 also includes M beam combiners / splitters 810 to 8M0. Each of the M beam combiners / splitters 810 to 8M0 has K input terminals and at least two output terminals. The figure shows an example with two output terminals. The K input terminals of the beam combiner / splitter 810 are respectively connected to the output terminals of the K first waveguides 511, 521, ..., 5K1 in the K transmitting modules, and the two output terminals of the beam combiner / splitter 810 are connected to the two transmitting terminals b of the chip. 11 b 12 The K input terminals of the beam combiner / splitter 820 are respectively connected to the output terminals of the other K first waveguides 512, 522, ..., 5K2 in the K transmitting components. The two output terminals of the beam combiner / splitter 820 are connected to the other two transmitting terminals b of the chip. 21b 22 ...The K input terminals of the beam combiner / splitter 8M0 are respectively connected to the output terminals of the K first waveguides 51M, 52M, ..., 5KM in the K transmitting components. The two output terminals of the beam combiner / splitter 8M0 are connected to the two transmitting terminals b of the chip. M1 b M2 .

[0290] Optionally, the K first optical signals received by the K transmitting modules are of different wavelengths. In each transmitting component, the coupling component splits the input single-wavelength first optical signal into M single-wavelength second optical signals. The M single-wavelength second optical signals are transmitted through M first waveguides to M beam combiners / splitters 810–8M0. Each of the M beam combiners / splitters 810–8M0 performs beam combining and splitting processing on the input K-wavelength second optical signals to obtain two transmitted signals, both of which are K-wavelength optical signals. The two K-wavelength transmitted signals are emitted from two transmitting ends of the chip to the scanning component, and scanned into the detection space by the scanning component. The 2M transmitted signals emitted by the M beam combiners / splitters are used to jointly measure the target in the detection space.

[0291] Alternatively, the K first optical signals received by the K transmitting modules can be of the same wavelength but with different polarization states, or of the same wavelength and with the same polarization state but with different polarization elements to distinguish their respective echo signals, or some of the first optical signals are of different wavelengths and others are of the same wavelength but with different polarization states, or some of the first optical signals are of the same wavelength but with different polarization states and others have the same wavelength and the same polarization state but are distinguished by polarization elements, and so on. There are many possible implementation methods, and no specific limitation is made here.

[0292] Optionally, similar to embodiment two above, as shown in Figure 22, the waveguide structure 400 may further include one or more receiving components. The local oscillator signal of each receiving component can be separated from the input signal, transmitted signal, or output signal of an element in one of the K coupling components (i.e., 410–4K0), K×M first waveguides (i.e., 511–51M, 521–52M, …, 5K1–5KM), M beam combiners / splitters (i.e., 810–8M0), and the waveguides after the M beam combiners / splitters. For example:

[0293] In one example, Figure 23a shows a structural diagram of a receiving component in a waveguide structure 400. This diagram illustrates the separation of the local oscillator signal S3 from the signal transmitted by the beam combiner / splitter 8M0. Schemes for separation from other beam combiners / splitters can be deduced by analogy to this diagram. In this example, the beam combiner / splitter 8M0 also has a third output terminal connected to the receiving module 610. The beam combiner / splitter 8M0 can also separate a K-wavelength local oscillator signal S3 from a synthesized K-wavelength beam signal. This K-wavelength local oscillator signal S3 enters the receiving module 610 and is mixed with the echo signal S4 received by the chip's receiving terminal c across K wavelengths to obtain an intermediate frequency signal.

[0294] In another example, Figure 23b shows a structural diagram of waveguide structure 400 including K receiving components, with K local oscillator signals S 13 S 23 ... S K3 Taking the input signals from coupling components 410, 420, ..., 4K0 as an example, the K receiving components are receiver 610, 620, ..., 6K0, and correspond one-to-one with the K coupling components 410 to 4K0. Each of the K coupling components 410 to 4K0 also has a second output terminal, which is connected to the corresponding receiving component. Each coupling component can also separate a single-wavelength local oscillator signal from the input single-wavelength first optical signal and transmit it to the connected receiving component. This single-wavelength local oscillator signal is mixed with the received echo signal at a single wavelength in the receiving component to obtain an intermediate frequency signal. When the first optical signal input to the K coupling components 410 to 4K0 has K wavelengths, the K local oscillator signals S 13 ~S K3 It also has K wavelengths, each local oscillator signal is a single wavelength, and each receiving component only mixes the signal with the same wavelength as the local oscillator signal in the echo signal it receives, and the signals of other wavelengths are treated as noise signals and are not used.

[0295] In another example, Figure 23c shows a different structural diagram of waveguide structure 400 including K receiving components 610-6K0, with K local oscillator signals S 13 S 23 ... S K3Taking the separation of signals transmitted from any of the first waveguides following coupling components 410 to 4K0 as an example, the waveguide structure 400 further includes K beam splitting elements. The illustration shows K directional couplers 710, 720, ..., 7K0 as an example. These K directional couplers 710 to 7K0 correspond one-to-one with K receiving components 610 to 6K0. Each directional coupler can be coupled between any first waveguide of any transmitting component and the input terminal of the corresponding receiving component. Each directional coupler is used to split a single-wavelength local oscillator signal from the single-wavelength optical signal transmitted through the coupled first waveguide, and outputs the single-wavelength local oscillator signal to the coupled receiving component. This single-wavelength local oscillator signal is mixed with the received echo signal in the receiving component at a single wavelength to obtain an intermediate frequency (IF) signal. When the first optical signal input to the K coupling components 410 to 4K0 has K wavelengths, the K receiving components can mix the signals to obtain the IF signals corresponding to each of the K wavelengths.

[0296] Based on the above implementation scheme three, K transmitting components and one or K receiving components can be set in the waveguide structure. When a single receiving component is set, its local oscillator signal can be separated from the combined optical signal, and the local oscillator signal is a multi-wavelength signal. When K receiving components are set, the local oscillator signal of each receiving component can be separated from the correlated signal of a transmitting component, and the local oscillator signals of the K receiving components are all single-wavelength signals with different wavelengths. This waveguide structure has high flexibility and versatility and can be adapted to various detection applications.

[0297] It is understandable that, unless otherwise specified or logically conflicting, the terminology and / or descriptions of the various implementation schemes described above are consistent and can be referenced from each other. The technical features of different implementation schemes can be combined to form new implementation schemes based on their inherent logical relationships.

[0298] Furthermore, the above implementation schemes can be modified to form new implementation schemes. For example, in another example, in implementation scheme three above, more than K receiving components can be set. For instance, a local oscillator signal can be separated from each first waveguide, resulting in M×K local oscillator signals, corresponding to M×K receiving components. Alternatively, local oscillator signals can be separated from at least two first waveguides connected by partially coupled components, forming any number of local oscillator signals more than K but less than M×K, and the same number of receiving components can be set. Alternatively, other beam splitting elements besides directional couplers and beam splitters can be used to achieve the effect of separating local oscillator signals. And so on, which will not be listed here.

[0299] The waveguide structures described above can be applied to chips, such as silicon photonic chips, specifically SOI silicon photonic chips.

[0300] Please refer to Figure 24a, which shows a possible structural schematic diagram of a silicon photonic chip provided in this application. The silicon photonic chip 2400 includes a waveguide structure, which can be any waveguide structure described above, such as the waveguide structure 400 in any of the figures in Figures 4a to 23c.

[0301] Optionally, when the silicon photonic chip 2400 is an SOI silicon photonic chip, as shown in Figure 24a, it may include a silicon substrate layer and a buried oxide layer stacked sequentially (e.g., stacked from bottom to top as shown in the figure), with the waveguide structure disposed on the buried oxide layer. Figure 24a uses the waveguide structure shown in Figure 7 as an example. In some scenarios, the layer containing the waveguide structure can also be called a waveguide layer. The waveguide layer is a layer made of waveguide material. In this case, the silicon photonic chip 2400 can also be considered to include a silicon substrate layer, a buried oxide layer, and a waveguide layer stacked sequentially, with the waveguide structure located in the waveguide layer.

[0302] Optionally, the area surrounding the waveguide structure, such as between the strips of the GC, between the GC and the first connection, or between the two branches, can be filled with a medium made of a low-refractive-index material. Here, "low-refractive-index" means less than the refractive index of the material used in the waveguide structure. Several possible designs exist, such as:

[0303] Design 1, as shown in Figure 24a, involves a waveguide structure exposed to air. Air is a low-refractive-index material, and the waveguide structure's direct contact with air is equivalent to being filled with a low-refractive-index medium, only the medium is air. This design can reduce the thickness of the silicon photonics chip 2400, saving the space occupied by the silicon photonics chip 2400.

[0304] Design 2, as shown in Figure 24b, further includes an upper cladding layer stacked on top of the buried oxide layer. The waveguide structure is embedded within the upper cladding layer, with its bottom contacting the buried oxide layer. The upper cladding layer can be made of any material with a refractive index lower than that of the waveguide structure, such as silicon oxide or silicon nitride. The upper cladding layer protects the internal waveguide structure.

[0305] The silicon photonics chip 2400 described above can be used in detection devices or systems with frequency modulation capabilities, such as the FMCW LiDAR mentioned above, or optical frequency domain reflectometry (OFDR) systems, optical coherence tomography (OCT) systems, etc., without any specific limitations.

[0306] Please refer to Figure 25, which shows a possible structural schematic diagram of a detection device provided in this application. The detection device 2500 may include the waveguide structure described above, or it may include the silicon photonic chip 2400 mentioned above, as shown in Figure 25.

[0307] Optionally, as shown in Figure 25, the detection device 2500 may further include a light source assembly 2510, which is used to emit an optical signal. The optical signal is incident on the GC in the silicon photonic chip 2400 in a direction perpendicular to or inclined to the plane of the silicon photonic chip 2400. After being converted into an optical signal parallel to the plane of the silicon photonic chip by the GC, it is coupled into the waveguide structure, transmitted through the transmitting component on the waveguide structure, and emitted from the transmitting end of the silicon photonic chip 2400.

[0308] Optionally, as shown in Figure 25, the detection device 2500 further includes a scanning component 2520, which scans the light signal emitted from the emitter of the silicon photonic chip 2400 into the detection space. After the light signal illuminates the target in the detection space, it is reflected by the target to form an echo signal. Optionally, the echo signal can also be scanned by the scanning component 2520 to the receiver of the silicon photonic chip 2400. The receiver of the silicon photonic chip 2400 can also be equipped with a coupling component, through which the echo signal is coupled to the waveguide structure of the silicon photonic chip 2400. After being mixed with the local oscillator signal by the receiving component in the waveguide structure, an intermediate frequency signal is generated, which is then converted into an electrical signal and output from the electrical output terminal of the silicon photonic chip 2400.

[0309] Further, optionally, as shown in FIG25, the detection device 2500 also includes a processing component 2531. The processing component 2531 is disposed on the electrical chip 2530. The input terminal of the electrical chip 2530 is connected between the electrical output terminal of the silicon photonic chip 2400 and the input terminal of the processing component 2531. Therefore, the electrical signal output by the electrical output terminal of the silicon photonic chip 2400 is transmitted to the processing component 2531. The processing component 2531 performs target detection based on the electrical signal, such as determining the distance and / or speed of the target.

[0310] Furthermore, alternatively, other components, such as an amplifier and an analog-to-digital converter (ADC), can also be incorporated into the electrical chip 2530, as shown in the figure. The input of the amplifier is connected to the electrical output of the silicon photonics chip 2400, and the ADC is connected between the output of the amplifier and the input of the processing component 2531. The amplifier amplifies the electrical signal output by the silicon photonics chip 2400, and the ADC discretizes the amplified electrical signal, converting it into a digital signal and outputting it to the processing component 2531, enabling the processing component 2531 to perform target detection based on the digital signal.

[0311] Optionally, as shown in Figure 25 above, the detection device 2500 may further include a window 2540, which is used to protect the various components inside the detection device 2500 and can transmit the light signal emitted by the detection device 2500.

[0312] It should be noted that the detection device architecture shown in Figure 25 is only an example. In other examples, the detection device may include more, fewer, or different structures, and each structure may include more, fewer, or different components. This application does not make any specific limitations in this regard.

[0313] Based on the structure and functional principle of the detection device described above, this application can also provide a terminal device, as shown in Figure 26. This terminal device 2600 may include the silicon photonics chip described above, or it may include the detection device 2500 described above, as shown in Figure 26.

[0314] Optionally, as shown in Figure 26, the terminal device 2600 may further include a processor 2610, which is used to call programs or instructions to control the operation of the detection device 2500. Furthermore, the processor 2610 can also receive target-related information from the detection device 2500. When the terminal device 2600 is a vehicle, the processor 2610 can also perform vehicle path planning, braking, or starting based on this information. For example, the vehicle's position can be determined using latitude and longitude, or the vehicle's direction of travel and destination in the future can be determined using speed and orientation, or the number and density of obstacles around the vehicle can be determined using the distance to surrounding objects.

[0315] Furthermore, optionally, the terminal device 2600 may also include a memory 2620 for storing programs or instructions. Of course, the terminal device 2600 may also include other devices, such as wireless communication devices.

[0316] Processor 2610 may include one or more processing units. For example, processor 2610 may include an application processor (AP), an image signal processor (ISP), a controller, a DSP, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Different processing units may be independent devices or integrated into one or more processors.

[0317] The memory 2620 includes, but is not limited to, random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. Exemplarily, the storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside within an ASIC.

[0318] For example, the terminal device 2600 may be a vehicle (e.g., unmanned vehicle, intelligent vehicle, electric vehicle, or digital car), robot, surveying equipment, drone, smart home device (e.g., television, robot vacuum cleaner, smart lamp, audio system, smart lighting system, electrical control system, home background music, home theater system, intercom system, or video surveillance), smart manufacturing equipment (e.g., industrial equipment), smart transportation equipment (e.g., AGV, unmanned transport vehicle, or truck), or smart terminal (mobile phone, computer, tablet, PDA, desktop computer, headphones, audio equipment, wearable device, in-vehicle device, virtual reality device, augmented reality device, etc.).

[0319] It should be noted that with the development of detection technology, the coherent calibration device structure provided in this application is also applicable to the same technical problems, and this application does not make specific limitations on it.

[0320] In the above content, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0321] Additionally, in this application, the terms "optionally" or "exemplary" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design described as "optional" or "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Alternatively, it can be understood that the use of the terms "exemplary" or "optional" is intended to present concepts in a specific manner and does not constitute a limitation of this application.

[0322] It is understood that the various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and inherent logic. Terms such as "first," "second," and similar expressions are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

Claims

1. A waveguide structure, characterized in that, include: A grating coupler, a first connecting part, and an N-stage beam splitter unit, where N is a positive integer; The input end of the N-level beam splitter is connected to the output end of the first connection part; The cross-sectional area of ​​the output end of the first connection part is greater than or equal to the cross-sectional area of ​​the input end of the first connection part; The first optical signal incident on the grating coupler is transmitted through the first connection part and becomes an optical signal in the multimode waveguide. The optical signal in the multimode waveguide is split into at least two second optical signals by the N-stage beam splitting unit. The optical power of each of the at least two second optical signals is less than the optical power of the first optical signal.

2. The waveguide structure as described in claim 1, characterized in that, The first connecting part satisfies the following conditions: The first connection portion includes a pattern converter, wherein the cross-sectional area of ​​the output terminal of the pattern converter is greater than or equal to the cross-sectional area of ​​the input terminal of the pattern converter; or, The first connection part includes a multimode waveguide and a mode converter. The output end of the multimode waveguide is connected to the input end of the mode converter. The cross-sectional area of ​​the output end of the mode converter is greater than or equal to the cross-sectional area of ​​the input end of the multimode waveguide.

3. The waveguide structure as described in claim 1 or 2, characterized in that, When N is 1: The N-level beam splitter includes a beam splitter with at least two branches. The inputs of the at least two branches are connected to the output of the first connection, and the outputs of the at least two branches serve as the outputs of the N-level beam splitter.

4. The waveguide structure as described in claim 1 or 2, characterized in that, When N is greater than or equal to 2: The first-stage beam splitting unit includes a beam splitter, which includes at least two branches. The input ends of the at least two branches are connected to the output end of the first connection part, and the output ends of the at least two branches are connected to the input end of the second-stage beam splitting unit through at least two second connection parts. Each of the second-level beam splitting units to the Nth-level beam splitting units includes one or more beam splitters. Each of the one or more beam splitters includes at least two branches. The input end of the one or more beam splitters is connected to the output end of the previous-level beam splitting unit through a second connection. The output end of the one or more beam splitters is connected to the input end of the next-level beam splitting unit through a second connection, or serves as the output end of the Nth-level beam splitting unit.

5. The waveguide structure as described in claim 3 or 4, characterized in that, In the direction from the input to the output of the branch: The cross-sectional shape of the branch remains unchanged; or, The height of the branch remains constant, while the width of the branch's cross-section tends to increase or decrease.

6. The waveguide structure as described in any one of claims 3 to 5, characterized in that, The branch includes a curved structure.

7. The waveguide structure as described in any one of claims 3 to 6, characterized in that, The cross-sectional area of ​​the output end of the second connection is greater than or equal to the cross-sectional area of ​​the input end.

8. The waveguide structure as described in claim 7, characterized in that, When N is greater than or equal to 2, the cross-sectional area of ​​the output end of the second connection between the first-level to the T-level beam splitting units is greater than the cross-sectional area of ​​the input end, and the cross-sectional area of ​​the output end of the second connection between the T-level to the N-level beam splitting units is equal to the cross-sectional area of ​​the input end, where T is a positive integer less than N.

9. The waveguide structure as described in any one of claims 1 to 8, characterized in that, The first connecting part and part or all of the N-level beam splitting unit are subwavelength grating structures.

10. The waveguide structure as described in claim 9, characterized in that, When all are subwavelength grating structures, the first connecting portion and the Nth-level beam splitter include a periodic region; When the part is a subwavelength grating structure, the first connecting part and the N-level beam splitter unit include a periodic region, a transition region and a continuous region, and the periodic region, the transition region and the continuous region are arranged along the direction from the first connecting part to the N-level beam splitter unit.

11. The waveguide structure as described in any one of claims 1 to 10, characterized in that, The waveguide structure further includes at least two first waveguides, which are connected to at least two first output terminals of the N-level beam splitter unit and are used to receive the at least two second optical signals output by the N-level beam splitter unit.

12. The waveguide structure as described in claim 11, characterized in that, The at least two first waveguides are both single-mode waveguides, and the mode size of the at least two first output terminals is the same as the mode size of the single-mode waveguide.

13. The waveguide structure as described in any one of claims 1 to 12, characterized in that, At least two first output terminals of the N-level beam splitter unit are connected to at least two transmitting terminals of the chip in which the waveguide structure is located. At least two second optical signals output by the at least two first output terminals serve as at least two transmitting signals of the chip. The at least two transmitting signals are scanned to the detection space by the scanning component for the purpose of detecting the target.

14. The waveguide structure as described in claim 13, characterized in that, The waveguide structure also includes a receiving component; The receiving component is used to acquire a local oscillator signal and an echo signal, and to mix the local oscillator signal and the echo signal to obtain an intermediate frequency signal, which is used to determine the speed and / or distance of the target. The local oscillator signal is derived from the input signal, transmitted signal, or output signal of the first connection part, any first-level beam splitting unit, or any first waveguide.

15. The waveguide structure as described in claim 14, characterized in that, The N-level beam splitter unit also has a second output terminal, which outputs the local oscillator signal, and the receiving component is connected between the second output terminal and the receiving terminal of the chip.

16. The waveguide structure as described in claim 14, characterized in that, The waveguide structure further includes a beam splitter element, which is coupled between any of the first waveguides and the input end of the receiving component; The beam splitter is used to split the second optical signal transmitted through the coupled first waveguide into the local oscillator signal and output the local oscillator signal to the receiving component.

17. The waveguide structure as described in claim 16, characterized in that, The beam splitting element is a directional coupler or a beam splitter.

18. The waveguide structure as described in any one of claims 1 to 12, characterized in that, The grating coupler, the first connection part, the N-level beam splitter and the at least two first waveguides are located in the transmitting assembly, and there are K transmitting assemblies, where K is an integer greater than or equal to 2; The waveguide structure further includes M beam combiners and splitters, where M is an integer greater than or equal to 2. Each of the M beam combiners and splitters has K input terminals and at least two first output terminals. The K input terminals are respectively connected to the output terminals of the K first waveguides in the K transmitting components, and the at least two first output terminals are connected to at least two transmitting terminals of the chip in which the waveguide structure is located. Each beam combiner / splitter is used to combine the K input optical signals into a beam and then split the beam into at least two transmitted signals. All the transmitted signals split by the M beam combiners and splitters are scanned into the detection space by the scanning component for target detection.

19. The waveguide structure as described in claim 18, characterized in that, The optical signals from the K emitting components have different wavelengths and / or different polarization states.

20. The waveguide structure as described in claim 18 or 19, characterized in that, The waveguide structure also includes a receiving component; The receiving component is used to acquire a local oscillator signal and an echo signal, and to mix the local oscillator signal and the echo signal to obtain an intermediate frequency signal, which is used to determine the speed and / or distance of the target. The local oscillator signal is derived from the input signal, transmitted signal, or output signal of the first connection part of any transmitting component, the N-level beam splitting unit of any transmitting component, the first waveguide of any transmitting component, or any beam combiner / splitter.

21. The waveguide structure as described in claim 20, characterized in that, There are K receiving components, and each of the K receiving components corresponds one-to-one with the K transmitting components. Each transmitting component has an N-level beam splitter unit with a second output terminal, which outputs the local oscillator signal. Each receiving component is connected between the second output terminal of the N-level beam splitter unit in the corresponding transmitting component and a receiving terminal of the chip.

22. The waveguide structure as described in claim 20, characterized in that, The M beam combiners and splitters include a first beam combiner and splitter, which also has a second output terminal. The receiving component is connected between the second output terminal and the receiving terminal of the chip. The first beam combiner / splitter is further configured to separate the local oscillator signal from the combined optical signal and output the local oscillator signal to the receiving component through the second output terminal.

23. The waveguide structure as described in claim 20, characterized in that, The receiving component has K components, and the waveguide structure also includes K beam splitting elements. The K beam splitting elements correspond one-to-one with the K transmitting components and the K receiving components. Each beam splitting element is coupled between a first waveguide of the corresponding transmitting component and the input end of the corresponding receiving component. The K beam splitting elements are used to split the local oscillator signal from the optical signal transmitted through the coupled first waveguide and output the local oscillator signal to the coupled receiving component.

24. The waveguide structure as described in any one of claims 14 to 17 and 20 to 23, characterized in that, The optical power of the local oscillator signal is less than the optical power of each of the at least two second optical signals.

25. The waveguide structure as described in any one of claims 14 to 17 and 20 to 24, characterized in that, The receiving component includes a beam splitter and at least two mixers. The input of the beam splitter is used to receive the local oscillator signal. The at least two outputs of the beam splitter are connected to the first inputs of the at least two mixers, and the second inputs of the at least two mixers are connected to the at least two receiving terminals of the chip. The beam splitter is used to split the local oscillator signal into at least two sub-local oscillator signals, and output the at least two sub-local oscillator signals to the at least two mixers; The at least two mixers are used to perform a mixing operation on the at least two sub-local oscillator signals and the at least two echo signals received by the at least two receiving ends of the chip to obtain at least two intermediate frequency signals.

26. The waveguide structure as described in claim 25, characterized in that, The receiving component further includes a detection element connected between the output terminals of the at least two mixers and the electrical output terminal of the chip; The detection element is used to perform photoelectric detection on the at least two intermediate frequency signals, obtain an electrical signal, and output it.

27. A silicon photonic chip, characterized in that, Includes the waveguide structure as described in any one of claims 1 to 26.

28. The silicon photonics chip as described in claim 27, characterized in that, The silicon photonic chip comprises a silicon substrate layer, a buried oxide layer, and a waveguide layer stacked sequentially, with the waveguide structure located in the waveguide layer.

29. The silicon photonics chip as described in claim 28, characterized in that, The waveguide structure is exposed to air, or the silicon photonic chip further includes an upper cladding layer, which is stacked on the waveguide layer, and the waveguide structure is embedded in the upper cladding layer; wherein the refractive index of air or the refractive index of the material of the upper cladding layer is lower than the refractive index of the material of the waveguide structure.

30. A detection device, characterized in that, Including the silicon photonics chip as described in any one of claims 27 to 29.

31. The detection device as described in claim 30, characterized in that, It also includes a light source assembly; The light source component is used to emit optical signals to the silicon photonic chip, and the optical signals are coupled into the waveguide structure through the grating coupler.

32. The detection device as described in claim 30 or 31, characterized in that, It also includes a scanning component; The scanning component is used to scan the optical signal emitted by the silicon photonic chip into the detection space.

33. The detection device according to any one of claims 30 to 32, characterized in that, It also includes a processing component disposed on the electrical chip; The processing component is used to determine the distance and / or speed of the target based on the electrical signal output by the silicon photonics chip.

34. A terminal device, characterized in that, Includes the detection device as described in any one of claims 30 to 33.

Images