Waveguide structure, silicon optical chip, detection device and terminal equipment

Abstract

The utility model discloses a waveguide structure, a silicon optical chip, a detection device and terminal equipment, relates to the technical field of sensors, and aims to improve the spot size of the waveguide structure. The waveguide structure comprises N stages of waveguides, the first stage of waveguide comprises N first waveguide units, the Ith stage of waveguide at most comprises N-I + 2 second waveguide units and N-I + 1 first waveguide units, the N-I + 2 second waveguide units are connected with the first waveguide units in the (I-1) th stage of waveguide, and when the (I + 1) th stage of waveguide exists, the N-I + 2 second waveguide units are connected with the first waveguide units in the (I-1) th stage of waveguide. The N-I + 1 first waveguide units are connected with the second waveguide units in the I + 1-stage waveguide, the I-stage waveguide is used for realizing coupling transmission of optical signals between the first waveguide units and the second waveguide units, N is an integer greater than or equal to 2, and I is an integer greater than or equal to 2 and less than or equal to N. The waveguide structure can realize large-spot-size signal reception or signal emission, and can improve the coupling efficiency of the port.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a laser radar and a waveguide structure and a silicon photonic chip of the laser radar. The laser radar can be applied but not limited to the field of transportation control. Background Art

[0002] In the silicon photonic chip process, the Silicon-On-Insulator (SOI) process is the most mature. This process achieves dielectric isolation between components in the chip by introducing a buried oxide layer (also called an insulating layer) between the top silicon and the back substrate. Compared with silicon nitride (SiN) and programmable logic chips (PLC), SOI silicon photonic chips have the advantages of small size, doping, support for active device integration such as photodiodes (PDs), high yield, and low cost.

[0003] At present, ports are usually set on the end face of SOI silicon photonic chips, including transmitting ports, receiving ports, or integrated transceiver ports. The transmitting port or the integrated transceiver port can emit the optical signal in the SOI silicon photonic chip to the outside of the SOI silicon photonic chip, while the receiving component or the integrated transceiver port can couple the optical signal outside the SOI silicon photonic chip into the SOI silicon photonic chip. The performance of these ports is crucial to the coupling efficiency of optical signals inside and outside the SOI chip. However, the current mainstream ports have a relatively small mode spot size, resulting in a relatively low coupling efficiency, which is not conducive to improving chip performance.

[0004] In summary, how to increase the mode spot size of the port is a technical problem that needs to be solved urgently in the field of SOI silicon photonic chips. Utility Model Content

[0005] The present application provides a waveguide structure, a silicon photonic chip, a detection device and a terminal device, which are used to increase the mode spot size of the waveguide structure (such as a port).

[0006] In a first aspect, the present application provides a waveguide structure, including N-level waveguides, the first-level waveguide includes N first waveguide units, the first-level waveguide includes at most N-I+2 second waveguide units and N-I+1 first waveguide units, wherein the N-I+2 second waveguide units are connected to the first waveguide unit in the I-1-level waveguide, and when there is an I+1-level waveguide, the N-I+1 first waveguide units are connected to the second waveguide unit in the I+1-level waveguide, N is an integer greater than or equal to 2, and I is an integer greater than or equal to 2 and less than or equal to N. The first-level waveguide is used to transmit an optical signal; the first-level waveguide is used to couple the optical signals transmitted on the N-I+2 second waveguide units to the N-I+1 first waveguide units for transmission, or to couple the optical signals transmitted on the N-I+1 first waveguide units to the N-I+2 second waveguide units for transmission.

[0007] Based on the above waveguide structure, the transmission of optical signals from the first-level waveguide to the N-level waveguide, or from the N-level waveguide to the first-level waveguide can be realized. The first-level waveguide has N first waveguide units, so the first-level waveguide has a large mode spot size. When the optical signal is transmitted from the N-level waveguide to the first-level waveguide, a large mode spot of the transmitted optical signal can be realized, thereby improving the transmission efficiency. When the optical signal is transmitted from the first-level waveguide to the N-level waveguide, a large mode spot of the received optical signal can be realized, thereby improving the receiving efficiency. In this way, whether it is used as a transmitting port, a receiving port, or a transceiver-integrated port, the waveguide structure can have a large mode spot size, thereby improving the coupling efficiency of the port.

[0008] It should be noted that the first-level waveguide includes at most N-I+2 second waveguide units and N-I+1 first waveguide units. It can be understood that the most ideal situation is to include N-I+2 second waveguide units and N-I+1 first waveguide units, so that the coupling transmission performance of the signal between the two waveguide units is the best. However, in some examples, less than N-I+2 second waveguide units and / or less than N-I+1 first waveguide units may be included. In other words, the number of first waveguide units and / or second waveguide units may be reduced, and other effects may be achieved by sacrificing the performance of partial signal coupling transmission, such as reducing material costs, reducing structural complexity, reducing occupied space, etc.

[0009] In a possible design, the waveguide units in each level of waveguide are placed in parallel, and the spacing between adjacent waveguide units is smaller than a set spacing.

[0010] Based on the above design, parallel placement allows the optical signals in multiple waveguide units to be transmitted in parallel without exciting multiple modes due to crossing and causing transmission losses. By setting adjacent waveguide units close enough, the optical signals can be coupled between adjacent waveguide units, reducing the coupling losses of the optical signals.

[0011] In a possible design, in the first-level waveguide, the second waveguide unit and the first waveguide unit are alternately placed.

[0012] Based on the above design, the second waveguide unit is closest to the first waveguide unit, and the first waveguide unit is closest to the second waveguide unit. In this way, the optical signal transmitted on the first waveguide unit can be smoothly coupled to the nearest second waveguide unit, and the optical signal of the second waveguide unit can also be smoothly coupled to the nearest first waveguide unit. This placement method can provide support for the coupled transmission of optical signals between the first waveguide unit and the second waveguide unit.

[0013] In a possible design, in the first-level waveguide, the second waveguide unit has the same shape as the first waveguide unit and is placed in opposite directions, wherein the placement in opposite directions can be understood as: the first waveguide unit is rotated 180° to become the second waveguide unit.

[0014] Based on the above design, by placing two waveguide units of the same shape in reverse, the narrowed part of one waveguide unit corresponds to the widened part of the other waveguide unit, and the narrowing and widening change trends or change rules are the same, but in opposite directions. In this way, the mode field released by the narrowed part of one waveguide unit can be completely or almost completely absorbed by the widened part of the other waveguide unit, so that the optical signal can be coupled from one waveguide unit to another waveguide unit with a higher coupling efficiency, effectively reducing the coupling loss.

[0015] In a possible design, when I is less than or equal to N-1, the first waveguide unit in the (I+1)th waveguide is also connected to the second waveguide unit in the Ith waveguide.

[0016] Based on the above design, the optical signals transmitted on multiple second waveguide units in a certain level of waveguide can also be transmitted to the first waveguide unit of the connected first-level waveguide without the need to be transmitted in a coupled manner. The connected transmission method is more efficient than the coupled transmission method.

[0017] In a further possible design, the first waveguide unit and the second waveguide unit are both trapezoidal. In this case, the second waveguide unit in the I-th level waveguide is connected to the first waveguide unit in the I-1-th level waveguide, including: the long bases of the two trapezoids are connected together; the first waveguide unit in the I+1-th level waveguide is connected to the second waveguide unit in the I-th level waveguide, including: the short bases of the two trapezoids are connected together.

[0018] Based on the above design, one or more connected first waveguide units and one or more second waveguide units can form a waveguide belt, and there are no relatively large gaps in the waveguide belt. Therefore, there will be no faults when the optical signal is transmitted on the waveguide belt, and the transmission efficiency is relatively high.

[0019] In a possible design, N-level waveguides form a multi-dent structure, the fork of the multi-dent structure is the first-level waveguide, and the fork tail is the N-th-level waveguide.

[0020] Based on the above design, the multi-trident structure is an axisymmetric structure, and the light transmission on both sides of the axis is exactly the same, which can achieve uniform transmission.

[0021] In a possible design, part or all of the first-order waveguide to the N-th-order waveguide are sub-wavelength grating structures.

[0022] Based on the above design, the sub-wavelength grating structure can be used to increase the mode spot size of the waveguide structure in another direction to achieve a two-dimensional large mode spot. For example, if the waveguide structure without the sub-wavelength grating structure has a large mode spot size in the first direction, the waveguide structure with the sub-wavelength grating structure will have a large mode spot size in both the first direction and the second direction, the second direction is perpendicular to the first direction, and the first direction and the second direction are both perpendicular to the light transmission direction.

[0023] In a further possible design, the sub-wavelength grating structure includes a block region, a transition region and a continuous region, and the block region, the transition region and the continuous region are arranged along the direction from the first-order waveguide to the N-th-order waveguide.

[0024] Based on the above design, the transition area can realize the transition of the optical signal from the block area to the continuous area, avoiding multi-mode collision of the optical signal.

[0025] In a further possible design, the block area includes a plurality of short waveguide blocks, the continuous area includes a long waveguide block, and the long waveguide block is connected to the middle parts of the plurality of short waveguide blocks to form a transition area.

[0026] Based on the above design, the continuous area and the block area themselves can form a transition area at the connection position without the need to set up an additional transition area, and the process cost is low.

[0027] It should be noted that in the above design, the block area is only a name, and the block area can be a completely disconnected block, that is, multiple short waveguide blocks are discrete from each other, or it can be a block that is not completely disconnected, such as a block with a part connected at the bottom, which is equivalent to opening many through grooves on a rectangular block to form a structure of rows, but the bottoms of the rows are connected together by relatively thin parts, or it may be other structures, as long as it can constitute a sub-wavelength grating structure, the present application does not make specific limitations on this.

[0028] In a possible design, the first-stage waveguide supports a first mode spot size, and the first mode spot size is positively correlated with the value of N.

[0029] Based on the above design, the value of N can be flexibly configured according to actual needs, so as to support different mold spot sizes and meet the needs of different chip scenarios.

[0030] In a further possible design, the first mode spot size satisfies one of the following conditions: when the N-level waveguides are all long waveguide blocks, the first mode spot size is elliptical; when the N-level waveguides include short waveguide blocks, the first mode spot size is elliptical or nearly circular. It can be understood that the first mode spot size when including short waveguide blocks is closer to a circle than the first mode spot size when all the waveguides are long waveguide blocks.

[0031] Based on the above design, compared with the prior art solution of using a single-mode waveguide as a port, the waveguide structure with a continuous waveguide block can achieve a larger mode spot in one direction, while the waveguide structure with a discrete waveguide block can achieve a larger mode spot in two directions. Regardless of the waveguide structure, the mode spot size can be increased and the coupling efficiency of the waveguide structure can be improved.

[0032] In a possible design, the Nth-order waveguide is connected to the transmitting component or the receiving component through the first waveguide, and the mode spot size of the Nth-order waveguide is the mode spot size of the first waveguide. The first waveguide can be a single-mode waveguide or a multi-mode waveguide, and the first waveguide unit in the Nth-order waveguide gradually changes to the mode spot size of the fundamental mode of a multi-mode waveguide and is then connected to the multi-mode waveguide.

[0033] Based on the above design, the single-mode waveguide has a smaller cross-sectional size and only transmits a single mode inside, so there will be no collision and interference between multiple modes, and it has a better light transmission effect. Although multi-mode waveguides may produce mode collisions, they can also achieve light transmission and are suitable for scenarios where multi-mode waveguides are required to transmit optical signals.

[0034] In one possible design, the waveguide structure can be used as various types of ports, with the first-level waveguide located at the edge of the chip, and the Nth-level waveguide connecting different optical components depending on the port type, such as:

[0035] In case 1, the waveguide structure is used as a transmitting port, and the Nth waveguide is connected to the transmitting component on the chip. In this case, the Nth waveguide is used as the input end, and the first waveguide is used as the output end. The first waveguide has a large mode spot size and can output a large mode spot transmission signal, with high transmission efficiency.

[0036] In the second scenario, the waveguide structure is used as a receiving port, and the Nth waveguide is connected to the receiving component on the chip. In this scenario, the first-level waveguide is used as the input end, and the Nth-level waveguide is used as the output end. The first-level waveguide has a large mode spot size, so it can receive echo signals with a large mode spot, and the receiving efficiency is high.

[0037] In the third scenario, the waveguide structure is used as a transceiver port, and the Nth-level waveguide is connected to the polarization element on the chip. The polarization element can separate the transmit signal from the receive signal based on different polarization states, so as to achieve the effect of transmitting the transmit signal to the Nth-level waveguide and transmitting the receive signal to the first-level waveguide. When the waveguide structure is used as a transceiver port, both high transmission efficiency and high reception efficiency can be achieved.

[0038] In a possible design, when the waveguide structure is used as a receiving port, the first waveguide unit in the Nth waveguide is connected to the receiving component; the first waveguide is used to receive the echo signal and transmit it to the second waveguide unit in the second waveguide; each waveguide in the second to N-1th waveguides is used to couple the echo signal transmitted on the second waveguide unit to the first waveguide unit and transmit it to the connected second waveguide unit; the Nth waveguide is used to couple the echo signals transmitted on the two second waveguide units to the first waveguide unit and send them to the receiving component.

[0039] Based on the above design, it is possible to receive the echo signal with a large mode spot size from the first-stage waveguide, and then transmit it to the Nth-stage waveguide, and output it to the receiving component with a small mode spot size. Even if the echo signal has a certain offset due to the wake-off phenomenon, as long as it is within the large mode spot size of the first-stage waveguide, the echo signal can be received, solving the problem of low receiving efficiency caused by the wake-off phenomenon.

[0040] In a possible design, when the waveguide structure is used as a transmitting port, the first waveguide unit in the Nth waveguide is connected to the transmitting component; the Nth waveguide is used to couple the optical signal output from the transmitting component to the first waveguide unit to the two second waveguide units, and transmit it to the first waveguide unit in the N-1th waveguide; each waveguide from the N-1th to the second waveguide is used to couple the optical signal transmitted on the first waveguide unit to the second waveguide unit, and transmit it to the connected first waveguide unit; the first waveguide is used to output the optical signals transmitted from the N first waveguide units to the outside of the waveguide structure.

[0041] Based on the above design, it is possible to receive a transmission signal with a small mode spot size from the Nth-level waveguide, and then transmit it to the first-level waveguide, so as to output as much of the transmission signal as possible outside the waveguide structure with a large mode spot size, thereby improving the transmission efficiency.

[0042] In a second aspect, the present application provides a waveguide structure, including multiple waveguide modules, which are placed in parallel to form a multi-pronged structure, and each waveguide module is at least partially coupled to an adjacent waveguide module, and the coupling is used to transmit an optical signal on the waveguide module to the adjacent waveguide module.

[0043] Based on the above waveguide structure, the optical signal can be transmitted from one waveguide module to an adjacent waveguide module through coupling between adjacent waveguide modules. Furthermore, since the multiple waveguide modules are presented as a multi-trident structure as a whole, if the fork head direction is the input end, the large mode spot signal can be received based on the fork head with a large mode spot size, and transmitted to the fork tail direction through coupling between adjacent waveguide modules, and then transmitted out, thereby achieving a higher receiving efficiency. If the fork tail direction is the input end, the optical signal can be received based on the fork tail, and transmitted to the fork direction through coupling between adjacent waveguide modules, and then transmitted out based on the fork head with a large mode spot size, thereby achieving a higher transmission efficiency. In this way, whether it is used as a transmitting port, a receiving port, or a transceiver-integrated port, the waveguide structure can have a large mode spot size, which can improve the coupling efficiency of the port.

[0044] In a possible design, each waveguide module includes one or more shuttle-shaped bodies, each shuttle-shaped body is wide in the middle and narrow at both ends, and adjacent waveguide modules are staggered by a distance of half the shuttle-shaped body.

[0045] Based on the above design, the wide part of the shuttle body is used to absorb the mode field, while the narrow part is used to release the mode field. Since adjacent waveguide modules are staggered by half the distance of the shuttle body, the narrow part of a waveguide module just corresponds to the wide part of the adjacent waveguide module. The mode field released by the narrow part of the waveguide module can be completely or almost completely absorbed by the wide part of the adjacent waveguide module, which can improve the coupling efficiency of optical signals between adjacent waveguide modules.

[0046] In a possible design, the spacing between adjacent waveguide modules is smaller than a set spacing.

[0047] Based on the above design, the set spacing can be understood as a spacing that makes adjacent waveguide modules close enough without causing signal crosstalk. Close enough can achieve coupling of optical signals between adjacent waveguide modules and reduce coupling loss of optical signals.

[0048] In a possible design, the prongs of the multi-prong structure have a first mold spot size, and the first mold spot size is positively correlated with the number of prongs.

[0049] Based on the above design, the number of forks can be configured according to the actual mold spot size requirements, so that the multi-fork structure can be adapted to various chip scenarios.

[0050] In a possible design, when a waveguide module includes a plurality of shuttle-shaped bodies, the narrow portions of the plurality of shuttle-shaped bodies are connected together.

[0051] Based on the above design, a waveguide module with multiple shuttle-shaped bodies can form a waveguide belt whose cross-sectional dimensions are alternatingly wide and narrow. The optical signal continuously releases and absorbs the mode field on the alternatingly wide and narrow cross-sections, and can be coupled and transmitted in one direction with a higher coupling efficiency.

[0052] In a possible design, in two adjacent waveguide modules, the narrow portion of one waveguide module and the wide portion of another waveguide module have the same variation trend. Here, the same variation trend can be understood as: the absolute value of the slope is the same but the direction is opposite.

[0053] Based on the above design, the widening and narrowing changes of two adjacent waveguide modules are the same, but the change directions are opposite. In this way, the mode field released by the narrowed part of one waveguide module can be completely or almost completely absorbed by the widened part of the other waveguide module. The optical signal can be coupled from one waveguide module to another with a higher coupling efficiency, effectively reducing the coupling loss.

[0054] In one possible design, the waveguide module located in the middle is the longest and the waveguide modules located on both sides are the shortest.

[0055] Based on the above design, the waveguide modules on both sides are symmetrical with respect to the waveguide module in the middle. Therefore, the optical signal is transmitted symmetrically on both sides of the waveguide module in the middle, thereby achieving uniform transmission of the optical signal.

[0056] In a possible design, the waveguide modules located on both sides include a shuttle-shaped body, and the waveguide module located in the middle includes K shuttle-shaped bodies. , N is the number of forks of the multi-pronged structure, and the value of N is an integer greater than or equal to 2. is a floor function.

[0057] Based on the above design, from the direction of the fork head to the fork tail, the multi-trident structure can gradually and evenly change from multi-end to single-end, and in the reverse direction, it can gradually and evenly expand from single-end to multi-end. In this way, the optical signal will not encounter sudden missing parts during the transmission from one end to the other end, and can try to ensure that all optical signals are transmitted to the other end.

[0058] In a possible design, the waveguide module located in the middle further includes a trapezoidal body, the narrow part of the trapezoidal body is connected to the end of the shuttle body of the waveguide module located in the middle, and the wide part of the trapezoidal body is connected to the first waveguide, wherein the cross-sectional size of the wide part of the trapezoidal body is equal to the cross-sectional size of the first waveguide.

[0059] Based on the above design, the trapezoidal body can be regarded as the connecting part between the shuttle-shaped body end of the middle waveguide module and the first waveguide connected to the rear end. After the pattern spot size of the shuttle-shaped body end is gradually changed to the pattern spot size of the first waveguide, it is connected to the first waveguide, so that the multi-pronged structure can accurately adapt to the first waveguide connected to the rear end.

[0060] In a further possible design, the first waveguide can be a single-mode waveguide or a multi-mode waveguide. If it is a multi-mode waveguide, the cross-sectional dimension of the wide portion of the trapezoidal body is equal to the cross-sectional dimension of the fundamental mode in the multi-mode waveguide.

[0061] Based on the above design, the single-mode waveguide has a smaller cross-sectional size and only transmits a single mode inside, so there will be no collision and interference between multiple modes, and it has a better light transmission effect. Although multi-mode waveguides may produce mode collisions, they can also achieve light transmission and are suitable for scenarios where multi-mode waveguides are required to transmit optical signals.

[0062] In a possible design, the number of forks of the multi-pronged structure is N, where N is an integer greater than or equal to 2, then: the waveguide structure includes 2N-1 waveguide modules, the 2N-1 waveguide modules are placed in parallel on both sides of the light propagation direction, the 2N-1 waveguide modules include a middle waveguide module and 2N-2 non-middle waveguide modules, every two adjacent waveguide modules in the 2N-2 non-middle waveguide modules form a group, the waveguide module located on the outside of each group of waveguide modules serves as a fork, and the waveguide module located on the inside is staggered by a distance of half a shuttle body relative to the waveguide module located on the outside.

[0063] Based on the above design, the waveguide modules on both sides of the middle waveguide module in the multi-trident structure are symmetrically distributed. Therefore, the optical signal transmission path on both sides is the same, and multiple modes will not be excited, ensuring that both the input and output are single-mode optical signals.

[0064] In one possible design, the two waveguide modules in each group of waveguide modules include the same number of shuttle bodies.

[0065] Based on the above design, it can be ensured that the two waveguide modules in each group of waveguide modules have the same structure and length, and the optical signal transmission is symmetrical.

[0066] In a possible design, a group of waveguide modules closer to the middle includes more shuttle-shaped bodies.

[0067] Based on the above design, the closer the waveguide module is to the middle, the longer its length is, and the optical signal can be transmitted to a farther position on the waveguide module, so that the optical signal can be transmitted from one end of the polyhedron structure to the other end.

[0068] In a possible design, the fork heads of the polyproton structure are divided into sub-wavelength grating structures, or the entire polyproton structure is a sub-wavelength grating structure.

[0069] In a further possible design, the sub-wavelength grating structure includes a block region, a transition region and a continuous region, and the block region, the transition region and the continuous region are arranged along the direction from the fork head to the fork tail.

[0070] In a further possible design, the block area includes a plurality of short waveguide blocks, the continuous area includes a long waveguide block, and the long waveguide block is connected to the middle parts of the plurality of short waveguide blocks to form a transition area.

[0071] In a possible design, the forks of the multi-pron structure are exposed on the end surface of the chip, and the forks of the multi-pron structure are connected to the first waveguide.

[0072] In a possible design, the prongs of the multi-prong structure support a first mold spot size, and the first mold spot size is positively correlated with the number of prongs.

[0073] In a further possible design, the first mode spot size satisfies one of the following conditions: when the polyhedron structure comprises long waveguide blocks, the first mode spot size is elliptical; when the polyhedron structure comprises short waveguide blocks, the first mode spot size is elliptical or nearly circular.

[0074] In a third aspect, the present application provides a silicon photonic chip, comprising the waveguide structure in the above-mentioned first aspect or any one of the designs of the first aspect, or comprising the waveguide structure in the above-mentioned second aspect or any one of the designs of the second aspect.

[0075] In one possible design, a silicon photonic chip includes a silicon substrate layer, a buried oxide layer, a waveguide layer, and a top oxide layer stacked in sequence, and the waveguide structure is located in the waveguide layer.

[0076] In one possible design, the waveguide structure is used as a transmitting port, a receiving port or a transceiver-in-one port of a silicon photonic chip, and the first-level waveguide or fork of the waveguide structure is located at the end face of the silicon photonic chip.

[0077] In one possible design, the silicon photonic chip also includes a transmitting component, which is connected between the input end of the silicon photonic chip and the Nth waveguide or fork tail of the waveguide structure. The transmitting component is used to split the detection signal from the input optical signal and transmit the detection signal to the waveguide structure.

[0078] In one possible design, the silicon photonic chip also includes a receiving component, which is connected between the electrical output end of the silicon photonic chip and the Nth waveguide or fork tail of the waveguide structure. The receiving component is used to receive the echo signal transmitted by the waveguide structure, and mix the echo signal and the local oscillator signal to obtain an intermediate frequency signal. The intermediate frequency signal is used to determine the speed and / or distance of the target.

[0079] In a fourth aspect, the present application provides a detection device, comprising the waveguide structure in the first aspect or any one of the designs of the first aspect, or comprising the waveguide structure in the second aspect or any one of the designs of the second aspect, or comprising the silicon photonic chip in the third aspect or any one of the designs of the third aspect.

[0080] In one possible design, when the detection device includes a silicon photonic chip, the detection device also includes a light source component, which is used to output an optical signal to the silicon photonic chip, and the optical signal is transmitted to the transmitting component on the silicon photonic chip through the waveguide structure on the silicon photonic chip.

[0081] In a possible design, when the detection device includes a silicon photonic chip, the detection device also includes a scanning component, and the scanning component is used to scan the optical signal emitted by the silicon photonic chip to the detection space.

[0082] In one possible design, when the detection device includes a silicon photonic chip, the detection device also includes a processing component, which is disposed on the electrical chip and is used to determine the distance and / or speed of the target based on the electrical signal output by the silicon photonic chip.

[0083] In a fifth aspect, the present application provides a terminal device, comprising the waveguide structure in the first aspect or any one of the designs of the first aspect, or comprising the waveguide structure in the second aspect or any one of the designs of the second aspect, or comprising the silicon photonic chip in the third aspect or any one of the designs of the third aspect, or comprising the detection device in the fourth aspect or any one of the designs of the fourth aspect.

[0084] The technical effects that can be achieved by the second to fifth aspects mentioned above can refer to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 A schematic diagram showing a possible application scenario to which the present application is applicable;

[0086] Figure 2a A schematic diagram of an architecture for producing a walk-off phenomenon is shown as an example;

[0087] Figure 2b The following is a schematic diagram of a multi-receiver silicon photonic chip architecture provided by the industry;

[0088] Figure 2c A schematic diagram of a waveguide structure with multiple cross-sectional dimensions provided by the industry is shown as an example;

[0089] Figure 3 A schematic structural diagram of a waveguide structure provided by Embodiment 1 is exemplarily shown;

[0090] Figure 4a A schematic diagram of hierarchical labeling of a waveguide structure provided by the first embodiment is exemplarily shown;

[0091] Figure 4b Another schematic top view of a waveguide structure provided by the first embodiment is exemplarily shown;

[0092] Figure 4c Another schematic top view of a waveguide structure provided by the first embodiment is exemplarily shown;

[0093] Figure 4d A schematic top view of another waveguide structure provided in the first embodiment is exemplarily shown;

[0094] Figure 5 A possible structural schematic diagram of a first waveguide unit and a second waveguide unit provided in Embodiment 1 is exemplarily shown;

[0095] Figure 6 A schematic structural diagram of dividing a waveguide structure into waveguide bands provided by the first embodiment is exemplarily shown;

[0096] Figure 7 An optical path transmission schematic diagram when N has different values ​​provided by the first embodiment is exemplarily shown;

[0097] Figure 8a A schematic diagram of a waveguide structure of a dident structure provided by the first embodiment is exemplarily shown;

[0098] Figure 8b A schematic diagram of a trident waveguide structure provided by the first embodiment is exemplarily shown;

[0099] Figure 8c A schematic diagram of a waveguide structure of a quadrudent structure provided by Embodiment 1 is exemplarily shown;

[0100] Fig. 9 A schematic diagram showing the morphology of the first pattern spot size when N has different values ​​provided in the first embodiment is exemplified;

[0101] Fig.10 A schematic diagram showing a comparison of the receiving efficiency of a multi-pronged structure and a common single-mode waveguide provided by the first embodiment is exemplified;

[0102] Fig.11a A schematic structural diagram of a waveguide structure provided by Embodiment 2 is exemplarily shown;

[0103] Fig.11b A schematic structural diagram of another waveguide structure provided by Embodiment 2 is exemplarily shown;

[0104] Fig.12 A schematic diagram showing the morphology of the first pattern spot size when N has different values ​​provided in the second embodiment is exemplified;

[0105] Fig.13 A schematic diagram showing a comparison of the receiving efficiency of a multi-pronged structure and a common single-mode waveguide provided by the second embodiment is exemplified;

[0106] Fig.14 A schematic structural diagram of another waveguide structure provided by the present application is exemplarily shown;

[0107] Fig.15 A possible structural schematic diagram of a silicon photonic chip provided by the present application is exemplified;

[0108] Fig.16a The schematic diagram of the structure of a silicon photonic chip after the top oxide layer is removed provided by the present application is exemplified;

[0109] Fig.16b The schematic diagram of the structure of another silicon photonic chip provided by the present application after the top oxide layer is removed is exemplified;

[0110] Fig.16c A schematic diagram showing the structure of another silicon photonic chip provided by the present application after the top oxide layer is removed is exemplified;

[0111] Fig.17 A schematic structural diagram of a waveguide layer provided by implementation method 1 is exemplarily shown;

[0112] Fig.18 A schematic diagram showing a specific structure of a waveguide layer provided by implementation method 1 is exemplified;

[0113] Fig.19 A schematic structural diagram of a waveguide layer provided by implementation method 2 is exemplarily shown;

[0114] Fig. 20 A schematic diagram showing a specific structure of a waveguide layer provided by implementation method 2 is exemplified;

[0115] Fig.21 A possible structural schematic diagram of a detection device provided by the present application is exemplified;

[0116] Fig. 22 A schematic diagram showing, by way of example, the layout of various components in a detection device provided by the present application;

[0117] Fig.23 A schematic diagram of the structure of a terminal device provided in the present application is exemplified. DETAILED DESCRIPTION

[0118] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0119] Below, some terms in this application are explained. It should be noted that these explanations are for the convenience of understanding by those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0120] 1. Silicon-on-insulator (SOI)

[0121] SOI is a technology for growing semiconductor thin films on insulating substrates. It introduces a buried oxide layer between the top silicon and the back substrate, which can effectively isolate the current leakage and mutual interference between different parts inside the chip, and improve the performance and reliability of the device. Chips made based on SOI technology have the advantages of high speed, low power consumption, high reliability, and high temperature and high pressure resistance.

[0122] 2. Single-mode waveguide

[0123] A single-mode waveguide is a waveguide in which only one propagation mode of light can be propagated. This propagation mode is called the fundamental mode. Therefore, it can also be considered that only the fundamental mode of light waves is transmitted in a single-mode waveguide, while all higher-order modes of light waves are cut off. Different types of waveguides can have different single-mode conditions. The realization of single-mode conditions can avoid multi-mode interference and signal distortion, making waveguide transmission more stable and reliable.

[0124] 3. Mold spot

[0125] Mode spot, also known as mode field, refers to the electric field distribution that can be supported on the waveguide cross section. The parameter that measures the 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.

[0126] 4. Evanescent wave coupling

[0127] Evanescent wave coupling is a wave interaction. In this application, it refers to the phenomenon that a wave on a waveguide couples to another waveguide during propagation. In the field of optics, evanescent wave coupling can use the evanescent waves generated when light waves propagate in a waveguide to exchange energy.

[0128] 5. Dot frequency

[0129] Point frequency refers to the total number of detection points completed and acquired by the lidar per second, also known as the number of output points or points per second.

[0130] 6. Multi-pronged halberd

[0131] A multi-pronged halberd has two ends, one end is called the halberd head, which has a multi-pronged structure with a long handle in the middle, and one end of the long handle serves as the other end of the multi-pronged halberd.

[0132] 7. Sub-wavelength grating

[0133] Subwavelength grating, also known as sub-wavelength grating, is an optical element with a subwavelength periodic structure. Compared with ordinary gratings, the period length of subwavelength gratings is smaller than the wavelength of the incident light. It can achieve a high degree of control over light through the diffraction and interference effects of light, and achieve higher optical resolution. The realization methods of this structure include periodic surface nanostructures and subwavelength optical waveguides.

[0134] 8. Linear Polarization State

[0135] Linear polarization is a form of light propagation. Light with linear polarization is called linear polarization, also known as linear polarization or plane polarization. In the propagation direction of light, the electric vector of each point is in a certain plane. Since the trajectory of the electric vector endpoint is a straight line, it is called linear polarization. The vibration plane of linear polarization is fixed and will not deflect. Among them, the vibration plane refers to the plane formed by the direction of the light vector and the propagation direction of light.

[0136] Common linear polarized light includes P light, S light, TE light, and TM light. P light and S light are lights with different polarization directions expressed in space. Simply put, the light vector is decomposed into two mutually perpendicular vibration directions in space. The light with the vibration direction within the incident plane is called the parallel component of the light vector, referred to as P light, and the light with the vibration direction perpendicular to the incident plane is called the perpendicular component of the light vector, referred to as S light. TE light and TM light are lights with different polarization directions expressed from the perspective of chip integration, and are mostly used to describe the propagation characteristics of electromagnetic waves. TE light is also called transverse electric wave, and the electric field component is perpendicular to the propagation direction of the electromagnetic wave, that is, the electric field component is parallel to the incident plane. TM light is also called transverse magnetic wave, and the magnetic field component is perpendicular to the propagation direction of the electromagnetic wave, that is, the electric field direction is perpendicular to the incident plane.

[0137] 9. Mixing

[0138] Mixing, also known as coherent demodulation, refers to the difference in frequency and phase between two signals. In FMCW LiDAR, the detection signal is usually a linear frequency modulation signal. After the linear frequency modulation signal interacts with the target object, the reflected echo signal (i.e., the received signal) will also have the same frequency change characteristics, but depending on the distance of the target, the echo signal will have a certain phase difference 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 subtracted to obtain a low-frequency beat signal, which is also called a beat frequency signal or an intermediate frequency signal. The intermediate frequency signal contains the frequency difference information between the two signals, and the frequency difference 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 intermediate frequency signal will also contain Doppler effect information caused by the movement of the target, and the speed of the target can be calculated based on the Doppler effect information.

[0139] The foregoing text introduces some of the terms involved in this application. The following text introduces possible application scenarios of this application.

[0140] In a possible implementation, the waveguide structure provided by the present application can be integrated into a detection device, and the detection device can be installed in a transportation vehicle, such as but not limited to: a vehicle, a ship, an airplane, a drone, a train, a subway, an automated guided vehicle (AGV) or an unmanned transport vehicle, etc. For example, see Figure 1 , showing a possible application scenario of the present application, in which the detection device is installed at the front bumper of the vehicle as an example, the detection device can be used as an information collection source for path planning to assist the driver in achieving or automatically achieving safe driving of the vehicle. It is understandable that the detection device can also be installed at other locations of the vehicle, such as around the headlights, around the rearview mirrors, near the doors, at the rear bumper, behind the windshield or on the roof, etc., to capture the vehicle's surrounding environment information. When the detection device is installed behind the windshield, it has a lower requirement for no gravel collision risk, and will not affect the appearance of the vehicle. In addition, the front windshield itself has window heating and demisting and wiper cleaning functions.

[0141] It should be understood that the above application scenarios are only examples, and the detection device provided in the present application can also be applied to other possible scenarios, not limited to the scenarios exemplified above. For example, the detection device can also be installed on a road side unit (RSU) as a roadside traffic detection device to realize intelligent vehicle-road collaborative communication. For example, the detection device can also be installed in the cabin of a vehicle as a liveness detection device to detect and prompt the user of children or pets left in the cabin. For another example, the detection device can also be applied to a terminal device or a component provided in a terminal device. The terminal device can be, for example, a smart phone, a smart home device, a smart manufacturing device, a medical device, an industrial equipment, a robot, etc. They are not listed one by one here.

[0142] It should be noted that the application scenarios described in this application are intended to more clearly illustrate the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application.

[0143] In addition, the above application scenarios can be applied to unmanned driving, assisted driving, intelligent driving, autonomous driving, connected vehicles, optical communications, security monitoring, biomedicine, surveying and mapping (such as three-dimensional mapping, remote sensing mapping), meteorological research, biomass and vegetation research, air quality monitoring, and aviation and aerospace applications.

[0144] The above detection devices may include but are not limited to laser radar (light detection and ranging, LiDAR), such as frequency modulated continuous wave LiDAR (FMCWLiDAR).

[0145] In order to achieve a sufficient point frequency, the LiDAR system is generally equipped with one or more fast-rotating scanning components, such as rotating mirrors, micro-electro-mechanical system (MEMS) galvanometers, scanning galvanometers (Galvo), etc. The scanning component can scan the laser signal emitted by the laser into the detection space, and can also scan the reflected echo signal to the receiver. However, since it takes a certain amount of time for the laser signal to be emitted, hit the target, and then reflected from the target to the scanning component, the scanning component has rotated a certain angle during this period of time. Therefore, the actual receiving optical path of the echo signal after being scanned by the scanning component is offset (walk-off) compared to the ideal receiving optical path. This phenomenon is called the walk-off effect. In some scenarios, it is also called the descan effect or other names.

[0146] As described in the background technology, the existing port has a relatively small mode spot size. When the port is used as the receiving port of the receiver, if the echo signal is offset due to the walk-off effect, the receiving port with a small mode spot size is likely to be unable to receive the offset echo signal, resulting in a decrease in receiving efficiency. For example, assuming that the ideal receiving optical path is Figure 2a As shown in (A), at the original scanning angle of the scanning component 210, the echo signal is scanned by the scanning component 210 to the receiving optical system 220, and then converged by the receiving optical system 220 to the receiving end center of the receiver 230. The receiver 230 can receive most or even all of the echo signals, and the receiving efficiency is the highest. However, if the scanning component 210 rotates counterclockwise during the period from sending to receiving, as shown in FIG. Figure 2a As shown in (B), the propagation direction of the echo signal after scanning by the scanning component 210 will be offset upward compared to the ideal propagation direction. Therefore, the position where the echo signal is focused on the receiving port will also be offset upward, for example, above the receiving port. Conversely, if the scanning component 210 rotates clockwise during this period, as shown in Figure 2a As shown in (C), the focus position of the echo signal is offset to the bottom of the receiving port. Regardless of whether it is offset to the top or the bottom, the actual echo signal cannot be accurately focused on the receiving port of the receiver 230. In serious cases, the receiver 230 may not even receive the echo signal, which greatly reduces the receiving efficiency of the receiver 230.

[0147] The walk-off effect is related to the angular velocity and flight time of the scanning component. The angular velocity of the scanning component refers to the rotation speed of the scanning component. The flight time can be understood as the time between the scanning component scanning the laser signal and the scanning component receiving the echo signal. When the speed of light is fixed, the flight time is proportional to the target distance (that is, the distance between the scanning component and the target). Therefore, it can also be considered that the walk-off effect is related to the angular velocity of the scanning component and the target distance. Generally, the farther the target distance is and the greater the angular velocity of the scanning component is, the more obvious the walk-off effect is, and the more the receiving efficiency decreases.

[0148] In order to reduce the impact of the walk-off effect on reception efficiency, the industry has proposed some solutions, mainly including the following two:

[0149] Solution 1: Propose a multi-receiver silicon photonic chip architecture, see Figure 2b . This architecture sets up multiple single-mode waveguides as receiving ends on the right end face of the silicon photonic chip, and sets up multiple receiving links corresponding to the multiple single-mode waveguides in the silicon photonic chip, each receiving link includes a mixer and a detector. Multiple single-mode waveguides are arranged in parallel in the focusing direction affected by the walk-off effect, for example, arranged in parallel along the up and down directions on the right end face. In this way, even if the focus position of the echo signal deviates from the center position and fluctuates up and down due to the walk-off effect, it is highly likely to be received or partially received by one of the single-mode waveguides and transmitted to the connected receiving link, thereby reducing the impact of the walk-off effect on the receiving efficiency.

[0150] However, setting up multiple receivers will lead to a significant increase in the process difficulty, number of devices, material cost, structural complexity and volume of the detection device on the receiving side. Moreover, due to the limitations of existing processes, it is actually impossible to achieve an ideal zero gap between different single-mode waveguides. Therefore, this method can only be effective for multiple specific discrete walk-off angles, and the effect on other walk-off angles is poor. In other words, when detecting certain distances, if the corresponding echo signal is not exactly focused on the center of a single-mode waveguide, there will still be a problem of low receiving efficiency.

[0151] Solution 2: Propose a waveguide structure with multiple cross-sectional dimensions, see Figure 2c. The left side cross-sectional dimensions of the waveguide structure are small, the right side cross-sectional dimensions are large, and the middle area is connected by a trapezoidal cone. The left cross-sectional area can be regarded as a single-mode waveguide, and the right cross-sectional area is a multi-mode waveguide. Based on this waveguide structure, when used as a transmitter, the light beam is transmitted from the left side to the right side of the waveguide structure. After passing through the middle area, the narrow fundamental mode signal is transformed into a wide fundamental mode signal and emitted from the right side. The emitted optical power loss is relatively small compared to the incident optical power loss, which is not a problem.

[0152] However, when it is used as a receiving end, the light beam is transmitted from the right side to the left side of the waveguide structure. Although the cross-sectional size on the right side is larger and can tolerate a certain walk-off angle, when the light beam entering the waveguide structure passes through the middle trapezoidal cone area, the wide fundamental mode signal will be excited into multiple modes, including narrow fundamental mode signals and multi-level high-order mode signals. Among them, only the narrow fundamental mode signal can be transmitted to the single-mode waveguide on the left side, and then coupled to the silicon photonic chip, while the light signals of other modes are wasted. Therefore, the power of the light signal emitted from the left side of the waveguide structure is low, and the waveguide structure cannot effectively improve the receiving efficiency of the silicon photonic chip. At the same time, the multi-mode mode will also increase the receiving noise. In addition, the fundamental mode signal of the multi-mode waveguide also has a relatively large effective refractive index. Therefore, when the light beam enters from the right side, the refractive index at the right end face of the waveguide structure suddenly increases, and the Fresnel reflection is large, which results in a decrease in the actual light beam entering the waveguide structure, further reducing the receiving efficiency of the receiving end.

[0153] In summary, the two solutions provided by the industry are actually unable to effectively improve the receiving efficiency of the receiving port. Instead, they will introduce other problems, such as increasing process complexity, increasing costs, and increasing receiving noise.

[0154] In view of this, the present application provides a waveguide structure that can achieve a large mode spot size. When the waveguide structure is used as a receiving port, the echo signal on the side of the large mode spot size can be allowed to have a certain offset, thereby solving the problem of decreased receiving efficiency due to the walk-off effect. At the same time, the waveguide structure achieves a large mode spot size based on its own structural characteristics. It does not require multiple receiving links to be set in the silicon photonic chip, and it will not excite multi-mode modes. Therefore, there will be no problems introduced by the two solutions provided by the industry, and it has the advantages of low process complexity, low material cost, low structural complexity, and low receiving noise.

[0155] The following is combined with Figure 3 To Attachment Fig.23 , the waveguide structure and related schemes proposed in this application are introduced in detail.

[0156] It should be noted that, in the various implementation schemes introduced below, unless otherwise specified or logically conflicting, the terms and / or descriptions between different implementation schemes are consistent and can be referenced to each other, and the technical features in different implementation schemes can be combined to form new implementation schemes based on their internal logical relationships.

[0157] In addition, in any of the following implementation schemes, any reference to "position", "angle", "direction", "shape" or the like does not refer to an absolute position, angle, direction, shape, etc., and a certain engineering error may be allowed. For example, it may be a close position, a close angle, a close direction, a close shape, etc., and there may be a certain error between the absolute position, angle, direction, shape, and the error is mainly limited by factors such as process manufacturing capability and assembly accuracy.

[0158] Implementation Plan 1

[0159] See also Figure 3 , showing a structural schematic diagram of a waveguide structure provided in implementation scheme one. Figure 3 (A) shows a three-dimensional diagram of the waveguide structure. Figure 3 (B) shows a top view of the waveguide structure. Figure 3 Based on the top view shown in (B), please refer to Figure 4a , showing a schematic diagram of graded labeling of the waveguide structure.

[0160] like Figure 4a As shown, the waveguide structure includes N-level waveguides, N is an integer greater than or equal to 2, and N=5 is taken as an example in the figure. In the N-level waveguide, the first-level waveguide includes N first waveguide units ("1" in the figure), and the I-level waveguide includes at most N-I+2 second waveguide units ("2" in the figure) and N-I+1 first waveguide units, wherein the N-I+2 second waveguide units are connected to the first waveguide unit in the I-1-level waveguide, and when there is an I+1-level waveguide, the N-I+1 first waveguide units are connected to the second waveguide unit in the I+1-level waveguide, and I is an integer greater than or equal to 2 and less than or equal to N. It can be understood that when I=N, the I-level is also the N-level waveguide, and the N-level waveguide includes two second waveguide units and one first waveguide unit, and the two second waveguide units are connected to the two first waveguide units in the N-1-level waveguide.

[0161] It should be noted that the first-level waveguide includes at most N-I+2 second waveguide units and N-I+1 first waveguide units. It can be understood that the most ideal situation is to include N-I+2 second waveguide units and N-I+1 first waveguide units, so that the number of waveguides included in the N-level waveguide is gradually increasing or decreasing, and the coupling transmission performance of the signal between the N-level waveguide units is the best. However, in some examples, less than N-I+2 second waveguide units and / or less than N-I+1 first waveguide units may be included. For example, Figure 4b The example shown is that there is one less first waveguide unit and one less second waveguide unit in the second-level waveguide. Figure 4c The example shown is one less first waveguide unit in the second-level waveguide and one less second waveguide unit in the third-level waveguide. Figure 4d The example shown in FIG. 1 is that only one second waveguide unit is missing in the fourth-level waveguide. There are many possible examples, which are not listed here one by one. By adopting the latter example, the number of first waveguide units and / or second waveguide units included in a certain level or multiple levels of waveguide units can be reduced, and other effects can be achieved by sacrificing the performance of some signal coupling transmission, such as reducing material costs, reducing structural complexity, reducing occupied space, etc.

[0162] Continue with Figure 4a Taking the structure shown as an example, the structural features of the waveguide structure are first explained.

[0163] Alternatively, if Figure 4a As shown, in each level of waveguide, each waveguide unit is placed in parallel, and the spacing between adjacent waveguide units is less than the set spacing. Here, parallel means that the center lines of each waveguide unit are parallel or approximately parallel. The center lines of each waveguide unit can be referred to Figure 3 The dotted line shown in (B) is perpendicular to Figure 3 The XY plane shown in (A). The set spacing can be understood as a distance that allows adjacent waveguide units to be close enough without signal crosstalk. The value of the set spacing is related to the material of the waveguide unit. Waveguide units of different materials will have different set spacings, and no specific limitation is given here. Based on this layout, multiple waveguide units are close to each other and parallel to each other, and the multiple waveguide units can be regarded as a whole. Parallel placement allows the optical signals in multiple waveguide units to be transmitted in parallel, and there will be no transmission loss caused by the excitation of multiple modes due to crossing. Setting adjacent waveguide units close enough can also achieve coupling of optical signals between adjacent waveguide units, reducing coupling losses of optical signals.

[0164] Alternatively, if Figure 4aAs shown, in each level of waveguides from the second to the Nth level waveguides, both the first waveguide unit and the second waveguide unit are included, and the first waveguide unit and the second waveguide unit are placed alternately. For example, in each level of waveguides, at least two second waveguide units and at least one first waveguide unit are included, and these waveguide units are placed alternately in the manner of the second waveguide unit, the first waveguide unit, the second waveguide unit, ..., the first waveguide unit, and the second waveguide unit. In this way, the second waveguide unit is closest to the first waveguide unit, and the first waveguide unit is closest to the second waveguide unit. The optical signal transmitted on the first waveguide unit can be smoothly coupled to the nearest second waveguide unit, and the optical signal of the second waveguide unit can also be smoothly coupled to the nearest first waveguide unit. The first waveguide unit and the second waveguide unit constitute an evanescent wave coupler to provide support for the coupled transmission of the optical signal between the first waveguide unit and the second waveguide unit.

[0165] Alternatively, if Figure 4a As shown in FIG. 1 , in each of the second to Nth waveguides, the first waveguide unit and the second waveguide unit have the same shape and are placed in opposite directions. Here, the opposite placement direction can be understood as: the first waveguide unit is rotated 180° to become the second waveguide unit. By placing two waveguide units of the same shape in reverse, the narrowed portion of one waveguide unit corresponds to the widened portion of the other waveguide unit, for example, Figure 4a As shown, assuming that the first waveguide unit and the second waveguide unit are both trapezoidal, when the first waveguide unit is placed flat with a short bottom side on the left and a long bottom side on the right, the second waveguide unit will be placed flat with a long bottom side on the left and a short bottom side on the right. In this way, from left to right, the width of the first waveguide unit changes from narrow to wide, while the width of the second waveguide unit changes from wide to narrow, and the widened part of the first waveguide unit corresponds to the narrowed part of the second waveguide unit, so the mode field released by the narrowed part of the second waveguide unit can be absorbed by the widened part of the first waveguide unit, and the optical signal can be coupled from the second waveguide unit to the first waveguide unit. Conversely, from right to left, the width of the first waveguide unit changes from wide to narrow, while the width of the second waveguide unit changes from narrow to wide, and the narrowed part of the first waveguide unit corresponds to the widened part of the second waveguide unit, so the mode field released by the narrowed part of the first waveguide unit can be absorbed by the widened part of the second waveguide unit, and the optical signal can be coupled from the first waveguide unit to the second waveguide unit.

[0166] In some examples, the shapes of the two waveguide units are exactly the same. For example, when the first waveguide unit and the second waveguide unit are both trapezoidal, the two trapezoids can be exactly the same, that is, they have the same size and can be exactly overlapped when put together. For example, the two trapezoids are isosceles trapezoids with exactly the same size, such as Figure 5 As shown in (A), or, it is a right-angled trapezoid with exactly the same size, such as Figure 5 As shown in (C), etc. Since the two trapezoids are placed in reverse, the change trends or change rules of the two trapezoids are exactly opposite, and the change slopes have the same value but opposite directions. In this way, the widths of the two trapezoids at the center are equal, and the value of one trapezoid narrowing is exactly the same as the value of the other trapezoid widening. The mode field released by the narrowed part of one trapezoid can be completely or almost completely absorbed by the widened part of the other trapezoid. The optical signal can be coupled from one trapezoid to the other with a higher coupling efficiency, and the coupling loss is very low.

[0167] In some other examples, the first waveguide unit and the second waveguide unit may also be similar in shape but not identical. In this case, the shape change trends of the opposite surfaces of the two waveguide units need to be opposite, and the widths of the two waveguide units at least at one position of the opposite surfaces are the same to ensure that the signals transmitted by the two waveguide units can collide at this position, thereby achieving coupled transmission of optical signals from one waveguide unit to another waveguide unit. For example, when the first waveguide unit and the second waveguide unit are both trapezoidal, the two trapezoids only need to ensure that the change trends of the opposite sides are the same and the widths of at least one point are equal. As for whether the sizes or change trends of other sides, long bottom sides or short bottom sides are the same, there is no limitation.

[0168] For example, see Figure 5 In (B), the upper trapezoid is an isosceles trapezoid, but the lower trapezoid is a right-angled trapezoid. On the opposite sides of the two, the slope of the upper trapezoid is equal to the slope of the lower trapezoid. The widths L1 and L2 of the two trapezoids at position M are the same. For another example, see Figure 5 In (C), the upper trapezoid is an isosceles trapezoid, but the lower trapezoid is an irregular trapezoid. On the opposite sides of the two, the slope of the upper trapezoid is fixed, while the slope of the lower trapezoid is larger at the beginning and smaller later. The widths L1 and L2 of the two trapezoids at position M are the same. For another example, see Figure 5 In (E), the upper trapezoid is a right-angled trapezoid, but the lower trapezoid is a non-trapezoid with a long inclined base. On the opposite sides of the two, the slope of the upper trapezoid is greater than the slope of the lower trapezoid. The widths L1 and L2 of the two trapezoids at position M are the same. For another example, see Figure 5 In (F), the upper trapezoid is a right-angled trapezoid, but the lower trapezoid is a trapezoid with a long base and a short base that are not much different. On the opposite sides of the two, the side slope value of the upper trapezoid is greater than the side slope value of the lower trapezoid. The widths L1 and L2 of the two trapezoids at position M are also the same.

[0169] for Figure 5For any of the trapezoidal combinations shown in (B), (C), (E), and (F), from left to right, the width of the upper trapezoid is still gradually narrowing, and the width of the lower trapezoid is still gradually widening, but the rates of narrowing of the upper trapezoid and widening of the lower trapezoid are somewhat the same and somewhat different, but both have the same width at at least one position M. Therefore, the mode field released by the narrowed part of the upper trapezoid can still be absorbed by the widened part of the lower trapezoid, but there will be some transmission loss, and the coupled transmission of the optical signal from the upper trapezoid to the lower trapezoid can also be achieved. Conversely, looking from right to left, the width of the upper trapezoid is still gradually widening, and the width of the lower trapezoid is still gradually narrowing, but the rates of widening of the upper trapezoid and narrowing of the lower trapezoid are somewhat the same and somewhat different, but they both have the same width at at least one position M. Therefore, the mode field released by the narrowed part of the lower trapezoid can still be absorbed by the widened part of the upper trapezoid, but there will be some transmission loss, and the coupled transmission of the optical signal from the lower trapezoid to the upper trapezoid can also be achieved.

[0170] Understandably, the above Figure 4a and Figure 5 The trapezoid shown is only one possible shape of the waveguide unit. In the actual waveguide structure, the waveguide unit can also be other structures, as long as the two waveguide units have opposite slopes on the opposite sides and ensure that the width of at least one position is the same. As for the slopes of the two waveguide units on the opposite sides, they can be the same or different, and the shapes of the two waveguide units can be the same or different, such as the trapezoid shown in the above figures, or non-trapezoidal. Some examples of non-trapezoidal shapes include but are not limited to: regular shapes with edges and corners such as rhombus, triangle, polygon, rectangle, smooth shapes with curves such as ellipse, circle, semicircle, irregular shapes with bent corners, combined shapes composed of straight lines, oblique lines and curves, and any shapes that may appear in the future, etc., which are not specifically limited here.

[0171] For the sake of convenience, the I-1 level waveguide is referred to as the previous level waveguide of the I level waveguide, and the I+1 level waveguide is referred to as the next level waveguide of the I level waveguide, where I is an integer from 2 to N, including 2 and N. The previous level and the next level here have nothing to do with the light transmission direction, and only indicate the numerical level of the waveguide. For example, the second level waveguide is the next level waveguide of the first level waveguide, the first level waveguide is the previous level waveguide of the second level waveguide, the third level waveguide is the next level waveguide of the second level waveguide, and the second level waveguide is the previous level waveguide of the third level waveguide. The other levels of waveguides are similar and are not listed here one by one.

[0172] Continuing with the trapezoidal structure as an example, Figure 4aAs shown, in each waveguide of the second to Nth waveguides, the second waveguide unit is connected to the first waveguide unit of the previous level, and the first waveguide unit is connected to the second waveguide unit of the next level. Optionally, in the case where the second waveguide unit exists in the previous waveguide, the first waveguide unit is also connected to the second waveguide unit of the previous level. For example, for the third waveguide, it includes both the first waveguide unit and the second waveguide unit, and both the first waveguide unit and the second waveguide unit exist in the previous waveguide, i.e., the second waveguide, and the next waveguide, i.e., the fourth waveguide. Therefore, the second waveguide unit in the third waveguide is connected to the first waveguide unit in the previous waveguide, i.e., the second waveguide, and the first waveguide unit in the third waveguide is connected to the second waveguide unit in the next waveguide, i.e., the fourth waveguide, and the first waveguide unit in the third waveguide is also connected to the second waveguide unit in the previous waveguide, i.e., the second waveguide.

[0173] Alternatively, if Figure 4a As shown, when the first waveguide unit and the second waveguide unit are both trapezoidal, the second waveguide unit is connected to the first waveguide unit of the previous level, or the first waveguide unit is connected to the second waveguide unit of the next level, specifically, the long bases of the two trapezoids are connected together. The first waveguide unit of the next level is connected to the second waveguide unit of the previous level, specifically, the short bases of the two trapezoids are connected together. The connection here can be understood as a partial connection or a full connection, for example Figure 4a What is shown in the figure is a structure in which two trapezoids are completely connected, but in other structures, the bases of the two trapezoids may be partially connected, or the base of one trapezoid may completely cover the base of the other trapezoid, etc., without specific limitation.

[0174] If the above connection relationship is extended to N-level waveguides, then each waveguide unit in the N-level waveguide will form 2N-1 waveguide bands after being connected. Figure 6 As shown, the example of the waveguide strip when N is 5 is shown, which specifically includes 9 waveguide strips, namely, waveguide strip m 11 、m 12 、m 13 、m 14 ,m0,m 21 、m 22 、m 23 、m 24 Each waveguide strip includes at least one first waveguide unit and at least one second waveguide unit alternately connected in the light transmission direction (horizontal direction in the figure), for example, in combination with the above Figure 4aEach waveguide strip can be regarded as being formed by alternately connecting the first waveguide unit, the second waveguide unit, the first waveguide unit, ..., the first waveguide unit. Since the connected first waveguide unit and the second waveguide unit constitute a waveguide strip, there is no relatively large gap in the waveguide strip, and the optical signal can be directly transmitted from one waveguide unit to the next waveguide unit on the waveguide strip without any transmission fault, and the transmission efficiency is high.

[0175] Alternatively, if Figure 6 As shown, every two adjacent waveguide strips are staggered by a certain displacement in the horizontal direction shown in the figure. For example, when the first waveguide unit and the second waveguide unit are both trapezoidal, the adjacent waveguide strips can also be staggered by a trapezoidal displacement in the horizontal direction shown in the figure. This displacement is used to make the width changes of the two adjacent waveguide strips different, for example, so that the widened part of one waveguide strip corresponds to the narrowed part of the adjacent waveguide strip, so that the mode field released by the narrowed part of one waveguide strip can be absorbed by the widened part of the adjacent waveguide strip, and the effect of coupling the optical signal from one waveguide strip to another waveguide strip can be achieved.

[0176] It can be understood that, since the middle waveguide strip is the longest, the waveguide strips on both sides are the shortest, and each waveguide strip forms a structure with one side wide and the other side narrow, the shape of the N-level waveguide is similar to a polyhedron in the top view, and it is called a polyhedron structure. The fork head part of the polyhedron structure is the first-level waveguide, the fork tail part is the N-level waveguide, and the mode spot size of the fork head part is larger than the mode spot size of the fork tail part.

[0177] Optionally, the first-level waveguide is located at the edge of the chip, or is arranged on the end face of the chip, and the N-level waveguide is connected to the optical element. In this case, the mode spot size of the fork tail portion is determined by the mode spot size of the optical element connected behind it. In other words, the length of the first waveguide unit in the N-level waveguide can be designed according to the optical element connected behind it, and different optical elements correspond to different lengths. Among them, the optical element can be the first waveguide, and the first waveguide can be any type of waveguide, such as a single-mode waveguide or a multi-mode waveguide, or it can also be a non-waveguide element, without limitation.

[0178] In one example, when the optical element is a single-mode waveguide, such as Figure 4a As shown in FIG. 1 , in the Nth order waveguide, the mode spot size of the rightmost end f1 of the first waveguide unit is equal to the mode spot size of the single-mode waveguide. In the Nth order waveguide, the position where the first waveguide unit is coupled with the two second waveguide units is called the coupling position f2. Figure 4a and Figure 7In the optical transmission form shown in N=5, from left to right, although the cross-sectional size of the coupling point f2 is relatively small, the mode spot size of the optical signal coupled from the two second waveguide units to the coupling point f2 of the first waveguide unit is relatively large, and the mode spot size is usually larger than the mode spot size of the single-mode waveguide. If the coupling point f2 is directly connected to the single-mode waveguide, a sudden change in the cross-sectional size will occur, affecting the efficiency of light beam transmission. Therefore, in order to avoid this problem, the first waveguide unit in the Nth level waveguide can be designed to be relatively long, at least longer than the length of the second waveguide unit in the Nth level waveguide. In the extra length, the mode spot size of the first waveguide unit gradually decreases until the mode spot size gradually changes to the mode spot size of the single-mode waveguide. At this time, the rightmost end f2 of the first waveguide unit is connected to the single-mode waveguide. In this way, it can be ensured that the first waveguide unit and the single-mode waveguide are connected together with the same mode spot size, avoiding sudden changes in the mode spot size, thereby reducing the optical signal transmission loss. It can be understood that if the mode spot size of the coupling point f2 is exactly equal to the mode spot size of the single-mode waveguide, the first waveguide unit and the second waveguide unit in the Nth level waveguide can be of equal length, and the coupling point f2 of the first waveguide unit is directly connected to the single-mode waveguide.

[0179] In another example, if the optical element is a multimode waveguide, or other types of waveguides, the length of the first waveguide unit in the Nth level waveguide may be longer than that of a single-mode waveguide. For example, taking a multimode waveguide as an example, the mode spot size of the first waveguide unit at the rightmost end f1 is exactly equal to the fundamental mode size of the multimode waveguide, and the first waveguide unit may have a relatively long length and be connected to the multimode waveguide when it just transitions to the fundamental mode size of the multimode waveguide. It can be understood that in other examples, the mode spot size of the rightmost end f1 may also be larger or smaller than the mode spot size of the connected optical element, in order to excite multiple modes to match the multimode working mode.

[0180] It is understandable that there may be other examples, which are not listed here one by one.

[0181] The above content introduces the structural features of the waveguide structure. The light transmission characteristics of the waveguide structure are explained below.

[0182] In the waveguide structure, the first-level waveguide is used to transmit optical signals. Specifically, the N first waveguide units in the first-level waveguide are used to transmit optical signals. For example, the optical signals in the N first waveguide units coupled into the first-level waveguide from the waveguide structure are transmitted to the N second waveguide units of the second-level waveguide, or the optical signals in the N first waveguide units transmitted from the N second waveguide units of the second-level waveguide are transmitted to the outside of the waveguide structure. Here, the outside of the waveguide structure refers to Figure 4a The left area of ​​the first-order waveguide.

[0183] In the waveguide structure, the intermediate waveguide is used to realize the coupling transmission of the optical signal between the second waveguide unit and the first waveguide unit. Specifically, assuming that the intermediate waveguide is the first waveguide, the first waveguide is used to couple the optical signals transmitted on its N-I+2 second waveguide units to the N-I+1 first waveguide units, or to couple the optical signals transmitted on the N-I+1 first waveguide units to the N-I+2 second waveguide units. For example, combined with Figure 4a and Figure 7 In the optical transmission form when N=5 shown in the figure, when the optical signal is transmitted from left to right, the optical signal on the second waveguide unit in each intermediate waveguide will be coupled to the adjacent first waveguide unit, and the optical signal is gradually coupled from the 5 first waveguide units of the second waveguide to the 4 first waveguide units, and then to the 3 first waveguide units in the third waveguide, and then to the 2 first waveguide units in the fourth waveguide, and then to the 1 first waveguide unit in the fifth waveguide, realizing the transformation from a large mode spot size to a small mode spot size. On the contrary, when the optical signal is transmitted from right to left, the optical signal on the first waveguide unit in each intermediate waveguide will be coupled to the adjacent second waveguide unit, and the optical signal is gradually coupled from one first waveguide unit of the fifth waveguide to two second waveguide units, and then to three second waveguide units in the fourth waveguide, and then to four second waveguide units in the third waveguide, and then to five second waveguide units in the second waveguide, realizing the transition from a small mode spot size to a large mode spot size.

[0184] In the waveguide structure, the last waveguide is also the Nth waveguide, which is used to couple the optical signals transmitted on its two second waveguide units to the first waveguide unit and transmit them, or to couple the optical signals input to the first waveguide unit to the two second waveguide units. Figure 4a As shown, the optical signals coupled from the two second waveguide units are transmitted to the optical element connected to the rightmost end f1 of the first waveguide unit, or the optical signal input from the optical element connected to the rightmost end f1 is transmitted to the left side of the first waveguide unit and then coupled to the two second waveguide units.

[0185] Optionally, the above waveguide structure can be used as a transmitting port, a receiving port or a transceiver integrated port. No matter which port is used, its first-level waveguide is located at the edge of the chip, or in other words, is set on the end face of the chip, and the Nth-level waveguide is connected to the transmitting component or the receiving component through the aforementioned optical element, such as being connected to the transmitting component or the receiving component through a single-mode waveguide.

[0186] When used as a transmitting port, the Nth waveguide is connected to the transmitting component through the aforementioned optical element, and the optical signal emitted by the transmitting component is input into the above waveguide structure, coupled to the chip end surface through the multi-level waveguide in the waveguide structure and emitted. Figure 4a As shown, in the Nth level waveguide, the rightmost end f1 of the first waveguide unit receives the optical signal from the transmitting component and transmits it to the left side of the first waveguide unit, and then couples to the two adjacent second waveguide units, and transmits it to the left to the two first waveguide units in the N-1th level waveguide via the two second waveguide units. In the N-1th level waveguide, the optical signal is transmitted to the left along the two first waveguide units to the left side of the two first waveguide units, and then couples to the three adjacent second waveguide units, and then transmits to the left to the three first waveguide units in the N-2th level waveguide via the three second waveguide units. .... And so on, until the second level waveguide, the optical signal is transmitted to the left along the N-1 first waveguide units to the left side of the N-1 first waveguide units, and then couples to the adjacent N second waveguide units, and then transmits to the left to the N first waveguide units in the first level waveguide via the N second waveguide units, and then output to the left to the outside of the chip via the N first waveguide units, such as output to the subsequent scanning components.

[0187] On the contrary, when used as a receiving port, the Nth waveguide is connected to the receiving component through the aforementioned optical element, and the echo signal reflected by the target is coupled to the first waveguide through the chip end face, and then coupled to the Nth waveguide through the multi-stage waveguide in the waveguide structure, and then transmitted to the receiving component. Specifically, Figure 4a As shown, in the first-level waveguide, the optical signal reflected by the target is coupled from the left side into the N first waveguide units and transmitted to the N second waveguide units in the second-level waveguide. In the second-level waveguide, the optical signal is transmitted to the right along the N second waveguide units to the right side of the N second waveguide units, and then coupled to the adjacent N-1 first waveguide units, and then transmitted to the right through the N-1 first waveguide units to the N-1 second waveguide units in the third-level waveguide. ... And so on, until the Nth-level waveguide, the optical signal is transmitted to the right along the two second waveguide units to the right side of the two second waveguide units, and then coupled to the adjacent first waveguide unit, and then transmitted to the right through the first waveguide unit to the receiving component.

[0188] Optionally, in Figure 4a In the example, the value of N is 5, so the waveguide structure is a pentadent structure. Figure 4a and the above Figure 7The optical path transmission form when N=5, when the pentadent structure is used as the receiving end, the optical signal is coupled from the left into the 5 first waveguide units in the first waveguide, and is transmitted to the right in the 5 first waveguide units to the 5 second waveguide units in the second waveguide, and the mode field is released on the 5 second waveguide units, and the released mode field is absorbed by the 4 first waveguide units in the second waveguide. The optical signal is coupled to the 4 first waveguide units and transmitted to the 4 second waveguide units in the third waveguide, and the mode field is released on the 4 second waveguide units, and the released mode field is absorbed by the 3 first waveguide units in the third waveguide. The optical signal is coupled to the three first waveguide units and transmitted to the three second waveguide units in the second-level waveguide. The mode field is released on the three second waveguide units, and the released mode field is absorbed by the two first waveguide units in the second-level waveguide. The optical signal is coupled to the two first waveguide units and transmitted to the two second waveguide units in the first-level waveguide. The mode field is released on the two second waveguide units, and the released mode field is absorbed by the first waveguide unit in the first-level waveguide. The optical signal is coupled to the first waveguide unit and transmitted to the far right, and is transmitted to the receiving component through subsequent optical elements (such as single-mode waveguides). On the contrary, when the pentadent structure is used as a transmitting port, the optical signal output by the transmitting component enters the first waveguide unit in the fifth-level waveguide from the right, then transmits to the left and releases the mode field, the released mode field is absorbed by the two second waveguide units in the fifth-level waveguide, the optical signal is coupled to the two second waveguide units, and is transmitted to the left to the two first waveguide units in the fourth-level waveguide, the mode field is released on the two first waveguide units, the released mode field is absorbed by the three second waveguide units in the fourth-level waveguide, the optical signal is coupled to the three second waveguide units, and is transmitted to the left to the three in the third waveguide. First waveguide units are formed, mode fields are released on three first waveguide units, the released mode fields are absorbed by four second waveguide units in the third-level waveguide, optical signals are coupled to four second waveguide units, and transmitted to the left to four first waveguide units in the second-level waveguide, mode fields are released on four first waveguide units, the released mode fields are absorbed by five second waveguide units in the second-level waveguide, optical signals are coupled to five second waveguide units, and transmitted to the left to five first waveguide units in the first-level waveguide, and then transmitted to the far left on the five first waveguide units, and emitted out of the waveguide structure.

[0189] It is understandable that the value of N may also be other values, and several examples are given below to illustrate.

[0190] In an example, the value of N is 2, such as Figure 8a As shown, a dident structure is formed. The dident structure includes two levels of waveguides, the first level waveguide includes two first waveguide units, the second level waveguide includes two second waveguide units and one first waveguide unit, and the positional relationship of these waveguide units is shown in FIG. Figure 8a As shown. Combined Figure 8a and the above Figure 7 The optical transmission form when N=2, when the dident structure is used as the receiving port, the optical signal is coupled into the two first waveguide units of the first-level waveguide from the left side of the figure, and then transmitted to the right to the two second waveguide units of the second-level waveguide. Since the width of the second waveguide unit gradually narrows, the two second waveguide units release the mode field in the process of transmitting to the right, and the released mode field is absorbed by the first waveguide unit whose width gradually widens in the second-level waveguide. The optical signal is coupled to the first waveguide unit of the second-level waveguide, and is transmitted to the right to the rightmost end in the first waveguide unit, and is transmitted to the receiving component through the subsequently connected optical elements (such as single-mode waveguide). On the contrary, when the dident structure is used as a transmitting port, the optical signal output by the transmitting component enters the first waveguide unit in the second-level waveguide from the right side of the figure, and then transmits to the left to the left side of the first waveguide unit, and releases the mode field in the narrowed part on the left side. The released mode field is absorbed by the two second waveguide units in the second-level waveguide, and the optical signal is coupled to the two second waveguide units, and is transmitted to the left in the two second waveguide units to the two first waveguide units in the first-level waveguide, and then emitted to the outside of the waveguide structure.

[0191] In another example, the value of N is 3, such as Figure 8b As shown, a trident structure is formed. To describe it from another angle, the trident structure is composed of five waveguide strips, namely waveguide strip m 11 , waveguide band m 12 , waveguide strip m0, waveguide strip m 21 and waveguide band m 11 , these five waveguide strips are placed in parallel, and the waveguide strip m 11 ,m0,m 21 The left end of the waveguide strip m0 is used as the fork head, and the right end of the waveguide strip m0 is used as the fork tail. 12 Inserted in waveguide strip m 11 , m0 and staggered by a trapezoidal distance, the waveguide strip m 22 Inserted in waveguide strip m 21 , m0 and staggered by a trapezoidal distance. Figure 8b and the above Figure 7 The optical transmission form when N=3. When the trident structure is used as the receiving port, the optical signal is coupled into the waveguide band m from the left side of the figure. 11 , m0 and m 21 The left trapezoid then transmits to the right into the waveguide strip m 11 , m0 and m 21 The middle trapezoid of the waveguide is formed, and the mode field is released at the middle trapezoid. The released mode field is carried by the waveguide with m 12 、m 22 The left side of the trapezoidal absorption, the optical signal is coupled into the waveguide band m 12 、m 22 On, and in the waveguide band m 12 、m22 The light is transmitted to the right from the inside to the right trapezoid, where the mode field is released. The released mode field is absorbed by the right trapezoid of the waveguide strip m0, and the optical signal is coupled to the waveguide strip m0 and transmitted to the right to the rightmost end, and then transmitted to the receiving component through subsequent optical components. Conversely, when the trident structure is used as a transmitting port, the optical signal output by the transmitting component enters the right trapezoid of the waveguide strip m0 from the right, and then transmits to the left to the middle part of the waveguide strip m0, where the mode field is released. The released mode field is absorbed by the waveguide strip m0. 12 and m 22 The right side of the trapezoidal absorption, the optical signal is coupled into the waveguide band m 12 and m 22 On, and in the waveguide band m 12 and m 22 The mode field is transmitted from the inside to the left to the left trapezoid, and the mode field is released at the left trapezoid. The released mode field is carried by the waveguide m 11 , m0 and m 21 The intermediate trapezoidal absorption, the optical signal is coupled into the waveguide band m 11 , m0 and m 21 On, and in the waveguide band m 11 , m0 and m 21 The light is transmitted from the inside to the left to the trapezoid on the left, and then emitted to the outside of the waveguide structure;

[0192] In another example, the value of N is 4, such as Figure 8c As shown, a quadruple structure is formed. The quadruple structure is composed of seven waveguide strips, namely, waveguide strip m 11 , waveguide band m 12 , waveguide band m 13 , waveguide strip m0, waveguide strip m 23 , waveguide band m 22 and waveguide band m 21 , these seven waveguide strips are placed in parallel, waveguide strip m 11 、m 13 、m 23 、m 21 The left end of the waveguide strip m0 is used as the fork head, and the right end of the waveguide strip m0 is used as the fork tail. 12 Inserted in waveguide strip m 11 、m 13 The waveguide strip m0 is inserted between the waveguide strip m and the waveguide strip m0 is inserted between the waveguide strip m 13 、m 23 The waveguide strip m 22 Inserted in waveguide strip m 21 、m 23 and staggered by a trapezoidal distance. Figure 8c and the above Figure 7The optical transmission form when N=4. When the quadrident structure is used as the receiving port, the optical signal is coupled into the waveguide band m from the left side. 11 、m 13 、m 21 and m 23 , in the waveguide band m 11 、m 13 、m 21 and m 23 The mode field is transmitted to the right and released. The released mode field is carried by the waveguide m 12 ,m0,m 22 absorption, so that the optical signal is coupled into the waveguide band m 12 ,m0,m 22 On; the optical signal in the waveguide band m 12 ,m0,m 22 The mode field is transmitted to the right and released. The released mode field is carried by the waveguide m 13 、m 23 absorption, so that the optical signal is coupled into the waveguide band m 13 、m 23 On; the optical signal in the waveguide band m 13 、m 23 The optical signal is transmitted to the right and releases the mode field. The released mode field is absorbed by the waveguide strip m0, so that the optical signal is coupled to the waveguide strip m0 and transmitted to the rightmost side. It is then transmitted to the receiving component through subsequent optical elements (such as single-mode waveguides). Conversely, when the quadruple structure is used as a transmitting port, the optical signal output by the transmitting component enters the rightmost end of the waveguide strip m0 from the right, then transmits to the left and releases the mode field. The released mode field is absorbed by the waveguide strip m0. 13 and m 23 absorption, so that the optical signal is coupled into the waveguide band m 13 and m 23 On; the optical signal in the waveguide band m 13 and m 23 The mode field is transmitted to the left and released. The released mode field is carried by the waveguide m 12 , m0 and m 22 absorption, so that the optical signal is coupled into the waveguide band m 12 , m0 and m 22 On; the optical signal in the waveguide band m 12 , m0 and m 22 The mode field is transmitted to the left and released. The released mode field is carried by the waveguide m 11 、m 13 、m 23 and m 21 absorption, so that the optical signal is coupled into the waveguide band m 11 、m 13 、m 23 and m 21 It is then transmitted to the far left and emitted out of the waveguide structure.

[0193] It can be understood that the value of N can also be any integer greater than 5, such as 6, 7, 8, 9, etc. The relevant optical path transmission forms can be directly derived by analogy and will not be listed here one by one.

[0194] Optionally, the waveguide structure is called a multi-pronged structure. Assuming that the multi-pronged structure has a first mode spot size on the chip end face on the fork (i.e., the first-order waveguide) side and a second mode spot size on the fork tail (i.e., the Nth-order waveguide), the first mode spot size is greater than the second mode spot size. The second mode spot size is related to the optical element connected to the fork tail side. For example, if a single-mode waveguide is connected, the second mode spot size is the mode spot size of the single-mode waveguide. The first mode spot size is related to the number of forks N. Specifically, there is a positive correlation. The larger the value of N, the larger the size of the first mode spot size.

[0195] Optionally, in the first embodiment, each waveguide unit is set as a continuous structure, that is, a continuous trapezoidal block, there is no disconnected part in the middle of each trapezoidal block, and the height of each trapezoidal block is the same. In other words, the polyhedron structure in the first embodiment is a structure composed of multiple continuous trapezoidal blocks of the same height. Under this structural feature, by designing the end face parameters of the polyhedron structure, the polyhedron structure can support a 1-dimensional (dimension, D) large mode spot, and the mode spot size of the 1D large mode spot (i.e., the first mode spot size) is specifically determined by the value of N.

[0196] For example, see Fig. 9 , shows a schematic diagram of the first mold spot size of a multi-pronged structure with different numbers of forks provided in the first embodiment, and the figure only shows four cases of N=2, N=3, N=4, and N=5, and other values ​​of N can be deduced accordingly. Fig. 9 As shown in the figure, when the value of N is 2, the first mode spot size is elliptical, and as the value of N gradually increases, the first mode spot size also increases in the X direction (called the first direction) in the figure, and the first mode spot size has a large mode spot in the X direction in the figure. Compared with the solution of using a single-mode waveguide as a port in the prior art, the mode spot size of the multi-pronged structure increases in the X direction in the figure compared to the mode spot size of the single-mode waveguide, and this direction is called the mode spot increase direction. The mode spot increase direction here is the connection direction of the N forks on the chip end face, such as Figure 3 As shown in (A).

[0197] Optionally, when the multi-pronged structure is used as a receiving port, the direction in which the first pattern spot size increases corresponds to the walk-off offset direction. Figure 2a and Fig. 9 , Figure 2aThe walk-off offset direction in the figure is vertical. Therefore, the polyhedron structure can be placed so that the polyhedron structure is Fig. 9 The X direction corresponds to Figure 2a In the vertical direction of the X direction, compared with the prior art without an enlarged mode spot (such as a common single-mode waveguide), a higher receiving efficiency can be achieved even if there is a walk-off offset in the X direction.

[0198] For example, taking the polyhedron structure with N=5 as an example, see Fig.10 , showing the receiving efficiency comparison diagram of the multi-pronged structure used as a receiving port compared with the ordinary single-mode waveguide as a receiving port. The horizontal axis in the figure corresponds to the walk-off offset in the first direction, and the first direction is the direction in which the mode spot of the multi-pronged structure increases, such as Fig. 9 The vertical axis in the figure corresponds to the receiving efficiency, or coupling efficiency. The solid line in the figure corresponds to Figure 2a The receiving efficiency curve of the prior art is shown, and the dotted line in the figure corresponds to the receiving efficiency curve of the polyhedron structure with N=5. Comparing the two curves, it can be seen that the prior art has a good receiving efficiency when the walk-off offset is small, such as less than or equal to 2°, and once the walk-off offset exceeds 2°, the receiving efficiency will drop sharply as the walk-off offset increases, and when the walk-off offset reaches 5°, the receiving efficiency will even drop to 5%. While using the polyhedron structure in the present application, although the receiving efficiency when the walk-off offset is less than or equal to 2° is not as good as the prior art, after the walk-off offset is greater than 2°, as the walk-off offset increases, the receiving efficiency drops relatively slowly, and even if the walk-off offset reaches 5°, its receiving efficiency can be maintained at about 30%. It can be seen from this that the polyhedron structure in the present application can compensate for the receiving efficiency of the far end (i.e., large walk-off offset) by sacrificing the receiving efficiency of the near end (i.e., small walk-off offset), so that the overall receiving efficiency will not drop particularly low.

[0199] Based on the above implementation scheme 1, a waveguide structure capable of generating a 1D large mode spot can be provided, and the waveguide structure has many advantages, including but not limited to: 1. When the waveguide structure is used as a receiving port, a large mode spot in the 1D direction is generated on the end face of the chip, so that the walk-off effect in this direction is alleviated, and the receiving efficiency can be improved; 2. When the waveguide structure is used as a receiving port, the optical signal in the detection space is coupled to the waveguide structure, and only a single-mode mode will be excited, and multi-mode and corresponding multi-mode noise will not be excited, which can reduce the receiving loss and further improve the receiving efficiency; 3. When the waveguide structure is used as a receiving port, the optical signal in the detection space is coupled to the waveguide structure, and only a single-mode mode will be excited, and multi-mode and corresponding multi-mode noise will not be excited, so as to reduce the receiving loss and further improve the receiving efficiency. 1. When the optical signal is transmitted or received from the waveguide layer of the chip to the detection space, the Fresnel reflection of the chip end face is smaller than that of the multi-mode large mode spot, that is, the optical power transmitted to the detection space or coupled into the waveguide structure of the chip will be greater, and the transmission efficiency or reception efficiency will be higher; 2. The waveguide structure can be prepared by one-time molding, so the process is simple. Based on this, the waveguide structure in Implementation Plan 1 has the advantages of low process complexity, low material cost, low structural complexity, low receiving noise, etc., which can solve the technical problems existing in the two solutions provided by the industry.

[0200] Implementation Plan 2

[0201] The waveguide structure in Implementation Option 2 is similar to that in Implementation Option 1. Overall, the waveguide structure in Implementation Option 2 also presents a poly-trident structure with N-level waveguides. The difference is that each waveguide unit in the poly-trident structure of Implementation Option 1 is continuous, such as continuous trapezoidal blocks of the same height, while the poly-trident structure of Implementation Option 2 contains a sub-wavelength grating structure.

[0202] Optionally, in the second embodiment, part or all of the first to Nth waveguides of the polytetrafluoroethylene structure are sub-wavelength grating structures. There are two possible forms, one form is as follows: Fig.11a As mentioned above, the overall structure includes a sub-wavelength grating structure. Another form is Fig.11b As shown, only the end face (i.e., the first-order waveguide side) and the subsequent part of the area contain sub-wavelength grating structures. Fig.11a and Fig.11b Here, only N=5 is taken as an example. The structures with other values ​​of N are similar and will not be listed here one by one.

[0203] Alternatively, if it is the first form, such as Fig.11aAs shown, each waveguide unit in the polyhedron structure is composed of a plurality of waveguide blocks. In detail, each waveguide unit includes short waveguide blocks one by one, and the distance between adjacent short waveguide blocks is small enough so that the plurality of short waveguide blocks present the shape of a waveguide unit in the first embodiment as a whole, and can realize the function of the waveguide unit in the first embodiment as described above.

[0204] It should be noted that each short waveguide block can be discrete or non-discrete. Fig.11a Take the former as an example. Discrete means that different short waveguide blocks are completely disconnected, and non-discrete means that different short waveguide blocks are not completely disconnected, for example, a part of the bottom is connected together, which is equivalent to opening a lot of through grooves on an overall structure to form a structure of rows, but the bottoms of the rows are connected together by relatively thin parts. Of course, there may be other structures, such as partially completely disconnected, some bottoms connected together, or the middle parts connected together, etc., which are not specifically limited.

[0205] Alternatively, if it is the second form, such as Fig.11b As shown, the polyhedron structure includes a block region, a transition region and a continuous region, and the block region, the transition region and the continuous region are arranged along the direction from the first-order waveguide to the Nth-order waveguide. One end of the transition region is connected to the block region, and the other end is connected to the continuous region, so as to realize the transition of the optical signal from the block region to the continuous region. For example, in a possible implementation form, Fig.11b As shown, the block area includes a plurality of short waveguide blocks, the continuous area includes a long waveguide block, and the long waveguide block is connected to the middle part of the plurality of short waveguide blocks to form a transition area. In this way, the continuous area and the block area themselves can form a transition area at the connection position without the need to set up an additional transition area, and the process cost is low.

[0206] It should be noted that in the above content, the block area is only a name, and the block area can be a completely disconnected block, that is, multiple short waveguide blocks are discrete from each other, or it can also be a block that is not completely disconnected, such as a relatively thin part of the bottom (or central area or top, etc., not limited) of multiple short waveguide blocks connected together, or some short waveguide blocks are connected together, and the remaining short waveguide blocks are completely disconnected, etc. There are many possible structures, as long as they can form a sub-wavelength grating structure, and this application does not make specific limitations on this.

[0207] In addition, similar to the first form, the spacing between multiple short waveguide blocks in the block area in the second form is small enough so that the multiple short waveguide blocks appear as a waveguide unit as a whole, and can realize the function of the waveguide unit in the above-mentioned embodiment one.

[0208] Also, in the second form, usually only the block area, transition area and continuous area can be arranged adjacent to each other in sequence, and the block area cannot be designed after the continuous area. Therefore, the first-level waveguide must be used as the block area, and the length of the block area can be designed according to actual needs. For example, only the first-level waveguide can be designed as the block area, or only part of the first-level waveguide can be designed as the block area, or part or all of the entire first-level waveguide and the second-level waveguide can be designed as a sub-wavelength grating structure, or the entire first-level waveguide, the entire second-level waveguide and part or all of the third-level waveguide can be designed as a sub-wavelength grating structure, etc., without specific limitation.

[0209] Optionally, in the second implementation scheme, the polyhedron structure includes a sub-wavelength grating structure. By designing the parameters of the two end faces of the polyhedron structure and the sub-wavelength grating structure, the polyhedron structure can support a 2D large mode spot. The mode spot size of the 2D large mode spot (i.e., the first mode spot size) is determined by the value of N. For example, refer to Fig.12 , shows a schematic diagram of the first pattern spot size of a multi-pronged structure with different numbers of forks provided by the second embodiment, and the figure only shows four cases of N=4 and N=5, and other values ​​of N can be deduced accordingly. Fig.12 As shown, the first mold spot size in the second embodiment has a large mold spot in both the X direction and the Y direction in the figure. Fig.12 The X direction in the figure refers to the direction of the connection of the N forks on the chip end surface, and the Y direction refers to the direction perpendicular to the connection of the N forks on the chip end surface. Fig.11a Middle (A) or Fig.11a As shown in (B).

[0210] Assumptions Fig.12 The X direction is the first direction, and the Y direction is the second direction. Then, compared with the mode spot size of the existing ordinary single-mode waveguide, the first mode spot size of the polyproton structure in the above embodiment one is only increased in the first direction, while the polyproton structure in the embodiment two increases the mode spot in both the first direction and the second direction. Therefore, the shape of the first mode spot size of the polyproton structure in the embodiment two is closer to a circle than that in the above embodiment one. It should be noted that when the value of N is relatively small, although the first mode spot size of the polyproton structure in the embodiment two is larger than the first mode spot size in the embodiment one in the second direction, the overall shape is still elliptical. When the value of N is relatively large, such as greater than or equal to 4, the first mode spot size in the first direction and the second direction are close to the same, so the overall shape is nearly circular. The nearly circular first mode spot size can alleviate the walk-off effect in all directions on the chip end face.

[0211] For example, taking the polyhedron structure with N=5 as an example, see Fig.13 , showing the receiving efficiency comparison diagram when the multi-pronged structure is used as a receiving port compared with the ordinary single-mode waveguide as a receiving end. Among them, Fig.13 The horizontal axis in the above figure corresponds to the walk-off offset in the first direction. Fig.13 The horizontal axis in the figure below corresponds to the walk-off offset in the second direction. The first direction and the second direction are the two mold spot enlargement directions of the multi-pronged structure. For example, the first direction is Fig.12 The horizontal direction in the second direction is Fig.12 The vertical direction in . Fig.13 In the above figure and Fig.13 The vertical axes in the following figures correspond to the receiving efficiency, the solid lines correspond to the receiving efficiency curves of the single-mode waveguide, and the dotted lines correspond to the receiving efficiency curves of the multi-trident structure with N=5.

[0212] Combination Fig.13 In the above figure and Fig.13 It can be seen from the four curves shown in the figure below that the prior art has a better receiving efficiency when the walk-off offset in the first direction and the second direction is small, and once the walk-off offset exceeds a certain value (for example Fig.13 2.1° in the first direction in the above figure, Fig.13 3° in the second direction in the figure below), as the walk-off offset increases, the receiving efficiency decreases faster. When the walk-off offset reaches 5°, the receiving efficiency in both directions will drop to 5%. With the polytrident structure in the present application, although the receiving efficiency is not as good as the prior art when the walk-off offset is small, after the walk-off offset is greater than a certain value, as the walk-off offset increases, the receiving efficiency decreases more slowly. Even if the walk-off offset in both directions reaches 5°, the receiving efficiency can be maintained at about 10%. It can be seen from this that the polytrident structure in Implementation Option 2 can compensate for the receiving efficiency at the far end (i.e., large walk-off offset) by sacrificing the receiving efficiency at the near end (i.e., small walk-off offset), so that the overall receiving efficiency will not drop too low.

[0213] Based on the above implementation scheme 2, a waveguide structure capable of generating a 2D large mode spot can be provided. In addition to having the advantages of the waveguide structure in the above implementation scheme 1, the waveguide structure can also generate a 2D large mode spot, thereby solving the problem of decreased receiving efficiency caused by the walk-off effect in both directions of the 2D large mode spot. In addition, although the waveguide structure in the implementation scheme 2 includes a sub-wavelength grating structure, the structure can also be directly prepared by one-time molding without adding additional process steps, that is, compared with the implementation scheme 1, the preparation difficulty and process complexity will not be increased.

[0214] Based on the above, from another perspective, the present application can also provide a waveguide structure, such as Fig.14 As shown. The waveguide structure includes multiple waveguide modules (which can be understood as the waveguide belts mentioned above), such as waveguide module U1, waveguide module U2, waveguide module U3, waveguide module U and waveguide module U5 shown in the figure. Multiple waveguide modules U1~U5 are placed in parallel to form a multi-prong structure, and each waveguide module is at least partially coupled with an adjacent waveguide module, and the coupling is used to transmit the optical signal on the waveguide module to the adjacent waveguide module.

[0215] Based on this waveguide structure, the optical signal can be transmitted from one waveguide module to an adjacent waveguide module through coupling between adjacent waveguide modules. Furthermore, since the multiple waveguide modules are presented as a multi-trident structure as a whole, if the fork head direction is the input end, the large mode spot signal can be received based on the fork head with a large mode spot size, and transmitted to the fork tail direction through coupling between adjacent waveguide modules, and then transmitted out, thereby achieving a higher receiving efficiency. If the fork tail direction is the input end, the optical signal can be received based on the fork tail, and transmitted to the fork direction through coupling between adjacent waveguide modules, and then transmitted out based on the fork head with a large mode spot size, thereby achieving a higher transmission efficiency. In this way, whether it is used as a transmitting port, a receiving port, or a transceiver-integrated port, the waveguide structure can have a large mode spot size, which can improve the coupling efficiency of the port.

[0216] Alternatively, if Fig.14 As shown, each waveguide module may include one or more shuttle-shaped bodies, each shuttle-shaped body is wide in the middle and narrow at both ends, and adjacent waveguide modules are staggered by half the distance of the shuttle-shaped body. Fig.14In the example, waveguide modules U1, U2, U4 and U5 all include a shuttle body, and waveguide module U3 includes a shuttle body and a trapezoid. A trapezoid can be regarded as half a shuttle body, so it can also be considered that waveguide module U3 includes a half shuttle body. Among them, waveguide modules U1, U3 and U5 are placed in parallel and aligned, while waveguide module U2 is inserted between waveguide modules U1 and U3, and waveguide module U4 is inserted between waveguide modules U5 and U3. Waveguide modules U2 and waveguide modules U4 are offset to the right by the distance of half a shuttle body relative to waveguide modules U1, U3 and U5. Among them, half a shuttle body can be understood as a trapezoid in the above content.

[0217] Based on the above structure and positional relationship, the wide part of the shuttle body is used to absorb the mode field, while the narrow part is used to release the mode field. Since the adjacent waveguide modules are staggered by half the distance of the shuttle body, the narrow part of a waveguide module just corresponds to the wide part of the adjacent waveguide module, and the mode field released by the narrow part of the waveguide module can be completely or almost completely absorbed by the wide part of the adjacent waveguide module, which can improve the coupling efficiency of the optical signal between the adjacent waveguide modules.

[0218] For example, taking the waveguide module U2 as an example, the widened part of the left half of the shuttle body in the waveguide module U2 corresponds exactly to the narrowed part of the right half of the shuttle body in the waveguide module U1, and the narrowed part of the shuttle body in the waveguide module U3. Therefore, when the optical signal is transmitted from left to right, the mode field released by the narrowed parts of the waveguide modules U1 and U3 can be absorbed by the widened part of the waveguide module U2. Therefore, the optical signals on the waveguide modules U1 and U3 can be coupled to the waveguide module U2. Based on the same functional principle, the optical signal with a large mode spot can be finally gathered on the waveguide module U3 and emitted to the right. Conversely, when the optical signal is transmitted from right to left, the mode field released by the narrowed part of the waveguide module U2 can be absorbed by the widened part of the waveguide modules U1 and U3. Therefore, the optical signal on the waveguide module U2 can be coupled to the waveguide modules U1 and U3. Based on the same functional principle, the optical signal transmitted on the waveguide module U3 can finally be transformed into an optical signal with a large mode spot and emitted to the left.

[0219] Optionally, the spacing between adjacent waveguide modules is smaller than the set spacing. Fig.14As shown, the spacing between waveguide modules U1 and U2, the spacing between waveguide modules U2 and U3, the spacing between waveguide modules U3 and U4, and the spacing between waveguide modules U4 and U5 are all smaller than the set spacing. The set spacing refers to a distance that enables adjacent waveguide modules to be sufficiently close without signal crosstalk. The value of the set spacing is related to the material of the waveguide module. Waveguide modules made of different materials will have different set spacings, and no specific limitation is given here. The multiple waveguide modules are set to be close enough so that the multiple waveguide modules can be regarded as a whole, so as to achieve coupling of optical signals between adjacent waveguide modules and reduce coupling losses of optical signals.

[0220] Optionally, the forks of the multi-pronged structure have a first pattern spot size, and the first pattern spot size is positively correlated with the number of forks. Fig.14 In the example, the left side of the waveguide modules U1, U3 and U5 is used as a fork, so the number of forks is 3. Compared with the multi-fork structure with 2 forks, the first mode spot size of the multi-fork structure with 3 forks is larger. Therefore, the number of forks can be configured according to the actual mode spot size requirements, so that the multi-fork structure is adapted to various chip scenarios. Among them, the specific content of the positive correlation can be referred to the above embodiment, which will not be repeated here.

[0221] Alternatively, if Fig.14 As shown, when a waveguide module includes multiple shuttle bodies, the narrow parts of the multiple shuttle bodies are connected together. For example, for the waveguide module U3, it includes a half shuttle body, and the left shuttle body and the narrow part of the half shuttle body on the right are connected together. In this way, the waveguide module with multiple shuttle bodies can form a waveguide belt, and the cross-sectional dimensions of the waveguide belt are alternately wide and narrow. The optical signal continuously releases the mode field and absorbs the mode field on the alternately wide and narrow cross-sections, and can be coupled and transmitted in one direction with a higher coupling efficiency.

[0222] Alternatively, if Fig.14 As shown in FIG. 1 , in two adjacent waveguide modules, the narrow part of one waveguide module and the wide part of another waveguide module have the same change trend. Here, the same change trend can be understood as: the absolute value of the slope is the same but the direction is opposite. For example, in Fig.14 In the example, the right half of the shuttle-shaped body of the waveguide module U1 gradually narrows, and the left half of the shuttle-shaped body of the waveguide module U2 gradually widens, and the absolute value of the slope of the former narrowing is the same as the slope of the latter widening. Therefore, the widening and narrowing change rules of the two waveguide modules are the same, but the change directions are opposite. The mode field released by the narrowed part of one waveguide module can be completely or almost completely absorbed by the widened part of the other waveguide module. The optical signal can be coupled from one waveguide module to another waveguide module with a higher coupling efficiency, effectively reducing the coupling loss.

[0223] It can be understood that on the opposite surfaces of adjacent waveguide modules, the changing trends of the widened and narrowed parts can also be different, as long as the width at at least one position is the same. For details, please refer to the introduction of the above embodiments, which will not be repeated here.

[0224] Alternatively, if Fig.14 As shown, the waveguide module in the middle is the longest, and the waveguide modules on both sides are the shortest. Therefore, the waveguide modules on both sides are symmetrical with respect to the waveguide module in the middle, and the optical signal is transmitted symmetrically on both sides of the waveguide module in the middle, so that uniform transmission of the optical signal can be achieved.

[0225] Alternatively, if Fig.14 As shown, the waveguide modules located on both sides include a shuttle body, and the waveguide module located in the middle includes K shuttle bodies. , N is the number of forks of the multi-pronged structure, and the value of N is an integer greater than or equal to 2. Based on this design, from the direction of the fork to the fork tail, that is, from left to right, the multi-fork structure can gradually and evenly change from multi-end to single-end, and from the reverse direction, that is, from right to left, it gradually and evenly expands from single-end to multi-end. In this way, the optical signal will not encounter a sudden missing part during the transmission from one end to the other end, and can try to ensure that all optical signals are transmitted to the other end.

[0226] Alternatively, if Fig.14 As shown, the waveguide module located in the middle also includes a trapezoidal body (which can also be regarded as a half-shuttle body), the narrow part of the trapezoidal body is connected to the end of the shuttle body of the waveguide module located in the middle, and the wide part of the trapezoidal body is connected to the first waveguide. The mold spot size of the wide part of the trapezoidal body is equal to the mold spot size of the first waveguide. The trapezoidal body can be regarded as the connecting part between the end of the shuttle body of the middle waveguide module and the first waveguide connected to the rear end. After the mold spot size of the end of the shuttle body is gradually changed to the mold spot size of the first waveguide, it is connected to the first waveguide, so that the multi-pronged structure can accurately adapt to the first waveguide connected to the rear end.

[0227] In the above content, the first waveguide can be a single-mode waveguide or a multi-mode waveguide. If it is a multi-mode waveguide, the mode spot size of the wide part of the trapezoidal body is smaller than the mode spot size of the fundamental mode in the multi-mode waveguide. The single-mode waveguide has a smaller mode spot size and only transmits a single mode inside. There will be no collision and interference problems between multiple modes and multiple modes, and it has a better light transmission effect. Although the multi-mode waveguide may produce mode collisions, it can also achieve light transmission and can be adapted to scenarios where multi-mode waveguides are required to transmit optical signals.

[0228] Alternatively, if Fig.14As shown, assuming that the number of forks of the polytrident structure is N, N is an integer greater than or equal to 2, then: the waveguide structure may include 2N-1 waveguide modules, the 2N-1 waveguide modules are placed in parallel on both sides of the light propagation direction, the 2N-1 waveguide modules include a middle waveguide module and 2N-2 non-middle waveguide modules, every two adjacent waveguide modules in the 2N-2 non-middle waveguide modules are a group, the waveguide module located on the outside of each group of waveguide modules is a fork, and the waveguide module located on the inside is staggered by half a shuttle body distance relative to the waveguide module located on the outside. For example, Fig.14 The structure shown is N=3, so the waveguide structure includes 2×3-1=5 waveguide modules. The waveguide modules on both sides are symmetrically distributed relative to the waveguide module in the middle. Therefore, the optical signal transmission path on both sides is the same, and multiple modes will not be excited, ensuring that both the input and output are single-mode optical signals.

[0229] Further, optionally, if Fig.14 As shown, the two waveguide modules in each group of waveguide modules contain the same number of shuttle bodies. For example, the waveguide modules in the middle group are waveguide module U2 and waveguide module U4, and both of these waveguide modules include a shuttle body. By making the structures of the two waveguide modules in each group of waveguide modules the same, it can be ensured that the lengths of the two waveguide modules are the same, and the optical signal transmission is symmetrical.

[0230] Further, optionally, if Fig.14 As shown, the closer a group of waveguide modules is to the middle, the more shuttle bodies it contains. Thus, the closer the waveguide module is to the middle, the longer it is, and the optical signal can be transmitted to a farther position on the waveguide module, so that the optical signal can be transmitted from one end of the polyhedron structure to the other end.

[0231] Optionally, the fork portion of the polypron structure is divided into a sub-wavelength grating structure, or the polypron structure as a whole is a sub-wavelength grating structure. For example, only the fork portion may be a sub-wavelength grating structure, or the fork portion and a part of the inner region may be a sub-wavelength grating structure, or the entire structure may be a sub-wavelength grating structure, without limitation.

[0232] Further, optionally, the sub-wavelength grating structure includes a block region, a transition region and a continuous region, and the block region, the transition region and the continuous region are arranged along the direction from the fork head to the fork tail. For example, in one example, the block region includes a plurality of short waveguide blocks, and the continuous region includes a long waveguide block, and the long waveguide block is connected to the middle part of the plurality of short waveguide blocks to form a transition region.

[0233] Optionally, the fork of the multi-pronged structure is exposed on the end surface of the chip, and the fork tail of the multi-pronged structure is connected to the first waveguide. The first waveguide can be a single-mode waveguide or a multi-mode waveguide, without limitation.

[0234] Optionally, the forks of the multi-pronged structure support a first mold spot size, and the first mold spot size is positively correlated with the number of forks. In other words, the more the number of forks, the larger the first mold spot size.

[0235] Further optionally, the first mode spot size may satisfy one of the following conditions: when the multident structure is composed of long waveguide blocks, the first mode spot size is elliptical; when the multident structure includes short waveguide blocks, the first mode spot size is elliptical or nearly circular. In other words, the first mode spot size corresponding to the multident structure including short waveguide blocks is closer to a circle than the first mode spot size corresponding to the multident structure including long waveguide blocks.

[0236] It should be noted that Fig.14 In the description, only the value of N is 3 as an example, but N can also take other values, such as 2, 3, 4, 5, etc. The relevant structure can refer to the introduction of the above embodiment, which will not be repeated here.

[0237] In addition, the relevant technical features of the multi-pronged structure or waveguide structure involved in this part can be found in the above introduction, and will not be repeated here.

[0238] The waveguide structure provided in the above content can be applied to silicon photonic chips, such as SOI silicon photonic chips.

[0239] See also Fig.15 , showing a possible structural schematic diagram of a silicon photonic chip provided by the present application. The silicon photonic chip 1500 includes a waveguide structure, and the waveguide structure can be any of the waveguide structures described above, such as the above Figure 3 , Figure 4a~Figure 4d , Figure 8a~Figure 8c , Fig.11a , Fig.11b , Fig.14 The waveguide structure described in any of the accompanying drawings.

[0240] Optionally, the above waveguide structure can be used as a transmitting port, a receiving port or a transceiver integrated port of a silicon photonic chip. Regardless of which port is used, the first-level waveguide in the waveguide structure is located on the end face of the silicon photonic chip. For example, the N first waveguide units in the first-level waveguide are located on the end face of the silicon photonic chip for sending detection signals or receiving echo signals.

[0241] Optionally, when the silicon photonic chip 1500 is a SOI silicon photonic chip, Fig.15 As shown, it may include a silicon substrate layer, a buried oxide layer and a top oxide layer stacked in sequence (for example, stacked from bottom to top as shown in the figure), the waveguide structure is buried in the top oxide layer, and the bottom contacts the buried oxide layer.

[0242] In some scenarios, the layer where the waveguide structure is located may also be called a waveguide layer, and the waveguide layer is a layer buried in the top oxide layer and composed of a waveguide material. In this case, the silicon photonic chip 1500 includes a silicon substrate layer, a buried oxide layer, a waveguide layer, and a top oxide layer stacked in sequence, and the waveguide structure is located in the waveguide layer.

[0243] For example, if the above implementation plan Figure 3 The waveguide structure shown in FIG. 1 is shown in FIG. 1 . After removing the top oxide layer, the structure of the silicon photonic chip 1500 is as follows: Fig.16a If the above implementation plan 2 Fig.11a The waveguide structure shown in FIG. 1 is shown in FIG. 1 . After removing the top oxide layer, the structure of the silicon photonic chip 1500 is as follows: Fig.16b If the above implementation plan 2 Fig.11b The waveguide structure shown in FIG. 1 is shown in FIG. 1 . After removing the top oxide layer, the structure of the silicon photonic chip 1500 is as follows: Fig.16c Other similar structures are not listed one by one.

[0244] The above silicon photonic chip 1500 can be applied to a detection device or system with a frequency modulation function, such as the FMCW LiDAR mentioned above, or an optical frequency domain reflectometry (OFDR) system, an optical coherence tomography (OCT) system, etc., without specific limitation.

[0245] Exemplarily, taking FMCW LiDAR as an example, the waveguide layer may include other structures in addition to the above waveguide structure. When the FMCW LiDAR is of different types, the waveguide structure is a different type of port, and there are some differences in the connection method between the waveguide structure and other components. For ease of understanding, the following exemplary implementation method 1 and implementation method 2 are used to illustrate the other structures in the waveguide layer of different types of FMCW LiDAR and the connection relationship with the waveguide structure.

[0246] Implementation method 1

[0247] See also Fig.17 , showing a schematic structural diagram of a waveguide layer provided in implementation mode 1. In implementation mode 1, the FMCW LiDAR is a non-coaxial FMCW LiDAR, in which some waveguide structures are used as transmitting ports and some waveguide structures are used as receiving ports. In other words, the transmitting port and the receiving port are different waveguide structures.

[0248] However, it should be understood that implementation method one is only explained by taking the example that both the transmitting port and the receiving port adopt the above waveguide structure. In other examples, only the transmitting port may adopt the above waveguide structure and the receiving port may adopt other structures, or only the receiving port may adopt the above waveguide structure and the transmitting port may adopt other structures. Other structures include but are not limited to single-mode waveguides, waveguides with inclined surfaces provided by the industry, etc.

[0249] In an example, Fig.17 As shown, the waveguide layer also includes an emission component. When the above waveguide structure is used as an emission port, the emission component is connected between the input end (a) of the silicon photonic chip and the waveguide structure. For example, the input end of the emission component is connected to the input end a of the silicon photonic chip, and the first output end of the emission component is connected to the first waveguide unit of the Nth waveguide in the waveguide structure. The emission component is used to receive an optical signal from the input end, split a detection signal from the optical signal, and then output the detection signal to the Nth waveguide in the waveguide structure. The detection signal is transmitted to the first waveguide through the multi-stage evanescent wave coupler in the waveguide structure, and then passes through the N first waveguide units in the first waveguide, and is emitted from the end face of the silicon photonic chip to the outside of the silicon photonic chip.

[0250] In an example, Fig.17 As shown, the waveguide layer also includes a receiving component. When the above waveguide structure is used as a receiving port, the receiving component is connected between the electrical output end (d) of the silicon photonic chip and the waveguide structure. For example, the output end of the receiving component is connected to the electrical input end d of the silicon photonic chip. The first input end of the receiving component is used to receive the local oscillator (LO) signal. After the detection signal is reflected by the target in the detection space, it returns to the end face of the silicon photonic chip, and then couples to the first waveguide unit of the first-level waveguide in the waveguide structure, and is transmitted to the Nth-level waveguide through the multi-level evanescent wave coupler in the waveguide structure, and then input into the receiving component. The receiving component is used to obtain the echo signal received by the waveguide structure, and mix the echo signal and the LO signal to obtain an intermediate frequency signal. The intermediate frequency signal is used to determine the speed and / or distance of the target.

[0251] Optionally, the LO signal can be separated from the transmitting component. Fig.17 As shown, the transmitting component also has a second output end, and the receiving component also has a second input end, and the second input end of the receiving component is connected to the second output end of the transmitting component. The transmitting component can also split the LO signal from the input optical signal and output it to the receiving component through the second output end. The receiving component obtains the echo signal input from the waveguide structure from the first input end, obtains the LO signal input from the transmitting component from the second input end, and mixes the echo signal and the LO signal.

[0252] Alternatively, if Fig.17As shown, the waveguide layer also includes a photodetector, which is connected between the output end of the receiving component and the electrical output end d of the silicon photonic chip. The photodetector can perform photoelectric detection on the intermediate frequency signal output by the receiving component, convert it into an electrical signal and output it to the electrical output end d of the silicon photonic chip, so as to be transmitted to devices other than the silicon photonic chip, such as an electrical chip, for subsequent distance measurement and speed measurement.

[0253] Optionally, for any one of the transmitting component and the receiving component, the component may be connected to the first waveguide unit of the Nth waveguide in the waveguide structure through the first waveguide, and the first waveguide may be a single-mode waveguide or a multi-mode waveguide. Taking the single-mode waveguide as an example, the first waveguide unit of the Nth waveguide in the waveguide structure has a second mode spot size, and the second mode spot size is the mode spot size of the single-mode waveguide.

[0254] There are many possible structures for the above transmitting and receiving components. For example, in one example, see Fig.18 , showing a specific structural schematic diagram of a waveguide layer provided by implementation method 1. In this example, assuming that the FMCW LiDAR is a four-channel, the silicon photonic chip has four transmitting ports and four receiving ports, and correspondingly, there are four waveguide structures as four transmitting ports and four waveguide structures as four receiving ports.

[0255] like Fig.18 As shown, the transmitting component may specifically include a spectrometer 1 and a spectrometer 2, wherein the input end of the spectrometer 1 is connected to the input end a of the silicon photonic chip, and an output end of the spectrometer 1 is connected to the input end of the spectrometer 2. The spectrometer 2 has four output ends, which are respectively connected to the four waveguide structures as the transmitting ports, and specifically, are respectively connected to the first waveguide units of the Nth order waveguides in the four waveguide structures. Based on the structure and the connection relationship, the spectrometer 1 is used to split the intermediate optical signal from the input optical signal, and output the intermediate optical signal to the spectrometer 2, and the spectrometer 2 is used to split the intermediate optical signal into four transmitting signals, and output them to the four waveguide structures respectively. These four transmitting signals are emitted to the outside of the silicon photonic chip via the four waveguide structures to realize four-channel detection. Optionally, the spectrometer 2 can split the intermediate optical signal into four transmitting signals of equal power with equal power, so that the four channels emit light evenly, and the four transmitting signals emitted to the detection space will also have the same power, which can detect targets at the same distance and has a better detection effect.

[0256] like Fig.18As shown, the receiving component may specifically include an optical splitter 3 and four mixers, namely mixer 1, mixer 2, mixer 3 and mixer 4. The other output end of the optical splitter 1 is connected to the input end of the optical splitter 3, and the four output ends of the optical splitter 3 are respectively connected to one input end of mixers 1 to 4, and the other input ends of mixers 1 to 4 are respectively connected to four waveguide structures as receiving ports, specifically, they are respectively connected to the first waveguide unit of the Nth order waveguide in the four waveguide structures, and the output ends of mixers 1 to 4 are connected to the electrical output end d of the silicon photonic chip, for example, connected to the electrical output end d through a photodetector. Based on this structure and connection relationship, the optical splitter 1 is also used to split the LO signal from the input optical signal and output the LO signal to the optical splitter 3, and the optical splitter 3 is used to split the LO signal into four sub-LO signals and output them to mixers 1 to 4 respectively. Each mixer receives an echo signal from the connected waveguide structure, mixes the echo signal with the sub-LO signal input from the optical splitter 3, and obtains an intermediate frequency signal. Optionally, mixers 1 to 4 can also send their respective intermediate frequency signals to a photodetector, which performs photoelectric detection on the four intermediate frequency signals and converts them into electrical signals, which are then output from the electrical output terminal d of the silicon photonic chip.

[0257] It should be noted that the above content is all based on four-channel detection as an example, but this is only a possible implementation method. In an actual silicon photonic chip, it can be any number of detection channels greater than or equal to 1. For example, in another example, the optical signal output from the output end of the optical splitter 1 can be directly used as a transmission signal. In this case, there can be only one waveguide structure and one mixer, and there is no optical splitter 2 and optical splitter 3, thereby realizing single-channel detection. Or, in another example, the optical splitter 1 can also separate two intermediate optical signals, one intermediate optical signal is directly used as a transmission signal, and the other intermediate optical signal is split into 4 transmission signals through the optical splitter 2, thereby realizing five-channel detection. In another example, the optical splitter 2 can also have only 2 output ends to realize two-channel detection, or 3 output ends to realize three-channel detection, or any number of output ends of more than 4 to realize any number of detection channels of more than four. Or, in another example, other optical splitters can be set on one or more output paths of the optical splitter 2 to separate any number of transmission signals greater than 4, and so on. There are many possible implementation methods, which are not listed here one by one.

[0258] In the above implementation method 1, the waveguide structure can be used as a transmitting port or a receiving port in a non-coaxial FMCW LiDAR. As a transmitting port, the transmitting efficiency can be improved, and as a receiving port, the receiving efficiency can be improved. As both a transmitting port and a receiving port, both the transmitting efficiency and the receiving efficiency can be improved.

[0259] Implementation method 2

[0260] See also Fig.19 , showing a schematic diagram of the structure of a waveguide layer provided by implementation method 2. In implementation method 2, the FMCW LiDAR is a coaxial FMCW LiDAR, and in the waveguide layer of the FMCW LiDAR, the waveguide structure serves as a transceiver integrated port, in other words, the transmitting port and the receiving port are the same port, and use the same waveguide structure.

[0261] Similar to the implementation method 1, the waveguide layer in the implementation method 2 also includes a transmitting component and a receiving component. The difference is that Fig.19 As shown, the waveguide layer in the second implementation also includes a polarization element. The transmitting component has an input end and two output ends, the receiving component has two input ends and one output end, and the polarization element has three communication ends, namely, a first communication end b1, a second communication end b2, and a third communication end b3. The input end of the transmitting component is connected to the input end a of the silicon photonic chip, the first output end of the transmitting component is connected to the first communication end b1 of the polarization element, and the second output end of the transmitting component is connected to the second input end of the receiving component; the second communication end b2 of the polarization element is connected to the first waveguide unit of the Nth level waveguide in the waveguide structure, the third communication end b3 of the polarization element is connected to the first input end of the receiving component, and the output end of the receiving component is connected to the electrical output end d of the silicon photonic chip.

[0262] Based on the above structure and connection relationship, the transmitting component receives the optical signal of the first linear polarization state from the input end, and splits the detection signal of the first linear polarization state and the LO signal of the first linear polarization state from the optical signal of the first linear polarization state, outputs the detection signal of the first linear polarization state through the first output end, so that the detection signal of the first linear polarization state enters the polarization element, and outputs the LO signal of the first linear polarization state through the second output end, so that the LO signal of the first linear polarization state enters the second input end of the receiving component. The polarization element transmits the detection signal of the first linear polarization state input by the first communication end b1 to the second communication end b2, so that the detection signal of the first linear polarization state is transmitted to the first waveguide unit of the Nth waveguide in the waveguide structure, and then through the multi-stage evanescent wave coupler in the waveguide structure, it is transmitted to the N first waveguide units in the first waveguide, and then emitted outside the silicon photonic chip.

[0263] Furthermore, the detection signal is reflected by the target in the detection space and becomes an optical signal of the second linear polarization state, and returns to the end face of the silicon photonic chip. On the end face, it is coupled into the N first waveguide units of the first-level waveguide in the waveguide structure, and then transmitted to the first waveguide unit in the N-th waveguide through the multi-stage evanescent wave coupler in the waveguide structure, and enters the second communication end b2 of the polarization element. The polarization element converts the echo signal of the second linear polarization state input by the second communication end b2 into an echo signal of the first linear polarization state, and transmits it to the third communication end b3, so that the echo signal of the first linear polarization state enters the first input end of the receiving component. The receiving component mixes the echo signal of the first linear polarization state input by the first input end with the LO signal of the first linear polarization state input by the second input end, obtains an intermediate frequency signal, and outputs it from the output end.

[0264] Optionally, similar to the above implementation mode 1, the waveguide layer of the implementation mode 2 also includes a photoelectric converter, such as Fig.19 The photodetector is connected between the output end of the receiving component and the electrical output end d of the silicon photonic chip. The photodetector can perform photoelectric detection on the intermediate frequency signal output by the receiving component, convert it into an electrical signal and output it to the electrical output end d of the silicon photonic chip, so as to be transmitted to devices other than the silicon photonic chip, such as an electrical chip, for subsequent distance measurement and speed measurement.

[0265] Optionally, see Fig. 20 , shows a schematic diagram of a specific structure of a waveguide layer provided by implementation method 2. Fig. 20 As shown, similar to the above implementation method 1, the transmitting component may also include a beam splitter 1 and a beam splitter 2, and the receiving component includes a beam splitter 3 and four mixers, namely mixers 1 to 4. In this case, there are four waveguide structures, which serve as four transceiver ports of the silicon photonic chip. The polarization element may include four polarization splitters (PSR), namely PSR1, PSR2, PSR3 and PSR4. PSR1 to 4 correspond to mixers 1 to 4 and the four waveguide structures respectively, and each PSR has three communication ends. The input end of the beam splitter 1 is connected to the input end a of the silicon photonic chip, and an output end of the beam splitter 1 is connected to the input end of the beam splitter 2. The beam splitter 2 has four output ends, which are respectively connected to one communication end of PSR1 to 4, and another communication end of PSR1 to 4 is respectively connected to the first waveguide unit of the Nth layer waveguide in the corresponding waveguide structure, and another communication end of PSR1 to 4 is respectively connected to the first input end of the corresponding mixer. The four output ends of the optical splitter 3 are connected to the second input ends of the mixers 1 to 4 respectively, and the output ends of the mixers 1 to 4 are connected to the electrical output end d of the silicon photonic chip.

[0266] Based on the above structure and connection relationship, the light in the first linear polarization state can be specifically TE light (or P light), and the light in the second linear polarization state can be specifically TM light (or S light). Assuming that the optical signal input to the optical splitter 1 is TE light, the optical splitter 1 is used to split the local oscillator signal and the intermediate optical signal from the TE light, output the local oscillator signal to the optical splitter 3, and output the intermediate optical signal to the optical splitter 2, and the local oscillator signal and the intermediate optical signal are both TE light. The optical splitter 2 is used to split the intermediate optical signal into 4 transmission signals, and output them to PSR1~4 respectively, and these 4 transmission signals are also TE light. Each PSR is used to keep the polarization direction of the input TE light unchanged, and output it to the first waveguide unit of the Nth level waveguide in the corresponding waveguide structure. The TE light is transmitted to the N first waveguide units of the first level waveguide in the waveguide structure through multiple evanescent wave couplers in the corresponding waveguide structure, and then emitted from the end face of the silicon photonic chip to the scanning component, and scanned to the detection space by the scanning component.

[0267] Furthermore, the echo signal reflected by the target in the detection space is converted into TM light and returns to the silicon photonic chip. It is coupled from the end face into the N first waveguide units of the first waveguide in the four waveguide structures, and is transmitted to the first waveguide unit of the Nth waveguide in the four waveguide structures through multiple evanescent wave couplers in the four waveguide structures, and then output to PSR1~4. PSR1~4 rotates the polarization direction of the four TM lights input by the four waveguide structures by 90° to convert them into four TE lights, and outputs them to mixers 1~4 from the third output end. On the receiving side, the optical splitter 3 splits the input local oscillator signal into four sub-local oscillator signals, which are also output to mixers 1~4. The local oscillator signal is TE light, so the four sub-local oscillator signals are also TE light. Mixers 1~4 respectively perform mixing processing on the received sub-local oscillator signals and echo signals to obtain intermediate frequency signals, and output the intermediate frequency signals to the electrical output end of the silicon photonic chip. For example, mixers 1 to 4 can send their respective intermediate frequency signals to the photodetector, which performs photoelectric detection on the four intermediate frequency signals and converts them into electrical signals, which are then output from the electrical output terminal d of the silicon photonic chip. Based on the transmission relationship of the optical signal, the sub-local oscillator signal and the echo signal are both TE light, and the mixing effect is better.

[0268] In the above implementation method 2, the waveguide structure can be used as a transceiver port in the coaxial FMCW LiDAR, which saves the number of waveguide structures that need to be arranged, saves cost and volume, and at the same time, improves both the transmission efficiency and the reception efficiency.

[0269] It can be understood that the other contents in the above implementation method 1 are also applicable to the implementation method 2. For example, the polarization element can also be connected to the first waveguide unit of the Nth waveguide in the waveguide structure through the first waveguide, and the first waveguide can be a single-mode waveguide or a multi-mode waveguide. For example, the first waveguide is a single-mode waveguide, so the first waveguide unit of the Nth waveguide has a second mode spot size, and the second mode spot size is the mode spot size of the single-mode waveguide. For another example, the four transmission signals output by PDR1~4 have the same optical power to achieve uniform light output of the four detection channels and improve the detection performance. And so on, they are not listed here one by one.

[0270] In addition, in the above implementation method 2, four-channel detection is also used as an example, but this is only a possible implementation method. In an actual silicon photonic chip, it can be any number of detection channels greater than or equal to 1. Fig. 20 Taking the structure shown as an example, in another example, the optical signal output from the output end of the optical splitter 1 can also be directly used as the transmission signal. In this case, there may be only one waveguide structure, one PSR and one mixer, and there are no optical splitters 2 and 3, thereby realizing single-channel detection. Or, in another example, the optical splitter 1 can also separate two intermediate optical signals, one intermediate optical signal is directly used as the transmission signal, and the other intermediate optical signal is split into 4 transmission signals through the optical splitter 2, thereby realizing five-channel detection. In another example, the optical splitter 2 can also have only 2 output ends to realize two-channel detection, or have 3 output ends to realize three-channel detection, or have any number of output ends more than 4 to realize any number of detection channels more than four. Or, in another example, other optical splitters can also be set on one or more output paths of the optical splitter 2 to separate any number of transmission signals more than 4, and so on. There are many possible implementation methods, which are not listed here one by one.

[0271] Based on the structure and functional principles of the waveguide structure or silicon photonic chip described above, the present application can also provide a detection device, including the waveguide structure or silicon photonic chip introduced in any of the above embodiments.

[0272] For example, taking silicon photonic chips as an example, please refer to Fig.21 , showing a possible structural schematic diagram of the detection device. Fig.21 As shown, the detection device 2100 may include the above Fig.15 The silicon photonic chip 1500 described herein, the waveguide layer structure in the silicon photonic chip 1500 may be as follows: Figure 17~Figure 20 Any structure in is not limited.

[0273] Alternatively, if Fig.21As shown, the detection device 2100 may also include a light source component 2110, which is used to emit an optical signal. The optical signal is coupled into the transmitting component from the end face of the silicon photonic chip 1500, transmitted through the transmitting component to the waveguide structure on the other end face as a transmitting port or a transceiver integrated port, and then emitted from the silicon photonic chip 1500.

[0274] Alternatively, if Fig.21 As shown, the detection device 2100 also includes a scanning component 2120, which is used to scan the optical signal emitted by the silicon photonic chip 1500 to the detection space. After the optical signal is irradiated to 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 2120 to a waveguide structure serving as a receiving port or a transceiver-integrated port in the silicon photonic chip 1500. The echo signal is transmitted to the receiving component through the waveguide structure, and after being mixed with the local oscillator signal in the receiving component, an intermediate frequency signal is generated, which is then converted into an electrical signal and output from the electrical output end of the silicon photonic chip 1500.

[0275] Alternatively, if Fig.21 As shown, the detection device 2100 also includes a transceiver optical system 2130, which is located between the transmitting end of the silicon photonic chip 1500 and the scanning component 2120, and is used to optically process the optical signal emitted by the silicon photonic chip 1500 and transmit it to the scanning component 2120, and is also used to optically process the echo signal scanned by the scanning component 2120 and transmit it to the silicon photonic chip 1500. Among them, the optical processing may include collimation and / or homogenization, or may also include other processing methods, which are not limited.

[0276] It can be understood that the transceiver optical system 2130 can be composed of one or more lenses. When the detection device 2100 is a coaxial transceiver device, the one or more lenses are used for optical processing of the optical signal emitted by the silicon photonic chip 1500 and for optical processing of the echo signal scanned by the scanning component 2120. Conversely, when the detection device 2100 is a non-coaxial transceiver device, the transceiver optical system 2130 can specifically include a transmitting optical system and a receiving optical system, and the transmitting optical system and the receiving optical system both include one or more lenses, and the one or more lenses in the transmitting optical system are used to optically process the optical signal emitted by the silicon photonic chip 1500, and the one or more lenses in the receiving optical system are used to optically process the optical signal scanned by the scanning component 2120.

[0277] It can be understood that the scanning component 2120 can be any type of component or combination of components that can achieve a scanning function, such as a swing mirror, a MEMS rotating mirror, a Galvo mirror, or a combination of at least two thereof.

[0278] For example, take the combination of rotating mirror and Galvo mirror as an example, see Fig. 22 , showing a schematic diagram of an actual layout of the components in the detection device. For the sake of clarity, Fig. 22 Only the waveguide layer and the scanning component are shown, and other components are not drawn. Fig. 22 The waveguide layer in the Fig. 20 Taking the waveguide layer structure in as an example, examples of other waveguide layer structures can be derived by analogy.

[0279] according to Fig. 22 In the layout shown, the rotation axis of the Galvo mirror serves as the fast axis of the detection device 2100, while the rotation axis of the rotating mirror serves as the slow axis of the detection device 2100. The fast axis direction corresponds to the walke-off direction, so when arranging the Galvo mirror and the rotating mirror:

[0280] If the waveguide structure in the waveguide layer adopts the structure in the first embodiment, since the size of the pattern spot of the waveguide structure at the right end of the figure is a 1D large pattern spot, the arrangement of the scanner and the optical system needs to make the rotation axis direction of the Galvo mirror parallel to the pattern spot increase direction of the 1D large pattern spot, that is, make the walk-off direction parallel to the pattern spot increase direction of the 1D large pattern spot, and the pattern spot increase direction is the waveguide structure at the right end of the figure. Fig. 22 The direction of the connection of the N forks on the right side is shown, for example Fig. 22 The vertical direction in

[0281] If the waveguide structure in the waveguide layer adopts the structure in the second embodiment above, since the pattern size of the waveguide structure at the right end of the figure is a 2D large pattern, the arrangement of the scanner and the optical system only needs to make the rotation axis direction of the Galvo mirror in the first plane. The first plane is a plane perpendicular to the light transmission direction, which can be understood as passing through Fig. 22 The connection direction of the N forks at the right end of the waveguide structure is perpendicular to Fig. 22 A face of the plane shown, or perpendicular to Fig. 22 It can be understood that, in combination with the above Fig.13 , since in the first direction (i.e. Fig. 22 The effect of increasing the pattern spot in the second direction (i.e., the direction perpendicular to the first direction on the first plane) is the most obvious, and the effect of increasing the pattern spot in the second direction (i.e., the direction perpendicular to the first direction on the first plane) is relatively weaker. Therefore, the best choice is to make the rotation axis direction of the Galvo mirror parallel to the first direction, followed by parallel to the second direction, and then parallel to other directions on the first plane.

[0282] Further, optionally, if Fig.21As shown, the detection device 2100 also includes a processing component 2141, which is arranged on the electrical chip 2140. The input end of the electrical chip 2140 is connected between the electrical output end of the silicon photonic chip 1500 and the input end of the processing component 2141. Therefore, the electrical signal output from the electrical output end of the silicon photonic chip 1500 is transmitted to the processing component 2141, and the processing component 2141 performs target detection according to the electrical signal, such as determining the distance and / or speed of the target.

[0283] Further, optionally, other components, such as an amplifier and an analog-to-digital converter (not shown in the figure), may be provided in the electrical chip 2140. The input end of the amplifier is connected to the electrical output end of the silicon photonic chip 1500, and the analog-to-digital converter is connected between the output end of the amplifier and the input end of the processing component 2141. The amplifier is used to amplify the electrical signal output by the silicon photonic chip 1500, and the analog-to-digital converter is used to perform discrete processing on the amplified electrical signal, convert it into a digital signal and output it to the processing component 2141, so that the processing component 2141 can detect the target according to the digital signal.

[0284] Optionally, as above Fig.21 As shown, the detection device 2100 may further include a window 2150 , which is used to protect various components inside the detection device 2100 and can transmit the optical signal emitted by the detection device 2100 .

[0285] It should be noted that Fig.21 The detection device architecture given 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 specific limitations on this.

[0286] Based on the structure and functional principle of the detection device described above, the present application can also provide a terminal device, see Fig.23 The terminal device 2300 may include the waveguide structure described in the foregoing content, or may include the above silicon photonic chip 1500, or may include the above detection device 2100, such as Fig.23 shown.

[0287] Taking the detection device 2100 as an example, Fig.23As shown, in one example, the terminal device 2300 may further include a processor 2310, and the processor 2310 is used to call a program or instruction to control the operation of the above-mentioned detection device 2100. Further, the processor 2310 may also receive associated information of the target from the detection device 2100. When the terminal device 2300 is a vehicle, the processor 2310 may also perform path planning, braking or starting of the vehicle based on the acquired information. For example, the position of the vehicle may be determined by longitude and latitude, or the driving direction and destination of the vehicle in the future may be determined by speed and direction, or the number and density of obstacles around the vehicle may be determined by the distance of surrounding objects.

[0288] Further, optionally, the terminal device 2300 may also include a memory 2320, and the memory 2320 is used to store programs or instructions. Of course, the terminal device 2300 may also include other devices, such as a wireless communication device.

[0289] The processor 2310 may include one or more processing units. For example, the processor 2310 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, etc. Different processing units may be independent devices or integrated into one or more processors.

[0290] The memory 2320 includes, but is not limited to, random access memory (RAM), flash memory, read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. Exemplarily, the storage medium is coupled to the processor so that the processor can read information from the storage medium 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 be located in an ASIC.

[0291] Exemplarily, the above terminal device 2300 can be, for example, a vehicle (such as an unmanned vehicle, a smart vehicle, an electric vehicle, or a digital car, etc.), a robot, a surveying and mapping equipment, a drone, a smart home device (such as a television, a sweeping robot, a smart desk lamp, an audio system, a smart lighting system, an electrical appliance control system, home background music, a home theater system, an intercom system, or video surveillance, etc.), smart manufacturing equipment (such as industrial equipment), smart transportation equipment (such as AGV, an unmanned transport vehicle, or a truck, etc.), or a smart terminal (a mobile phone, a computer, a tablet computer, a PDA, a desktop computer, headphones, audio, wearable devices, vehicle-mounted devices, virtual reality devices, augmented reality devices, etc.), etc.

[0292] 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 any specific limitations on this.

[0293] In the above, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0294] In addition, in this application, the word "optionally" or "exemplary" is used to indicate an example, illustration or description. Any embodiment or design described as "optional" or "exemplary" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Alternatively, it can be understood that the use of the word "exemplary" or "optional" is intended to present concepts in a specific way and does not constitute a limitation on this application.

[0295] It is to be understood that the various digital numbers involved in the present application are only for the convenience of description and are not intended to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the order of execution of each process should be determined by its function and inherent logic. The terms "first", "second" and similar expressions are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, including a series of steps or units. Methods, systems, products or equipment are not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

Claims

1. A waveguide structure, characterized in that: include: N-level waveguide, N is an integer greater than or equal to 2; The first-order waveguide includes N first waveguide units, the first-order waveguide includes at most N-I+2 second waveguide units and N-I+1 first waveguide units, the N-I+2 second waveguide units are connected to the first waveguide unit in the I-1th-order waveguide, and when there is an I+1th-order waveguide, the N-I+1 first waveguide units are connected to the second waveguide unit in the I+1th-order waveguide, and I is an integer greater than or equal to 2 and less than or equal to N; The first-level waveguide is used to transmit optical signals; The first-level waveguide is used to couple the optical signals transmitted on the N-I+2 second waveguide units to the N-I+1 first waveguide units for transmission, or to couple the optical signals transmitted on the N-I+1 first waveguide units to the N-I+2 second waveguide units for transmission.

2. The waveguide structure according to claim 1, characterized in that The waveguide units in each level of waveguide are placed in parallel, and the spacing between adjacent waveguide units is less than the set spacing.

3. The waveguide structure according to claim 1 or 2, characterized in that: In the first-level waveguide, the second waveguide unit and the first waveguide unit are staggered, have the same shape, and are placed in opposite directions.

4. The waveguide structure according to claim 1 or 2, characterized in that: When I is less than or equal to N-1, the first waveguide unit in the (I+1)th waveguide is also connected to the second waveguide unit in the (I)th waveguide.

5. The waveguide structure according to claim 4, characterized in that The first waveguide unit and the second waveguide unit are both trapezoidal in shape; The second waveguide unit in the I-th level waveguide is connected to the first waveguide unit in the I-1-th level waveguide, comprising: two long bottom sides of the trapezoid are connected together; The first waveguide unit in the (I+1)th level waveguide is connected to the second waveguide unit in the (I)th level waveguide, including: short base sides of two trapezoids are connected together.

6. The waveguide structure according to claim 1 or 2, characterized in that: The N-level waveguides form a polyhedron structure, the fork of the polyhedron structure is the first-level waveguide, and the fork tail is the N-th-level waveguide.

7. The waveguide structure according to claim 1 or 2, characterized in that: Part or all of the first-order waveguide to the N-th-order waveguide are sub-wavelength grating structures.

8. The waveguide structure according to claim 7, characterized in that The sub-wavelength grating structure includes a block region, a transition region and a continuous region, and the block region, the transition region and the continuous region are arranged along a direction from the first-order waveguide to the N-th-order waveguide.

9. The waveguide structure according to claim 8, characterized in that The block area includes a plurality of short waveguide blocks, and the continuous area includes a long waveguide block, wherein the long waveguide block is connected to middle portions of the plurality of short waveguide blocks to form the transition area.

10. The waveguide structure according to claim 1 or 2, characterized in that: The first-stage waveguide supports a first mode spot size, and the first mode spot size is positively correlated with the value of N.

11. The waveguide structure according to claim 10, characterized in that The first mold spot size satisfies one of the following conditions: The N-level waveguides are all long waveguide blocks, and the first mode spot size is elliptical; The N-level waveguide includes a short waveguide block, and the first mode spot size is elliptical or nearly circular.

12. The waveguide structure according to claim 1 or 2, characterized in that: The waveguide structure is used as a transmitting port, a receiving port or a transmitting-receiving integrated port. The first-level waveguide is located at the edge of the chip, and the Nth-level waveguide is connected to the transmitting component, the receiving component or the polarization element on the chip.

13. The waveguide structure according to claim 12, characterized in that The Nth-order waveguide is connected to the transmitting component, the receiving component or the polarization element through a single-mode waveguide, and the mode spot size of the Nth-order waveguide is the mode spot size of the single-mode waveguide.

14. The waveguide structure according to claim 1 or 2, characterized in that: The waveguide structure is used as a receiving port, and the first waveguide unit in the Nth level waveguide is connected to the receiving component: The first-stage waveguide is used to receive the echo signal and transmit it to the second waveguide unit in the second-stage waveguide; Each of the second to N-1th waveguide stages is used to couple the echo signal transmitted on the second waveguide unit to the first waveguide unit and transmit it to the connected second waveguide unit; The Nth-order waveguide is used to couple the echo signals transmitted on the two second waveguide units to the first waveguide unit and send them to the receiving component.

15. The waveguide structure according to claim 1 or 2, characterized in that: The waveguide structure is used as a launch port, and the first waveguide unit in the Nth level waveguide is connected to the launch component: The Nth-order waveguide is used to couple the optical signal output by the transmitting component to the first waveguide unit to the two second waveguide units, and transmit it to the first waveguide unit in the N-1th-order waveguide; Each waveguide of the N-1th to the second waveguide is used to couple the optical signal transmitted on the first waveguide unit to the second waveguide unit, and transmit it to the connected first waveguide unit; The first-level waveguide is used to output the optical signals transmitted from the N first waveguide units to the outside of the waveguide structure.

16. A silicon photonic chip, characterized in that: Comprising the waveguide structure as claimed in any one of claims 1 to 15.

17. The silicon photonic chip according to claim 16, wherein: The silicon photonic chip comprises a silicon substrate layer, a buried oxide layer, a waveguide layer and a top oxide layer stacked in sequence, and the waveguide structure is located in the waveguide layer.

18. The silicon photonic chip according to claim 16 or 17, characterized in that: The waveguide structure serves as a transmitting port, a receiving port or an integrated transmitting and receiving port of the silicon photonic chip, and the first-level waveguide is located on an end face of the silicon photonic chip.

19. The silicon photonic chip according to claim 16 or 17, characterized in that: The silicon photonic chip further comprises a transmitting component, wherein the transmitting component is connected between an input end of the silicon photonic chip and an Nth level waveguide of the waveguide structure; The transmitting component is used to split the detection signal from the input optical signal and transmit the detection signal to the waveguide structure.

20. The silicon photonic chip according to claim 16 or 17, characterized in that: The silicon photonic chip further comprises a receiving component, wherein the receiving component is connected between the electrical output end of the silicon photonic chip and the Nth level waveguide of the waveguide structure; The receiving component is used to receive the echo signal transmitted by the waveguide structure, and mix the echo signal with the local oscillator signal to obtain an intermediate frequency signal, and the intermediate frequency signal is used to determine the speed and / or distance of the target.

21. A detection device, characterized in that: Comprising the silicon photonic chip as claimed in any one of claims 16 to 20.

22. The detection device according to claim 21, characterized in that Also included is a light source assembly; The light source component is used to output an optical signal to the silicon photonic chip, and the optical signal is transmitted to the transmitting component on the silicon photonic chip through the waveguide structure on the silicon photonic chip.

23. The detection device according to claim 21 or 22, characterized in that: Also included is a scanning component; The scanning component is used to scan the optical signal emitted by the silicon photonic chip to a detection space.

24. The detection device according to claim 21 or 22, characterized in that: Also included is a processing component, wherein the processing component is 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 photonic chip.

25. A terminal device, characterized in that: Comprising a detection device as claimed in any one of claims 21 to 24.

Images