Optical phased array chip and laser radar

Abstract

The embodiment of the invention provides an optical phased array chip and a laser radar, and the chip comprises a beam splitter which is used for carrying out the beam splitting of an inputted emergent laser beam, and obtaining a plurality of emergent laser sub-beams; the phase shifter is optically connected with the beam splitter and is used for carrying out phase modulation treatment on the emergent laser sub-beams to obtain the emergent laser sub-beams subjected to phase modulation; the optical phased-array antenna array comprises a plurality of optical antennas, and the optical antennas are optically connected with the phase shifter and used for emitting the emergent laser sub-beams subjected to phase modulation to a detection area; and the compensation structure is matched with the optical phased-array antenna array and is used for performing local temperature regulation and control on the optical phased-array antenna array so as to change the effective refractive index of the corresponding optical antennae. According to the application, far-field light spots of the transmitting antenna and the receiving antenna of the laser radar can reach design values, and the accuracy of the laser radar is improved. And the detection performance of the laser radar system is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of lidar, and more particularly, to an optical phased array chip and a lidar. Background Art

[0002] In related technologies, an optical phased array (OPA) chip generally uses silicon-on-insulator material as a substrate and utilizes the good properties of silicon to fabricate various structures on the optical phased array chip, thereby realizing the basic functions of a lidar.

[0003] As the size of the OPA increases, due to environmental conditions and manufacturing non-ideality, it is difficult to ensure the ideal shape of the OPA output light spot. Specifically, even if the design parameters of the OPA antennas are the same, due to manufacturing errors or unevenness of the wafer surface, the near-field isophase plane of the OPA will be distorted. As shown in Figure 1 As shown, as the transmission length increases, phase noise accumulates and the isophase plane gradually distorts, causing the OPA output light spot to deviate from the ideal shape, reducing the effective aperture of the transmitting and receiving antennas, and degrading the detection performance of the lidar system.

[0004] It can be seen that the optical phased array chip in related technologies has the problem of reducing the detection performance of the lidar system due to the wavefront distortion of the isophase plane of the optical phased array. Summary of the Invention

[0005] The embodiments of the present application provide an optical phased array chip and a lidar to at least solve the problem that the optical phased array chip in related technologies has a reduced detection performance of the lidar system due to the wavefront distortion of the isophase plane of the optical phased array.

[0006] According to an embodiment of the present application, there is provided an optical phased array chip, including: a beam splitter for splitting an input output laser beam to obtain a plurality of output laser sub-beams; a phase shifter optically connected to the beam splitter for performing phase modulation on the plurality of output laser sub-beams to obtain the phase-modulated plurality of output laser sub-beams; an optical phased array antenna array including a plurality of optical antennas, the optical antennas being optically connected to the phase shifter for emitting the phase-modulated output laser sub-beams into a detection area; a compensation structure arranged in matching with the optical phased array antenna array for locally controlling the temperature of the optical phased array antenna array to change the equivalent refractive index of the corresponding optical antenna.

[0007] According to another embodiment of the present application, a lidar is provided, including: a light source, the optical phased array chip of any one of the above embodiments, a detection module, and a data processing module: wherein, the optical phased array chip receives the outgoing laser signal provided by the light source, emits the outgoing laser signal into the detection space, and receives the echo signal formed by the reflection of the object to be detected in the detection space, and provides the echo signal to the detection module; the detection module is configured to receive the echo signal, perform beat frequency on the echo signal and its corresponding local oscillator signal to obtain a beat frequency signal, and provide the beat frequency signal to the data processing module; the data processing module calculates the information of the object to be detected according to the beat frequency signal.

[0008] Through the embodiment provided by the present application, the optical phased array chip includes a beam splitter, a phase shifter, an optical phased array antenna array, and a compensation structure. Among them, by splitting the input outgoing laser through the beam splitter, multiple outgoing laser sub-beams can be formed; the phase shifter is optically connected to the beam splitter, and through the phase shifter, multiple outgoing laser sub-beams can be phase-modulated to obtain multiple phase-modulated outgoing laser sub-beams. Thus, the multiple phase-modulated outgoing laser sub-beams can achieve the focusing and fast scanning of the light spot; then, the multiple phase-modulated outgoing laser sub-beams are emitted into the detection area through the optical phased array antenna array. Here, the optical phased array antenna array includes multiple optical antennas, and the optical antennas are optically connected to the phase shifter one by one; the compensation structure is arranged in a matching manner with the optical phased array antenna array, and can perform local temperature control on the optical phased array antenna array to change the equivalent refractive index of the corresponding optical antenna, thereby correcting the distortion of the OPA near-field equal phase surface caused by factors such as manufacturing errors or unevenness of the wafer surface, so that the far-field light spots of the transmitting antenna and the receiving antenna of the lidar reach the design value, and further improving the effective aperture of the transmitting and receiving antennas. Through the embodiment of the present application, the problem that the detection performance of the lidar system is reduced due to the wavefront distortion of the equal phase surface of the optical phased array in the related art can be solved, and the technical effect of improving the detection performance of the lidar system is achieved. Description of the Drawings

[0009] Figure 1 is a schematic diagram of the gradual distortion of the equal phase surface of light in the waveguide / antenna with the transmission length;

[0010] Figure 2 is a schematic structural diagram of an optional optical phased array chip according to an embodiment of the present application;

[0011] Figure 3 is a schematic structural diagram of another optional optical phased array chip according to an embodiment of the present application;

[0012] Figure 4It is a schematic structural diagram of another optional optical phased array chip according to an embodiment of the present application;

[0013] Figure 5 It is a schematic structural diagram of an optional light source according to an embodiment of the present application;

[0014] Figure 6 It is a schematic structural diagram of another optional optical phased array chip according to an embodiment of the present application;

[0015] Figure 7 It is a schematic structural diagram of an optional beam splitter according to an embodiment of the present application;

[0016] Figure 8 It is a schematic diagram of an optional optical phased array antenna array according to an embodiment of the present application;

[0017] Figure 9 It is a schematic diagram of another optional optical phased array antenna array according to an embodiment of the present application;

[0018] Figure 10 It is a schematic structural diagram of another optional optical phased array chip according to an embodiment of the present application;

[0019] Figure 11 It is a schematic diagram of the component positions of an optional optical phased array chip according to an embodiment of the present application;

[0020] Figure 12 It is a schematic diagram of the component positions of another optional optical phased array chip according to an embodiment of the present application;

[0021] Figure 13 It is a schematic diagram of the component positions of another optional optical phased array chip according to an embodiment of the present application;

[0022] Figure 14 It is a schematic diagram of the component positions of another optional optical phased array chip according to an embodiment of the present application;

[0023] Figure 15 It is a schematic structural diagram of an optional correction unit according to an embodiment of the present application;

[0024] Figure 16 It is a schematic diagram of an optional optical phased array chip according to an embodiment of the present application;

[0025] Figure 17 It is a schematic diagram of another optional optical phased array chip according to an embodiment of the present application. Detailed implementation manners

[0026] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a series of systems, products or devices included do not have to be limited to the units clearly listed, but may include other units not clearly listed or inherent to these products or devices.

[0028] According to one aspect of the embodiments of this application, an optical phased array chip is provided. This optical phased array chip can be applied to various types of optical measurement devices or lidars, such as optical phased array lidars, and can also be applied to other terminals or devices.

[0029] The concept of optical phased array lidar has been proposed for a long time. Currently, optical phased array lidar chips generally use silicon-on-insulator (SOI) materials as substrates and utilize the good properties of silicon to fabricate various on-chip structures to achieve the basic functions of lidar. Specifically, the outgoing beam provided by the laser source is coupled to the optical phased array chip through the input coupler. After beam splitting and phase modulation on the optical phased array chip, it is emitted from the transmitting antenna on the optical phased array chip to the detection area, and the echo signal reflected by the object in the detection area is received through the receiving antenna on the optical phased array chip. In an ideal state, the near-field wavefronts of the transmitting and receiving antennas in the same phased array are plane waves, and the light intensity of their far-field spots shows a distribution form similar to a Gaussian distribution. Thus, the energy-concentrated outgoing beam and echo signal can be efficiently used to obtain target object information. It can be understood that when the transmitting antenna emits a laser beam to the detection area, a transmitting spot of the transmitting antenna (hereinafter collectively referred to as the spot of the transmitting antenna) can be formed in the detection area; while the receiving antenna usually does not have an outgoing spot. However, based on the principle of reversibility of the optical path in the optical antenna, the receiving antenna can also be used as a transmitting antenna. At this time, the spot of the transmitting antenna (i.e., the receiving antenna used as a transmitter) can be regarded as the receiving spot of the receiving antenna (hereinafter collectively referred to as the spot of the receiving antenna).

[0030] However, even if the design values of devices such as waveguides, beam splitters, and optical antennas are the same, due to the influence of manufacturing processes, such as inaccurate waveguide widths caused by etching precision, rough and non-perpendicular waveguide edges, and poor flatness of the wafer surface, the propagation speeds of light on different optical paths in the OPA chip are inconsistent (hereinafter collectively referred to as phase noise). As a result, the isophase surfaces of the transmitting and receiving antennas at the same length position are distorted, and the far-field spots of the transmitting and receiving antennas cannot reach the ideal focusing state, leading to a certain degree of mismatch of the spots and unable to ensure that the lidar system obtains the best detection performance (for example, ranging performance).

[0031] The embodiments of the present application provide an optical phased array chip and a lidar. A phase compensation structure (hereinafter referred to as the compensation structure) is adopted in the OPA to correct the optical path difference of the optical path, thereby offsetting the wavefront distortion of the near-field isophase surface of the OPA, and then improving the far-field spot of the OPA to make it reach the design value, thereby increasing the effective apertures of the transmitting and receiving antennas, and solving the problem that the detection performance of the lidar system is reduced due to the wavefront distortion of the isophase surface of the optical phased array in the related art, that is, in the lidar system, due to the manufacturing process, the far-field spots of the transmitting and receiving antennas cannot reach the ideal focusing state, resulting in a certain degree of mismatch between the transmitting spot and the receiving spot, and thus unable to ensure that the lidar system obtains the best detection performance.

[0032] Here, OPA is a key technology for implementing an integrated lidar, which refers to controlling the phase of an array waveguide in the optical band so that the signal lights interfere constructively or destructively with each other. They interfere constructively in the specified direction and emit with high intensity, while interfering destructively in other directions to suppress the intensity of the signal lights.

[0033] According to one aspect of the embodiments of the present application, an optical phased array chip is provided, as Figure 2 shown. The optical phased array chip includes a beam splitter 201 (i.e., the first beam splitter), a phase shifter 202, an optical phased array antenna array 203, and a compensation structure 204. Among them, the phase shifter 202 is optically connected to the beam splitter 201; the compensation structure 204 is arranged in a matching manner with the optical phased array antenna array 203. For example, the compensation structure 204 can be arranged above or below the optical phased array antenna array 203.

[0034] The beam splitter 201 is used to split the input outgoing laser beam to obtain a plurality of outgoing laser sub-beams.

[0035] The beam splitter 201 is an optical device that can split a beam of light into two or more beams of light. Optionally, the beam splitter 201 can be a directional coupler or a multimode interference coupler.

[0036] In some embodiments, the obtained plurality of outgoing laser sub-beams can be arranged in a one-dimensional or two-dimensional shape. The wavefront phases of each outgoing laser sub-beam are kept consistent.

[0037] In some embodiments, in order to increase the input power, a silicon nitride material can be used to form the beam splitter 201, or the first few levels of the beam splitter 201 (multi-stage beam splitting structure) can be formed of a silicon nitride material, so that the optical power after being split by the first few levels can meet the normal transmission in the silicon waveguide.

[0038] The phase shifter 202 is used to perform phase adjustment on the plurality of outgoing laser sub-beams to obtain a plurality of phase-adjusted outgoing laser sub-beams.

[0039] Here, the phase shifter 202 is a device capable of adjusting the phase of a light beam. The phase shifter 202 mainly performs real-time control on the phase of an optical signal. Usually, the phase shift ability of the phase shifter 202 adopted by OPA needs to be greater than 2π.

[0040] In some embodiments, the phase shifter 202 is used to perform phase modulation on multiple emitted laser sub-beams. Since there is phase noise in different optical paths of the OPA chip, it will cause the distortion of the equal-phase surface at the same length position before the phase shifter 202. Therefore, it is necessary to use the phase shifter 202 to calibrate the phases of different optical paths in the OPA chip so that the phases of each path of light are consistent after passing through their respective phase shifters 202. While applying the calibrated phase bias to the phase shifter 202 and then applying a specific phase gradient, the rapid scanning of the light spot can be completed. Specifically, before emitting multiple emitted laser sub-beams to the detection area via the transmitting antenna, the phase shifter 202 (for example, an electro-optic phase shifter) can be used to perform phase modulation on the light in the corresponding optical path and provide the modulated light to the optical phased array antenna array 203 to achieve the focusing and rapid scanning of the light spot.

[0041] Optionally, during the process of receiving the echo signal, a thermo-optic phase shifter with low optical loss can be used to perform phase modulation on the received echo signal, which can effectively reduce the optical loss and achieve the efficient reception of the echo signal. In addition, in some other embodiments, only an electro-optic phase shifter or a thermo-optic phase shifter can be used to realize the phase adjustment of the emitted laser sub-beams and the echo signal.

[0042] The optical phased array antenna array 203 includes multiple optical antennas. The multiple optical antennas correspond to the multiple emitted laser sub-beams one by one. Each optical antenna is used to emit the corresponding phase-modulated emitted laser sub-beam to the detection area.

[0043] Here, the optical antenna can be composed of silicon material, silicon nitride material, or silicon and silicon nitride materials. When different materials are selected for the optical antenna, the parameters of the formed optical antenna are also different. The materials constituting the optical antenna can be designed according to actual needs.

[0044] In some embodiments, the array size of the optical phased array antenna array 203 is designed by the narrowest full width at half maximum of the preset target beam.

[0045] The compensation structure 204 is arranged in a matching manner with the optical phased array antenna array 203. It can be arranged above or below the optical phased array antenna array 203 and is used to perform local temperature control on the optical phased array antenna array 203 to change the equivalent refractive index of one or more corresponding optical antennas, and then change the phase of light in the optical antenna, so as to correct the equal-phase surface distortion introduced by the waveguide or antenna, etc., and further make the far-field light spots of the transmitting and receiving antennas reach the design value. Exemplarily, the compensation structure 204 can be a structure similar to a thermo-optic phase shifter, for example, a single-sided heating type thermo-optic phase shifter.

[0046] Optionally, the compensation structure 204 can be connected to the optical phased array antenna array 203 through a waveguide (a channel in an optical device for light propagation, which confines light in the channel through total internal reflection). A waveguide is a channel for light propagation in an optical device. Similar to an optical fiber, a waveguide confines light in the channel through total internal reflection (propagating from a material with a high refractive index to a material with a low refractive index). The compensation structure 204 transfers heat to the antenna through the waveguide. Such a structural arrangement has a simple process, high heating efficiency, and does not affect the light output efficiency.

[0047] It can be understood that, for the consideration of the optical path layout, there may be a need to connect the phase shifter 202 to the antenna (i.e., the aforementioned optical antenna) through a relatively long waveguide, with a length of about 1 mm to 5 mm. The specific length depends on the number of antennas. The existence of the additional waveguide will introduce additional phase noise, thereby causing the re-distortion of the corrected equiphase surface. Additionally, it can be understood that since the antenna itself is relatively long (the length of the antenna is generally 2 mm to 10 mm), the antenna itself will also introduce additional phase noise. Therefore, it is necessary to place the compensation structure 204 in front of and / or in the middle of the antenna to correct the additional phase noise introduced by the waveguide or the antenna.

[0048] In some embodiments, the compensation structure 204 can be an integral heating structure or composed of multiple groups of local heating structures, aiming to achieve uniform heating. Optionally, the compensation structure 204 includes a heating electrode and a heating structure (e.g., a heating resistor). By applying a bias voltage to the heating electrode, the heating structure generates heat and transfers it to the optical phased array antenna array 203 through the waveguide, changing the temperature of the optical antennas in the optical phased array antenna array 203, thereby correcting the wavefront distortion caused by phase noise during the transmission of light in the waveguide or the antenna, and enabling the far-field light spot of the transmitting antenna or the receiving antenna to reach an ideal focusing state to ensure that the lidar system obtains the best detection performance. Among them, the bias voltage of the compensation structure 204 is determined according to the form of the wavefront distortion of the equiphase surface at the position where the compensation structure 204 is located.

[0049] As described above, in the OPA, phase errors accumulate as light propagates in their respective antennas or waveguides. The reasons for this are the geometric shape of the waveguide or antenna, material properties, and the surface unevenness of the SOI wafer used to fabricate the waveguide, etc. The above reasons will cause an equivalent refractive index difference Δn between adjacent waveguides or antennas in the same propagation mode. eff , the existence of the equivalent refractive index difference will cause the propagation speeds of light between adjacent waveguides or antennas to be different, thereby leading to the distortion of the equiphase surface. It can be understood that since the variation laws of the geometric shape of the antenna, material properties, and the surface unevenness of the SOI wafer used to fabricate the waveguide, etc. are quasi-continuous, the form of the equiphase surface distortion is also quasi-continuous, that is, the phase difference between adjacent antennas or waveguides is not too large.

[0050] By applying a bias voltage to the heating electrode, heat is generated in the heating resistor and transmitted through the waveguide to the optical phased array antenna array 203, changing the temperature of the antenna, thereby changing the refractive index of the antenna, so that the equiphase surface of the light after passing through the adjacent compensation structure 204 is changed. Optionally, the compensation structure 204 may be an array of compensation structures, which may include a heating resistor of 50um×1um, disposed at the end of each antenna, and the number is the same as the number of antennas. In this solution, regardless of the type of phase surface distortion, the phase compensation generated by the compensation structure 204 can match the equiphase surface distortion existing in the antenna in front of the compensation structure 204.

[0051] The target (the optical antenna in this embodiment) compensation phase distribution is not preset. An optimization algorithm can be used to determine the voltage required to be output by each compensation structure finally with the maximum ratio of the peak value of the main lobe of the far-field light spot emitted by the antenna to the peak value of the maximum side lobe of the phase direction distribution (side lobe suppression ratio) as the optimization target. For example, a global optimization algorithm (such as particle swarm algorithm, genetic algorithm, climbing algorithm, etc.) can be used to optimize the side lobe suppression ratio of the far-field light spot emitted by the antenna. After a certain number of iterations, the change of the side lobe suppression ratio approaches convergence, and the voltage required to be output by the compensation structure at this time is also determined accordingly.

[0052] In some embodiments, the bias voltage applied by the heating electrode to the heating structure is usually 0-10 volts, so that heat is generated in the heating resistor and transmitted through the waveguide to the optical phased array antenna array 203. For every 1 degree Celsius increase in the temperature of the optical phased array antenna array 203, the equivalent refractive index changes by 1.8×10 -4 ~2.5×10 -4 , after determining the voltage required for each compensation structure through the optimization algorithm, the current bias voltage is maintained to reach thermal equilibrium to maintain the target equiphase surface.

[0053] Through the embodiments provided in this application, a compensation structure is optically matched with the optical phased array antenna array in the optical phased array chip package, and the local temperature of the optical phased array antenna array is regulated through the compensation structure to correct the wavefront distortion caused by the phase noise of the waveguide or antenna, so that the light spots of the transmitting antenna and the receiving antenna of the lidar are adjusted to the ideal focusing state; furthermore, the problem that the detection performance of the lidar system is reduced due to the wavefront distortion of the equiphase surface of the optical phased array in the related art is solved, and the detection performance of the lidar system is improved.

[0054] In an exemplary embodiment, the compensation structure 204 can be placed at any position where local temperature regulation of the optical phased array antenna array 203 can be performed. To improve the heating efficiency of the compensation structure, the compensation structure 204 can be disposed on the same layer as the optical antenna. It can be located at the front end, middle section, or end of the optical phased array antenna array 203, or can also be located on the side of the optical phased array antenna array 203. The compensation structure 204 and the optical phased array antenna array 203 can be connected through a waveguide, so that heat can be transferred to the optical antenna of the optical phased array antenna array 203 through the waveguide. Such a structural arrangement has a simple process, high heating efficiency, and does not affect the light emission efficiency.

[0055] In another exemplary embodiment, the compensation structure 204 can be disposed on a different layer from the optical antenna (a stacked structure can be formed between the two), and the compensation structure 204 can be located above or below the optical phased array antenna array 203. The projection of the compensation structure 204 in the vertical direction can at least partially overlap with the projection of the corresponding optical antenna in the optical phased array antenna array 203 in the vertical direction, thereby improving the heating efficiency of the optical phased array antenna array.

[0056] Optionally, to ensure the heating efficiency of the compensation structure, the compensation structure 204 can be disposed adjacent to the optical phased array antenna array 203 on the same layer, and the distance between the two can be less than 500 μm (micrometers), or it can be other values; or, the compensation structure 204 can be stacked with the optical phased array antenna array 203 (the projections of the two in the vertical direction partially overlap), and the distance between the two can be less than 5 μm, or it can be other values. To avoid optical crosstalk between the antennas in the optical phased array antenna array 203, the distance between the two can be set between 1 and 5 micrometers. The relative position between the optical phased array antenna array and the compensation structure and the distance between the two can be set according to refractive index adjustment requirements, heating performance of the compensation structure, etc., and will not be specifically limited here.

[0057] Optionally, the compensation structure 204 can be any structure capable of heating the optical phased array antenna array 203. For example, a thermo-optic phase shift structure, an electro-optic phase shift structure, etc. Using phase shift structures such as a thermo-optic phase shift structure and an electro-optic phase shift structure as the compensation structure to perform local temperature regulation on the optical phased array antenna array can improve the accuracy of temperature control. Here, the compensation structure 204 can include a heating resistor and a heating electrode. The heating electrode is used to connect to the current passing through the heating resistor, so that the optical phased array antenna array 203 can be locally temperature-regulated through the heating resistor.

[0058] Optionally, the heating resistor may be a combination of an integral body heating structure or a local heating structure. The parts of the optical antenna heated by different local heating structures are different. The resistance values of the heating resistors in different local heating structures may be different, and the currents passing through the heating resistors in different local heating structures may be different. By flexibly setting the resistance values of the heating resistors in different local heating structures and the currents passing through the heating resistors in different local heating structures, the purpose of separately adjusting the refractive indices of different local regions of different optical antennas can be achieved.

[0059] Through the embodiments provided in the present application, the compensation structure is disposed on the same layer as the optical antenna (it may be located at the front end or the rear end of the optical antenna) or on a separate layer, and the compensation structure and the optical antenna are connected by a waveguide, which can simplify the manufacturing process of the optical phased array chip and improve the heating efficiency while not affecting the light output efficiency; the heating resistor adopts a combination of local heating structures, which can achieve the purpose of separately adjusting the refractive indices of different local regions of different optical antennas and improve the flexibility of refractive index adjustment.

[0060] In an exemplary embodiment, as Figure 3 shown, the optical phased array chip further includes:

[0061] A coupler 301, optically connected to the beam splitter 201, for coupling the output laser beam onto the chip and providing it to the beam splitter 201.

[0062] The coupler 301 may be an input coupler. For example, an end-face coupler or a grating coupler. The input end of the coupler 301 is connected to the laser through an optical fiber (when there is a semiconductor optical amplifier, it is connected to the semiconductor optical amplifier), and receives the output laser beam provided by the light source (or the output laser beam amplified by the semiconductor optical amplifier) through the above optical fiber; the output end of the coupler 301 is connected to the beam splitter 201 through a waveguide, couples the output laser beam onto the chip, and provides it to the beam splitter 201.

[0063] It should be noted that the light source and the semiconductor optical amplifier may also be integrated on the optical phased array chip together. At this time, the semiconductor optical amplifier directly provides the amplified output laser beam to the beam splitter 201, and the coupler 301 may no longer be required.

[0064] In some embodiments, according to the relative position of the optical fiber and the chip, the coupler 301 can generally be divided into two types, one is plane coupling, also known as edge coupling (EC), which means that the optical fiber and the chip are located in the same plane, located on the side of the chip, and coupled by means of tapered waveguides, etc.; the other is vertical coupling, also known as grating coupling (GC). Grating coupling uses the diffraction effect of the grating for coupling. For different orders of diffraction, the diffraction direction of light is different, so it can be used as a device to change the direction of light, for example, coupling the light of the optical fiber in the vertical direction to the chip in the horizontal direction.

[0065] In an exemplary embodiment, reference Figure 4 The optical phased array chip further includes a light source 401, which can be used to generate the above-mentioned outgoing laser beam. The structure of the light source 401 can be various and can be configured as needed.

[0066] As an optional implementation, the light source 401 includes:

[0067] Multiple lasers and a beam combiner (i.e., a first beam combiner, such as Figure 5 As shown), wherein the wavelengths of the laser beams generated by different lasers among the multiple lasers are different from each other (that is, the central wavelengths of the laser beams are different), and the outgoing laser beam is obtained by laser combining the laser beams of multiple wavelengths generated by the multiple lasers through a first beam combiner.

[0068] In some embodiments, the laser may be a laser diode (LD), which may be a single-wavelength laser. A plurality of single-wavelength lasers may provide a plurality of laser beams with different central wavelengths.

[0069] In some embodiments, the first beam combiner can perform laser beam combining through wavelength division multiplexing (WDM), that is, multiple laser beams with different central wavelengths are combined together through the first beam combiner and coupled into the same transmission path.

[0070] Optionally, the first combiner can be a fiber combiner, whose main function is to combine beams and can split, reflect, focus, and perform other operations on multiple laser beams generated by multiple single-wavelength lasers, and finally synthesize them into a multi-wavelength laser beam (i.e., an outgoing laser beam).

[0071] As another optional implementation, the light source 401 includes:

[0072] At least one of a multi-wavelength laser, a tunable laser, and an optical frequency comb is used to generate a multi-wavelength light beam, where the output laser light beam is a multi-wavelength light beam. In this case, the light source 401 can directly generate a multi-wavelength light beam without the need to set up a first beam combiner.

[0073] In an exemplary embodiment, referring to Figure 6 , the optical phased array chip further includes:

[0074] A semiconductor optical amplifier 601, which is optically connected to the light source 401 and the beam splitter 201 respectively, is used to amplify the output laser light beam to obtain an amplified output laser light beam. By using a semiconductor optical amplifier 601 (Semiconductor Optical Amplifier, abbreviated as SOA) to amplify the output laser light beam, the optical power can be increased and the detection distance can be extended. The semiconductor optical amplifier 601 can be selected and set according to the actual application scenario of the lidar.

[0075] Here, the semiconductor optical amplifier 601 is a device that amplifies optical signals and can be used to increase data transmission power and extend the transmission distance. The semiconductor optical amplifier can use a semiconductor material as the gain medium, can amplify the optical power of small signals without significantly reducing other optical indicators, and can be widely used as a preamplifier, wavelength converter, high-speed optical shutter, etc. in lidar systems, optical communication transmission systems, and fiber optic sensing systems.

[0076] In an exemplary embodiment, in the optical phased array chip, the beam splitter 201 is formed of silicon material; or, the beam splitter 201 is formed of silicon nitride material; or, the beam splitter 201 includes a plurality of cascaded beam splitting structures, where the first N-stage beam splitting structures of the beam splitter 201 are formed of silicon nitride material, and the remaining beam splitting structures are formed based on silicon material, where N is a positive integer greater than or equal to 1, and the beam splitter 201 is a multi-stage beam splitting structure, that is, the beam splitter 201 includes a plurality of cascaded beam splitting structures.

[0077] It can be understood that since it is difficult for high-power light to be transmitted with low loss in a silicon waveguide, in some embodiments, in order to increase the input power, the beam splitter 201 is formed of silicon nitride material or silicon material, or, for the beam splitter 201 with a multi-stage beam splitting structure, the first N-stage beam splitting structures of the beam splitter 201 are formed of silicon nitride material so that the optical power after being split by the first N-stage beam splitting structures can meet the conditions for normal transmission in the silicon waveguide.

[0078] Optionally, the beam splitter 201 includes a plurality of cascaded beam splitting structures. The optical phased array chip further includes: a first material structure layer formed of silicon nitride or silicon nitride-like material, wherein the first N stages of the beam splitting structures of the beam splitter 201 are integrated in the first material structure layer; and a second material structure layer formed of silicon material, and other beam splitting structures of the beam splitter 201 except the first N stages of the beam splitting structures are integrated in the second material structure layer.

[0079] For example, as Figure 7 shown, the first beam splitter adopts a multi-stage beam splitting structure, including a first beam splitting structure and a plurality of second beam splitting structures. The first beam splitting structure is located in the first material structure layer, and the plurality of second beam splitting structures are located in the second material structure layer; the first material structure layer further includes a coupler (i.e., an input coupler); the second material structure layer further includes a phase shifter and an optical phased array antenna array.

[0080] It should be noted that Figure 7 the compensation structure in can also be located after the optical phased array antenna array in the second material structure layer, and can be specifically set according to the actual application situation of the optical phased array chip, and the present application does not make a limitation here.

[0081] In an exemplary embodiment, in the optical phased array chip, the phase shifter 202 includes:

[0082] an electro-optic phase shifter for phase modulating a plurality of emitted laser sub-beams;

[0083] a thermo-optic phase shifter for phase modulating the echo signal received by the optical phased array antenna array 203.

[0084] Before the emitted laser sub-beams are emitted to the detection area, the electro-optic phase shifter can be used to phase modulate the emitted laser sub-beams to achieve fast scanning of the light spot. The electro-optic phase shifter can also be used to phase modulate the received incident laser beam. At this time, only the electro-optic phase shifter can be used to achieve phase adjustment of the emitted laser sub-beams and the echo signal.

[0085] Optionally, during the process of receiving the echo signal, using a thermo-optic phase shifter (Thermal Phase Shifter) with low optical loss to phase modulate the received echo signal can effectively reduce the optical loss and achieve efficient reception of the echo signal. Here, the thermo-optic phase shifter can be realized based on the thermo-optic effect of silicon material. Due to the high thermo-optic coefficient of silicon material, the thermo-optic modulation for adjusting the equivalent refractive index of the silicon waveguide is completed by changing the temperature of the silicon material.

[0086] In an exemplary embodiment, in an optical phased array chip, the optical phased array antenna array 203 includes a plurality of antenna arrays, the plurality of antenna arrays including at least one transmitting array and at least one receiving array, wherein isolation holes or isolation grooves are provided between the plurality of antenna arrays.

[0087] In some embodiments, the optical phased array antenna array 203 includes a plurality of antenna arrays. For example, one transmitting array and one receiving array; one transmitting array and a plurality of receiving arrays; a plurality of transmitting arrays and a plurality of receiving arrays. Via holes (Vias) or isolation grooves can be provided between the arrays to block the transmission of light between the antenna arrays.

[0088] Optionally, for the case where there are multiple receiving arrays, the multiple receiving arrays can be symmetrically distributed on both sides of at least one transmitting array, as Figure 8 and Figure 9 shown.

[0089] Referring to Figure 8 , the optical phased array antenna array 203 includes one transmitting array and six receiving arrays, wherein the transmitting array is represented as "TX" in Figure 8 , and the receiving arrays are represented as "RX" in Figure 8 .

[0090] Referring to Figure 9 , the optical phased array antenna array 203 includes one transmitting array and four receiving arrays, wherein the transmitting array is represented as "TX" in Figure 9 , and the receiving arrays are represented as "RX" in Figure 9 .

[0091] In an exemplary embodiment, as Figure 10 shown, the optical phased array chip further includes:

[0092] A correction unit 1002, configured to adjust the voltage of the phase shifter 202 according to the intensity of the afterglow of each optical antenna, so as to focus the light spots of each optical antenna.

[0093] The correction unit 1002 is respectively connected to the optical phased array antenna array 203 and the phase shifter 202, and it can adjust the voltage of the phase shifter 202 according to the intensity of the afterglow of each optical antenna in the optical phased array antenna array 203. The correction unit 1002 can convert the intensity of the afterglow of multiple optical antennas into an electrical signal, and adjust the voltage of the phase shifter 202 based on the intensity of the converted electrical signal, so as to focus the light spots of each optical antenna.

[0094] In an exemplary embodiment, the antenna structure of the optical antenna can be of various types, including but not limited to at least one of the following: a first antenna structure formed of silicon material; a second antenna structure formed of silicon nitride material; a third antenna structure formed by combining the first antenna structure and the second antenna structure, where the third antenna structure can be formed by coupling the first antenna structure and the second antenna structure.

[0095] For an optical antenna including the first antenna structure, the optical antenna, the beam splitter 201, the phase shifter 202, and the compensation structure 204 can be arranged on the same layer, and the compensation structure 204 is located before or after the optical antenna. For an optical antenna including the second antenna structure, the optical antenna, the beam splitter 201, the phase shifter 202, and the compensation structure 204 are arranged in layers, and the compensation structure 204 is located before or after the optical antenna. For an optical antenna including the third antenna structure (an antenna formed of silicon material and silicon nitride material), the optical antenna, the beam splitter 201, the phase shifter 202, and the compensation structure 204 are arranged on the same layer, and the compensation structure 204 is located before or after the optical antenna.

[0096] For example, referring to Figure 11 , when the optical antenna of the optical phased array antenna array is formed of silicon material, the antenna, the first beam splitter (i.e., the beam splitter 201), the electro-optic phase shifter (i.e., the phase shifter 202), and the compensation structure are arranged on the same layer, and the compensation structure is located before the optical antenna. Referring to Figure 12 , when the optical antenna of the optical phased array antenna array is formed of silicon nitride material, the antenna, the first beam splitter, the electro-optic phase shifter (i.e., the phase shifter 202), and the compensation structure are arranged in layers, and the compensation structure is located before the optical antenna. Referring to Figure 13 , when the optical antenna of the optical phased array antenna array is formed of silicon material and silicon nitride material, the compensation structure is located before the optical antenna. Referring to Figure 14 , when the optical antenna of the optical phased array antenna array is formed of silicon material and silicon nitride material, the compensation structure is located after the optical antenna.

[0097] Here, according to the actual application situation, the optical phased array chip may further include a light source, a semiconductor optical amplifier ( Figures 11 to 14 denoted as "SOA" in

[0098] ), and a correction unit.

[0099] In an exemplary embodiment, as Figure 15 shown, the correction unit 1002 includes:

[0100] A second beam combiner for combining the residual light of each optical antenna in the optical phased array antenna array;

[0101] A photoelectric detector (abbreviated as PD) for converting the combined residual light by the second beam combiner into corresponding electrical signals;

[0102] A processor for adjusting the voltage of the phase shifter according to the intensity of the electrical signals output by the photoelectric detector, so as to focus the light spots of each optical antenna.

[0103] Here, the second beam combiner, the photoelectric detector, and the processor can belong to the correction unit of the optical phased array chip. The second beam combiner can be an optical fiber beam combiner, and the processor can be a processor on the terminal. Here, the second beam combiner can be used to receive and combine the residual light of each optical antenna, and provide the combined residual light to the electro-optical detector. In the electro-optical detector, the optical signal is converted into an electrical signal and provided to the processor. The processor optimally adjusts the voltage applied to the phase shifter according to the intensity of the electrical signal, so as to focus the light spots of each optical antenna.

[0104] Optionally, refer to Figure 16 , it is possible to combine the beams first and then demultiplex the wavelength division: combine multiple laser beams generated by multiple lasers through the first beam combiner (which can be combined by wavelength division multiplexing), and provide the combined multi-wavelength beam to the optical phased array chip; in the receiving module of the optical phased array antenna array, demultiplex the received echo signal. Here, the second beam splitter splits the beam into two paths, one path is the local oscillator signal (LO), and the other path is the detection signal (the light used for target information detection). The third beam combiner is used to combine the multi-wavelength local oscillator signal and the echo signal. Optionally, refer to Figure 17 , it is also possible to demultiplex the wavelength division first and then combine the local oscillator signals and echo signals of each wavelength. Among them, LD _1 to LD _n are multiple lasers in the light source, the semiconductor optical amplifier is denoted as "SOA", the optical phased array antenna array includes OPA antennas, the detector array includes multiple photoelectric detectors, and the correction unit includes PC and PD.

[0105] Here, wavelength division multiplexing is a technology that combines two or more optical carrier signals of different wavelengths (carrying various information) through a multiplexer (or wavelength combiner) at the transmitting end and couples them into the same optical antenna of the optical line; at the receiving end, the optical carrier signals of various wavelengths are separated by a demultiplexer (or wavelength splitter or demultiplexer), and then further processed to restore the original signal.

[0106] It should be noted that the optical phased array chip can also be used to adjust the beam deflection angle (beam incident angle) of the incident laser beam received. Optionally, the compensation structure applies a bias voltage to the heating electrode, so that the heating resistor generates heat, and the heat is transmitted to the optical phased array antenna array through the waveguide, changing the temperature of the antennas in the optical phased array antenna array, thereby changing the refractive index of the antennas, so that the beam incident angle of the received incident laser beam is changed, so as to make the beam exit angle of the spot of the transmitting antenna match the beam incident angle of the spot of the receiving antenna, so as to ensure that the lidar system obtains the best ranging performance.

[0107] According to another aspect of the embodiments of the present application, a lidar is further provided. The lidar uses the optical phased array chip shown in any one of the foregoing embodiments, and has been described above, so details will not be repeated here.

[0108] In an exemplary embodiment, the lidar provided in the embodiments of the present application may include a light source, an optical phased array chip, a detection module, and a data processing module, wherein,

[0109] The optical phased array chip is configured to receive the emitted laser signal provided by the light source, emit the emitted laser signal to the detection space, and receive the echo signal formed by the reflection of the object to be detected in the detection space, and provide the echo signal to the detection module;

[0110] The detection module is configured to receive the echo signal, perform beat frequency on the echo signal and its corresponding local oscillator signal to obtain a beat frequency signal, and provide the beat frequency signal to the data processing module;

[0111] The data processing module is configured to solve the information of the object to be detected according to the beat frequency signal.

[0112] Optionally, the optical phased array chip may include the foregoing beam splitter 201, phase shifter 202, optical phased array antenna array 203, and compensation structure 204, and may also include other components, which are not limited in this embodiment.

[0113] Through the embodiments provided by the present application, a compensation structure is optically matched with the optical phased array antenna array in the optical phased array chip package, and the local temperature of the optical phased array antenna array is regulated through the compensation structure to correct the wavefront distortion caused by the phase noise of the waveguide or antenna, so that the spots of the transmitting antenna and the receiving antenna of the lidar are adjusted to the ideal focusing state; furthermore, the problem that the detection performance of the lidar system is reduced due to the wavefront distortion of the equal phase surface of the optical phased array in the related art is solved, and the detection performance of the lidar system is improved.

[0114] In an exemplary embodiment, the compensation structure is disposed on the same layer as the optical antenna, located at the front end or the rear end of the optical antenna, and is connected to the optical antenna through a waveguide.

[0115] In an exemplary embodiment, the distance between the compensation structure and the optical phased array antenna array is less than 500 μm.

[0116] In an exemplary embodiment, the compensation structure is a thermo-optic phase-shifting structure or an electro-optic phase-shifting structure.

[0117] In an exemplary embodiment, the compensation structure is a heating resistor and a heating electrode, located on the side of the optical phased array antenna array opposite to the light-emitting side, and at least part of the projection of the compensation structure in the vertical direction overlaps with the projection of the corresponding optical antenna in the vertical direction.

[0118] In an exemplary embodiment, the heating resistor is a combination of an integral heating structure or a local heating structure.

[0119] In an exemplary embodiment, the optical phased array chip further includes:

[0120] A coupler, optically connected to the beam splitter, for coupling the outgoing laser beam onto the chip and providing it to the beam splitter.

[0121] In an exemplary embodiment, the optical phased array chip further includes a light source for generating an outgoing laser beam, the light source including: a plurality of lasers and a combiner, wherein the wavelengths of the laser beams generated by different lasers among the plurality of lasers are different from each other, and the outgoing laser beam is obtained by laser beam combining of the laser beams of multiple wavelengths generated by the plurality of lasers; or at least one of a multi-wavelength laser, a tunable laser, and an optical frequency comb for generating a multi-wavelength beam, wherein the outgoing laser beam is a multi-wavelength beam.

[0122] In an exemplary embodiment, the optical phased array chip further includes: a semiconductor optical amplifier, optically connected to the light source and the beam splitter respectively, for amplifying the outgoing laser beam to obtain an amplified outgoing laser beam.

[0123] In an exemplary embodiment, the beam splitter is a multi-stage beam splitting structure; the beam splitter is formed of silicon nitride material; or the beam splitter is formed of silicon material; or the first N-stage structure of the beam splitter is formed of silicon nitride material, and the other beam splitting structures of the beam splitter except the first N-stage structure are formed of silicon material; wherein N is a positive integer greater than or equal to 1.

[0124] In an exemplary embodiment, the phase shifter includes: an electro-optical phase shifter for performing phase modulation on a plurality of emitted laser sub-beams; and a thermo-optical phase shifter for performing phase modulation on the echo signals received by the optical phased array antenna array.

[0125] In an exemplary embodiment, the plurality of optical antennas include at least one transmitting antenna and at least one receiving antenna, wherein an isolation hole or an isolation groove is provided between the receiving antenna and the transmitting antenna.

[0126] In an exemplary embodiment, the optical antenna includes: a first antenna structure formed of silicon material; or, a second antenna structure formed of silicon nitride material; or, a third antenna structure formed by combining the first antenna structure and the second antenna structure.

[0127] In an exemplary embodiment, the optical phased array chip includes: a correction unit for adjusting the voltage of the phase shifter according to the intensity of the residual light of each optical antenna so as to focus the light spots of each optical antenna.

[0128] Specific examples in this embodiment may refer to the examples described in the above embodiments and exemplary embodiments, and will not be elaborated herein.

[0129] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the embodiments of the present application can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. They can be implemented by program codes executable by the computing device, so that they can be stored in a storage device and executed by the computing device. And in some cases, the steps shown or described can be executed in a different order than here, or they can be separately fabricated into individual integrated circuit modules, or multiple modules or steps among them can be fabricated into a single integrated circuit module to implement. Thus, the embodiments of the present application are not limited to any specific combination of hardware and software.

[0130] The above are only the preferred embodiments of the present application and are not used to limit the embodiments of the present application. For those skilled in the art, various changes and modifications can be made to the embodiments of the present application. Any modification, equivalent replacement, improvement, etc. made within the principle of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. An optical phased array chip, characterized in that Comprising: A beam splitter for splitting an input output laser beam to obtain multiple output laser sub-beams; A phase shifter optically connected to the beam splitter for performing phase modulation on the multiple output laser sub-beams to obtain the phase-modulated multiple output laser sub-beams; An optical phased array antenna array including multiple optical antennas, the optical antennas being optically connected to the phase shifter for transmitting the phase-modulated output laser sub-beams to a detection area; A compensation structure arranged in matching with the optical phased array antenna array for locally controlling the temperature of the optical phased array antenna array to change the equivalent refractive index of the corresponding optical antenna.

2. The optical phased array chip according to claim 1, wherein The compensation structure is arranged on the same layer as the optical antenna, located at the front end or the rear end of the optical antenna, and is connected to the optical antenna through a waveguide.

3. The optical phased array chip according to claim 2, characterized in that, The distance between the compensation structure and the optical phased array antenna array is less than 500 μm.

4. The optical phased array chip according to claim 2, wherein The compensation structure is a thermo-optic phase shift structure or an electro-optic phase shift structure.

5. The optical phased array chip according to claim 1, characterized in that, The compensation structure is a heating resistor and a heating electrode, located on the side of the optical phased array antenna array opposite to the light output side, and at least part of the projection of the compensation structure in the vertical direction overlaps with the projection of the corresponding optical antenna in the vertical direction.

6. The optical phased array chip according to claim 5, characterized in that, The heating resistor is a combination of an integral body heating structure or a local heating structure.

7. The optical phased array chip according to claim 1, wherein, The optical phased array chip further includes: A coupler optically connected to the beam splitter for coupling the output laser beam onto the chip and providing it to the beam splitter.

8. The optical phased array chip according to claim 1, characterized in that, The optical phased array chip further includes a light source for generating the output laser beam, and the light source includes: Multiple lasers and a combiner, wherein the wavelengths of the laser beams generated by different lasers among the multiple lasers are different from each other, and the output laser beam is obtained by laser beam combining of the multiple laser beams with multiple wavelengths generated by the multiple lasers by the combiner; or, At least one of a multi-wavelength laser, a tunable laser, and an optical frequency comb for generating a multi-wavelength beam, wherein the output laser beam is the multi-wavelength beam.

9. The optical phased array chip according to claim 8, wherein, The optical phased array chip further includes: A semiconductor optical amplifier optically connected to the light source and the beam splitter respectively for amplifying the output laser beam to obtain the amplified output laser beam.

10. The optical phased array chip according to claim 1, characterized in that, The beam splitter is a multi-stage beam splitting structure; The beam splitter is formed of a silicon nitride material; or, the beam splitter is formed of a silicon material; or, the first N-stage structure of the beam splitter is formed of a silicon nitride material, and the other beam splitting structures of the beam splitter except the first N-stage structure are formed of a silicon material; wherein, N is a positive integer greater than or equal to 1.

11. The optical phased array chip according to claim 1, wherein, The phase shifter includes: An electro-optic phase shifter for performing phase modulation on the multiple output laser sub-beams; A thermo-optic phase shifter for performing phase modulation on the echo signal received by the optical phased array antenna array.

12. The optical phased array chip according to claim 1, characterized in that, The multiple optical antennas include at least one transmitting antenna and at least one receiving antenna, and an isolation hole or an isolation groove is provided between the receiving antenna and the transmitting antenna.

13. The optical phased array chip according to claim 1, characterized in that, The optical antenna includes: a first antenna structure formed of silicon material; or, a second antenna structure formed of silicon nitride material; or, a third antenna structure formed by combining the first antenna structure and the second antenna structure.

14. The optical phased array chip according to any one of claims 1 to 13, characterized in that, The optical phased array chip further includes: a correction unit configured to adjust the voltage of the phase shifter according to the intensity of the residual light of each of the optical antennas, so as to focus the light spots of each of the optical antennas.

15. A lidar, characterized in that, It includes a light source, the optical phased array chip according to any one of claims 1 to 14, a detection module, and a data processing module, wherein, the optical phased array chip is configured to receive the emitted laser signal provided by the light source, emit the emitted laser signal into the detection space, and receive the echo signal formed by the reflection of the object to be detected in the detection space, and provide the echo signal to the detection module; the detection module is configured to receive the echo signal, perform beat frequency on the echo signal and its corresponding local oscillator signal to obtain a beat frequency signal, and provide the beat frequency signal to the data processing module; the data processing module is configured to calculate the information of the object to be detected according to the beat frequency signal.

16. The lidar according to claim 15, wherein The light source includes: a plurality of lasers and a beam combiner, wherein the wavelengths of the laser beams generated by different lasers among the plurality of lasers are different from each other, and the emitted laser beam is obtained by laser beam combination of the plurality of laser beams with different wavelengths generated by the plurality of lasers by the beam combiner; or, at least one of a multi-wavelength laser, a tunable laser, and an optical frequency comb, configured to generate a multi-wavelength beam, wherein the emitted laser beam is the multi-wavelength beam.

17. The lidar according to claim 15 or 16, characterized in that, The lidar further includes: a semiconductor optical amplifier, optically connected to the light source and the beam splitter respectively, configured to perform amplification processing on the emitted laser beam to obtain the amplified emitted laser beam.

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