Imaging system with multiple nucles

Abstract

An imaging system includes a photonic circuit chip having a plurality of cores. Each core includes an optical switch and a plurality of alternating waveguides. The optical switch in each core is configured to direct an outgoing optical signal to any one of the alternating waveguides, the alternating waveguide to which the outgoing optical signal is directed being an active waveguide. Each core outputs an outgoing LIDAR signal from the active waveguide while receiving an incoming LIDAR signal that includes light from the outgoing LIDAR signal that has exited from and returned to the imaging system. Each core includes an optical splitter configured to receive the outgoing LIDAR signal and the incoming LIDAR signal.

Description

[0001] Related Applications

[0002] This application is a continuation of U.S. patent application No. 17 / 829,328, filed on May 31, 2022, and entitled “Imaging System Having Multiple Cores.” U.S. patent application No. 17 / 829,328 is a partial continuation of U.S. patent application serial number 17 / 580,623, filed on January 20, 2022, and entitled “Imaging System Having Multiple Cores,” and all of its contents are incorporated herein. Technical Field

[0003] The present invention relates to optical devices. In particular, the present invention relates to LIDAR systems. Background Art

[0004] As optical imaging systems support more and more applications, the performance requirements for optical imaging systems are also getting higher and higher. Optical imaging systems generally generate data for a series of sample areas, each of which is illuminated in turn by a system output signal. The data for the sample area indicates the radial velocity and / or distance between the imaging system and one or more objects located in the sample area. The imaging system can scan the system output signal to multiple different sample areas. The sample areas can be spliced ​​together to form the field of view of the imaging system. Therefore, the combination of data from different sample areas provides data for objects within the field of view.

[0005] Increasing the rate at which data can be generated for a field of view can increase the frequency at which the field of view can be scanned, can increase the size of the field of view, and / or can increase the resolution of the field of view. LIDAR systems designed to increase data generation rate and / or resolution utilize circulators that separate light emitted from the LIDAR system from light returning to the LIDAR system. However, these circulators increase the cost and assembly complexity of the LIDAR system. Therefore, there is a need for a LIDAR system that can provide a desired data generation rate and / or resolution without the use of a circulator. Summary of the invention

[0006] An imaging system includes a photonic circuit chip having multiple cores. Each core includes an optical switch and multiple alternating waveguides. The optical switch in each core is configured to guide an outgoing optical signal to any one of the alternating waveguides, and the alternating waveguide to which the outgoing optical signal is guided is an active waveguide. Each core outputs an outgoing LIDAR signal from the active waveguide while receiving an incoming LIDAR signal, which includes light from the outgoing LIDAR signal that has left the imaging system and has returned to the imaging system. Each core includes a signal splitter that receives the outgoing LIDAR signal and the incoming LIDAR signal. The signal splitter extracts a portion of the outgoing LIDAR signal that acts as a reference signal and extracts at least a portion of the incoming LIDAR signal that acts as a comparison signal. Each core includes a signal combiner that combines light from the reference signal with light from the comparison signal to generate a composite signal that beats at a beat frequency. The electronic device calculates LIDAR data for each core based on the beat frequency of the composite signal generated by each core. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A An imaging system comprising a chip having a photonic circuit is shown.

[0008] Figure 1B Another embodiment of an imaging system including a photonic circuit chip is shown.

[0009] Figure 1C Another embodiment of an imaging system including a photonic circuit chip is shown.

[0010] Figure 2 is a schematic diagram of an imaging system including multiple different cores on a chip.

[0011] FIG. 3A to FIG. 3B An example of a processing component is shown, which is suitable for use as a processing component according to Figure 1A and Figure 1B The processing components in the constructed LIDAR system. Figure 3A is a schematic diagram of an example of a suitable optical-to-electrical assembly for use with a processing component.

[0012] Figure 3B Provides electronic components and Figure 3A Schematic diagram of the relationship between optoelectronic components.

[0013] Figure 3C The frequency of the signal output from the imaging system is shown over time.

[0014] Figure 3D Provides electronic components and Figure 3ASchematic diagram of the relationship between optoelectronic components.

[0015] Figure 3E yes Figure 3A A schematic diagram of another relationship between the sensors in the optoelectronic assembly and the electronics in the LIDAR system.

[0016] Figure 4 is a cross section of a silicon-on-insulator wafer.

[0017] Figure 5A and Figure 5B An example of an optical switch comprising cascaded Mach-Zehnder interferometers is shown. Figure 5A is a top view of a light switch.

[0018] Figure 5B It is along Figure 5A The line marked B in Figure 5A Cross-section of the optical switch shown in .

[0019] Figure 6 Shows Figure 2 A LIDAR system is modified to have multiple signal directors, each signal director receiving a LIDAR output signal from a different core.

[0020] Figure 7 Shows Figure 2 LIDAR systems in which the light source is located outside the chip.

[0021] Figure 8 A portion of a LIDAR chip including a reference waveguide used in conjunction with a beam dump is shown. DETAILED DESCRIPTION

[0022] The imaging system includes a photonic circuit chip having a plurality of cores. Each core includes an optical switch and a plurality of alternating waveguides. The optical switch in each core is configured to guide an outgoing optical signal to any one of the alternating waveguides, and the alternating waveguide to which the outgoing optical signal is guided acts as an active waveguide. Each core outputs an outgoing LIDAR signal from the active waveguide while also receiving an incoming LIDAR signal. The incoming LIDAR signal includes light from the outgoing LIDAR signal that has left the imaging system and has returned to the imaging system. Each core includes a signal separator that receives the outgoing LIDAR signal and the incoming LIDAR signal. The signal separator extracts a portion of the outgoing LIDAR signal to act as a reference signal, and also extracts at least a portion of the incoming LIDAR signal to act as a comparison signal. Each core includes a signal combiner that combines light from the reference signal with light from the comparison signal to generate a beat signal that beats at a beat frequency. The electronic device calculates LIDAR data for each core based on the beat frequency of the beat signal generated by each core. Since the beat signal is generated based on the optical signal separated by the signal separator, a circulator is not required. The elimination of the circulator reduces the cost and assembly complexity associated with the LIDAR system.

[0023] Figure 1A is a schematic diagram of a portion of a LIDAR system including a LIDAR chip 2 . Figure 1A A top view of a portion of a LIDAR chip 2 is included. The LIDAR chip includes a LIDAR core 4. The LIDAR core 4 includes a photonic integrated circuit.

[0024] The LIDAR core 4 may include a light source 10 that outputs an outgoing LIDAR signal. The LIDAR core includes a utility waveguide 12 that receives the outgoing LIDAR signal from the light source 10. The utility waveguide 12 carries the outgoing LIDAR signal to a signal guiding component 14. The signal guiding component 14 may be operated by electronics to guide light from the light source output signal to one of a plurality of different alternating waveguides 16. There are N alternating waveguides, and each alternating waveguide 16 is associated with an alternating waveguide index i, where i has a value from 1 to N. Suitable values ​​for N include, but are not limited to, values ​​less than 128, 64, or 32 and / or values ​​greater than 2, 8, or 16. In one example, N is between 2 and 128.

[0025] Each alternating waveguide 16 may receive an outgoing LIDAR signal from the signal guiding component 14. When any of the alternating waveguides 16 receives an outgoing LIDAR signal, the alternating waveguide 16 acts as an active waveguide and carries the outgoing LIDAR signal to the port 18, through which the outgoing LIDAR signal may exit the LIDAR chip and act as a LIDAR output signal. Thus, the outgoing LIDAR signal is output from the active waveguide.

[0026] The outgoing LIDAR signal is guided to the alternating waveguide 16 with alternating waveguide index i. The resulting optical signal is classified into the bearer channel (C i ) optical signal. Therefore, each LIDAR output signal is associated with a different one of the alternating waveguide index channel indexes i=1 to N. For example, in Figure 1A , the path of the LIDAR output signal carrying the channel with alternating waveguide index 2 is labeled C2. For illustration purposes, the LIDAR system is shown as generating three LIDAR output signals (N=3) labeled C1 to C3. Each of the different LIDAR output signals may carry a different channel, however, each of the different channels may carry the same selection of wavelength(s) or substantially the same selection of wavelength(s).

[0027] The LIDAR input signal returns to the LIDAR chip, making the carrier channel C i The LIDAR input signal of the input channel enters the alternating waveguide 16 associated with the same alternating waveguide index i. Therefore, the LIDAR input signals carrying different channels are guided to different alternating waveguides. The portion of the LIDAR input signal entering the alternating waveguide 16 acts as the incoming LIDAR signal. Therefore, the alternating waveguide receiving the incoming LIDAR signal can guide the outgoing LIDAR signal while also guiding the incoming LIDAR signal in the opposite direction. The alternating waveguide 16 receiving the incoming LIDAR signal carries the incoming LIDAR signal to the signal guiding component 14. The signal guiding component 14 outputs the incoming LIDAR signal on the utility waveguide 12.

[0028] The utility waveguide 12 carries the incoming LIDAR signal to a 2x2 splitter 24, which moves a portion of the incoming LIDAR signal from the utility waveguide 12 to a comparison waveguide 26 as a comparison signal. The comparison waveguide 26 carries the comparison signal to a processing component 28 for further processing. Suitable splitters 24 include, but are not limited to, optical couplers, y-junctions, and MMIs. In some cases, the splitter 24 is configured so that the power of the incoming LIDAR signal is evenly or substantially evenly distributed between the utility waveguide 12 and the comparison waveguide 26.

[0029] Utility waveguide 12 also carries the outgoing LIDAR signal to splitter 24. Splitter 24 moves a portion of the outgoing LIDAR signal from utility waveguide 12 to reference waveguide 32 as a reference signal. Reference waveguide 32 carries the reference signal to processing element 28 for further processing.

[0030] As will be described in more detail below, processing component 28 combines the comparison signal with the reference signal to form a composite signal that carries LIDAR data for a sample area on the field of view. Thus, the composite signal can be processed to extract LIDAR data for the sample area (radial velocity and / or distance between the LIDAR system and an object external to the LIDAR system).

[0031] The LIDAR chip may include a control branch for controlling the operation of the light source 10. The control branch includes a directional coupler 66 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 to the control waveguide 68. The coupled portion of the outgoing LIDAR signal acts as a tapped signal. Figure 1A A directional coupler 66 is shown moving a portion of the outgoing LIDAR signal to the control waveguide 68, but other signal tapping components may be used to move a portion of the outgoing LIDAR signal from the utility waveguide 12 to the control waveguide 68. Examples of suitable signal tapping components include, but are not limited to, y-junctions and MMIs.

[0032] The control waveguide 68 carries the tap signal to the control component 70. The control component may be in electrical communication with the electronics 62. Figure 1A The electronics are shown as a separate component from the processing component(s) 28, but a portion of the electronics may be included in each of the processing component(s) 28. During operation, the electronics 62 may adjust the frequency of the outgoing LIDAR signal in response to the output of the control component. An example of a suitable configuration for the control component is provided in U.S. Patent Application Serial No. 15 / 977,957, filed May 11, 2018, entitled "Optical Sensor Chip," and incorporated herein in its entirety.

[0033] The incoming LIDAR signal passes through the signal guide 14. The signal guide 14 may be a source of optical loss. This source of optical loss may be eliminated by moving a portion of the incoming LIDAR signal, which serves as a comparison signal, to the comparison waveguide 26 before the incoming LIDAR signal reaches the signal guide 14. For example, Figure 1B Shows Figure 1A The LIDAR chip of FIG. 1 is modified so that a splitter 24 is positioned along each alternating waveguide 16 between the signal guiding component 14 and the port 18. Thus, the comparison signal is extracted from the alternating waveguide 16 before the incoming LIDAR signal reaches the signal guiding component 14.

[0034] Figure 1A and Figure 1B The comparison shows that Figure 1B LIDAR chip ratio Figure 1A The LIDAR chip requires more processing components 28. As will be apparent below, increasing the number of processing components 28 required will increase the number of analog-to-digital converters required for the LIDAR system. However, common processing components 28 can be used to reduce the number of analog-to-digital converters. For example, Figure 1C Shows Figure 1B The LIDAR chip is modified so that each comparison waveguide 26 carries one of the comparison signals to a common processing component 72. In addition, each reference waveguide 32 carries one of the reference signals to a common processing component 72.

[0035] The LIDAR system may include a LIDAR chip having a plurality of LIDAR cores 4. For example, Figure 2 FIG. 1 shows a LIDAR chip including a plurality of different cores. The cores are each labeled as core k , where k represents the kernel index k. Each LIDAR kernel can be Figures 1A to 1C Each LIDAR core outputs a different LIDAR output signal. From the LIDAR core labeled k The LIDAR output signal of the core output can be used k,i , where i represents the channel index. Therefore, S k,i is a function of the alternating waveguide index i and the core index k. For example, by S k,i The LIDAR output signal from the core k output and received by the alternating waveguide index i. Therefore, by S k,i The LIDAR output signal from the core k Output and carry channel C i .

[0036] The LIDAR system can include an optical component assembly 75 that receives the LIDAR output signals from the different cores and outputs system output signals, each system output signal comprising, consisting of, or consisting essentially of light from different ones of the LIDAR output signals. The optical component assembly 75 can be operated by the electronics 280 to steer the system output signals to different sample areas in the field of view of the LIDAR system.

[0037] Figure 2An optical component assembly 75 is shown, which includes a signal director 76 that receives each LIDAR output signal. The signal director 76 changes the direction of travel of at least a portion of the LIDAR output signal and outputs each LIDAR output signal as a redirected LIDAR output signal. Suitable signal directors 76 include, but are not limited to, convex lenses and concave mirrors. The optical component assembly 75 includes one or more beam steering components 78 that receive the redirected LIDAR output signal output from the signal director 76 as a system output signal. The system output signal is directed away from the LIDAR system in a direction of travel. Figure 2 The electronics may operate one or more beam steering components 78 to steer each system output signal to a different sample region in the field of view. Figure 2 As can be seen from the arrows marked A and B in FIG, one or more beam steering components 78 can be configured to enable the electronic device to steer the system output signal in one or two dimensions. Therefore, one or more beam steering components 78 can be used as a beam steering mechanism operated by the electronic device to steer the system output signal within the field of view of the LIDAR system. Suitable beam steering components 78 include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPA), gratings, and actuated gratings. In some cases, the signal director 76 and / or one or more beam steering components 78 are configured to operate on the system output signals so that the system output signals are collimated or substantially collimated when they travel away from the LIDAR system. Additionally or alternatively, the LIDAR system may include one or more collimating optical components (not shown) that operate on the LIDAR output signals, redirected LIDAR output signals, and / or system output signals so that the system output signals are collimated or substantially collimated when they travel away from the LIDAR system.

[0038] The system output signal may be reflected by an object located outside the LIDAR system. All or a portion of the reflected light from the system output signal may be returned to the LIDAR system as a system return signal. Each system return signal is received at one or more beam steering components 78. One or more beam steering components 78 output at least a portion of each system return signal as a return signal. Each return signal is received at a signal guide 76. The signal guide 76 outputs at least a portion of each return signal as a LIDAR input signal. Each different LIDAR input signal is received by a different one of the cores 4. Each LIDAR input signal includes light from a LIDAR output signal output from a core receiving the LIDAR input signal, or consists of light from a LIDAR output signal output from a core receiving the LIDAR input signal. In addition, the LIDAR input signal received at the alternating waveguide includes light from a LIDAR output signal output from the same alternating waveguide, or consists of light from a LIDAR output signal output from the same alternating waveguide.

[0039] The one or more signal directors 76 may redirect the direction of the LIDAR output signal traveling away from the one or more signal directors 76 so that the direction of the LIDAR output signal is different from the resulting redirected LIDAR output signal. In some cases, the one or more signal directors 76 are selected so that all or a portion of the redirected LIDAR output signal travels away from the one or more signal directors 76 in a non-parallel direction. For example, in Figure 2 In one embodiment, one or more of the signal directors 76 are lenses, and each different LIDAR output signal is incident on the lens at a different angle of incidence. Therefore, the redirected LIDAR output signals each travel away from the signal directors 76 in a different direction. In addition, the redirected LIDAR output signals travel away from the signal directors 76 in non-parallel directions. Figure 2 It can be clearly seen that different directions of the system output signal can cause the system output signal to travel away from the LIDAR system in different directions. In some cases, the system output signal travels away from the LIDAR system in non-parallel directions.

[0040] Operating the signal directing component 14 on a core may change the location at which one or more signal directors 76 receive the LIDAR output signal and may accordingly change the direction in which the system output signal originating from the core travels away from the LIDAR system. Figure 2 The dashed line in FIG. 1 shows the result of operating the signal guiding component 14 on core1, so that the core output is S k，i+1 The LIDAR output signal is represented by S k，i Represents the LIDAR output signal. Figure 2It can be clearly seen that this operation of the signal guiding component 14 changes the direction in which the system output signal output from core1 travels away from the LIDAR system. Therefore, the electronic device can operate the signal guiding components 14 on different cores to steer the system output signal within the field of view of the LIDAR system. Therefore, the electronic device can operate the signal guiding components 14 and / or one or more beam steering components 78 on different cores to steer the system output signal within the field of view of the LIDAR system. A suitable method for operating signal guiding components 14 and / or one or more beam steering components 78 on different cores to steer the system output signal to different sample areas within the field of view of the LIDAR system is disclosed in U.S. patent application serial number 17 / 580,623, entitled "Imaging System with Multiple Cores," filed on January 20, 2022, which is incorporated herein in its entirety.

[0041] The optical component assembly 75 may have Figure 2 Configurations other than those shown. For example, one or more beam steering components 78 can be located between the signal director 76 and the LIDAR chip. In addition, the optical component assembly 75 can include optical components not shown. For example, the optical component assembly 75 can include one or more lenses configured to increase the collimation of the LIDAR output signal and / or other signals derived from the LIDAR output signal and / or including light from the LIDAR output signal.

[0042] The wavelengths of the LIDAR output signals output from different cores can be the same or different. Thus, the light sources on different cores can be configured to output outgoing light signals, each outgoing light signal having a different, the same, or substantially the same wavelength selection. Thus, the wavelength selection in the output signals of different systems can be different, the same, or substantially the same.

[0043] All or part of the electronics 62 associated with different cores may optionally be combined in Figure 2 The combined electronics 280 may be located on the LIDAR chip, or may be located external to the LIDAR chip. The combined electronics 280 may collect or generate LIDAR data results from different cores, and / or may coordinate LIDAR data results from different cores to assemble LIDAR data results for the field of view of the LIDAR system.

[0044] although Figure 2 Four cores on the LIDAR chip are shown, but the LIDAR chip may include one, two, or more than two cores. Suitable numbers of cores on the LIDAR chip include, but are not limited to, numbers greater than or equal to 2, 4, or 6 and / or less than 32, 64, or 128.

[0045] FIG. 3A to FIG. 3BAn example of a processing component is shown, which is suitable for use as a processing component according to Figure 1A and Figure 1B The processing unit 28 in the constructed LIDAR system includes an optoelectronic component configured to convert an optical signal into an electrical signal. Figure 3A 2 is a schematic diagram of an example of a suitable optoelectronic component, which includes a first splitter 200 that distributes a comparison signal received from the comparison waveguide 26 onto a first comparison waveguide 204 and a second comparison waveguide 206. The first comparison waveguide 204 carries a first portion of the comparison signal to an optical combiner 211. The second comparison waveguide 206 carries a second portion of the comparison signal to a second optical combiner 212.

[0046] Figure 2 The processing part of A also includes a second splitter 202, which distributes the reference signal received from the reference waveguide 32 to a first reference waveguide 210 and a second reference waveguide 208. The first reference waveguide 210 carries a first portion of the reference signal to an optical combiner 211. The second reference waveguide 208 carries a second portion of the reference signal to a second optical combiner 212.

[0047] The second optical combiner 212 combines the second part of the comparison signal and the second part of the reference signal into a second composite signal. Due to the frequency difference between the second part of the comparison signal and the second part of the reference signal, the second composite signal beats between the second part of the comparison signal and the second part of the reference signal. The first composite signal and the second composite signal are both examples of composite signals.

[0048] The second optical combiner 212 also splits the resulting second composite signal onto a first auxiliary detector waveguide 214 and a second auxiliary detector waveguide 216. The first auxiliary detector waveguide 214 carries a first portion of the second composite signal to a first auxiliary optical sensor 218, which converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 216 carries a second portion of the second composite signal to a second auxiliary optical sensor 220, which converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0049] In some cases, the second optical combiner 212 splits the second composite signal so that a portion of the comparison signal included in the first portion of the second composite signal (i.e., a portion of the second portion of the comparison signal) is phase-shifted by 180° relative to a portion of the comparison signal in the second portion of the second composite signal (i.e., a portion of the second portion of the comparison signal), but a portion of the reference signal in the second portion of the second composite signal (i.e., a portion of the second portion of the reference signal) is not phase-shifted relative to a portion of the reference signal in the first portion of the second composite signal (i.e., a portion of the second portion of the reference signal). Alternatively, the second optical combiner 212 splits the second composite signal so that a portion of the reference signal in the first portion of the second composite signal (i.e., a portion of the second portion of the reference signal) is phase-shifted by 180° relative to a portion of the reference signal in the second portion of the second composite signal (i.e., a portion of the second portion of the reference signal), but a portion of the comparison signal in the first portion of the second composite signal (i.e., a portion of the second portion of the comparison signal) is not phase-shifted relative to a portion of the comparison signal in the second portion of the second composite signal (i.e., a portion of the second portion of the comparison signal). Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0050] The first optical combiner 211 combines the first part of the comparison signal and the first part of the reference signal into a first composite signal. Due to the frequency difference between the first part of the comparison signal and the first part of the reference signal, the first composite signal beats between the first part of the comparison signal and the first part of the reference signal.

[0051] The optical combiner 211 also splits the first composite signal onto a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 carries a first portion of the first composite signal to a first optical sensor 223, which converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 carries a second portion of the second composite signal to a second optical sensor 224, which converts the second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0052] In some cases, the optical combiner 211 splits the first composite signal such that a portion of the comparison signal included in the first portion of the composite signal (i.e., a portion of the first portion of the comparison signal) is phase-shifted by 180° relative to a portion of the comparison signal in the second portion of the composite signal (i.e., a portion of the first portion of the comparison signal), but a portion of the reference signal in the first portion of the composite signal (i.e., a portion of the first portion of the reference signal) is not phase-shifted relative to a portion of the reference signal in the second portion of the composite signal (i.e., a portion of the first portion of the reference signal). Alternatively, the optical combiner 211 splits the composite signal such that a portion of the reference signal in the first portion of the composite signal (i.e., a portion of the first portion of the reference signal) is phase-shifted by 180° relative to a portion of the reference signal in the second portion of the composite signal (i.e., a portion of the first portion of the reference signal), but a portion of the comparison signal in the first portion of the composite signal (i.e., a portion of the first portion of the comparison signal) is not phase-shifted relative to a portion of the comparison signal in the second portion of the composite signal (i.e., a portion of the first portion of the comparison signal).

[0053] When the second optical combiner 212 splits the second composite signal so that the portion of the comparison signal in the first portion of the second composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the second composite signal, the optical combiner 211 also splits the composite signal so that the portion of the comparison signal in the first portion of the composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the composite signal. When the second optical combiner 212 splits the second composite signal so that the portion of the reference signal in the first portion of the second composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the second composite signal, the optical combiner 211 also splits the composite signal so that the portion of the reference signal in the first portion of the composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the composite signal.

[0054] The first reference waveguide 210 and the second reference waveguide 208 are configured to provide a phase shift between a first portion of the reference signal and a second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 can be configured to provide a 90 degree phase shift between the first portion of the reference signal and the second portion of the reference signal. For example, one reference signal portion can be an in-phase component and the other reference signal portion can be an orthogonal component. Therefore, one of the reference signal portions can be a sine function and the other reference signal portion can be a cosine function. In one example, the first reference waveguide 210 and the second reference waveguide 208 are configured so that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Therefore, a portion of the reference signal in the second composite signal is phase shifted relative to a portion of the reference signal in the first composite signal, however, a portion of the comparison signal in the first composite signal is not phase shifted relative to a portion of the comparison signal in the second composite signal.

[0055] The first light sensor 223 and the second light sensor 224 may be connected as balanced detectors, and the first auxiliary light sensor 218 and the second auxiliary light sensor 220 may also be connected as balanced detectors. The balanced detector(s) act as light sensors that convert optical signals into electrical signals. Figure 3B A schematic diagram of the relationship between the electronics, first light sensor 223, second light sensor 224, first auxiliary light sensor 218, and second auxiliary light sensor 220 is provided. The symbol of a photodiode is used to represent the first light sensor 223, second light sensor 224, first auxiliary light sensor 218, and second auxiliary light sensor 220, but one or more of these sensors may have other configurations. In some cases, Figure 3B All components shown in the schematic are included on the LIDAR chip. In some cases, Figure 3B The components shown in the schematic diagram are distributed between the LIDAR chip and the electronic devices located outside the LIDAR chip.

[0056] The electronic device connects the first light sensor 223 and the second light sensor 224 as a first balanced detector 225, and connects the first auxiliary light sensor 218 and the second auxiliary light sensor 220 as a second balanced detector 226. In particular, the first light sensor 223 and the second light sensor 224 are connected in series. In addition, the first auxiliary light sensor 218 and the second auxiliary light sensor 220 are connected in series. The series connection in the first balanced detector communicates with the first data line 228, which carries the output from the first balanced detector as a first data signal. The series connection in the second balanced detector communicates with the second data line 232, which carries the output from the second balanced detector as a second data signal. The first data line and the second data line are both examples of data lines. The first data signal is an electrical data signal carrying a representation of the first composite signal, and the second data signal is an electrical data signal carrying a representation of the second composite signal. Therefore, the first data signal includes contributions from the first waveform and the second waveform, and the second data signal is a composite of the first waveform and the second waveform. A portion of the first waveform in the first data signal is phase-shifted relative to a portion of the first waveform in the first data signal, but a portion of the second waveform in the first data signal is in phase with a portion of the second waveform in the first data signal. For example, the second data signal includes a portion of the reference signal that is phase-shifted relative to a different portion of the reference signal included in the first data signal. In addition, the second data signal includes a portion of the comparison signal that is in phase with a different portion of the comparison signal included in the first data signal. The first data signal and the second data signal beat due to a beat between the comparison signal and the reference signal (i.e., a beat in the first composite signal and the second composite signal).

[0057] The electronic device 62 includes a transformation mechanism 238 configured to perform a mathematical transformation on the first data signal and the second data signal. For example, the mathematical transformation can be a complex Fourier transform with the first data signal and the second data signal as input. Since the first data signal is an in-phase component and the second data signal is its orthogonal component, the first data signal and the second data signal together act as a complex data signal, wherein the first data signal is the real part of the input and the second data signal is the imaginary part of the input.

[0058] The conversion mechanism 238 includes a first analog-to-digital converter (ADC) 264, which receives a first data signal from the first data line 228. The first analog-to-digital converter (ADC) 264 converts the first data signal from an analog form to a digital form and outputs a first digital data signal. The conversion mechanism 238 includes a second analog-to-digital converter (ADC) 266, which receives a second data signal from the second data line 232. The second analog-to-digital converter (ADC) 266 converts the second data signal from an analog form to a digital form and outputs a second digital data signal. The first digital data signal is a digital representation of the first data signal, and the second digital data signal is a digital representation of the second data signal. Therefore, the first digital data signal and the second digital data signal together act as a complex signal, wherein the first digital data signal acts as the real part of the complex signal, and the second digital data signal acts as the imaginary part of the complex data signal.

[0059] The transform mechanism 238 includes a transform component 268 that receives a complex data signal. For example, the transform component 268 receives a first digital data signal from a first analog-to-digital converter (ADC) 264 as an input, and also receives a second digital data signal from a first analog-to-digital converter (ADC) 266 as an input. The transform component 268 can be configured to perform a mathematical transform on the complex signal to convert from the time domain to the frequency domain. The mathematical transform can be a complex transform, such as a complex fast Fourier transform (FFT). A complex transform (e.g., a complex fast Fourier transform (FFT)) provides a clear solution for comparing the frequency shift of a signal relative to a system output signal.

[0060] The electronics include a LIDAR data generator 270 that receives and processes the output from the transform component 268 to generate LIDAR data (the distance and / or radial velocity between the reflecting object and the LIDAR chip or LIDAR system). The LIDAR data generator performs a peak search on the output of the transform component 268 to identify one or more peaks in the beat frequency.

[0061] The electronics use the one or more frequency peaks for further processing to generate LIDAR data (the distance and / or radial velocity between the reflecting object and the LIDAR chip or LIDAR system). The transformation component 268 may perform the attributed function using firmware, hardware, or software, or a combination thereof.

[0062] Figure 3C An example of the relationship between the frequency, time, cycle, and data period of the system output signal is shown. The fundamental frequency (f o ) can be the frequency of the system output signal at the beginning of the cycle.

[0063] Figure 3C Shown is the cycle j and cycle j+1 The frequency-versus-time relationship of two cyclic sequences of . In some cases, the frequency-versus-time pattern repeats in each cycle, such as Figure 3C The cycles shown do not include a repositioning period, and / or the repositioning period is not located between cycles. Therefore, Figure 3C The result of a continuous scan is shown, where the turning of the system output signal is continuous.

[0064] Each cycle consists of K data cycles, each of which is associated with a cycle index k and is labeled DP k .exist Figure 3C In the example, each cycle consists of a DP k Three data cycles, where k = 1, 2 and 3. In some cases, such as Figure 3C As shown in FIG. 1 , the frequency-to-time pattern is the same for data periods corresponding to each other in different cycles. Corresponding data periods are data periods with the same cycle index. Therefore, each data period DP1 can be regarded as a corresponding data period, and the related frequency-to-time pattern is Figure 3C At the end of the cycle, the electronics restores the frequency to the same frequency level at which it started the previous cycle.

[0065] During the data period DP1 and the data period DP2, the electronic device operates the light source so that the frequency of the system output signal changes at a linear rate α. The direction of the frequency change during the data period DP1 is opposite to the direction of the frequency change during the data period DP2.

[0066] Figure 3C The sample regions are labeled, each of which is associated with a sample region index k and is labeled Rn k . Figure 3C The sample area Rn is marked k and Rnk+1 Each sample area is Figure 3C The data period associated with the sample region shown is illuminated using the system output signal. k The sample regions Rn are illuminated by the system output signal during the data periods labeled DP1 to DP3. The sample region index k may be assigned relative to time. For example, the sample regions may be illuminated by the system output signal in the order indicated by the index k. Thus, the sample regions Rn 10 It can be after the sample area Rn9 and before Rn 11 Previously illuminated.

[0067] LIDAR systems are typically configured to provide reliable LIDAR data when an object is within an operating distance range from the LIDAR system. The operating distance range may extend from a minimum operating distance to a maximum operating distance. The maximum round trip time may be the time required for a system output signal to leave the LIDAR system, travel to the maximum operating distance of an object, and return to the LIDAR system, and may be Figure 3C The symbol is τ M .

[0068] Since there is a delay between the system output signal being transmitted and returning to the LIDAR system, the composite signal does not include a contribution from the LIDAR signal before the system return signal returns to the LIDAR system. Since the composite signal requires a contribution from the system return signal in order for the LIDAR beat frequency to be present, the electronics measures the LIDAR beat frequency produced by the system return signal returning to the LIDAR system during a data window in the data cycle. The data window is Figure 3C The contribution of the LIDAR signal to the composite signal will appear when the maximum operating time delay (τ M ) time. Therefore, the data window is shown as a delay from the maximum operating time (τ M ) extends to the end of the data period.

[0069] The frequency peaks in the output from the complex Fourier transform represent the beat frequencies of composite signals, each of which includes a comparison signal against a reference signal beat frame. The beat frequencies from two or more different data periods can be combined to generate LIDAR data. For example, the beat frequencies from Figure 3C The beat frequency determined by DP1 in Figure 3C The beat frequency determined by DP2 in is combined to determine the LIDAR data. For example, the following equation applies during a data period in which the electronics increases the frequency of the outgoing LIDAR signal during the data period, e.g. Figure 3C What happens in data cycle DP1: ub =-f d +ατ, where f ubis the frequency provided by the conversion component, f d represents the Doppler frequency shift (f d =2vf c / c), where f c represents the optical frequency (f o ), c represents the speed of light, v is the radial velocity between the reflecting object and the LIDAR system, where the direction from the reflecting object toward the chip is assumed to be the positive direction, τ is the time it takes for light from the system output signal to travel to the object and back to the LIDAR system (round trip time), and c is the speed of light. The following equation applies during such data periods, where the electronics reduce the frequency of the outgoing LIDAR signal, e.g. Figure 3C What happens in data cycle DP2: db =-f d -ατ, where f db is the frequency provided by the transform component (in this case, f i，LDP Determined from DP2). In these two equations, f d and τ are unknowns. The electronics solves these two equations for the two unknowns. Then, the Doppler shift (v = c*f d / (2f c )) can calculate the radial velocity of the sample area and / or can calculate the separation distance of the sample area according to c*τ / 2. Therefore, the electronic device can use each beat frequency as a variable in one or more equations to derive LIDAR data. Since LIDAR data can be generated for each corresponding frequency pair output by the transform, separate LIDAR data can be generated for each object in the sample area. Therefore, the electronic device can determine more than one radial velocity and / or more than one radial separation distance based on a single sampling of a single sample area in the field of view.

[0070] Figure 3C The data period marked as DP3 in is optional. As described above, there are situations where there are multiple objects in the sample area. For example, during the feedback period for cycle2 in DP1 and also during the feedback period for cycle2 in DP2, more than one frequency pair may be matched. In these cases, it may not be clear which frequency peaks from DP2 correspond to which frequency peaks from DP1. Therefore, it may not be clear which frequencies need to be used together to generate LIDAR data for objects in the sample area. Therefore, it may be necessary to identify corresponding frequencies. Identification of corresponding frequencies can be performed so that the corresponding frequencies are frequencies from the same reflecting object in the sample area. The data period marked as DP3 can be used to find corresponding frequencies. LIDAR data can be generated for each pair of corresponding frequencies and the LIDAR data can be regarded and / or processed as LIDAR data for different reflecting objects in the sample area.

[0071] An example of corresponding frequency identification uses a LIDAR system, where a cycle includes three data cycles (DP1, DP2, and DP3), such as Figure 3C When there are two objects in the sample area illuminated by the LIDAR output signal, the transformation component outputs f during DP1. ub Two different frequencies: f u1 and f u2 , and output f during DP2 db Two other different frequencies: f d1 and f d2 In this case, the possible frequency pairings are: (f d1 , f u1 );(f d1 , f u2 );(f d2 , f u1 ); and (f d2 , f du2 ). f can be calculated for each possible frequency pairing d and τ. f d Substitute each pair of values ​​of and into f3 = -f d +α3τ0, to generate a theoretical f3 for each possible frequency pairing. The value of α3 is different from the value of α used in DP1 and DP2. Figure 3C , the value of α3 is zero. In this case, the transformation component also outputs two values ​​for f3, each associated with an object in the sample area. The frequency pair for which the theoretical f3 value is closest to each of the actual f3 values ​​is considered a corresponding pair. As described above, LIDAR data can be generated for each corresponding pair and the LIDAR data can be considered and / or processed as LIDAR data for different reflecting objects in the sample area. Each set of corresponding frequencies can be used in the above equation to generate LIDAR data. The generated LIDAR data will be for one of the objects in the sample area. Therefore, multiple different LIDAR data values ​​can be generated for the sample area, wherein each different LIDAR data value corresponds to a different object in the objects in the sample area.

[0072] Figure 1A The processing unit in receives a series of comparison signals, which carry different channels and thus come from different sample areas. Figure 1A The processing means in provides LIDAR data for a series of sample areas illuminated by the system output signals carrying different channels. The series of sample areas for which the processing means provides LIDAR data may be the same as the series of sample areas that are illuminated. FIG. 3A to FIG. 3C The processing unit configuration can also be used Figure 1B However, Figure 1B The processing unit 28 receives the comparison signal carrying only one of the channels. Figure 1B The processing unit 28 in FIG. 3A to FIG. 3C When configured, each processing element provides LIDAR data for a series of sample areas illuminated by the system output signal carrying only one of the channels.

[0073] exist Figure 1C In a LIDAR system of FIG. 1 , the electronics from different processing components 28 can be combined so that the beat signals are combined electronically rather than optically. Figure 1C Each processing unit 28 in the LIDAR system may include Figure 3A optoelectronic components. Figure 3D Is from Figure 3A Schematic diagram of the relationship between the first light sensor 223, the second light sensor 224, the first auxiliary light sensor 218 and the second auxiliary light sensor 220 in each optoelectronic assembly and the electronic device. Since each different processing unit 28 receives a LIDAR input signal carrying a different channel, Figure 3D A first light sensor 223, a second light sensor 224, a first auxiliary light sensor 218, and a second auxiliary light sensor 220 are shown in association with channels received by the light sensors.

[0074] exist Figure 3D , from different processing components 28 ( Figure 1C ) to form a common processing component 72. The first data line 228 from each different first balanced detector 225 carries the first data signal to the first electrical multiplexer 272. The first electrical multiplexer 272 outputs the first data signal from the different first data lines 228 on the common data line 273. Since the system output signals from the same core and carrying different channels are serially output from the LIDAR system, in response to the signal directing component 14 on the core being operated so that the system output signal carrying channel i is output from the LIDAR system, the processing component 28 ( Figure 1C) receives the first comparison signal. In addition, in response to the signal directing component 14 being operated so that the system output signal carrying channel i is output from the LIDAR system, the (one or more) processing components 28 that are not configured to receive the comparison signal carrying channel i substantially do not receive the first comparison signal. Since the system output signals carrying different channels from the same core are output serially from the LIDAR system, the comparison signals carrying different channels are received serially at different processing components 28, but some overlap of different channels may occur. Since different processing components 28 serially receive the comparison signals carrying different channels, the first common data line 273 carries the first data signals carrying different channels serially. Therefore, the first common data line 273 carries electrical data signals that are each an electrical representation of the first composite signal, and each electrical data signal serially carries a different channel. There may be some short-term overlap between channels in the first data signal series, however, in Figure 3C No overlap occurs in the data windows shown. The first common data line 273 carries a series of first data signals to the first analog-to-digital converter (ADC) 264 .

[0075] The second data line 232 from each different second balanced detector 226 carries the second data signal to the second electrical multiplexer 274. The second electrical multiplexer 274 outputs the second data signal from the different second data lines 232 to the second common data line 275. The first common data line and the second common data line are both examples of common data lines. As described above, the (one or more) processing components 28 serially receive the first comparison signal carrying different channels. Therefore, the second common data line 275 carries the second data signal serially carrying the different channels. Therefore, the second common data line 275 carries electrical data signals, each of which is an electrical representation of the second composite signal, and each electrical data signal serially transmits a different channel. There may be some short-term overlap between the channels in the second data signal series, but in Figure 3C No overlap occurs in the data windows shown. A second common data line 275 carries a second series of data signals to a second analog-to-digital converter (ADC) 266 .

[0076] Figure 3D The transformation mechanism 238 and the LIDAR data generator 270 can be based on FIG. 3A to FIG. 3C For example, the first analog-to-digital converter (ADC) 264 converts the first data signal from analog form to digital form and outputs the first digital data signal. The second analog-to-digital converter (ADC) 266 converts the second data signal from analog form to digital form and outputs the second digital data signal.

[0077] The first digital data signal and the second digital data signal carrying the same channel are together as a complex signal, wherein the first digital data signal is the real part of the complex signal and the second digital data signal is the imaginary part of the complex data signal. The electronic device is configured so that the first digital data signal and the second digital data signal carrying the same channel are simultaneously received by the LIDAR data generator 270. Therefore, the LIDAR data generator 270 receives complex signals carrying different channels in series. The LIDAR data generator 270 can generate LIDAR data for each different channel. Therefore, the data generator 270 can generate LIDAR data for each sample area illuminated by the system output signal carrying a series of channels.

[0078] In another embodiment of the LIDAR system, Figure 3A The relationship between the sensors in the optoelectronic components and the electronic devices in the LIDAR system is based on Figure 3D The electronic device operates the electrical multiplexer as a switch that can be operated by the electronic device. Therefore, the electronic device can operate the first electrical multiplexer 272 to select which of the first data signals is output on the common data line 273, and can operate the second electrical multiplexer 274 to select which of the second data signals is output on the second common data line 275. Therefore, the LIDAR system can be configured to simultaneously output system output signals carrying different channels. For example, the LIDAR chip can be configured to simultaneously output each LIDAR output signal carrying a different channel. For example, the signal guiding component 14 can be configured to guide the outgoing LIDAR system to one or more alternating waveguides 16. In the example where the signal guiding component 14 is configured to guide the outgoing LIDAR system to all N alternating waveguides 16, the signal guiding component can be a signal separator.

[0079] When the LIDAR system outputs system output signals carrying different channels simultaneously, each different processing component 28 can simultaneously receive a first LIDAR input signal carrying one of the channels. Therefore, the first data line 228 from each different processing component 28 simultaneously carries the first data signal to the first electrical multiplexer 272. Therefore, the first electrical multiplexer 272 simultaneously receives multiple first data signals, each of which carries a different channel and comes from a different processing component 28. The electronic device uses the switching function of the first electrical multiplexer 272 to operate the first electrical multiplexer 272 so that the first electrical multiplexer 272 outputs the first data signals carrying different channels in series. Therefore, the first common data line 273 carries the first data signals carrying different channels in series. Examples of suitable channel sequences include, but are not limited to, channel sequences with channel indexes i=1 to N in a digital sequence from i=1 to i=N.

[0080] The second data lines 232 from each different processing component 28 simultaneously carry the second data signal to the second electrical multiplexer 274. Therefore, the second electrical multiplexer 274 simultaneously receives a plurality of second data signals, each of which carries a different channel and comes from a different processing component 28. The electronic device uses the switching function of the second electrical multiplexer 274 to operate the second electrical multiplexer 274 so that the second electrical multiplexer 274 outputs the second data signals carrying different channels in series. Therefore, the second data lines 275 carry the second data signals carrying different channels in series.

[0081] Figure 3D The transformation mechanism 238 and the LIDAR data generator 270 can be based on FIG. 3A to FIG. 3C For example, the first analog-to-digital converter (ADC) 264 converts the first data signal from analog form to digital form and outputs the first digital data signal. The second analog-to-digital converter (ADC) 266 converts the second data signal from analog form to digital form and outputs the second digital data signal.

[0082] The operation of the first electrical multiplexer 272 and the second electrical multiplexer 274 causes the first data line 273 and the second data line 275 to carry the same channel at the same time. Therefore, the first digital data signal and the second digital data signal output from the first analog-to-digital converter (ADC) 264 and the second analog-to-digital converter (ADC) 266 carry the same channel at the same time. The first digital data signal and the second digital data signal carrying the same channel act together as a complex signal, wherein the first digital data signal serves as the real part of the complex signal and the second digital data signal serves as the imaginary part of the complex signal. The first digital data signal and the second digital data signal carrying the same channel are simultaneously received by the LIDAR data generator 270. Therefore, the LIDAR data generator 270 receives complex signals carrying different channels in series. The LIDAR data generator 270 can generate LIDAR data for each channel in the serial channel. Therefore, the data generator 270 can generate LIDAR data for each sample area illuminated by the system output signal carrying the serial channel.

[0083] An alternative to the first electrical multiplexer 272 and / or the second electrical multiplexer 274 is to provide an electrical node where the first data lines 228 from each of the different first balanced detectors 225 are in electrical communication with each other; and to provide a second electrical node where the second data lines 232 from each of the different second balanced detectors 226 are in electrical communication with each other. Thus, the outputs of the optical sensors (e.g., the first balanced detectors 225) are effectively electrically connected to each other, and the outputs of the optical sensors (e.g., the second balanced detectors 226) are effectively electrically connected to each other. For example, Figure 3E Shows Figure 3Darrangement, which is modified so that the first data line 228 from each of the different first balanced detectors 225 is in electrical communication with the first common data line 273. Since the LIDAR system outputs system output signals that carry different channels in series, the first common data line 273 carries the first data signals that carry different channels in series. Although there may be some overlap between channels that are adjacent to each other in the series, no overlap occurs during the data window. In addition, the second data line 232 from each of the different second balanced detectors 226 is in electrical communication with the second common data line 275. Since the LIDAR system outputs system output signals that carry different channels in series, the second common data line 275 carries the second data signals that carry different channels in series. Although there may be some overlap between channels that are adjacent to each other in the series, no overlap occurs during the data window. Since the first common data line 273 carries the first data signals that carry different channels in series, and the second common data line 275 carries the second data signals that carry different channels in series, as in Figure 6 As also occurs in the LIDAR system of D, the transformation mechanism 238 and the LIDAR data generator 270 can be based on Figure 3E The system operates in the manner disclosed in the context of the present invention to generate LIDAR data for each sample area illuminated by a system output signal carrying a series of channels.

[0084] In accordance with Figure 3E In a constructed LIDAR system, during a cycle when the LIDAR system is outputting a system output signal carrying channel i, an optoelectronic assembly included in a processing component configured to receive a current channel i (an active processing component) receives a first LIDAR input signal carrying channel i during at least a data window, while a processing component not configured to receive the current channel i (an inactive processing component(s)) does not receive the first LIDAR input signal. However, the inactive processing component(s) continue to receive a reference signal during at least the data window. Light from the reference signal(s) received by the inactive processing component(s) may pass through the optoelectronic assembly and become noise in an electrical signal (e.g., a first data signal and a second data signal).

[0085] In some cases, it may be desirable to fully or partially attenuate all or part of the reference signal(s) received by the working processing component(s). Figure 1C ) may each optionally include an optical attenuator 276. The attenuator 276 may be operated by electronics to fully or partially attenuate a reference signal guided by the reference waveguide 32 along which the attenuator 276 is positioned.

[0086] Figure 1C The processing unit 28 serving as the working processing unit and Figure 1C The (one or more) processing components marked as 28 that act as (one or more) non-working processing components change with the change of the channel carried by the system output signal. Therefore, the electronic device can change the attenuated (one or more) reference signals in response to the change of the channel currently carried in the system output signal. For example, the electronic device can operate the attenuator 276 so that the reference signal received by the working processing component is not attenuated or substantially not attenuated. In addition, the electronic device can operate the attenuator 276 so that the (one or more) reference signals received by all or part of the (one or more) non-working processing components are completely or partially attenuated. Since the (one or more) reference signals received by all or part of the (one or more) non-working processing components are completely or partially attenuated, the amount of light from the reference signal actually received by the (one or more) non-working processing components is reduced. Therefore, the attenuated light is not a noise source in the first data signal and the second data signal.

[0087] Although optical attenuator 276 is shown located Figure 1C The reference waveguide 32, but the optical attenuator 276 may be located Figure 1A and Figure 1B The electronic device can operate the variable optical attenuator 276 to achieve the desired attenuation level of the reference signal power.

[0088] Suitable devices suitable for use as optical attenuator 276 include, but are not limited to, variable optical attenuators (VOAs), PIN diodes, and Mach-Zehnder modulators. Examples of suitable optical attenuators can be found in U.S. patent application Ser. No. 17 / 396,616, filed on Aug. 6, 2021, entitled “Carrier Injector Having Increased Compatibility,” and the entirety of which is incorporated herein.

[0089] Suitable platforms for LIDAR chips include, but are not limited to, silicon dioxide, indium phosphide, and silicon-on-insulator wafers. Figure 4 is a cross-section of a silicon-on-insulator wafer. A silicon-on-insulator (SOI) wafer includes a buried layer 300 between a substrate 302 and an optical transmission medium 304. In a silicon-on-insulator wafer, the buried layer 300 is silicon dioxide, while the substrate 302 and the optical transmission medium 304 are silicon. The substrate of an optical platform such as an SOI wafer can serve as a base for a LIDAR chip. For example, in some cases, Figures 1A to 1C The optical components shown in FIG. 1 can be positioned on or above the top and / or sides of the same substrate. Thus, the substrate of an optical platform such as an SOI wafer can serve as Figure 2 The substrate 298 is shown in FIG.

[0090] Figure 4 The portion of the LIDAR chip shown in FIG. 1 includes a waveguide structure suitable for use with a chip constructed from a silicon-on-insulator wafer. A ridge 306 of the optical transmission medium 304 extends away from a slab region 308 of the optical transmission medium 304. The optical signal is confined between the top of the ridge and the buried layer 300. Thus, the ridge 306 at least partially defines a waveguide.

[0091] The size of the ridge waveguide is Figure 4 . For example, the ridge has a width labeled w and a height labeled h. The thickness of the slab region is labeled t. For LIDAR applications, these dimensions may be more important than for other applications because higher levels of optical power need to be used than for other applications. The ridge width (labeled w) is greater than 1 μm and less than 4 μm, the ridge height (labeled h) is greater than 1 μm and less than 4 μm, and the slab region thickness is greater than 0.5 μm and less than 3 μm. These dimensions may apply to straight or substantially straight portions of the waveguide, curved portions of the waveguide, and tapered portions of (one or more) waveguides. Therefore, these portions of the waveguide will be single-mode. However, in some cases, these dimensions apply to straight or substantially straight portions of the waveguide. Additionally or alternatively, the curved portion of the waveguide may have a reduced plate thickness to reduce optical losses in the curved portion of the waveguide. For example, the curved portion of the waveguide may have a ridge that extends away from the slab region having a thickness greater than or equal to 0.0 μm and less than 0.5 μm. While the above dimensions will typically provide a straight or substantially straight portion of the waveguide having a single-mode structure, they may result in tapered portion(s) and / or curved portion(s) being multi-mode. Coupling between a multi-mode geometry and a single-mode geometry may be achieved using a taper that does not substantially excite higher-order modes. Thus, a waveguide may be constructed such that a signal carried in the waveguide is carried in a single mode even when the signal is carried in a portion of the waveguide having multi-mode dimensions. Figure 4 The waveguide structure is suitable for Figures 1A to 1C Construct all or part of the waveguide on the LIDAR chip.

[0092] Suitable signal directing components 14 for use with LIDAR chips include, but are not limited to, optical switches such as cascaded Mach-Zehnder interferometers and microring resonator switches. In one example, the signal directing component 14 includes a cascaded Mach-Zehnder interferometer using a thermal or free carrier injection phase shifter. Figure 5A and Figure 5B An example of an optical switch comprising cascaded Mach-Zehnder interferometers 416 is shown. Figure 5A is a top view of a light switch. Figure 5B It is along Figure 5A The line marked B in Figure 5A Cross-section of the optical switch shown in .

[0093] The optical switch receives an outgoing LIDAR signal from the utility waveguide 12. The optical switch is configured to direct the outgoing LIDAR signal to one of the plurality of alternating waveguides 16. The optical switch includes an interconnecting waveguide 414 that connects a plurality of Mach-Zehnder interferometers 416 in a cascade arrangement. Each Mach-Zehnder interferometer 416 directs the outgoing LIDAR signal to one of the two interconnecting waveguides 414. Electronics can operate each Mach-Zehnder to select which of the two interconnecting waveguides 414 receives the outgoing LIDAR signal from the Mach-Zehnder interferometer 416. The interconnecting waveguide 414 that receives the outgoing LIDAR signal can be selected so that the outgoing LIDAR signal is directed to a specific one of the alternating waveguides 16 by the optical switch.

[0094] Each Mach-Zehnder interferometer 416 includes two branch waveguides 418, each branch waveguide 418 receiving a portion of the outgoing LIDAR signal from the utility waveguide 12 or the interconnect waveguide 414. Each Mach-Zehnder interferometer 416 includes a directional component 420 that receives the two portions of the outgoing LIDAR signal from the branch waveguides 418. The directional component 420 steers the outgoing LIDAR signal to one of the two interconnect waveguides 414 configured to receive the outgoing LIDAR signal from the directional component 420. The interconnect waveguide 414 to which the outgoing LIDAR signal is directed varies depending on the phase difference between the two different portions of the outgoing LIDAR signal received by the directional component 420. Although Figure 5A A directional coupler is shown operating as the directional component 420, but other directional components 420 may be used. Suitable alternative directional components 420 include, but are not limited to, multi-mode interference (MMI) devices and tapered couplers.

[0095] Each Mach-Zehnder interferometer 416 includes a phase shifter 422 positioned along one of the branch waveguides 418. The output component includes a conductor 424 in electrical communication with the phase shifter 422. The conductors 424 are shown as dashed lines so that they can be easily distinguished from underlying features. The conductors 424 each terminate at a contact pad 426. The contact pad 426 can be used to provide electrical communication between the conductor 424 and the electronic device. Therefore, the conductor 424 provides electrical communication between the electronic device and the phase shifter 422, and allows the electronic device to operate the phase shifter 422. Suitable conductors 424 include, but are not limited to, metal traces. Suitable materials for the conductor include, but are not limited to, titanium, aluminum, and gold.

[0096] The electronics may operate each phase shifter 422 to control the phase difference between portions of the outgoing LIDAR signal received by the directional component 420. In one example, the phase shifter 422 may be operated to change the refractive index of at least a portion of the branch waveguide 418. Changing the refractive index of a portion of the branch waveguide 418 in the Mach-Zehnder interferometer 416 changes the effective length of the branch waveguide 418 and, therefore, changes the phase difference between portions of the outgoing LIDAR signal received by the directional component 420. The ability of the electronics to change the phase difference allows the electronics to select the interconnect waveguide 414 that receives the outgoing LIDAR signal from the directional component 420.

[0097] Figure 5B An example of a suitable configuration of a phase shifter 422 on a branch waveguide 418 is shown. The branch waveguide 418 is at least partially defined by a ridge 306 of the light-transmitting medium 304, the ridge 306 extending away from a slab region 308 of the light-transmitting medium 304. Doped regions 428 extend into the slab region 308, wherein one of the doped regions includes an n-type dopant and one of the doped regions 428 includes a p-type dopant. A first cladding 430 is located between the light-transmitting medium 304 and the conductors 424. The conductors 424 each extend through an opening in the first cladding 430 in contact with one of the doped regions 428.

[0098] A second cladding 432 is optionally located above the first cladding 430 and above the conductor 424. The electronics may apply a forward bias to the conductor 424 to generate a current through the branch waveguide 418. The resulting carrier injection into the branch waveguide 418 results in free carrier absorption, which changes the refractive index in the branch waveguide 418.

[0099] Figure 5B The first cladding 430 and / or the second cladding 432 shown in the figure can each represent one or more layers of material. The materials used for the first cladding 430 and / or the second cladding 432 can be selected to provide electrical isolation of the conductor 424, a lower refractive index relative to the optical transmission medium 304, stress reduction, and mechanical and environmental protection. Suitable materials for the first cladding 430 and / or the second cladding 432 include, but are not limited to, silicon nitride, tetraorthosilicate (TEOS), silicon dioxide, silicon nitride, and aluminum oxide. One or more materials used for the first cladding 430 and / or the second cladding 432 can be doped or undoped.

[0100] Where the LIDAR system includes multiple cores, the LIDAR system may include multiple signal directors 76, and different signal directors 76 may receive LIDAR output signals from different selections of signal directors 76. For example, Figure 6 Shows Figure 2The LIDAR system is modified to have multiple signal directors 76, each signal director receiving the LIDAR output signal from a different one of the cores.

[0101] Figures 1A to 1C Each core is shown to include a different light source 10. However, multiple cores, all cores, or a portion of the cores may receive outgoing LIDAR signals from a common light source. In some cases, the cores are arranged in groups, where each core in a group receives outgoing LIDAR signals from the same common light source, and cores in different groups receive outgoing LIDAR signals from different common light sources. In some cases, a group of cores may include a single core in the cores. For example, Figure 7 Shows Figure 2 A LIDAR system in which the light source 10 is located outside the core and each core receives an outgoing LIDAR signal from the light source.

[0102] The first optical link 440 provides optical communication between the light source 10 and the signal separator 442. The second optical link 444 provides optical communication between the signal separator 442 and the utility waveguide 12 on different cores 4. The light source 10 outputs a preliminary signal received on the first optical link 440. The signal separator 442 receives the preliminary signal from the first optical link 440. The signal separator 442 divides the preliminary signal into a plurality of branch signals, each of which is received on a different one of the second optical links 444. Each utility waveguide 12 receives a branch signal from a different one of the optical links 444. The branch signal portion entering the utility waveguide serves as an outgoing LIDAR signal.

[0103] The LIDAR system may optionally include an amplifier 446 positioned along the first optical link 440 to amplify the power of the preliminary signal. Suitable amplifiers 446 for use along the optical link include, but are not limited to, SOAs, erbium doped fiber amplifiers (EDFAs), and praseodymium doped fiber amplifiers (PDFAs).

[0104] When it is desired that different outgoing LIDAR signals have the same or substantially the same wavelength distribution, suitable signal separators 442 include, but are not limited to, wavelength-independent signal combiners such as optical couplers, y-junctions, MMIs, cascaded attenuated optical couplers, and cascaded y-junctions. When it is desired that different outgoing LIDAR signals have different wavelength distributions, suitable signal separators 442 include, but are not limited to, wavelength-dependent signal separators 442, which include optical demultiplexers such as arrayed waveguide gratings (AWGs) and trapezoidal gratings.

[0105] In some cases where multiple different cores receive outgoing LIDAR signals from a common light source, only one core that receives its outgoing LIDAR signal from the common light source includes a control branch. Thus, other cores that receive outgoing LIDAR signals from the same common light source may not include a control branch. Figures 1A to 1C The directional coupler 66, control waveguide 68 and control component 70 are shown in FIG.

[0106] from Figure 1A and Figure 1B As is apparent from FIG. 4 , the LIDAR system may optionally include one or more optical signal amplifiers 446. For example, the amplifiers 446 may optionally be positioned along a utility waveguide, such as Figure 1A In another example, the amplifier 446 is optionally positioned along all or a portion of the alternating waveguide 16, such as Figure 1B 446 to amplify the power of the outgoing LIDAR signal, thereby amplifying the power of the system output signal. The electronics can operate each amplifier 446 to amplify the power of the outgoing LIDAR signal. Suitable amplifiers 446 for use on the LIDAR chip include, but are not limited to, semiconductor optical amplifiers (SOAs).

[0107] Figure 1A and Figure 1B The amplifier 446 shown in the figure is respectively located before one of the splitters 24. In some cases, this position of the amplifier 446 may cause saturation of one or more components selected from the group consisting of the first auxiliary light sensor 218, the second auxiliary light sensor 220, the first light sensor 223, and the second light sensor 224. For example, the amplifier 446 may increase the power level of the reference signal to a level at which saturation occurs. A beam dump may be used to reduce the power level of the reference signal to a level at which saturation is reduced or eliminated.

[0108] from Figure 3B , Figure 3D and Figure 3E It will be apparent that the LIDAR system may optionally include one or more electrical signal amplifiers 447. Each amplifier 447 is positioned to provide amplification of a first data signal traveling between a first light sensor (e.g., first balanced detector 225) and an analog-to-digital converter, or a second data signal traveling between a second light sensor (e.g., second balanced detector 226) and an analog-to-digital converter. Figure 3D Each electrical signal amplifier 447 positioned along the first data line 228 or the second data line 232 is shown, but the electrical signal amplifier 447 may be positioned along the common data line 273 or the second common data line 275. Figure 3E Each electrical signal amplifier 447 is shown positioned along the common data line 273 or the second common data line 275, but the electrical signal amplifier 447 may be positioned along the first data line 228 or the second data line 232. Suitable electrical signal amplifiers 447 include, but are not limited to, transimpedance amplifiers (TIA).

[0109] Figure 8 A portion of a LIDAR chip is shown, which includes a reference waveguide 32 used in conjunction with a beam dump configured to reduce the power level of a reference signal carried on the reference waveguide 32. The reference waveguide 32 carries the reference signal to a splitter 448, which moves a portion of the reference signal from the reference waveguide 32 to a collection waveguide 450 as a collection signal. The collection waveguide 450 carries the collection signal to a beam dump 452.

[0110] The beam dump 452 is configured to scatter the collection signal without reflecting a substantial amount of light from the collection signal back into the collection waveguide 450. For example, the beam dump 452 can be a recess 454 etched into the optical transmission medium of the silicon-on-insulator wafer, the depth of which causes the collection signal to be incident on one or more sides of the recess 454. The recess 454 can be shaped to cause scattering of the collection signal. For example, the recess 454 can have a star shape, or can include any number of irregularly positioned sides. In some cases, the recess 454 can extend through the optical transmission medium to an underlying layer, such as a buried layer of the silicon-on-insulator wafer.

[0111] The splitter 448 can be configured to control the percentage of the reference signal power transmitted to the collection waveguide. Increasing the percentage of the reference signal power transmitted to the collection waveguide increases the attenuation of the reference signal power, thereby reducing the power of the signal received by all or part of the optical sensor selected from the group consisting of the first auxiliary optical sensor, the second auxiliary optical sensor, the first optical sensor, and the second optical sensor. The decrease in the optical signal power received by all or part of the optical sensor reduces the possibility of saturation. Suitable splitters 448 include, but are not limited to, 1×2 splitters, including optical couplers, y-type connectors, and MMIs. In some cases, the splitter 448 is configured so that the percentage of the reference signal power transmitted to the collection waveguide 450 is greater than or equal to 0.1%, 0.5%, or 1% and less than or equal to 2%, 10%, or 20%.

[0112] The optical sensor that interfaces with the waveguide on the LIDAR chip can be a component that is separated from the chip and then attached to the chip. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, InGaAsPIN photodiodes manufactured by Hamamatsu located in Hamamatsu City, Japan or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu located in Hamamatsu City, Japan. These optical sensors can be located in the center of the LIDAR chip. Alternatively, all or part of the waveguide that terminates at the optical sensor can terminate at a small facet located at the edge of the chip, and the optical sensor can be attached to the edge of the chip above the small facet so that the optical sensor receives light transmitted through the small facet. The use of an optical sensor as a component separated from the chip is applicable to all or part of the optical sensors selected from the group consisting of a first optical sensor and a second optical sensor.

[0113] As an alternative to the light sensor being a separate component, all or part of the light sensor may be integrated with the chip. For example, examples of light sensors interfaced with ridge waveguides on a chip comprised of a silicon-on-insulator wafer may be found in: Optics Express Vol. 15, No. 21, 13965-13971 (2007); U.S. Patent No. 8,093,080, issued January 10, 2012; U.S. Patent No. 8,242,432, issued August 14, 2012; and U.S. Patent No. 6,108,472, issued August 22, 2000, each of which is incorporated herein in its entirety. The use of a light sensor integrated with the chip is applicable to all or part of the light sensor selected from the group consisting of a first light sensor and a second light sensor.

[0114] Suitable electronics 62 for use in a LIDAR system may include, but are not limited to, a controller comprising or consisting of analog circuits, digital circuits, processors, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), computers, microcomputers, or combinations thereof suitable for performing the above-described operations, monitoring, and control functions. In some cases, the controller may access a memory that includes instructions for the controller to execute during the execution of the operations, control, and monitoring functions. Although the electronics are shown as a single component in a single location, the electronics may include multiple different components that are independent of each other and / or placed in different locations. In addition, as described above, all or part of the disclosed electronics may be included on a chip, including electronics integrated with a chip.

[0115] The components on the LIDAR chip can be fully or partially integrated with the LIDAR chip. For example, the integrated optical component can include or consist of a portion of a wafer on which the LIDAR chip is manufactured. A wafer that can serve as a platform for a LIDAR chip can include multiple layers of material. At least a portion of different layers can be different materials. For example, a silicon-on-insulator wafer includes a buried layer 300 between a substrate 302 and an optical transmission medium 304, such as Figure 4 As shown. The integrated on-chip component can be formed by using etching and masking techniques to define the features of the component in the optical transmission medium 304. For example, the plate 318 defining the waveguide and the stop recess can be formed in the desired area of ​​the wafer using different etchings of the wafer. Thus, the LIDAR chip includes a portion of the wafer, and the integrated on-chip components can each include or be composed of a portion of the wafer. In addition, the integrated on-chip component can be configured so that the optical signal traveling through the component travels through one or more layers originally included in the wafer. For example, Figure 4 The waveguide guides the optical signal through the optical transmission medium 304 in the chip. The integrated component can optionally include materials other than those present on the chip. For example, the integrated component can include reflective materials and / or cladding.

[0116] Numeric labels (e.g., first, second, third, etc.) are used to distinguish different features and components, and do not indicate the order or presence of lower numbered features. For example, the second component may be present without the first component and / or the third step may be performed before the first step. The optical signals disclosed above each include, consist of, or consist essentially of light from (one or more) previous optical signals from which the optical signal is derived. For example, the incoming LIDAR signal includes, consists of, or consists essentially of light from the LIDAR input signal.

[0117] Although the LIDAR system is disclosed to use a complex signal such as a complex data signal, the LIDAR system may also use a real signal. Thus, the mathematical transformation may be a real transformation, and components associated with the generation and use of orthogonal components may be removed from the LIDAR system. Thus, the LIDAR system may use a single signal combiner. Additionally or alternatively, a single light sensor may replace each balanced detector.

[0118] In view of these teachings, those skilled in the art will readily recognize other embodiments, combinations and modifications of the present invention. Therefore, the present invention is limited only by the appended claims, which include all such embodiments and modifications when viewed in conjunction with the above description and drawings.

Claims

1. An imaging system, comprising: A photonic circuit chip, the photonic circuit chip comprising a plurality of cores, each core comprising an optical switch and a plurality of alternating waveguides, the optical switch in each core being configured to guide an outgoing optical signal to any one of the alternating waveguides, the alternating waveguide to which the outgoing optical signal is guided being an active waveguide; Each LIDAR core is configured to output the outgoing LIDAR signal from the active waveguide simultaneously with the active waveguide receiving the incoming LIDAR signal; The incoming LIDAR signal includes light from the outgoing LIDAR signal that has exited from the imaging system and returned to the LIDAR system; each core comprising a light splitter configured to receive the outgoing LIDAR signal and the incoming LIDAR signal, The optical separator extracts a portion of the outgoing LIDAR signal to serve as a reference signal and extracts a portion of the incoming LIDAR signal to serve as a comparison signal; Each core includes a signal combiner configured to combine light from the reference signal with light from the comparison signal to generate a composite signal that beats at a beat frequency; and The electronics uses the beat frequency of the composite signal generated by the core to calculate radial velocity and / or distance between one or more objects external to the imaging system and the imaging system.

2. The imaging system according to claim 1, wherein: The photonic circuit chip is constructed on a silicon-on-insulator platform.

3. The imaging system according to claim 1, wherein: The signal splitter is positioned along the active waveguide such that the portion of the outgoing LIDAR signal that serves as the reference signal is extracted from the active waveguide and the portion of the incoming LIDAR signal that serves as the comparison signal is extracted from the active waveguide.

4. The imaging system according to claim 3, wherein: The splitter is one of a plurality of splitters contained in each of the cores, and one of the signal splitters is positioned along each of the alternating waveguides.

5. The imaging system according to claim 4, wherein: The electronic device converts the composite signal into an electrical data signal, An electrical multiplexer is in electrical communication with a plurality of different first data lines and is configured to receive the electrical data signal from one of the first data lines and output the electrical data signal on a common data line.

6. The imaging system according to claim 5, wherein: The first data line from which the electrical multiplexer receives the electrical data signal changes in response to a change in the alternating waveguide to which the outgoing LIDAR signal is directed.

7. The imaging system according to claim 6, wherein: The electronic device includes an analog-to-digital converter that receives the electrical data signal from the common data line.

8. The imaging system of claim 1, wherein: The optical switch receives an outgoing LIDAR signal from a utility waveguide, and the signal separator is positioned along the utility waveguide so that the portion of the outgoing LIDAR signal serving as the reference signal is extracted from the utility waveguide and the portion of the incoming LIDAR signal serving as the comparison signal is extracted from the utility waveguide.

9. The imaging system of claim 8, wherein: The LIDAR chip is configured such that an outgoing LIDAR signal from each core is output from the LIDAR chip to serve as a LIDAR output signal, and a lens receives the LIDAR output signals from different cores.

10. The imaging system according to claim 4, wherein: The electronics convert the composite signal into an electrical data signal, which is an electrical representation of the composite signal.

11. The imaging system according to claim 10, wherein: A plurality of different data lines are configured to receive electrical data signals, and the data line receiving the electrical data signal changes in response to a change in the alternating waveguide to which the outgoing LIDAR signal is directed.

12. The imaging system of claim 11, wherein: The electrical data signals carried on the different data lines are each associated with a different channel, and the common data line receives the electrical data signals from the different data lines such that the electrical data signals associated with the different channels are carried serially on the common data line.

13. The imaging system of claim 12, wherein: An electrical multiplexer is in electrical communication with the data lines and is configured to output electrical data signals on the common data lines.

14. The imaging system of claim 12, wherein: The common data line is directly connected to each of the different data lines at the nodes.

15. The imaging system of claim 14, wherein: Each core includes a reference waveguide carrying a reference signal, and an optical attenuator is positioned along each of the reference waveguides.

16. The imaging system of claim 14, wherein: The electronics operate the attenuator such that a portion of the reference signal carried on the different reference waveguide is attenuated while another portion of the reference signal carried on the different reference waveguide is not attenuated.

17. The imaging system of claim 14, wherein: The reference signal in the respective attenuated reference signal portions is attenuated in response to the reference signal not being combined with the comparison signal.

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