Imaging system having a plurality of cores

Abstract

The imaging system includes a photonic circuit chip having a plurality of cores. Each of the cores includes one optical switch and a plurality of alternative waveguides. The optical switch within each core is configured to direct an output optical signal to any one of the alternative waveguides, and the alternative waveguide to which the output optical signal is directed is an active waveguide. Each core outputs an output LIDAR signal from the active waveguide while receiving light from the output LIDAR signal, exiting the imaging system, and receiving an incident LIDAR signal that is returned to the imaging system. Each core includes a signal splitter that receives the output LIDAR signal and the incident LIDAR signal. The signal splitter extracts a portion of the output LIDAR signal that functions as a reference signal and a portion of the incident LIDAR signal that functions as at least a comparison signal. Each core includes a signal combiner that combines light from the reference signal and light from the comparison signal to generate a composite signal that beats at a beat frequency. The electronic device calculates the LIDAR data of each core from the beat frequency of the composite signal generated by the core.

Description

Related Applications

[0001] This application is a continuation of U.S. Patent Application No. 17 / 829,328, titled "Imaging System with Multiple Cores," filed on May 31, 2022, which is a divisional continuation of U.S. Patent Application Serial No. 17 / 580,623, titled "Imaging System with Multiple Cores," filed on January 20, 2022, the entire contents of which are incorporated herein by reference. Field

[0002] The present invention relates to an optical device, specifically a LIDAR system. Background

[0003] As optical imaging systems support an increasing number of applications, the requirements for their functions are increasing. Optical imaging systems generally generate data in a series of sample regions that are sequentially irradiated by a system output signal. The data of the sample region indicates the radial velocity and / or distance between the imaging system and one or more objects located within the sample region. The imaging system can scan the system output signal to a plurality of different sample regions. The sample regions can be combined to form the field of view of the imaging system. As a result, a combination of data from different sample regions provides data of the objects within the field of view.

[0004] By increasing the speed at which data for the field of view can be generated, the frequency at which the field of view can be scanned can be increased, the size of the field of view can be increased, and / or the resolution of the field of view can be increased. LIDAR systems designed to increase the data generation speed and / or resolution use a circulator that separates the light emitted from the LIDAR system from the light that is returned to the LIDAR system. However, these circulators increase the cost and assembly complexity of the LIDAR system. As a result, there is a need for a LIDAR system that can provide the desired data generation speed and / or resolution without using a circulator. Summary

[0005] The imaging system includes a photonic circuit chip having a plurality of cores. Each of the cores includes one optical switch and a plurality of alternative waveguides. The optical switch within each core is configured to direct an output optical signal to any one of the alternative waveguides, and the alternative waveguide to which the output optical signal is directed is an active waveguide. Each core outputs an output LIDAR signal from the active waveguide while receiving light from the output LIDAR signal and receiving an incident LIDAR signal that exits the imaging system and returns to the imaging system. Each core includes a signal splitter that receives the output LIDAR signal and the incident LIDAR signal. The signal splitter extracts a portion of the output LIDAR signal that functions as a reference signal and a portion of the incident LIDAR signal that functions as at least a comparison signal. Each core includes a signal combiner that combines light from the reference signal and light from the comparison signal to generate a composite signal that beats at a beat frequency. The electronic device calculates the LIDAR data of each core from the beat frequency of the composite signal generated by the core.

Brief Description of the Drawings

[0006] FIG. 1A shows an imaging system including a chip having a photonic circuit.

[0007] FIG. 1B shows another embodiment of an imaging system including a photonic circuit chip.

[0008] FIG. 1C shows another embodiment of an imaging system including a photonic circuit chip.

[0009] FIG. 2 is a schematic diagram of an imaging system including a plurality of different cores on a chip.

[0010] FIGS. 3A-3B show an example of a processing unit suitable for use as a processing unit in a LIDAR system constructed in accordance with FIGS. 1A and 1B. FIG. 3A is a schematic diagram of an example of an optoelectronic assembly suitable for use within the processing unit.

[0011] FIG. 3B provides a schematic diagram of the relationship between the electronic device and the optoelectronic assembly of FIG. 3A.

[0012] Figure 3C shows the frequency of the signal output from the imaging system over time.

[0013] Figure 3D provides a schematic diagram of the relationship between the electronic device and the optoelectronic assembly of Figure 3A.

[0014] Figure 3E is a schematic diagram of another relationship between the sensor in the optoelectronic assembly of Figure 3A and the electronic device in the LIDAR system.

[0015] Figure 4 is a cross-sectional view of a silicon-on-insulator wafer.

[0016] Figures 5A and 5B show an example of an optical switch including a cascaded Mach-Zehnder interferometer. Figure 5A is a top view of the optical switch.

[0017] Figure 5B is a cross-sectional view of the optical switch shown in Figure 5A taken along the line labeled B in Figure 5A.

[0018] Figure 6 shows the LIDAR system of Figure 2 modified to have a plurality of signal directors each receiving the LIDAR output signal from a different core.

[0019] Figure 7 shows the LIDAR system of Figure 2 with the light source located outside the chip.

[0020] Figure 8 shows a portion of a LIDAR chip including a reference waveguide used in combination with a beam dump. Detailed description

[0021] The imaging system includes a photonic circuit chip having a plurality of cores. Each of the cores includes one optical switch and a plurality of alternative waveguides. The optical switch in each core is configured to direct an output optical signal to any one of the alternative waveguides, and the alternative waveguide to which the output optical signal is directed functions as an active waveguide. Each core outputs an output LIDAR signal from the active waveguide while also receiving an incident LIDAR signal. The incident LIDAR signal includes light from the output LIDAR signal that is emitted from and returned to the imaging system. Each core includes a signal splitter that receives the output LIDAR signal and the incident LIDAR signal. The signal splitter extracts a portion of the output LIDAR signal to function as a reference signal and extracts at least a portion of the incident LIDAR signal to function as a comparison signal. Each core includes a signal combiner that combines the light from the reference signal and the light from the comparison signal to generate a beat signal that beats at a beat frequency. An electronic device calculates LIDAR data for each core from the beat frequency of the beat signal generated by the core. Since the beat signal is generated from the optical signals separated by the signal splitter, a circulator is not required. The removal of the circulator reduces the cost and assembly complexity associated with the LIDAR system.

[0022] FIG. 1A is a schematic diagram of a portion of a LIDAR system including a LIDAR chip 2. FIG. 1A includes a top view of a portion of the LIDAR chip 2. The LIDAR chip includes a LIDAR core 4. The LIDAR core 4 includes a photonic integrated circuit.

[0023] The LIDAR core 4 can include a light source 10 that outputs an emitted LIDAR signal. This LIDAR core includes a utility waveguide 12 that receives the emitted LIDAR signal from the light source 10. This utility waveguide 12 transmits the emitted LIDAR signal to a signal guiding section 14. This signal guiding section 14 can be operated by an electronic device, thereby guiding the light from the light source output signal to one of a plurality of different alternative waveguides 16. There are N alternative waveguides, and each alternative waveguide 16 is associated with an alternative waveguide index i, where the value of i ranges from 1 to N. Appropriate values of N include, but are not limited to, values less than 128, 64, or 32, and / or greater than 2, 8, or 16. In one example, N is from 2 to 128.

[0024] Each of the alternative waveguides 16 can receive the emitted LIDAR signal from the signal guiding section 14. When any of the alternative waveguides 16 receives the emitted LIDAR signal, the alternative waveguide 16 functions as an active waveguide and transmits the emitted LIDAR signal to port 18. The emitted LIDAR signal can exit the LIDAR chip through port 18 and function as a LIDAR output signal. Thus, the emitted LIDAR signal is output from the active waveguide.

[0025] An optical signal generated from the emitted LIDAR signal guided to the alternative waveguide 16 with the alternative waveguide index i is classified as an optical signal that transmits through channel (C i )). Thus, each LIDAR output signal is associated with a different one of the alternative waveguide indices i = 1 to N. For example, the path of the LIDAR output signal that transmits through the channel with the alternative waveguide index of 2 is denoted as C2 in FIG. 1A. For the sake of illustration, this LIDAR system is shown as generating three LIDAR output signals (N = 3) denoted as C1 to C3. Each of the different LIDAR output signals can transmit through a different channel, and each of the different channels can transmit a selection of the same wavelength or a selection of substantially the same wavelength.

[0026] The LIDAR input signal is in channel C iFeedback the LIDAR input signal to be transmitted to the LIDAR chip so that it is incident on the alternative waveguide 16 associated with the same alternative waveguide index i. As a result, LIDAR input signals transmitting different channels are induced to different alternative waveguides. The portion of the LIDAR input signal incident on the alternative waveguide 16 functions as the incident LIDAR signal. As a result, the alternative waveguide receiving the incident LIDAR signal can induce the outgoing LIDAR signal while also inducing the incident LIDAR signal in the opposite direction. The alternative waveguide 16 receiving the incident LIDAR signal transmits the incident LIDAR signal to the signal guiding unit 14. This signal guiding unit 14 outputs the incident LIDAR signal onto the utility waveguide 12.

[0027] This utility waveguide 12 transmits the incident LIDAR signal to a 2x2 splitter 24 that moves a portion of the incident LIDAR signal from the utility waveguide 12 onto the comparison waveguide 26 as a comparison signal. This comparison waveguide 26 transmits this comparison signal to a processing unit 28 for further processing. Suitable splitters 24 include, but are not limited to, optical couplers, y-junctions, and MMIs. In some examples, the splitter 24 is configured such that the power of the incident LIDAR signal is evenly or substantially evenly divided between the utility waveguide 12 and the comparison waveguide 26.

[0028] The utility waveguide 12 also transmits the outgoing LIDAR signal to the splitter 24. This splitter 24 moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto the reference waveguide 32 as a reference signal. This reference waveguide 32 transmits the reference signal to the processing unit 28 for further processing.

[0029] As will be described in more detail below, this processing unit 28 combines the comparison signal with the reference signal to form a composite signal that transmits LIDAR data of a sample region in the field of view. Accordingly, the composite signal can be processed to extract LIDAR data (radial velocity and / or distance between the LIDAR system and an object external to the LIDAR system) of the sample region.

[0030] The LIDAR chip can 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 emitted LIDAR signal from the utility waveguide 12 onto the control waveguide 68. The combined portion of the emitted LIDAR signal functions as a tapped signal. FIG. 1A shows the directional coupler 66 that moves a portion of the emitted LIDAR signal onto the control waveguide 68, but other signal tap portions can be used to move a portion of the emitted LIDAR signal from the utility waveguide 12 onto the control waveguide 68. Examples of suitable signal tap portions include, but are not limited to, Y-junctions and MMIs.

[0031] The control waveguide 68 transmits the tapped signal to the control unit 70. The control unit can communicate electrically with the electronic device 62. FIG. 1A shows the electronic device as a separate component from the processing unit 28, but a portion of the electronic device can be included in each of the processing units 28. During operation, the electronic device 62 can adjust the frequency of the emitted LIDAR signal in response to the output from the control unit. An example of a suitable configuration of the control unit is described in U.S. Patent Application Serial No. 15 / 977,957, titled "Optical Sensor Chip," filed on May 11, 2018, the entire disclosure of which is incorporated herein by reference.

[0032] The incident LIDAR signal passes through the signal guiding section 14. This signal guiding section 14 can be a light loss source. Before the incident LIDAR signal reaches the signal guiding section 14, this light loss source can be removed by moving a part of the incident LIDAR signal that functions as a comparison signal onto the comparison waveguide 26. As an example, FIG. 1B shows the LIDAR chip of FIG. 1A modified such that the splitter 24 is arranged along each of the alternative waveguides 16 between the signal guiding section 14 and the port 18. As a result, before the incident LIDAR signal reaches the signal guiding section 14, the comparison signal is extracted from the alternative waveguide 16.

[0033] Comparing FIG. 1A and FIG. 1B, it can be seen that the LIDAR chip of FIG. 1B requires more processing units 28 than the LIDAR chip of FIG. 1A. As will be made clear below, when the required number of processing units 28 increases, the number of analog-to-digital converters required for the LIDAR system also increases. However, the number of analog-to-digital converters can be reduced by using a common processing unit 28. As an example, FIG. 1C shows the LIDAR chip of FIG. 1B modified such that each of the comparison waveguides 26 transmits one of them to a common processing unit 72. Further, each of the reference waveguides 32 transmits one of the reference signals to this common processing unit 72.

[0034] The LIDAR system can include a LIDAR chip having a plurality of LIDR cores 4. As an example, FIG. 2 shows a LIDAR chip including a plurality of different cores. The cores are each denoted as core k where k represents the index k. Each of the LIDAR cores can be constructed as disclosed in the context of FIGS. 1A - 1C or can have an alternative structure. Each of the LIDAR cores outputs a different LIDAR output signal. The LIDAR output signal output from the core denoted as core k can be represented as S k,i where i represents the channel index. As a result, S k,i is a function of the alternative waveguide index i and the core index k. As an example, the LIDAR output signal represented by S k,i is from corek Output from k,i The LIDAR output signal represented by S k is output from the core i and transmitted through channel C.

[0035] The LIDAR system can include an optical component assembly 75 that receives LIDAR output signals from different cores and outputs a system output signal that includes, consists of, or consists essentially of light from a different one of the LIDAR output signals. This optical component assembly 75 can be operated by an electronic device 280 to direct the system output signal to different sample regions in the field of view of the LIDAR system.

[0036] FIG. 2 shows an optical component assembly 75 including a signal director 76 that receives each of the LIDAR output signals. This signal director 76 changes the direction in which at least a portion of the LIDAR output signal is moving and outputs each of the LIDAR output signals 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 units 78 that receive the redirected LIDAR output signal output from the signal director 76 as a system output signal. The direction in which the system output signal travels away from the LIDAR system is denoted as d2 in FIG. 2. The electronic device can operate one or more beam steering units 78 to steer each of the system output signals to different sample regions within the field of view. As is apparent from the arrows denoted as A and B in FIG. 2, one or more beam steering units 78 can be configured such that the electronic device can steer the system output signal in one or two dimensions. As a result, one or more beam steering units 78 can function as a beam steering mechanism operated by the electronic device, thereby enabling the system output signal to be steered within the field of view of the LIDAR system. Suitable beam steering units 78 include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), diffraction gratings, and driven diffraction gratings. In some examples, the signal director 76 and / or one or more beam steering units 78 are configured to operate on the system output signal, whereby the system output signal is collimated or substantially collimated as it travels away from the LIDAR system. Additionally or alternatively, the LIDAR system can include one or more collimating optical components (not shown) that operate on the LIDAR output signal, the redirected LIDAR output signal, and / or the system output signal, whereby the system output signal is collimated or substantially collimated as it travels away from the LIDAR system.

[0037] The system output signal can be reflected by an object located outside the LIDAR system. All or part of the reflected light from the system output signal can be fed back to the LIDAR system as a system feedback signal. Each of the system feedback signals is received by one or more beam steering units 78. The one or more beam steering units 78 output at least a portion of each of the system feedback signals as a feedback signal. Each of the feedback signals is received by a signal director 76. The signal director 76 outputs at least a portion of each of the feedback signals as a LIDAR input signal. Each of the different LIDAR input signals is received by a different one of the cores 4. Each of the LIDAR input signals includes or consists of light from the LIDAR output signal output from the core that receives the LIDAR input signal. Also, the LIDAR input signal received by an alternative waveguide includes or consists of light from the LIDAR output signal output from the same alternative waveguide.

[0038] One or more signal directors 76 can change the direction in which the LIDAR output signal moves away from the one or more signal directors 76, whereby the direction of the LIDAR output signal is different from that of the resulting re-directed LIDAR output signal. In some examples, the one or more signal directors 76 are selected such that all or a portion of the re-directed LIDAR output signal moves away from the one or more signal directors 76 in a non-parallel direction. As an example, in FIG. 2, the one or more signal directors 76 are lenses, and each of the different LIDAR output signals impinges on the lens at a different angle of incidence. As a result, each of the re-directed LIDAR output signals travels away from the signal director 76 in a different direction. Further, the re-directed LIDAR output signals travel away from the signal director 76 in non-parallel directions. As is apparent from FIG. 2, the different directions of the system output signal allow the system output signal to travel away from the LIDAR system in different directions. In some examples, the system output signal travels away from the LIDAR system in non-parallel directions.

[0039] By operating the signal guiding unit 14 on the core, the location where the LIDAR output signal is received by one or more signal guides 76 can be changed, and thus, the direction in which the system output signal originating from the core travels away from the LIDAR system can be changed. As an example, the dashed line in FIG. 2 shows the result of operating the signal guiding unit 14 on the core, whereby this core outputs a LIDAR output signal represented by S k,i instead of the LIDAR output signal represented by S k,i+1 As is apparent from FIG. 2, the operation of this signal guiding unit 14 changes the direction in which the system output signal output from the core 1 travels away from the LIDAR system. As a result, the electronic device can operate the signal guiding unit 14 on different cores, thereby steering the system output signal within the field of view of the LIDAR system. Accordingly, the electronic device can operate the signal guiding unit 14 on different cores and / or one or more beam steering units 78, thereby steering the system output signal within the field of view of the LIDAR system. A suitable method of operating the signal guiding unit 14 on different cores and / or one or more beam steering units 78 to thereby steer the system output signal within the field of view of the LIDAR system is disclosed in U.S. Patent Application Serial No. 17 / 580,623, entitled "Imaging System Having Multiple Cores," filed on January 20, 2022, the entirety of which is incorporated herein by reference.

[0040] The optical component assembly 75 can have a configuration other than the configuration shown in FIG. 2. For example, the one or more beam steering units 78 can be disposed between the signal guide 76 and the LIDAR chip. Also, 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 and / or including light from the LIDAR output signal.

[0041] The wavelengths of the LIDAR output signals output from different cores may be the same or different. As a result, the light sources on different cores can be configured to output optical signal outputs each having a different, same, or substantially the same wavelength selection. Therefore, the wavelength selections in different system output signals can be different, the same, or substantially the same.

[0042] All or part of the electronic devices 62 associated with different cores may optionally be fixed within the electronic device 280 shown in FIG. 2. The fixed electronic device 280 may be disposed on the LIDAR chip or may be external to the LIDAR chip. The fixed electronic device 280 can collect or generate LIDAR data results from different cores and / or coordinate LIDAR data results from different cores to assemble LIDAR data results for the field of view of the LIDAR system.

[0043] FIG. 2 shows four cores on the LIDAR chip, but the LIDAR chip can include one, two, or more than two cores. The appropriate number of cores on the LIDAR chip includes, but is not limited to, a number greater than 2, 4, or 6 and / or less than 32, 64, or 128.

[0044] FIGS. 3A-3B show an example of a processing unit suitable for use as the processing unit 28 in a LIDAR system constructed according to FIGS. 1A and 1B. The processing unit includes an optoelectronic assembly configured to convert an optical signal into an electrical signal. FIG. 3A is a schematic diagram of an example of a suitable optoelectronic assembly including a first splitter 200 that splits a comparison signal received from the comparison waveguide 26 into a first comparison waveguide 204 and a second comparison waveguide 206. The first comparison waveguide 204 transmits a first portion of the comparison signal to the optical coupler 211. The second comparison waveguide 206 transmits a second portion of the comparison signal to the second optical coupler 212.

[0045] The processing unit in FIG. 2A also includes a second splitter 202 that splits the reference signal received from the reference waveguide 32 onto the first reference waveguide 210 and the second reference waveguide 208. The first reference waveguide 210 transmits the first portion of the reference signal to the optical coupling unit 211. The second reference waveguide 208 transmits the second portion of the reference signal to the second optical coupling unit 212.

[0046] The second optical coupling unit 212 combines the second portion of the comparison signal and the second portion of the reference signal into a second composite signal. Due to the frequency difference between the second portion of the comparison signal and the second portion of the reference signal, the second composite signal beats between the second portion of the comparison signal and the second portion of the reference signal. The first composite signal and the second composite signal are both examples of composite signals.

[0047] The second optical coupling unit 212 also splits the obtained second composite signal onto the first auxiliary detector waveguide 214 and the second auxiliary detector waveguide 216. The first auxiliary detector waveguide 214 transmits the first portion of the second composite signal to the first auxiliary optical sensor 218 that converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 216 transmits the second portion of the second composite signal to the second auxiliary optical sensor 220 that 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).

[0048] In some examples, the second optical coupler 212 splits the second composite signal, whereby the portion of the comparison signal included in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is phase-shifted by 180° with respect to the portion of the comparison signal in the second portion of the second composite signal (i.e., the second portion of the comparison signal), while the portion of the reference signal in the second portion of the second composite signal (i.e., the second portion of the reference signal) is not phase-shifted with respect to the portion of the reference signal in the first portion of the second composite signal (i.e., the second portion of the reference signal). Alternatively, the second optical coupler 212 splits the second composite signal, whereby the portion of the reference signal in the first portion of the second composite signal (i.e., the second portion of the reference signal) is phase-shifted by 180° with respect to the portion of the reference signal in the second portion of the second composite signal (i.e., the second portion of the reference signal), while the portion of the comparison signal in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is not phase-shifted with respect to the portion of the comparison signal in the second portion of the second composite signal (i.e., the second portion of the comparison signal). Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0049] The first optical coupler 211 combines the first portion of the comparison signal and the first portion of the reference signal into a first composite signal. Due to the frequency difference between the first portion of the comparison signal and the first portion of the reference signal, the first composite signal beats between the first portion of the comparison signal and the first portion of the reference signal.

[0050] The optical coupler 211 also splits the first composite signal onto a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 transmits the first portion of the first composite signal to a first optical sensor 223 that converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 transmits the second portion of the second composite signal to a second optical sensor 224 that 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).

[0051] In some examples, the optical coupler 211 splits the first composite signal, whereby the portion of the comparison signal included in the first portion of the composite signal (i.e., the first portion of the comparison signal) is phase-shifted by 180° with respect to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal), while the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is not phase-shifted with respect to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal). Alternatively, the optical coupler 211 splits the composite signal, whereby the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is phase-shifted by 180° with respect to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal), while the portion of the comparison signal in the first portion of the composite signal (i.e., the first portion of the comparison signal) is not phase-shifted with respect to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal).

[0052] If the second optical coupler 212 splits the second composite signal such that the portion of the comparison signal in the first portion of the second composite signal is phase-shifted by 180° with respect to the portion of the comparison signal in the second portion of the second composite signal, then the optical coupler 211 also splits the composite signal such that the portion of the comparison signal in the first portion of the composite signal is phase-shifted by 180° with respect to the portion of the comparison signal in the second portion of the composite signal. If the second optical coupler 212 splits the second composite signal such that the portion of the reference signal in the first portion of the second composite signal is phase-shifted by 180° with respect to the portion of the reference signal in the second portion of the second composite signal, then the optical coupler 211 also splits the composite signal such that the portion of the reference signal in the first portion of the composite signal is phase-shifted by 180° with respect to the portion of the reference signal in the second portion of the composite signal.

[0053] The first reference waveguide 210 and the second reference waveguide 208 are constructed 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 constructed to provide a 90° phase shift between a first portion of the reference signal and a second portion of the reference signal. As an example, one reference signal portion may be an in-phase component, and the other reference signal portion may be a quadrature component. Accordingly, 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 constructed such that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Accordingly, the portion of the reference signal in the second composite signal is phase-shifted with respect to the portion of the reference signal in the first composite signal, but the portion of the comparison signal in the first composite signal is not phase-shifted with respect to the portion of the comparison signal in the second composite signal.

[0054] The first optical sensor 223 and the second optical sensor 224 can be connected as a balanced detector, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 can also be connected as a balanced detector. The balanced detector functions as an optical sensor that converts an optical signal into an electrical signal. FIG. 3B shows a schematic diagram of the relationship between the electronic device, the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220. The symbol of the photodiode is used to represent the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220, but one or more of these sensors can have other configurations. In some examples, all of the components shown in the schematic diagram of FIG. 3B are included on the LIDAR chip. In some examples, the components shown in the schematic diagram of FIG. 3B are distributed between the LIDAR chip and an electronic device located away from the LIDAR chip.

[0055] The electronic device connects the first optical sensor 223 and the second optical sensor 224 as the first balanced detector 225, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 as the second balanced detector 226. Specifically, the first optical sensor 223 and the second optical sensor 224 are connected in series. Also, the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 are connected in series. The series connection in the first balanced detector communicates with the first data line 228 that transmits the output from the first balanced detector as the first data signal. The series connection in the second balanced detector communicates with the second data line 232 that transmits the output from the second balanced detector as the second data signal. Both the first data line and the second data line are examples of data lines. The first data signal is an electrical data signal that transmits the representation of the first composite signal, and the second data signal is an electrical data signal that transmits the 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. The portion of the first waveform in the first data signal is phase-shifted with respect to the portion of the first waveform in the first data signal, while the portion of the second waveform in the first data signal is in-phase with respect to the 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 with respect to different portions of the reference signal included in the first data signal. Also, the second data signal includes a portion of the comparison signal that is in-phase with different portions of the comparison signal included in the first data signal. The first data signal and the second data signal are beating as a result of the beat between the comparison signal and the reference signal, that is, the beat in the first composite signal and the second composite signal.

[0056] The electronic device 62 includes a conversion 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 that takes the first data signal and the second data signal as inputs. Since the first data signal is the in-phase component and the second data signal is the quadrature component, the first data signal and the second data signal together act as a complex data signal, where the first data signal is the real component of the input and the second data signal is the imaginary component of the input.

[0057] The conversion mechanism 238 includes a first analog-to-digital converter (ADC) 264 that 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 format to a digital format and outputs a first digital data signal. The conversion mechanism 238 includes a second analog-to-digital converter (ADC) 266 that 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 format to a digital format 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. Thus, the first digital data signal and the second digital data signal together act as a composite signal, where the first digital data signal acts as the real component of the composite signal and the second digital data signal acts as the imaginary component of the composite data signal.

[0058] The conversion mechanism 238 includes a conversion unit 268 that receives a composite data signal. For example, the conversion unit 268 receives the first digital data signal as an input from the first analog-to-digital converter (ADC) 264 and also receives the second digital data signal as an input from the first analog-to-digital converter (ADC) 266. The conversion unit 268 can be configured to perform a mathematical conversion on the composite signal and convert it from the time domain to the frequency domain. The mathematical conversion can be a composite conversion such as a composite fast Fourier transform (FFT). By a composite conversion such as a composite fast Fourier transform (FFT), the frequency of the comparison signal is clearly shifted with respect to the system output signal.

[0059] The electronic device includes a LIDAR data generator 270 that receives the output from the conversion unit 268 and processes the output from the conversion unit 268 in order 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 peak detection on the output of the conversion unit 268 and identifies one or more peaks at the beat frequency.

[0060] The electronic device uses 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 conversion unit 268 can perform attribution functions using firmware, hardware, software, or a combination thereof.

[0061] FIG. 3C shows an example of the relationship between the frequency, time, cycle, and data period of the system output signal. The base frequency of the system output signal (f0) can be the frequency of the system output signal at the start of the cycle.

[0062] FIG. 3C shows, in some examples, the cycle j and cycle j+i showing the frequency versus time for the order of two cycles labeled as such. In some examples, the frequency-versus-time pattern is repeated in each cycle as shown in FIG. 3C. The illustrated cycles do not include a rearrangement period and / or the rearrangement period is not placed between cycles. As a result, FIG. 3C shows the result of a continuous scan in which the system output signal is continuously steered.

[0063] Each cycle includes K data periods, each associated with a period index k, denoted as DP k as denoted. In the example of FIG. 3C, each cycle is DP kIncludes three data periods denoted as such, where k = 1, 2, and 3. In some examples, the frequency - time pattern is the same for corresponding data periods in different cycles, as shown in FIG. 3C. Corresponding data periods are data periods having the same cycle index. As a result, each data period DP1 can be regarded as a corresponding data period, and the associated frequency - time pattern is the same in FIG. 3C. At the end of a cycle, the electronic device returns the frequency to the same frequency level at which the previous cycle started.

[0064] Between data period DP1 and data period DP2, the electronic device operates the light source such that the frequency of the system output signal changes at a linear rate α. The direction of the frequency change during data period DP1 is opposite to the direction of the frequency change during data period DP2.

[0065] FIG. 3C represents sample regions respectively associated with the sample region index k and denoted as Rn k FIG. 3C represents the sample regions denoted as Rn k and Rn k+1 Each sample region is irradiated with the system output signal during the data period shown as associated with that sample region in FIG. 3C. For example, sample region Rn k is irradiated with the system output signal during the data periods denoted as DP1 - DP3. The sample region index k can be assigned with respect to time. For example, the sample regions can be irradiated by the system output signal in the order indicated by index k. As a result, sample region Rn 10 can be irradiated after sample region Rn9 and before sample region Rn 11 .

[0066] A LIDAR system is typically configured to provide reliable LIDAR data when the object is within the operating distance range from the LIDAR system. The operating distance range can extend from a minimum operating distance to a maximum operating distance. The maximum round-trip time can be the time required for a system output signal to be emitted from the LIDAR system, travel the maximum operating distance to the object, and then return to the LIDAR system. In Figure 3C, it is denoted as τ M as indicated.

[0067] Due to the delay between the transmitted system output signal and the signal that returns to the LIDAR system, the composite signal does not include the contribution from the LIDAR signal until after the system feedback signal has returned to the LIDAR system. Since the composite signal requires the contribution from the system feedback signal for the presence of the LIDAR beat frequency, the electronic device measures the LIDAR beat frequency resulting from the system feedback signal that returns to the LIDAR system during the data period and within the data window of the data period. The data window is denoted as "W" in Figure 3C. The contribution from the LIDAR signal to the composite signal exists at a time greater than the maximum operating time delay (τ M ). As a result, the data window is shown to extend from the maximum operating time delay (τ M ) to the end of the data period.

[0068] The frequency peaks in the output from the complex Fourier transform represent the beat frequencies of the composite signal, each containing a comparison signal that beats against the reference signal. The beat frequencies from two or more different data periods can be combined to generate LIDAR data. For example, in Figure 3C, the beat frequency measured from DP1 can be combined with the beat frequency measured from DP2 in Figure 3C to measure the LIDAR data. As an example, the following equation is applied during a data period in which the electronic device increases the frequency of the emitted LIDAR signal as occurs in data period DP1 of Figure 3C: f ub = -f d +ατ, where f ub is the frequency given by the conversion unit, and f drepresents the Doppler shift (f d = 2νf c / c), where f c represents the optical frequency (f0), c represents the speed of light, ν is the radial velocity between the reflecting object and the LIDAR system assuming the direction from the reflecting object towards the chip is the positive direction, τ is the time (round-trip time) for the light from the system output signal to travel to the object and return to the LIDAR system, and c is the speed of light. The following equation is applied during the data period when the electronic device reduces the frequency of the emitted LIDAR signal such that it occurs during the data period DP2 of FIG. 3C: f db = -f d -ατ, where f db is the frequency given by the conversion unit (in this case, f i, LDP ) measured from DP2). In these two equations, f d and τ are unknowns. The electronic device solves these two equations for these two unknowns. Next, the radial velocity of the sample region can be calculated from the Doppler shift (ν = c*f d / (2f c )) and / or the separation distance of the sample region can be calculated from c*τ / 2. As a result, the electronic device uses each beat frequency as a variable in one or more equations that generate LIDAR data. Since LIDAR data can be generated for each corresponding frequency pair output by the conversion, separate LIDAR data can be generated for each object within the sample region. Therefore, the electronic device can measure multiple radial velocities and / or multiple radial separation distances from a single sampling of a single sample region within the field of view.

[0069] In FIG. 3C, the data period denoted as DP3 is optional. As described above, there may be two or more objects within the sample region. For example, during the feedback period in DP1 for cycle 2, and during the feedback period in DP2 for cycle 2, two or more frequency pairs can be matched. In these situations, it may be unclear which frequency peak from DP2 corresponds to which frequency peak from DP1. As a result, it may be unclear which frequencies need to be used together to generate the LIDAR data of the objects within the sample region. As a result, it is necessary to identify the corresponding frequencies. The identification of the corresponding frequencies can be performed such that the corresponding frequencies are the frequencies from the same reflecting object within the sample region. The data period denoted as DP3 can be used to find the corresponding frequencies. LIDAR data can be generated for each pair of corresponding frequencies and considered and / or processed as the LIDAR data of different reflecting objects within the sample region.

[0070] In an example of identifying the corresponding frequencies, as shown in FIG. 3C, a LIDAR system in which a cycle includes three data periods (DP1, DP2, and DP3) is used. When there are two objects in the sample region irradiated by the LIDAR output signal, the conversion unit outputs two different frequencies (f ub with respect to f u1 and f u2 ) during DP1, and outputs another two different frequencies (f db with respect to f d1 and f d2 ) during DP2. In this example, the possible frequency pairings are (f d1 , f u1 ), (f d1 , f u2 ), (f d2 , f u1 ), and (f d2 , f du2 ). Values of f d and τ can be calculated for each possible frequency pairing. Each pair of values of f d and τ is f3 = -f dSubstitute into +α3τ0, and the theoretical value of f3 can be generated for each possible frequency pairing. The value of α3 is different from the α value used in DP1 and DP2. In FIG. 3C, the value of α3 is zero. In this case, the conversion unit also outputs two f3 values respectively associated with one of the objects in the sample region. The frequency pair having the theoretical value of f3 closest to each of the actual f3 values is regarded as the corresponding pair. LIDAR data can be generated for each corresponding pair as described above, regarded as and / or processed as LIDAR data of different reflective objects in the sample region. To generate LIDAR data, each set of corresponding frequencies can be used in the above formula. The generated LIDAR data will be related to one of the objects in the sample region. As a result, a plurality of different LIDAR data values can be generated for the sample region, and each different LIDAR data value corresponds to one of the different objects in the sample region.

[0071] The processing unit in FIG. 1A transmits different channels and thus receives a series of comparison signals from different sample regions. As a result, the processing unit in FIG. 1A provides LIDAR data of a series of sample regions irradiated by the system output signal transmitting different channels. The series of sample regions for which the processing unit provides LIDAR data can be the same as the series of irradiated sample regions. The configuration of the processing unit in FIGS. 3A to 3C can also be used for the processing unit in FIG. 1B. However, the processing unit 28 in FIG. 1B receives a comparison signal transmitting only one of the channels. As a result, if the processing unit 28 in FIG. 1B is constructed according to FIGS. 3A to 3C, each processing unit provides LIDAR data of a series of sample regions irradiated by the system output signal transmitting only one channel.

[0072] In the LIDAR system of FIG. 1C, the electronics from different processing units 28 can be combined such that the pulsating signals are coupled electronically rather than optically. For example, each processing unit 28 in the LIDAR system according to FIG. 1C can include the optoelectronic assembly of FIG. 3A. FIG. 3D is a schematic diagram of the relationship between the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220 and the electronics within each optoelectronic assembly of FIG. 3A. Since each different processing unit 28 receives LIDAR input signals that transmit different channels, FIG. 3D shows the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220 associated with the channels received by the optical sensors.

[0073] In FIG. 3D, electronic devices from different processing units 28 (FIG. 1C) are combined to form a common processing unit 72. Each first data line 228 from a different first balance detector 225 transmits a first data signal to a first electrical multiplexer 272. The first electrical multiplexer 272 outputs the first data signal from different first data lines 228 onto a common data line 273. Since system output signals that are output from the same core and transmit different channels are continuously output from the LIDAR system, a processing unit 28 (FIG. 1C) configured to receive a first comparison signal for transmitting channel i receives the first comparison signal in response to the signal guiding unit 14 on the core operating and the system output signal for transmitting channel i being output from the LIDAR system. Also, a processing unit 28 not configured to receive a comparison signal for transmitting channel i substantially does not receive the first comparison signal in response to the signal guiding unit 14 being operated so that the system output signal for transmitting channel i is output from the LIDAR system. Since system output signals that transmit different channels from the same core are continuously output from the LIDAR system, comparison signals for transmitting different channels are continuously received by different processing units 28, but there may be an overlap of different channels. Since different processing units 28 continuously receive comparison signals for transmitting different channels, the first common data line 273 transmits first data signals that continuously transmit different channels. Accordingly, the first common data line 273 transmits electrical data signals, each of which is an electrical representation of a first composite signal and each of which continuously transmits one of different channels. There may be some short-term overlaps between channels in a series of first data signals, but this overlap does not occur in the data window shown in FIG. 3C. The first common data line 273 transmits a series of first data signals to a first analog-to-digital converter (ADC) 264.

[0074] Each second data line 232 from a different second balance detector 226 transmits a second data signal to a second electrical multiplexer 274. The second electrical multiplexer 274 outputs the second data signal from different second data lines 232 onto a second common data line 275. Both the first common data line and the second common data line are examples of a common data line. As described above, the processing unit 28 continuously receives first comparison signals that transmit different channels. As a result, the second common data line 275 continuously transmits second data signals that transmit different channels. Thus, the second common data line 275 transmits electrical data signals, each of which is an electrical representation of a second composite signal and each of which continuously transmits one of different channels. There may be some short-term overlaps between channels in a series of second data signals, but this overlap does not occur within the data window shown in FIG. 3C. The second common data line 275 transmits a series of second data signals to a second analog-to-digital converter (ADC) 266.

[0075] The conversion mechanism 238 and the LIDAR data generator 270 of FIG. 3D can operate as disclosed in the context of FIGS. 3A-3C. For example, a first analog-to-digital converter (ADC) 264 converts a first data signal from an analog format to a digital format and outputs a first digital data signal. A second analog-to-digital converter (ADC) 266 converts a second data signal from an analog format to a digital format and outputs a second digital data signal.

[0076] The first and second digital data signals that transmit on the same channel act together as a composite signal in which the first digital data signal acts as the real component of the composite signal and the second digital data signal acts as the imaginary component of the composite data signal. The electronic device is configured such that the first and second digital data signals that transmit on the same channel are received simultaneously by the LIDAR data generator 270. As a result, the LIDAR data generator 270 receives a composite signal that transmits on different channels continuously. The LIDAR data generator 270 can generate LIDAR data for each of the different channels. As a result, the data generator 270 can generate LIDAR data for each sample region irradiated by a system output signal that transmits a series of channels.

[0077] In another embodiment of the LIDAR system in which the relationship between the sensor in the optoelectronic assembly from FIG. 3A and the electronic device in the LIDAR system is constructed according to FIG. 3D, the electronic device operates an electrical multiplexer as a switch operated by the electronic device. As a result, this electronic device can operate the first electrical multiplexer 272 to select which of the first data signals is output to the common data line 273, and can operate the second electrical multiplexer 274 to select which of the second data signals is output to the second common data line 275. As a result, the LIDAR system can be configured to simultaneously output system output signals that transmit on different channels. For example, the LIDAR chip can be configured to simultaneously output each of the LIDAR output signals that transmit on different channels. The signal guiding unit 14 can be configured to guide the outgoing LIDAR system to one or more alternative waveguides 16. In an example where the signal guiding unit 14 is configured to guide the outgoing LIDAR system to all N alternative waveguides 16, the signal guiding unit can be a signal splitter.

[0078] When the LIDAR system simultaneously outputs system output signals that transmit different channels, each of the different processing units 28 can simultaneously receive a first LIDAR input signal that transmits one of the channels. Accordingly, the first data lines 228 from each of the different processing units 28 simultaneously transmit the first data signal to the first electrical multiplexer 272. As a result, the first electrical multiplexer 272 simultaneously receives a plurality of first data signals that respectively transmit different channels and originate from different processing units 28. The electronic device operates the first electrical multiplexer 272 using the switching function of the first electrical multiplexer 272, whereby the first electrical multiplexer 272 outputs a first data signal that continuously transmits different channels. As a result, the first common data line 273 transmits a first data signal that continuously transmits different channels. Examples of suitable channel series include, but are not limited to, a channel order in which the channel index has i = l to i = N in numerical order from i = 1 to i = N.

[0079] The second data lines 232 from each of the different processing units 28 simultaneously transmit the second data signal to the second electrical multiplexer 274. As a result, the second electrical multiplexer 274 simultaneously receives a plurality of second data signals that respectively transmit different channels and originate from different processing units 28. The electronic device operates the second electrical multiplexer 274 using the switching function of the second electrical multiplexer 274, whereby the second electrical multiplexer 274 outputs a second data signal that continuously transmits different channels. As a result, the second data line 275 transmits a second data signal that continuously transmits different channels.

[0080] The 3D conversion mechanism 238 and the LIDAR data generator 270 can operate as disclosed in the context of FIGS. 3A-3C. For example, the first analog-to-digital converter (ADC) 264 converts the first data signal from analog form to digital form and outputs a 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 a second digital data signal.

[0081] The first electrical multiplexer 272 and the second electrical multiplexer 274 are operated such that the first data line 273 and the second data line 275 transmit the same channel simultaneously. As a result, 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 transmit the same channel simultaneously. The first digital data signal and the second digital data signal transmitting the same channel act together as a composite signal in which the first digital data signal acts as the real component of the composite signal and the second digital data signal acts as the imaginary component of the composite data signal. The first digital data signal and the second digital data signal transmitting the same channel are received simultaneously by the LIDAR data generator 270. As a result, the LIDAR data generator 270 receives a composite signal that transmits different channels continuously. The LIDAR data generator 270 can generate LIDAR data for each channel within a series of channels. As a result, the data generator 270 can generate LIDAR data for each sample area irradiated by a system output signal that transmits a series of channels.

[0082] As an alternative to the first electrical multiplexer 272 and / or the second electrical multiplexer 274, an electrical node and a second electrical node are provided. At the electrical node, first data lines 228 from each of different first balanced detectors 225 communicate electrically with each other, and at the second electrical node, second data lines 232 from each of different second balanced detectors 226 communicate electrically with each other. As a result, the outputs of optical sensors such as the first balanced detector 225 are effectively electrically connected to each other, and the outputs of optical sensors such as the second balanced detector 226 are effectively electrically connected to each other. As an example, FIG. 3E shows the configuration of FIG. 3D modified such that the first data lines 228 from each of different first balanced detectors 225 communicate electrically with a first common data line 273. Since the LIDAR system outputs a system output signal that continuously transmits different channels, the first common data line 273 transmits a first data signal that continuously transmits different channels. There may be some overlap between channels that are continuously adjacent to each other, but this overlap does not occur during the data window. Also, the second data lines 232 from each of different second balanced detectors 226 communicate electrically with a second common data line 275. Since the LIDAR system outputs a system output signal that continuously transmits different channels, the second common data line 275 transmits a second data signal that continuously transmits different channels. There may be some overlap between channels that are continuously adjacent to each other, but this overlap does not occur during the data window. Since the first common data line 273 transmits a first data signal that continuously transmits different channels, and the second common data line 275 transmits a second data signal that continuously transmits different channels as also occurs in the LIDAR system of FIG. 6D, the conversion mechanism 238 and the LIDAR data generator 270 can operate as disclosed in the context of FIG. 3E to generate LIDAR data for each sample region irradiated by a system output signal that transmits a series of channels.

[0083] In the LIDAR system constructed according to FIG. 3E, during the cycle in which the LIDAR system outputs a system output signal transmitting through channel i, the optoelectronic assembly included in the processing unit (active processing unit) configured to receive current channel i receives at least a first LIDAR input signal transmitting through channel i during at least the data window. On the other hand, the processing unit (inactive processing unit) not configured to receive current channel i does not receive the first LIDAR input signal. However, the inactive processing unit continues to receive a reference signal during at least the data window. The light from the reference signal received by the inactive processing unit can pass through the optoelectronic assembly and become noise in electrical signals such as the first data signal and the second data signal.

[0084] In some examples, it may be desirable to completely or partially attenuate all or part of the reference signal received by the (one or more) inactive processing units. For example, the reference waveguide 32 (FIG. 1C) can optionally include optical attenuators 276 respectively. This attenuator 276 can be operated by electronics to completely or partially attenuate the reference signal induced by the reference waveguide 32 in which it is disposed.

[0085] The processing unit that functions as the active processing unit indicated by 28 in FIG. 1C and the processing unit that functions as the non-active processing unit indicated by 28 in FIG. 1C change when the channel transmitted by the system output signal changes. As a result, the electronic device can change the reference signal that is attenuated in response to the change in the channel transmitted by the system output signal. For example, the electronic device can operate the attenuator 276 so that the reference signal to be received by the active processing unit is not attenuated or is substantially not attenuated. Also, the electronic device can operate the attenuator 276 so that the reference signal to be received by all or part of the non-active processing unit is completely or partially attenuated. Since the reference signal to be received by all or part of the non-active processing unit is completely or partially attenuated, the amount of light from the reference signal actually received by the non-active processing unit is reduced. As a result, the attenuated light is not a noise source in the first data signal and the second data signal.

[0086] Although the optical attenuator 276 is shown to be disposed on the reference waveguide 32 of FIG. 1C, the optical attenuator 276 can be disposed on all or a part of the reference waveguide 32 shown in the imaging systems of FIGS. 1A and 1B. The electronic device can operate the variable optical attenuator 276 so as to attenuate the power of the reference signal to a desired level.

[0087] Suitable devices applicable to the optical attenuator 276 include, but are not limited to, variable optical attenuators (VOAs), PIN diodes, and Mach-Zehnder modulators. An example of a suitable optical attenuator can be found in U.S. Patent Application Serial No. 17 / 396,616, entitled "Carrier Injector with Improved Compatibility," filed on August 6, 2021, the entire disclosure of which is incorporated herein by reference.

[0088] Suitable platforms for LIDAR chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. FIG. 4 is a cross-sectional view 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 silica, while the substrate 302 and the optical transmission medium 304 are silicon. The substrate of an optical platform such as an SOI wafer can function as the base of a LIDAR chip. For example, in some examples, the optical components shown in FIGS. 1A-1C can be disposed on the top surface and / or side surface of the same substrate. As a result, the substrate of an optical platform such as an SOI wafer can function as the base 298 shown in FIG. 2B.

[0089] The portion of the LIDAR chip shown in FIG. 4 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. As a result, the ridge 306 at least partially defines the waveguide.

[0090] The dimensions of the ridge waveguide are shown in FIG. 4. For example, the ridge has a width denoted as w and a height denoted as h. The thickness of the slab region is denoted as t. In LIDAR applications, these dimensions may be more important than those used in other applications because they need to use a higher level of optical power. The ridge width (denoted as w) is greater than 1 μm and less than 4 μm, the ridge height (denoted as h) is greater than 1 μm and less than 4 μm, and the thickness of the slab region is greater than 0.5 μm and less than 3 μm. These dimensions can be applied to the straight or substantially straight portions of the waveguide, the curved portions of the waveguide, and the tapered portions of the waveguide. Thus, these portions of the waveguide are single-mode. However, in some examples, these dimensions are applied to the straight or substantially straight portions of the waveguide. Additionally or alternatively, in order to reduce the optical loss in the curved portion of the waveguide, the curved portion of the waveguide can have a reduced slab thickness. For example, the curved portion of the waveguide can have a ridge extending away from a slab region with a thickness greater than or equal to 0.0 μm and less than 0.5 μm. The above dimensions generally provide a straight or substantially straight portion of the waveguide having a single-mode structure, but they can result in multimode tapered and / or curved portions. The coupling between the multimode geometry and the single-mode geometry can be performed using a taper that does not substantially excite higher-order modes. Thus, the waveguide can be configured such that the signal transmitted within the waveguide is transmitted in single mode even when it is transmitted through a waveguide section having multimode dimensions. The waveguide structure of FIG. 4 is suitable for all or part of the waveguide on the LIDAR chip constructed according to FIGS. 1A - 1C.

[0091] A suitable signal guiding section 14 for use with a LIDAR chip includes, but is not limited to, optical switches such as cascaded Mach-Zehnder interferometers and micro-ring resonator switches. In one example, the signal guiding section 14 includes a cascaded Mach-Zehnder interferometer that uses a thermal phase shifter or a phase shifter of free carrier injection. FIGS. 5A and 5B show an example of an optical switch including a cascaded Mach-Zehnder interferometer 416. FIG. 5A is a top view of the optical switch. FIG. 5B is a cross-sectional view of the optical switch shown in FIG. 5A taken along the line indicated as B in FIG. 5A.

[0092] The optical switch receives the outgoing LIDAR signal from the utility waveguide 12. The optical switch is configured to direct the outgoing LIDAR signal to one of a plurality of alternative waveguides 16. The optical switch includes an interconnect waveguide 414 that connects a plurality of Mach-Zehnder interferometers 416 in a cascaded arrangement. Each Mach-Zehnder interferometer 416 directs the outgoing LIDAR signal to one of two interconnect waveguides 114. The electronics can operate each Mach-Zehnder to select which of the two interconnect waveguides 414 receives the outgoing LIDAR signal from the Mach-Zehnder interferometer 416. The interconnect waveguide 414 that receives the outgoing LIDAR signal can be selected such that the outgoing LIDAR signal is directed through the optical switch to a particular one of the alternative waveguides 16.

[0093] Each Mach-Zehnder interferometer 416 includes two branch waveguides 418, each of which receives a portion of the emitted LIDAR signal from the utility waveguide 12 or from the interconnect waveguide 414. Each Mach-Zehnder interferometer 416 includes a guiding section 420 that receives two portions of the emitted LIDAR signal from the branch waveguides 418. The guiding section 420 steers the emitted LIDAR signal to one of the two interconnect waveguides 414 configured to receive the emitted LIDAR signal from the guiding section 420. The interconnect waveguide 414 to which the emitted LIDAR signal is guided is a function of the phase difference between two different portions of the emitted LIDAR signal received by the guiding section 420. FIG. 5A shows a directional coupler operating as the guiding section 420, but other guiding sections 420 can be used. Suitable alternatives to the guiding section 420 include, but are not limited to, multimode interference (MMI) devices and taper couplers.

[0094] Each Mach-Zehnder interferometer 416 includes a phase shifter 422 disposed along one of the branch waveguides 418. The output section includes a conductor 424 in electrical communication with the phase shifter 422. Since the conductor 424 is shown by a dashed line, it can be easily distinguished from the components below it. The conductor 424 terminates at contact pads 426, respectively. The contact pads 426 can be used to provide electrical communication between the conductor 424 and the electronics. Thus, the conductor 424 provides electrical communication between the electronics and the phase shifter 422, enabling the electronics 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.

[0095] The electronic device can operate each phase shifter 422 so as to control the phase difference between portions of the emitted LIDAR signal received by the induction unit 420. In one example, the phase shifter 422 can be operated to change the refractive index of at least a part of the branched waveguide 418. By changing the refractive index of a part of the branched waveguide 418 within the Mach-Zehnder interferometer 416, the effective length of the branched waveguide 418 is changed, and thus the phase difference between portions of the emitted LIDAR signal received by the induction unit 420 is changed. Due to the function of the electronic device to change the phase difference, the electronic device can select the interconnecting waveguide 414 that receives the emitted LIDAR signal from the induction unit 420.

[0096] FIG. 5B shows an example of a suitable configuration of the phase shifter 422 on the branched waveguide 418. The branched waveguide 418 is at least partially defined by a ridge 306 of the optical transmission medium 304 that extends away from the slab region 98 of the optical transmission medium 304. The doped region 428 extends into the slab region 308, one of the doped regions contains an n-type dopant, and one of the doped regions 428 contains a p-type dopant. The first cladding 430 is disposed between the optical transmission medium 304 and the conductor 424. The conductors 424 each extend through an opening in the first cladding 430 to contact one of the doped regions 428. The second cladding 432 is optionally disposed on the first cladding 430 and on the conductor 424. To generate a current through the branched waveguide 418, the electronic device can apply a forward bias to the conductor 424. As a result, by injecting carriers into the branched waveguide 418, absorption of free carriers that change the refractive index within the branched waveguide 418 is caused.

[0097] The first cladding 430 and / or the second cladding 432 shown in FIG. 5B can each represent one or more layers of material. The materials of the first cladding 430 and / or the second cladding 432 can be selected to achieve electrical insulation of the conductor 424, a reduction in refractive index with respect 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 of the first cladding 430 and / or the second cladding 432 may or may not be added.

[0098] When the LIDAR system includes a plurality of cores, the LIDAR system can include a plurality of signal directors 76, and different signal directors 76 can receive LIDAR output signals from different selections of the signal directors 76. As an example, FIG. 6 shows the LIDAR system of FIG. 2 modified to have a plurality of signal directors 76 each receiving a LIDAR output signal from one of different cores.

[0099] FIGS. 1A - 1C show each of the cores including different light sources 10. However, a plurality of cores, all of the cores, or a portion of the cores can receive the emitted LIDAR signal from a common light source. In some examples, the cores are arranged in groups, with each core within a group receiving the emitted LIDAR signal from the same common light source and the cores within different groups receiving the emitted LIDAR signal from different common light sources. In some examples, a group of cores can include one of the cores. As an example, FIG. 7 shows the LIDAR system of FIG. 2, where the light source 10 is located outside the cores and each of these cores receives the emitted LIDAR signal from the light source.

[0100] The first optical link 440 provides optical communication between the light source 10 and the signal splitter 442. The second optical link 444 provides optical communication between the signal splitter 442 and the utility waveguide 12 on a different core 4. The light source 10 outputs a preliminary signal received on the first optical link 440. The signal splitter 442 receives the preliminary signal from the first optical link 440. The signal splitter 442 splits the preliminary signal into split signals respectively received on different ones of the second optical links 444. Each of the utility waveguides 12 receives a split signal from a different one of the optical links 444. The portion of the split signal incident on the utility waveguide functions as an outgoing LIDAR signal.

[0101] The LIDAR system can optionally include an amplifier 446 disposed along the first optical link 440 to amplify the power of the preliminary signal. Amplifiers 446 suitable for use along an optical link include, but are not limited to, SOAs, erbium-doped fiber amplifiers (EDFAs), and praseodymium-doped fiber amplifiers (PDFAs).

[0102] When it is desirable for the different outgoing LIDAR signals to have the same or substantially the same wavelength distribution, a suitable signal splitter 442 includes, but is not limited to, a wavelength-independent signal combiner, such as an optical coupler, a y-junction, an MMI, a cascaded evanescent optical coupler, and a cascaded-connected y-junction. When it is desirable for the different outgoing LIDAR signals to have different wavelength distributions, a suitable signal splitter 442 includes, but is not limited to, a wavelength-dependent signal splitter 442, such as an arrayed waveguide grating (AWG) and an optical demultiplexer such as an echelle grating.

[0103] In some examples where multiple different cores receive an outgoing LIDAR signal from a common light source, only one of the cores receiving the outgoing LIDAR signal from the common light source includes a control branch. As a result, other cores receiving the outgoing LIDAR signal from the same common light source can exclude the directional coupler 66, the control waveguide 68, and the control unit 70 shown in FIGS. 1A-1C.

[0104] As is apparent from FIGS. 1A and 1B, the LIDAR system can optionally include one or more optical signal amplifiers 446. For example, the amplifier 446 can optionally be arranged along a utility waveguide as shown in the LIDAR system of FIG. 1A. In another example, the amplifier 446 can optionally be arranged along all or part of an alternative waveguide 16 as shown in the LIDAR system of FIG. 1B. The electronics can operate the amplifier 446 to amplify the emitted LIDAR signal and thus the power of the system output signal. The electronics can operate each of the amplifiers 446 to amplify the power of the emitted LIDAR signal. Suitable amplifiers 446 for use on the LIDAR chip include, but are not limited to, semiconductor optical amplifiers (SOAs).

[0105] Each of the amplifiers 446 shown in FIGS. 1A and 1B is arranged in front of one of the splitters 24. In some examples, this arrangement of the amplifier 446 can cause saturation of one or more components selected from the group consisting of the first auxiliary optical sensor 218, the second auxiliary optical sensor 220, the first optical sensor 223, and the second optical sensor 224. For example, the amplifier 446 can increase the power level of the reference signal to a level at which saturation occurs. A beam dump can be used to reduce the power level of the reference signal to a level at which saturation is reduced or eliminated.

[0106] As is apparent from FIGS. 3B, 3D, and 3E, the LIDAR system can optionally include one or more electrical signal amplifiers 447. Any of the amplifiers 447 is arranged to provide amplification of a first data signal traveling between a first optical sensor such as the first balanced detector 225 and an analog-to-digital converter, or a second data signal traveling between a second optical sensor such as the second balanced detector 226 and an analog-to-digital converter. FIG. 3D shows each of the electrical signal amplifiers 447 arranged along the first data line 228 or the second data line 232, but the electrical signal amplifiers 447 can be arranged along the common data line 273 or the second common data line 275. FIG. 3E shows each of the electrical signal amplifiers 447 arranged along the common data line 273 or the second common data line 275, but the electrical signal amplifiers 447 can be arranged 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 (TIAs).

[0107] FIG. 8 shows a portion of a LIDAR chip that includes a reference waveguide 32 used with a beam dump configured to reduce the power level of a reference signal transmitted on the reference waveguide 32. The reference waveguide 32 transmits the reference signal to a splitter 448 that moves a portion of the reference signal from the reference waveguide 32 onto a dump waveguide 450 as a dump signal. The dump waveguide 450 transmits the dump signal to the beam dump 452.

[0108] The beam dump 452 is configured to scatter the dump signal without reflecting a substantial amount of light from the dump signal into the dump waveguide 450. For example, the beam dump 452 can be a recess 454 etched into the optical transmission medium of a silicon-on-insulator wafer to a depth at which the dump signal impinges on one or more sides of the recess 454. The recess 454 can be shaped to cause scattering of the dump signal. For example, the recess 454 can have a star shape or can include any number of randomly arranged side facets. In some examples, the recess 454 can extend through the optical transmission medium to a lower layer, such as a buried layer of the silicon-on-insulator wafer.

[0109] The splitter 448 can be constructed to control the proportion of the reference signal power transmitted to the dump waveguide. Increasing the proportion of the reference signal power transmitted to the dump waveguide increases the attenuation of the reference signal power and thus decreases the power of the signal received by all or some of the optical sensors 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. When the power of the optical signal received by all or some of the optical sensors is reduced, the chance of saturation is reduced. Suitable splitters 448 include, but are not limited to, 1×2 splitters such as optical couplers, y-junctions, and MMIs. In some examples, the splitter 448 is configured such that the proportion of the reference signal power transmitted to the dump waveguide 450 is 0.1%, 0.5% or 1% or more and 2%, 10% or 20% or less.

[0110] The optical sensor that interferes with the waveguide on the LIDAR chip can be a component separated from the chip and 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, InGaAs PIN photodiodes or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu in Hamamatsu, Japan. These optical sensors can be centrally located on the LIDAR chip. Alternatively, all or part of the waveguide terminated by the optical sensor can be terminated with a facet at the edge of the chip, and the optical sensor can be attached to the edge of the chip on the facet so that the optical sensor receives the light passing through the facet. The use of an optical sensor as a separate component is suitable for all or part of the optical sensor selected from the group consisting of the first optical sensor and the second optical sensor.

[0111] As an alternative to a separate-component optical sensor, all or part of the optical sensor can be integrated with the chip. For example, examples of optical sensors that interfere with ridge waveguides on chips constructed from silicon-on-insulator wafers can be found in Optics Express Vol.15, No.21, 13965 - 13971 (2007); U.S. Patent No. 8,093,080 issued on January 10, 2012; U.S. Patent No. 8,242,432 issued on August 14, 2012; and U.S. Patent No. 6,108,472 issued on August 22, 2000, all of which are hereby incorporated by reference in their entirety. The use of an optical sensor integrated with the chip is suitable for all or part of the optical sensor selected from the group consisting of the first optical sensor and the second optical sensor.

[0112] The electronic device 62 applicable to the LIDAR system includes, but is not limited to, an analog electric circuit, a digital electric circuit, a processor, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a computer, a microcomputer, or a controller including or composed of a combination suitable for performing the above-described operation, monitoring, and control functions. In some examples, the controller has access to a memory including instructions executed by the controller during execution of the operation, control, and monitoring functions. Although the electronic device is shown as a single part in a single location, these can include a plurality of different parts that are independent of each other and / or are arranged in different locations. Also, as described above, all or part of the disclosed electronic device may be included on a chip including an electronic device integrated with the chip.

[0113] The components on the LIDAR chip can be fully or partially integrated with the LIDAR chip. For example, the integrated optical components can include or consist of a part of the wafer from which the LIDAR chip is fabricated. The wafer that can function as a platform for the LIDAR chip can include multiple material layers. At least a part of different layers can be of different materials. As an example, a silicon-on-insulator wafer including an embedded layer 300 between a substrate 302 and an optical transmission medium 304 is shown in FIG. 4. The integrated on-chip components can be formed by using etching and masking techniques to define the features of the components in the optical transmission medium 304. For example, a slab 318 defining a waveguide and a stop recess can be formed in a desired region of the wafer using different etchings of the wafer. As a result, the LIDAR chip can include a part of the wafer, and each of the integrated on-chip components can include or consist of a part of the wafer. Further, the integrated on-chip components can be configured such that an optical signal traveling through the component travels through one or more of the layers originally included in the wafer. For example, the waveguide in FIG. 4 guides an optical signal from the wafer through the optical transmission medium 304. The integrated components can optionally include other materials of the materials present on the wafer. For example, the integrated components can include a reflective material and / or a cladding.

[0114] Numerical notations such as first, second, third, etc. are used to distinguish different features and components and do not indicate the order or presence of features denoted by smaller numerical values. For example, a second component can be present without a first component being present, and / or a third step can be performed before a first step. The optical signals disclosed above each include, consist of, or are essentially composed of light from the optical signals before the optical signals are derived. For example, an incident LIDAR signal includes, consists of, or is essentially composed of light from the LIDAR input signal.

[0115] LIDAR systems are disclosed as using composite signals such as composite data signals, but LIDAR systems can also use actual signals. As a result, the mathematical transformation can be an actual transformation, and components related to the generation and use of orthogonal components can be removed from the LIDAR system. As a result, the LIDAR system can use a single signal combiner. Additionally or alternatively, a single optical sensor can replace each of the balanced detectors.

[0116] Those skilled in the art will readily conceive of other embodiments, combinations, and modifications of the present invention in view of this teaching. Accordingly, the present invention should be limited only by the following claims, which, in conjunction with the above specification and the accompanying drawings, include all such embodiments and modifications.

Claims

1. An imaging system, wherein the imaging system is Each photon circuit chip includes a plurality of cores, each containing one optical switch and a plurality of alternative waveguides, wherein the optical switch in each core is configured to guide an outgoing optical signal to any one of the alternative waveguides, the alternative waveguide to which the outgoing optical signal is guided is an active waveguide; Each LIDAR core is configured such that the active waveguide receives the incident LIDAR signal and simultaneously outputs the outgoing LIDAR signal from the active waveguide; The incident LIDAR signal includes light from the outgoing LIDAR signal that is emitted from the imaging system and returned to the LIDAR system; Each core includes an optical divider positioned along an active waveguide and configured to extract from the active waveguide a portion of the output LIDAR signal that serves as a reference signal and a portion of the input LIDAR signal that serves as a comparison signal; Each core includes a signal coupler configured to combine light from the reference signal and light from the comparison signal to generate a composite signal that pulsates at a pulsating frequency; and The electronic device uses the pulsation frequency of the composite signal generated by the core to calculate the radial velocity and / or distance between one or more objects located outside the imaging system and the imaging system. Imaging system.

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

3. The imaging system according to claim 1, wherein the divider is one of a plurality of dividers included in each of the cores, and one of the signal dividers is arranged along each of the alternative waveguides.

4. The electronic device converts the composite signal into an electrical data signal. The imaging system according to claim 3, wherein the electrical multiplexer is configured to communicate with a plurality of different first data lines, receive an electrical data signal from one of the first data lines, and output the electrical data signal on a common data line.

5. The imaging system according to claim 4, wherein the first data line on which the electrical multiplexer receives the electrical data signal changes in response to a change in the alternative waveguide on which the output LIDAR signal is induced.

6. The imaging system according to claim 5, wherein the electronic device includes an analog-to-digital converter that receives the electrical data signal from the common data line.

7. The imaging system according to claim 1, wherein the optical switch receives the outgoing LIDAR signal from a utility waveguide, and the signal divider is arranged along the utility waveguide so that a portion of the outgoing LIDAR signal functioning as the reference signal is extracted from the utility waveguide, and a portion of the incident LIDAR signal functioning as the comparison signal is extracted from the utility waveguide.

8. The imaging system according to claim 7, wherein the LIDAR chip is configured such that the LIDAR signals emitted from each core are output from the LIDAR chip and function as LIDAR output signals, and the lens receives LIDAR output signals from different cores.

9. The imaging system according to claim 3, wherein the electronic device converts the composite signal into an electrical data signal, and the electrical data signal is an electrical representation of the composite signal.

10. The imaging system according to claim 9, wherein a plurality of different data lines are configured to receive the electrical data signal, and the data line receiving the electrical data signal changes in response to a change in the alternative waveguide from which the output LIDAR signal is induced.

11. The imaging system according to claim 10, wherein electrical data signals transmitted on different data lines are each associated with different channels, and a common data line receives the electrical data signals from the different data lines, thereby transmitting the electrical data signals associated with different channels continuously on the common data line.

12. The imaging system according to claim 11, wherein the electrical multiplexer is configured to communicate with the data line and output the electrical data signal on the common data line.

13. The imaging system according to claim 11, wherein the common data line is directly connected to each of the different data lines at a node.

14. The imaging system according to claim 13, wherein each of the cores includes a reference waveguide for transmitting the reference signal, and optical attenuators are arranged along each of the reference waveguides.

15. The imaging system according to claim 13, wherein the electronic device operates the attenuator so that a portion of the reference signal transmitted over different reference waveguides is attenuated, but another portion of the reference signal transmitted over different reference waveguides is not attenuated.

16. The imaging system according to claim 13, wherein the reference signal in each portion of the reference signal that is attenuated is attenuated in response to the fact that the reference signal is not coupled with the comparison signal.

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