Identification of chirp rate

Abstract

A LIDAR system includes a signal splitter configured to split a common optical signal into a first optical signal and a second optical signal. The system also includes a signal combiner configured to combine light from the first light signal and light from the second light signal to form a combined signal that is beat-oscillated at a beat frequency. The system also includes electronics including a beat frequency identifier configured to identify a beat frequency of the combined signal. The electronic device also includes a chirp rate generator configured to calculate a chirp rate of the common optical signal from a beat frequency of the combined signal.

Description

[0001] Related Applications

[0002] This application is a continuation of U.S. Patent Application Serial No. 17 / 970,508, filed on October 20, 2022, titled "Identification of Chirp Rates", the entire content of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to optical devices. In particular, the present invention relates to imaging systems and LIDAR systems that use signals with chirped frequencies. Background Art

[0004] There is an increasing commercial demand for LIDAR systems that can be deployed in applications such as ADAS (Advanced Driver Assistance Systems) and AR (Augmented Reality). These LIDAR systems typically output a system output signal that is reflected by an object located outside the LIDAR system. At least a portion of the reflected light signal returns to the LIDAR system. The LIDAR system directs the received light signal to an optical sensor, which converts the light signal into an electrical signal. Electronic devices can use the output of the optical sensor to quantify LIDAR data that indicates the radial velocity and / or distance between the object and the LIDAR system.

[0005] Many LIDAR systems chirp the frequency of the system output signal at a target chirp rate in order to accurately measure data. However, the actual chirp rate achieved is typically different from the target chirp rate. This difference between the target chirp rate and the actual chirp rate is a major source of error in LIDAR data. Therefore, there is a need for a LIDAR system that corrects for the difference between the target chirp rate and the actual chirp rate. Summary of the Invention

[0006] A LIDAR system includes a signal splitter configured to split a common optical signal into a first optical signal and a second optical signal. The system also includes a signal combiner configured to combine the light from the first optical signal and the light from the second optical signal to form a combined signal that oscillates at a beat frequency. The system also includes electronics that include a beat frequency identifier configured to identify the beat frequency of the combined signal. The electronics also include a chirp rate generator configured to calculate the chirp rate of the common optical signal based on the beat frequency of the combined signal.

[0007] A method of operating a LIDAR system includes splitting a common optical signal into a first optical signal and a second optical signal. The method further includes combining light from the first optical signal and light from the second optical signal to form a combined signal that beats at a beat frequency. The method further includes identifying the beat frequency of the combined signal and calculating a chirp rate of the common optical signal based on the calculated beat frequency of the combined signal. Description of the Drawings

[0008] Figure 1A An imaging system including a chip having a photonic circuit is shown.

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

[0010] Figure 1C Another embodiment of an imaging system including a photonic circuit chip is shown.

[0011] Figure 2 is a schematic diagram of an imaging system including a plurality of different cores on a chip.

[0012] Figures 3A to 3B Shows a suitable use as according to Figure 1A and Figure 1B An example of a signal processor constructed in a LIDAR system is shown. Figure 3A is a schematic diagram of an example of a suitable optical-to-electrical assembly for a signal processor.

[0013] Figure 3B Provides a schematic diagram of the relationship between an electronic device and Figure 3A the optical-to-electrical conversion component.

[0014] Figure 3C Shows the frequency of the signal output from the imaging system over time.

[0015] Figure 3D Provides a schematic diagram of the relationship between an electronic device and Figure 3A the optical-to-electrical conversion component.

[0016] Figure 3E is Figure 3A Another schematic diagram of the relationship between the sensor in the optical-to-electrical conversion component and the electronic device in the LIDAR system.

[0017] Figures 3F to 3H Shows a suitable use as Figures 1A to 1C An example of a chirp rate identifier in an imaging system is shown. Figure 3F is a schematic diagram of an example of a suitable optical-to-electrical conversion component for a chirp rate identifier.

[0018] Figure 3G Provides a schematic diagram of the relationship between an electronic device and Figure 3F the optoelectronic conversion component.

[0019] Figure 3H Shows Figure 3B a schematic diagram, which is modified to include Figure 3G the chirp rate generator shown.

[0020] Figure 3I Shows Figure 3D a schematic diagram, which is modified to include Figure 3G the chirp rate generator shown.

[0021] Figure 3J Shows Figure 3E a schematic diagram, which is modified to include Figure 3G the chirp rate generator shown.

[0022] Figure 4 is a cross-section of a silicon-on-insulator wafer.

[0023] Figure 5A and Figure 5B show an example of an optical switch including a cascaded Mach-Zehnder interferometer. Figure 5A is a top view of the optical switch.

[0024] Figure 5B is Figure 5A a cross-section of the optical switch shown in Figure 5A taken along the line marked B in

[0025] Figure 6 Shows Figure 2 a LIDAR system, which is modified to have a plurality of signal directors, each of which receives a LIDAR output signal from a different core.

[0026] Figure 7 Shows Figure 2 a LIDAR system, in which the light source is located outside the chip.

[0027] Figure 8 Shows a part of a LIDAR chip including a reference waveguide used in combination with a beam dump. Detailed Description

[0028] The imaging system includes a chirp rate identifier that can be operated by electronics to identify the chirp rate of an optical signal output from the imaging system. The identified chirp rate can be used to calculate LIDAR data that indicates the radial velocity and / or distance between the imaging system and an object located outside the imaging system. Using the identified chirp rate instead of a target chirp rate to calculate the LIDAR data reduces errors in the LIDAR data.

[0029] Figure 1A is a schematic diagram of a part of a LIDAR system including LIDAR chip 2. Figure 1A A top view of a part including LIDAR chip 2. The LIDAR chip can be a semiconductor chip, such as a silicon-on-insulator chip. The LIDAR chip includes a LIDAR core 4. The LIDAR core 4 includes a photonic integrated circuit.

[0030] The LIDAR core 4 can include a light source 10 that outputs an outgoing LIDAR signal. The LIDAR core includes a utility waveguide 12 that receives the outgoing LIDAR signal from the light source 10. The utility waveguide 12 carries the outgoing LIDAR signal to a signal director 14. The LIDAR system can include electronics that operate the signal director 14. For example, the electronics can include a director controller 15 that operates the signal director 14 to direct light from the light source output signal to any one of a plurality of different alternating waveguides 16. There are N alternating waveguides, and each alternating waveguide 16 is associated with an alternating waveguide index i, where i has a value from 1 to N. Suitable values of N include, but are not limited to, values less than 128, 64, or 32 and / or values greater than 2, 8, or 16. In one example, N is between 2 and 128.

[0031] Each alternating waveguide 16 can receive the outgoing LIDAR signal from the signal director 14. When any one of the alternating waveguides 16 receives the outgoing LIDAR signal, the alternating waveguide 16 acts as an active waveguide and carries the outgoing LIDAR signal to a port 18 through which the outgoing LIDAR signal can leave the LIDAR chip and act as a LIDAR output signal. Thus, the outgoing LIDAR signal is output from the active waveguide.

[0032] The optical signal obtained by directing the outgoing LIDAR signal to the alternating waveguide 16 having the alternating waveguide index i is classified as an optical signal carrying channel (C i )). Thus, each LIDAR output signal is associated with a different one of the alternating waveguide indices i = 1 to N. For example, in Figure 1A , the path of the LIDAR output signal carrying the channel with the alternating waveguide index 2 is labeled C 2For illustrative purposes, the LIDAR system is shown as generating three LIDAR output signals (N = 3) labeled C 1 through C 3 Each of the different LIDAR output signals may carry a different channel, however, each of the different channels may carry a selection of the same (one or more) wavelengths or a selection of substantially the same (one or more) wavelengths.

[0033] The LIDAR input signal returns to the LIDAR chip such that the LIDAR input signal carrying channel C i enters the alternating waveguide 16 associated with the same alternating waveguide index i. Thus, LIDAR input signals carrying different channels are directed to different alternating waveguides. The portion of the LIDAR input signal entering the alternating waveguide 16 acts as the incoming LIDAR signal. Thus, the alternating waveguide receiving the incoming LIDAR signal may direct the outgoing LIDAR signal while also directing the incoming LIDAR signal in the opposite direction. The alternating waveguide 16 receiving the incoming LIDAR signal carries the incoming LIDAR signal to the signal director 14. The signal director 14 outputs the incoming LIDAR signal on the utility waveguide 12.

[0034] The utility waveguide 12 carries the incoming LIDAR signal to the 2x2 splitter 24, which moves a portion of the incoming LIDAR signal from the utility waveguide 12 onto the comparison waveguide 26 as a comparison signal. The comparison signal includes light from the outgoing LIDAR signal that leaves the imaging system, is reflected by an object located outside the imaging system, and returns to the imaging system. The comparison waveguide 26 carries the comparison signal to the signal processor 28 for further processing. Suitable splitters 24 include, but are not limited to, optical couplers, y-junctions, and MMIs. In some cases, the splitter 24 is configured such that the power of the incoming LIDAR signal is evenly or substantially evenly distributed between the utility waveguide 12 and the comparison waveguide 26.

[0035] The utility waveguide 12 also carries the outgoing LIDAR signal to the splitter 24. The splitter 24 moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto the reference waveguide 32 as a reference signal. The reference waveguide 32 carries the reference signal to the signal processor 28 for further processing.

[0036] As will be described in more detail below, the signal processor 28 combines the comparison signal with the reference signal to form a composite signal that carries LIDAR data for a sample region in the field of view. Thus, 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) for the sample region.

[0037] The LIDAR chip may include a chirp branch for identifying the chirp rate of an outgoing LIDAR signal. Thus, the chirp branch can identify the chirp rate of the signal output from the LIDAR system to generate LIDAR data, such as the system output signal. The chirp branch includes a signal splitter 66 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto a common waveguide 68. The coupled portion of the outgoing LIDAR signal acts as a common signal. The common waveguide 68 transmits the common signal to the chirp rate identifier 70. Examples of suitable signal splitters 66 include, but are not limited to, directional couplers, Y-junctions, and MMIs.

[0038] The electronic device 62 may include a light source controller 63. The light source controller 63 can operate the light source such that the outgoing LIDAR signal and thus the system output signal has a particular frequency-versus-time relationship pattern. For example, the light source controller 63 can operate the light source such that the outgoing LIDAR signal and thus the system output signal has different chirp rates during different data periods.

[0039] The light source controller 63 can adjust the voltage and / or current applied to the light source to achieve a desired frequency-versus-time relationship pattern in the optical signal including light from the outgoing LIDAR signal. When the light source 10 is a gain element or a laser chip, the light source controller 63 can change the frequency of the outgoing LIDAR signal by changing the current level applied through the gain element or the laser cavity. Additionally or alternatively, the light source 10 can include a modulator (not shown) configured to modulate the frequency of the outgoing LIDAR signal. When the light source 10 includes a modulator, the light source controller 63 can operate the modulator to achieve a desired frequency-versus-time relationship pattern in the optical signal including light from the outgoing LIDAR signal.

[0040] The LIDAR chip can optionally include a control branch for controlling the operation of the light source 10. For example, the control branch can provide a feedback loop that the light source controller 63 uses to operate the light source such that the outgoing LIDAR signal has a desired frequency-versus-time relationship pattern.

[0041] The control branch includes a directional coupler 71 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto a control waveguide 72. The coupled portion of the outgoing LIDAR signal acts as a tapped signal. Although Figure 1A the directional coupler 71 is shown moving a portion of the outgoing LIDAR signal onto the control waveguide 72, other signal taps can be used to move a portion of the outgoing LIDAR signal from the utility waveguide 12 onto the control waveguide 72. Examples of suitable signal taps include, but are not limited to, Y-junctions and MMIs.

[0042] The control waveguide 72 carries the tapped signal to the feedback system 73. The feedback system 73 may include one or more optical sensors (not shown) that convert the optical signal carried by the feedback system 73 into an electrical signal output from the feedback system 73. The light source controller 63 may receive the electrical signal output from the feedback system 73. During operation, the light source controller 63 may adjust the frequency of the outgoing LIDAR signal in response to the output of the electrical signal output from the feedback system 73. Examples of suitable configurations and operations of the feedback system 73 and the light source controller 63 are provided in: U.S. Patent Application Serial No. 16 / 875,987, filed May 16, 2020, entitled "Monitoring Signal Chirp in LIDAR Output Signals", the entire content of which is incorporated herein; and U.S. Patent Application Serial No. 17 / 244,869, filed April 29, 2021, entitled "Reducing Size of LIDAR System Control Assemblies", the entire content of which is incorporated herein.

[0043] Although Figure 1A the electronic device 62 is shown as a component separate from the (one or more) signal processors 28, a portion of the electronic device may be included in each of the (one or more) signal processors 28.

[0044] In Figure 1A it, the incoming LIDAR signal passes through the signal director 14. The signal director 14 may be a source of optical loss. This source of optical loss can be eliminated by moving a portion of the incoming LIDAR signal that serves as a comparison signal to the comparison waveguide 26 before the incoming LIDAR signal reaches the signal director 14. For example, Figure 1B is shown modified such that the separator 24 is positioned along each alternate waveguide 16 between the signal director 14 and the port 18 Figure 1A of the LIDAR chip. The signal separator extracts a portion of the outgoing LIDAR signal from the alternate waveguide to serve as a reference signal and also extracts at least a portion of the incoming LIDAR signal from the alternate waveguide to serve as a comparison signal. Thus, the comparison signal is extracted from the alternate waveguide 16 before the incoming LIDAR signal reaches the signal director 14.

[0045] Figure 1A and Figure 1B The comparison of Figure 1B shows that the LIDAR chip of Figure 1AThe LIDAR chip requires more signal processors 28. As will be apparent below, increasing the number of required signal processors 28 increases the number of analog-to-digital converters required for the LIDAR system. However, a common signal processor 28 can be used to reduce the number of analog-to-digital converters. For example, Figure 1C shows a LIDAR chip that is modified such that each comparison waveguide 26 carries one of the comparison signals to a common signal processor 74 Figure 1B . In addition, each reference waveguide 32 carries one of the reference signals to the common signal processor 74.

[0046] The LIDAR system can include a LIDAR chip having a plurality of LIDR cores 4 on a support 77. For example, Figure 2 shows a LIDAR chip including a plurality of different cores. Each core is labeled core k , where k represents the core index k. Each LIDAR core can be constructed in the manner disclosed in the context of Figures 1A to 1C , or can have an alternative construction. Each LIDAR core outputs a different LIDAR output signal. The LIDAR output signal output from the core labeled core k can be represented by S k,i , where i represents the alternate waveguide index. Thus, S k,i is a function of the alternate waveguide index i and the core index k. For example, the LIDAR output signal represented by S k,i is output from core k and received by the alternate waveguide index i. Thus, the LIDAR output signal represented by S k,i is output from core k and carries channel C i .

[0047] The LIDAR system can optionally include an optical component assembly 75 that receives the LIDAR output signals from different cores and outputs a system output signal, each system output signal including light from a different one of the LIDAR output signals, consisting of or substantially consisting of light from a different one of the LIDAR output signals. The optical component assembly 75 can be operated by a component controller 280 to direct the system output signals to different sample regions in the LIDAR system field of view.

[0048] Figure 2An optical component assembly 75 is shown that includes a signal director 76 that receives each LIDAR output signal. The signal director 76 changes the direction of travel of at least a portion of the LIDAR output signals and outputs each LIDAR output signal as a redirected LIDAR output signal. Suitable signal directors 76 include, but are not limited to, convex lenses and concave mirrors. The optical component assembly 75 includes one or more beam directors 78 that receive the redirected LIDAR output signals output from the signal director 76 as system output signals. The direction in which the system output signals travel away from the LIDAR system is marked as d in Figure 2 and is labeled d 2 . The component controller 280 can operate the one or more beam directors 78 to steer each system output signal to a different sample region in the field of view. As can be clearly seen from the arrows labeled A and B in Figure 2 , the one or more beam directors 78 can be configured such that the component controller 280 can steer the system output signals in one or two dimensions. Accordingly, the one or more beam directors 78 can be used as a beam steering mechanism operated by electronics to steer the system output signals within the field of view of the LIDAR system. Suitable beam directors 78 include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), gratings, and actuated gratings. In some cases, the signal director 76 and / or the one or more beam directors 78 are configured to operate on the system output signals such that the system output signals are collimated or substantially collimated as they travel away from the LIDAR system. Additionally or alternatively, the LIDAR system can include one or more optical collimators (not shown) that operate on the LIDAR output signals, the redirected LIDAR output signals, and / or the system output signals such that the system output signals are collimated or substantially collimated as they travel away from the LIDAR system.

[0049] The system output signal can be reflected by an object located outside the LIDAR system. All or a portion of the reflected light from the system output signal can return to the LIDAR system as a system return signal. Each system return signal is received at one or more beam directors 78. One or more beam directors 78 output at least a portion of each system return signal as a return signal. Each return signal is received at a signal director 76. The signal director 76 outputs at least a portion of each return signal as a LIDAR input signal. Each different LIDAR input signal is received by a different one of the cores 4. Each LIDAR input signal comprises light from or consists of light from a LIDAR output signal output from the core that receives the LIDAR input signal. Additionally, the LIDAR input signals received at the alternating waveguides comprise light from or consist of light from a LIDAR output signal output from the same alternating waveguide.

[0050] One or more signal directors 76 can change the direction in which the LIDAR output signal travels away from the one or more signal directors 76 such that the direction of the LIDAR output signal is different from the resulting redirected LIDAR output signal. In some cases, the one or more signal directors 76 are selected such that all or a portion of the redirected LIDAR output signal travels away from the one or more signal directors 76 in non-parallel directions. For example, in Figure 2 one or more signal directors 76 are lenses and each different LIDAR output signal impinges on the lens at a different angle of incidence. Accordingly, the redirected LIDAR output signals each travel away from the signal director 76 in different directions. Additionally, the redirected LIDAR output signals travel away from the signal director 76 in non-parallel directions. It can be seen from Figure 2 that different directions of the system output signal can result in the system output signal traveling away from the LIDAR system in different directions. In some cases, the system output signal travels away from the LIDAR system in non-parallel directions.

[0051] Operating the signal director 14 on the core can change the location at which the one or more signal directors 76 receive the LIDAR output signal and can correspondingly change the direction in which the system output signal originating from that core travels away from the LIDAR system. For example, Figure 2 the dashed lines in 1 illustrate the result of operating the signal director 14 on the core such that the core outputs the LIDAR output signal represented by S k,i+1 instead of the LIDAR output signal represented by S k,i . It can be seen from Figure 2It can be clearly seen that this operation of the signal director 14 changes the direction in which the system output signal output from the core 1 travels away from the LIDAR system. Accordingly, the electronics 62 associated with different cores can operate the associated signal director 14 to steer the system output signal within the LIDAR system's field of view. For example, the director controller 14 associated with different cores can operate the associated signal director 14 to steer the system output signal within the LIDAR system's field of view. Accordingly, the electronics 62 associated with different cores can operate the associated signal director 14 to steer the system output signal within the LIDAR system's field of view and / or the component controller 280 can operate one or more beam directors 78 to steer the system output signal within the LIDAR system's field of view. Suitable methods for operating the signal director 14 and / or one or more beam directors 78 on different cores to steer the system output signal to different sample regions within the LIDAR system's field of view are disclosed in U.S. Patent Application Serial No. 17 / 580,623, entitled "Imaging System Having Multiple Cores," filed on January 20, 2022, the entire disclosure of which is incorporated herein by reference.

[0052] The optical component assembly 75 can have a configuration other than Figure 2 the configuration shown. For example, one or more beam directors 78 can be located between the signal director 76 and the LIDAR chip. Additionally, 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 LIDAR output signal and / or other signals derived from the LIDAR output signal and / or to collimate light included in the LIDAR output signal.

[0053] The wavelengths of the LIDAR output signals output from different cores can be the same or different. Accordingly, the light sources on different cores can be configured to output outgoing optical signals, each having a different, the same, or substantially the same wavelength selection. Accordingly, the wavelength selections in different system output signals can be different, the same, or substantially the same.

[0054] Although Figure 2 four cores on the LIDAR chip are shown, the LIDAR chip can include one, two, or more than two cores. Suitable numbers of cores on the LIDAR chip include, but are not limited to, numbers greater than or equal to 2, 4, or 6 and / or less than 32, 64, or 128.

[0055] Figures 3A to 3B is shown as being suitable for use as in accordance with Figure 1A and Figure 1BAn example of a signal processor of the signal processor 28 in the constructed LIDAR system. The signal processor includes a photoelectric conversion component configured to convert an optical signal into an electrical signal. Figure 3A Is a schematic diagram of an example of a suitable photoelectric conversion component, which includes a first separator 200 that distributes the comparison signal received from the comparison waveguide 26 onto the first comparison waveguide 204 and the second comparison waveguide 206. The first comparison waveguide 204 carries the first part of the comparison signal to the optical signal combiner 211. The second comparison waveguide 206 carries the second part of the comparison signal to the second optical signal combiner 212.

[0056] Figure 3A The signal processor further includes a second separator 202 that distributes 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 carries the first part of the reference signal to the optical signal combiner 211. The second reference waveguide 208 carries the second part of the reference signal to the second optical signal combiner 212.

[0057] The second optical signal combiner 212 combines the second part of the comparison signal and the second part of the reference signal into a second composite signal. Due to the frequency difference between the second part of the comparison signal and the second part of the reference signal, the second composite signal beats between the second part of the comparison signal and the second part of the reference signal. The first composite signal and the second composite signal are both examples of composite signals.

[0058] The second optical signal combiner 212 also splits the resulting second composite signal onto the first auxiliary detector waveguide 214 and the second auxiliary detector waveguide 216. The first auxiliary detector waveguide 214 carries the first part of the second composite signal to the first auxiliary optical sensor 218, which converts the first part of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 216 carries the second part of the second composite signal to the second auxiliary optical sensor 220, which converts the second part of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0059] In some cases, the second optical signal combiner 212 splits the second composite signal such that the portion of the comparison signal included in the first part of the second composite signal (i.e., the portion of the second part of the comparison signal) is phase-shifted by 180° relative to the portion of the comparison signal in the second part of the second composite signal (i.e., the portion of the second part of the comparison signal), but the portion of the reference signal in the second part of the second composite signal (i.e., the portion of the second part of the reference signal) is not phase-shifted relative to the portion of the reference signal in the first part of the second composite signal (i.e., the portion of the second part of the reference signal). Alternatively, the second optical signal combiner 212 splits the second composite signal such that the portion of the reference signal in the first part of the second composite signal (i.e., the portion of the second part of the reference signal) is phase-shifted by 180° relative to the portion of the reference signal in the second part of the second composite signal (i.e., the portion of the second part of the reference signal), but the portion of the comparison signal in the first part of the second composite signal (i.e., the portion of the second part of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second part of the second composite signal (i.e., the portion of the second part of the comparison signal). Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0060] The first optical signal combiner 211 combines the first part of the comparison signal and the first part of the reference signal into a first composite signal. Due to the frequency difference between the first part of the comparison signal and the first part of the reference signal, the first composite signal beats between the first part of the comparison signal and the first part of the reference signal.

[0061] The optical signal combiner 211 also splits the first composite signal onto a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 carries the first part of the first composite signal to a first optical sensor 223, which converts the first part of the second composite signal into a first electrical signal. The second detector waveguide 222 carries the second part of the second composite signal to a second optical sensor 224, which converts the second part of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0062] In some cases, the optical signal combiner 211 splits the first composite signal such that the portion of the comparison signal included in the first part of the composite signal (i.e., the portion of the first part of the comparison signal) is phase-shifted by 180° relative to the portion of the comparison signal in the second part of the composite signal (i.e., the portion of the first part of the comparison signal), but the portion of the reference signal in the first part of the composite signal (i.e., the portion of the first part of the reference signal) is not phase-shifted relative to the portion of the reference signal in the second part of the composite signal (i.e., the portion of the first part of the reference signal). Alternatively, the optical signal combiner 211 splits the composite signal such that the portion of the reference signal in the first part of the composite signal (i.e., the portion of the first part of the reference signal) is phase-shifted by 180° relative to the portion of the reference signal in the second part of the composite signal (i.e., the portion of the first part of the reference signal), but the portion of the comparison signal in the first part of the composite signal (i.e., the portion of the first part of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second part of the composite signal (i.e., the portion of the first part of the comparison signal).

[0063] When the second optical signal combiner 212 splits the second composite signal such that the portion of the comparison signal in the first part of the second composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second part of the second composite signal, the optical signal combiner 211 also splits the composite signal such that the portion of the comparison signal in the first part of the composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second part of the composite signal. When the second optical signal combiner 212 splits the second composite signal such that the portion of the reference signal in the first part of the second composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second part of the second composite signal, the optical signal combiner 211 also splits the composite signal such that the portion of the reference signal in the first part of the composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second part of the composite signal.

[0064] Examples of suitable optical signal combiners 211 and second optical signal combiners 212 are multimode interference (MMI) devices, such as 2×2 MMI devices. Other suitable optical signal combiners that can be used as the optical signal combiner 211 and the second optical signal combiner 212 include, but are not limited to, adiabatic splitters and directional couplers. In some cases, the functions of the shown optical signal combiners are performed by more than one optical component or a combination of optical components.

[0065] The first reference waveguide 210 and the second reference waveguide 208 are configured to provide a phase shift between a first portion of the reference signal and a second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 may be configured to provide a 90-degree phase shift between a first portion of the reference signal and a second portion of the reference signal. For example, one reference signal portion may be an in-phase component, while the other reference signal portion may be a quadrature component. Thus, one of the reference signal portions may be a sine function, while the other reference signal portion may be a cosine function. In one example, the first reference waveguide 210 and the second reference waveguide 208 are configured such that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Thus, the portion of the reference signal in the second composite signal is phase-shifted relative to the portion of the reference signal in the first composite signal. However, the portion of the comparison signal in the first composite signal is not phase-shifted relative to the portion of the comparison signal in the second composite signal.

[0066] The first optical sensor 223 and the second optical sensor 224 may be connected as a balanced detector, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 may also be connected as a balanced detector. The (one or more) balanced detectors act as optical sensors that convert optical signals into electrical signals. Figure 3B A schematic diagram of the relationship between the electronic device 62, the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220 is provided. The symbol of a 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 may have other configurations. In some cases, Figure 3B all of the components shown in the schematic diagram of are included on the LIDAR chip. In some cases, Figure 3B the components shown in the schematic diagram of are distributed between the LIDAR chip and the electronic device 62 located outside the LIDAR chip.

[0067] The electronic device 62 connects the first optical sensor 223 and the second optical sensor 224 as a first balanced detector 225, and connects the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 as a second balanced detector 226. In particular, the first optical sensor 223 and the second optical sensor 224 are connected in series. In addition, 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 a first data line 228 that carries the output from the first balanced detector as a first data signal. The series connection in the second balanced detector communicates with a second data line 232 that carries the output from the second balanced detector as a 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 carrying a representation of a first composite signal, and the second data signal is an electrical data signal carrying a representation of a second composite signal. Thus, the first data signal includes contributions from a first waveform and a 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, but 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 a reference signal that is phase-shifted with respect to a different portion of the reference signal included in the first data signal. In addition, the second data signal includes a portion of a comparison signal that is in-phase with a different portion of the comparison signal included in the first data signal. The first data signal and the second data signal beat due to beating between the comparison signal and the reference signal, i.e., beating in the first composite signal and the second composite signal.

[0068] The electronic device 62 includes a data processor 237 configured to generate LIDAR data. The data processor 237 includes a beat frequency identifier 238 configured to identify the beat frequency of the composite signal from the first data signal and the second data signal. The beat frequency identifier 238 receives the first data signal and the second data signal. Since the first data signal is the in-phase component and the second data signal is its 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 part of the complex data signal and the second data signal is the imaginary part of the complex data signal.

[0069] The data processor 237 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 form to a digital form and outputs a first digital data signal. The beat frequency identifier 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 form to a digital form and outputs a second digital data signal. The first digital data signal is a digital representation of the first data signal, and the second digital data signal is a digital representation of the second data signal. Thus, the first digital data signal and the second digital data signal together act as a complex signal, where the first digital data signal acts as the real part of the complex signal and the second digital data signal acts as the imaginary part of the complex data signal.

[0070] The beat frequency identifier 238 includes a mathematical transformer 268 that receives the complex data signal. For example, the mathematical transformer 268 receives the first digital data signal from the first analog-to-digital converter (ADC) 264 as an input and also receives the second digital data signal from the first analog-to-digital converter (ADC) 266 as an input. The mathematical transformer 268 can be configured to perform a mathematical transformation on the complex signal to convert from the time domain to the frequency domain. The mathematical transformation can be a complex transformation, such as a complex fast Fourier transform (FFT). The complex transformation (such as a complex fast Fourier transform (FFT)) provides a clear solution for comparing the frequency shift of the signal relative to the system output signal.

[0071] The mathematical transformer 268 can include a peak finder (not shown) that is configured to identify peaks in the output of the mathematical transformer 268. The peak finder can be configured to identify any frequency peaks associated with the reflection of the system output signal by one or more objects located outside the LIDAR system. For example, the frequency peaks associated with the reflection of the system output signal by one or more objects located outside the LIDAR system can fall within a frequency range. The peak finder can identify the frequency peaks within the frequency range associated with the reflection of the system output signal by one or more objects located outside the LIDAR system. The frequency of the identified frequency peaks represents the beat frequency of the complex signal.

[0072] The data processor 237 includes a LIDAR data generator 270 that receives the beat frequency of the complex signal from the peak finder. The LIDAR data generator 270 processes the beat frequency of the complex signal to generate LIDAR data (the distance and / or radial velocity between the reflecting object and the LIDAR chip or LIDAR system).

[0073] Figure 3CAn example of the relationship between the frequency, time, cycle, and data period of the system output signal is shown. The fundamental frequency (f o ) of the system output signal can be the frequency of the system output signal at the start of the cycle.

[0074] Figure 3C Shows the frequency-versus-time relationship patterns of two cycle sequences labeled cycle j and cycle j+1 , where j represents the cycle index. In some cases, the frequency-versus-time pattern repeats in each cycle, as Figure 3C shown. The cycles shown do not include a repositioning period and / or the repositioning period is not located between cycles. Thus, Figure 3C shows the results of a continuous scan, where the steering of the system output signal is continuous.

[0075] Each cycle includes K data periods, each data period is associated with a period index n and labeled DP n . In the Figure 3C example, each cycle includes three data periods, labeled DP n , where n = 1, 2, and 3. In some cases, as Figure 3C shown, the frequency-versus-time pattern is the same for corresponding data periods in different cycles. Corresponding data periods are data periods with the same period index. Thus, each data period DP 1 can be considered a corresponding data period, and the associated frequency-versus-time pattern is the same in Figure 3C . At the end of the cycle, the light source controller 63 restores the frequency to the same frequency level as when it started the previous cycle.

[0076] During data period DP 1 and data period DP 2 , the light source controller 63 operates the light source such that the frequency of the system output signal changes at a linear target chirp rate tα n , where n represents the period index. Figure 3C shows the calculation of the target chirp rate for one of the data periods labeled DP 1 . For example, the duration of the data period is labeled τ and the magnitude of the frequency change during the data period is labeled B. The target chirp rate tα 1 can be determined according to tα 1 = Β / τ.

[0077] The target chirp rate may be different for different data periods. For example, in Figure 3C , the direction of the target chirp rate during data period DP 1 is different from that during data period DP2 The direction of the target chirp rate during is opposite. However, the data period DP 1 The magnitude of the target chirp rate during is the same as that of the data period DP 2 The magnitude of the target chirp rate during. Therefore, tα 1 =-tα 2 .

[0078] The electronic device 62 is configured to provide the same target chirp rate for data periods having the same cycle index. For example, the target chirp rate for each data period associated with the cycle index n = 1 is equal to α 1 . However, as time passes and the number of cycles increases, the resulting actual chirp rate (α n ) becomes less reliable. When calculating the LIDAR data for each sample region using the target chirp rate, the difference between the actual chirp rate (α n ) and the target chirp rate (tα n ) will be a source of error for the LIDAR data.

[0079] Figure 3C Sample regions are marked, each associated with a sample region index k and labeled as Rn k . Figure 3C Sample region Rn is marked k and Rn k+1 . Each sample region is illuminated by the system output signal during the data period associated with the sample region as shown in Figure 3C . For example, sample region Rn k is illuminated by the system output signal during the data periods labeled as DP 1 to DP 3 . The sample region index k can be assigned with respect to time. For example, the sample regions can be illuminated by the system output signal in the order indicated by the index k. Therefore, sample region Rn 10 can be illuminated after sample region Rn 9 and before Rn 11 .

[0080] Different sample regions and / or different cycles can be associated with different channels. For example, each sample region can be illuminated by the system output signal carrying the same channel during each data period associated with the sample region. Additionally, different sample regions can be illuminated by the system output signal carrying a different one of the channels in the channel set. Therefore, the director controller 15 can operate the signal director 14 to direct the light from the light source output signal to a different one of the alternating waveguides in the alternating waveguide 16 when changing to a different cycle or between cycles, and / or when changing to a different sample region or between sample regions.

[0081] LIDAR systems are typically configured to provide reliable LIDAR data when an object is within an operating distance range from the LIDAR system. The operating distance range may extend from a minimum operating distance to a maximum operating distance. The maximum round trip time may be the time required for a system output signal to leave the LIDAR system, travel the maximum operating distance to an object, and return to the LIDAR system, and may be Figure 3C The symbol is τ M .

[0082] Since there is a delay between the system output signal being transmitted and returning to the LIDAR system, the composite signal does not include a contribution from the LIDAR signal before the system return signal returns to the LIDAR system. Since the composite signal requires a contribution from the system return signal in order for the beat frequency to exist, the beat frequency identifier 238 outputs the beat frequency of the composite signal generated by the system return signal returning to the LIDAR system during the data window of the data period. The data window is Figure 3C The contribution of the LIDAR signal to the composite signal will appear when the maximum operating time delay (τ M ) time. Therefore, the data window is shown as a delay from the maximum operating time (τ M ) extends to the end of the data period.

[0083] The frequency peaks in the output from the complex Fourier transform represent the beat frequencies of composite signals, each of which includes a comparison signal against a reference signal beat frame. The beat frequencies from two or more different data periods can be combined to generate LIDAR data. For example, the beat frequencies from Figure 3C DP 1 The determined beat frequency is Figure 3C DP 2 The determined beat frequency is combined to determine the LIDAR data. For example, the following equation applies during a data period where the frequency of the outgoing LIDAR signal increases during the data period, such as during Figure 3C Data period DP 1 What happens in: ub =-f d +α n τ, where f ub is the frequency provided by the mathematical converter, f d represents the Doppler frequency shift (f d =2νf c / c), where f c represents the optical frequency (f o), where c represents the speed of light, ν is the radial velocity between the reflecting object and the LIDAR system, with the direction from the reflecting object towards the chip assumed to be the positive direction, τ is the time (round-trip time) for light from the system output signal to travel to the object and back to the LIDAR system, and c is the speed of light. Additionally, α n represents the chirp rate during the data period with period index n. For example, α 1 represents the same data period DP ub that causes the mathematical transducer to provide f 1 during which the chirp rate is present. Thus, α n and f ub are associated with the same data period DP n .

[0084] The following equation applies during such a data period where the frequency of the outgoing LIDAR signal decreases, for example Figure 3C the data period DP 2 in which the following occurs: f db = -f d - α n τ, where f db is the frequency provided by the mathematical transducer (in this example, f i,LDP is determined according to DP 2 ). Additionally, α n represents the chirp rate during the data period with period index n. For example, α 2 represents the same data period DP ub that causes the mathematical transducer to provide f 2 during which the chirp rate is present. Thus, α n and f ub are associated with the same data period DP n .

[0085] In these two equations (f db = -f d - α n τ and f ub = -f d + α n τ), f d and τ are unknowns. These unknowns are obtained by solving these equations. The LIDAR data generator can calculate the radial velocity of the sample area based on the Doppler shift (ν = c * f d / (2f c )) and / or can calculate the separation distance of the sample area based on c * τ / 2. For example, when the system output signal has a frequency-versus-time relationship pattern as shown in Figure 3C , the distance (r) between the LIDAR system and an object external to the LIDAR system can be determined according to r = c(f ub-f db ) / (2(α 1 -α 2 )) and the radial velocity between the LIDAR system and the object can be calculated according to ν = c(α 2 f ub -α 1 f db ) / (2f c (α 1 -α 2 ))). Thus, the calculated chirp rate (α 1 ) and the calculated composite signal beat frequency are variables in the equations used by the LIDAR data generator to calculate LIDAR data. In addition, the LIDAR data generator 270 can combine the chirp rates (α n ) and beat frequencies from different data cycles to calculate the LIDAR data for the sample area. Since LIDAR data can be generated for each corresponding frequency pair output by the transformation, separate LIDAR data can be generated for each object in the sample area. Thus, the data processor 237 can determine more than one radial velocity and / or more than one radial separation distance based on a single sampling of a single sample area within the field of view.

[0086] Figure 3C The data cycle marked as DP 3 is optional. As described above, there are cases where there are multiple objects in the sample area. For example, during the feedback cycle for cycle 1 in DP 2 and also during the feedback cycle for cycle 2 in DP 2 , multiple frequency pairs can be matched. In these cases, it may not be clear which frequency peaks from DP 2 correspond to which frequency peaks from DP 1 . Thus, it may not be clear which frequencies need to be used together to generate the LIDAR data for the objects in the sample area. Therefore, it may be 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 area. The data cycle marked as DP 3 can be used to find the corresponding frequencies. LIDAR data can be generated for each pair of corresponding frequencies and the LIDAR data can be regarded as and / or processed as the LIDAR data for different reflecting objects in the sample area.

[0087] An example of corresponding frequency identification uses a LIDAR system where the period includes three data cycles (DP 1 , DP 2 and DP 3 ), as shown in Figure 3CWhen there are two objects in the sample area illuminated by the LIDAR output signal, the mathematical transformer 1 Output f ub Two different frequencies: f u1 and f u2 , and in DP 2 Output f db Two other different frequencies: f d1 and f d2 In this case, the possible frequency pairings are: (f d1 ,f u1 );(f d1 ,f u2 );(f d2 ,f u1 ); and (f d2 ,f du2 ). f can be calculated for each possible frequency pairing d and τ. f d Substitute each pair of values ​​of and into f 3 =-f d +α 3 τ 0 , to generate theoretical f for each possible frequency pairing 3 α 3 The value of DP 1 and DP 2 The values ​​of α used in Figure 3C In, α 3 The value of is zero. In this case, the math transformer also outputs f 3 Two values ​​of , each associated with an object in the sample area. Theoretical f 3 The value is closest to the actual f 3 The frequency pair of each of the values ​​is considered a corresponding pair. LIDAR data can be generated for each corresponding pair as described above, and the LIDAR data can be considered and / or processed as LIDAR data for a different one of the reflecting objects in the sample area. Each set of corresponding frequencies can be used in the above equation to generate LIDAR data. The generated LIDAR data will be for one of the objects in the sample area. Therefore, multiple different LIDAR data values ​​can be generated for the sample area, where each different LIDAR data value corresponds to a different one of the objects in the sample area.

[0088] Figure 1A The signal processor in receives a series of comparison signals, which carry different channels and therefore come from different sample areas. Figure 1AThe signal processor therein provides LIDAR data for a series of sample regions illuminated by the system output signals carrying different channels. The series of sample regions for which the signal processor provides LIDAR data may be the same as the series of sample regions being illuminated. Figures 3A to 3C The signal processor configuration of Figure 1B can also be used for Figure 1B The signal processor 28 of Figure 1B receives a comparison signal carrying only one of the channels. Thus, when Figures 3A to 3C the signal processor 28 in

[0089] is constructed, each signal processor provides LIDAR data for a series of sample regions illuminated by the system output signals carrying only one of the channels. Figure 1C In the Figure 1C LIDAR system of Figure 3A components from different signal processors 28 can be combined such that the beat signals are combined electronically rather than optically. For example, each signal processor 28 in the Figure 3D LIDAR system of Figure 3A can include the Figure 3D photoelectric conversion components of

[0090] In Figure 3D , components from different signal processors 28 ( Figure 1C ) are combined to form a common signal processor 74. The first data lines 228 from each different first balance detector 225 carry first data signals to a first electrical multiplexer 272. The first electrical multiplexer 272 outputs the first data signals from different first data lines 228 on a common data line 273. Since the system output signals from the same core and carrying different channels are serially output from the LIDAR system, the signal processor 28 ( Figure 1C)Receiving a first comparison signal in response to the signal director 14 on the core being operated such that a system output signal carrying channel i is output from the LIDAR system. In addition, the (one or more) signal processors 28 not configured to receive the comparison signal for channel i do not substantially receive the first comparison signal in response to the signal director 14 being operated such that the system output signal carrying channel i is output from the LIDAR system. Since the system output signals carrying different channels from the same core are serially output from the LIDAR system, the comparison signals for different channels are serially received at different signal processors 28, but some overlap of different channels may occur. Since different signal processors 28 serially receive the comparison signals for different channels, the first common data line 273 serially carries the first data signals that would carry different channels. Thus, the first common data line 273 carries electrical data signals, each of which is an electrical representation of a first composite signal, and each electrical data signal serially carries a different one of the channels. There may be some short-term overlap between the channels in the series of first data signals, but, in Figure 3C no overlap occurs in the data window shown. The first common data line 273 carries a series of first data signals to the first analog-to-digital converter (ADC) 264.

[0091] The second data lines 232 from each different second balance detector 226 carry the second data signals to the second electrical multiplexer 274. The second electrical multiplexer 274 outputs the second data signals from the different second data lines 232 onto the second common data line 275. The first common data line and the second common data line are both examples of common data lines. As described above, the (one or more) signal processors 28 serially receive the first comparison signals for different channels. Thus, the second common data line 275 serially receives the second data signals for different channels. Thus, the second common data line 275 carries electrical data signals, each of which is an electrical representation of a second composite signal, and each electrical data signal serially conveys a different one of the channels. There may be some short-term overlap between the channels in the series of second data signals, but, in Figure 3C no overlap occurs in the data window shown. The second common data line 275 carries the series of second data signals to the second analog-to-digital converter (ADC) 266.

[0092] Figure 3D The beat frequency identifier 238 and the LIDAR data generator 270 of Figures 3A to 3C can operate in the manner disclosed in the context of Figures 3A to 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.

[0093] The first digital data signal and the second digital data signal carrying the same channel are together as a complex signal, wherein the first digital data signal is the real part of the complex signal, and the second digital data signal is the imaginary part of the complex data signal. The first digital data signal and the second digital data signal carrying the same channel are simultaneously received by the mathematical converter 268. Therefore, the mathematical converter 268 receives complex signals serially carrying different channels. Therefore, the LIDAR data generator 270 serially receives the beat frequencies of the complex signals carrying different channels. Therefore, the LIDAR data generator 270 can generate LIDAR data for each different channel. Therefore, the LIDAR data generator 270 can generate LIDAR data for each sample area illuminated by the system output signal carrying a series of channels.

[0094] In another embodiment of the LIDAR system, Figure 3A the relationship between the sensor in the photoelectric conversion component in Figure 3D construction, the data processor 237 operates the electrical multiplexer as a switch operable by the electronic device. Therefore, the data processor 237 can operate the first electrical multiplexer 272 to select which one of the first data signals to output on the common data line 273, and can operate the second electrical multiplexer 274 to select which one of the second data signals to output on the second common data line 275. Therefore, the LIDAR system can be configured to simultaneously output system output signals carrying different channels. For example, the LIDAR chip can be configured to simultaneously output each LIDAR output signal carrying different channels. Therefore, the signal director 14 can be configured to direct the outgoing LIDAR system to one or more alternative waveguides 16. In an example where the signal director 14 is configured to direct the outgoing LIDAR system to all N alternative waveguides 16, the signal director can be a signal splitter.

[0095] When the LIDAR system simultaneously outputs system output signals carrying different channels, each different signal processor 28 can simultaneously receive a first LIDAR input signal carrying one of the channels. Thus, the first data lines 228 from each different signal processor 28 simultaneously carry first data signals to the first electrical multiplexer 272. Accordingly, the first electrical multiplexer 272 simultaneously receives a plurality of first data signals, each first data signal transmitting a different channel and coming from a different signal processor 28. The data processor 237 operates the first electrical multiplexer 272 using the switching function of the first electrical multiplexer 272 such that the first electrical multiplexer 272 outputs first data signals serially carrying different channels. Thus, the first common data line 273 serially carries first data signals that would carry different channels. Examples of suitable channel sequences include, but are not limited to, a channel sequence having alternating waveguide indices i = 1 to N in a digital sequence from i = 1 to i = N.

[0096] The second data lines 232 from each different signal processor 28 simultaneously carry second data signals to the second electrical multiplexer 274. Accordingly, the second electrical multiplexer 274 simultaneously receives a plurality of second data signals, each second data signal transmitting a different channel and coming from a different signal processor 28. The data processor 237 operates the second electrical multiplexer 274 using the switching function of the second electrical multiplexer 274 such that the second electrical multiplexer 274 outputs second data signals serially carrying different channels. Thus, the second data line 275 serially carries second data signals that would carry different channels.

[0097] Figure 3D The beat frequency identifier 238 and the LIDAR data generator 270 can operate in the manner disclosed in the context of Figures 3A to 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.

[0098] The operation of the first electrical multiplexer 272 and the second electrical multiplexer 274 causes the first data line 273 and the second data line 275 to carry the same channel simultaneously. Thus, the first digital data signal and the second digital data signal output from the first analog-to-digital converter (ADC) 264 and the second analog-to-digital converter (ADC) 266 carry the same channel simultaneously. The first digital data signal and the second digital data signal carrying the same channel act together as a complex signal, where the first digital data signal is the real part of the complex signal and the second digital data signal is the imaginary part of the complex signal. The first digital data signal and the second digital data signal carrying the same channel are received by the mathematical transducer 268 simultaneously. Thus, the mathematical transducer 268 receives a complex signal serially carrying different channels. Thus, the LIDAR data generator 270 receives the beat frequencies of the complex signals carrying different channels serially. Thus, the LIDAR data generator 270 can generate LIDAR data for each of the different channels. Thus, the LIDAR data generator 270 can generate LIDAR data for each sample area illuminated by the system output signal carrying the serial channels.

[0099] An alternative to the first electrical multiplexer 272 and / or the second electrical multiplexer 274 is to provide electrical nodes where the first data lines 228 from each of the different first balanced detectors 225 are in electrical communication with each other, and to provide a second electrical node where the second data lines 232 from each of the different second balanced detectors 226 are in electrical communication with each other. Thus, the outputs of the optical sensors (e.g., the first balanced detectors 225) are effectively electrically connected together, and the outputs of the optical sensors (e.g., the second balanced detectors 226) are effectively electrically connected together. For example, Figure 3E is shown Figure 3D an arrangement which is modified such that the first data lines 228 from each of the different first balanced detectors 225 are in electrical communication with a first common data line 273. Since the LIDAR system outputs a system output signal serially carrying different channels, the first common data line 273 serially carries first data signals of different channels. Although there may be some overlap between channels adjacent to each other in series, no overlap occurs during the data window. Additionally, the second data lines 232 from each of the different second balanced detectors 226 are in electrical communication with a second common data line 275. Since the LIDAR system outputs a system output signal serially carrying different channels, the second common data line 275 carries second data signals serially carrying different channels. Although there may be some overlap between channels adjacent to each other in series, no overlap occurs during the data window. Since the first common data line 273 carries first data signals serially carrying different channels and the second common data line 275 carries second data signals serially carrying different channels, as in Figure 3DAs also occurs in the LIDAR system, the beat frequency identifier 238 and the LIDAR data generator 270 may operate in the manner disclosed in the context of Figure 3E to generate LIDAR data for each sample area illuminated by the system output signal carrying a series of channels.

[0100] In a LIDAR system constructed according to Figure 3E during a cycle when the LIDAR system is outputting a system output signal carrying channel i, the optoelectronic conversion component included in the signal processor (working signal processor) configured to receive the current channel i receives the first LIDAR input signal carrying channel i during at least the data window, while the signal processor(s) not configured to receive the current channel i ((one or more) non-working signal processors) do not receive the first LIDAR input signal. However, the (one or more) non-working signal processors continue to receive the reference signal during at least the data window. The light from the (one or more) reference signals received by the (one or more) non-working signal processors may pass through the optoelectronic conversion component and become noise in the electrical signals (e.g., the first data signal and the second data signal).

[0101] In some cases, it may be desirable to completely or partially attenuate all or part of the (one or more) reference signals received by the (one or more) working signal processors. For example, the reference waveguides 32 ( Figure 1C ) may each optionally include an optical attenuator 276. The attenuator 276 may be operated by the electronics 62 to completely or partially attenuate the reference signal guided by the reference waveguide 32 along which the attenuator 276 is positioned.

[0102] Figure 1C The signal processor labeled 28 that acts as the working signal processor in Figure 1C and the (one or more) signal processors labeled 28 that act as the (one or more) non-working signal processors in

[0103] Although the optical attenuator 276 is shown as being located on Figure 1C reference waveguide 32 of Figure 1A and Figure 1B it may be located on all or part of reference waveguide 32 as shown in the imaging system of

[0104] Suitable devices for use as optical attenuator 276 include, but are not limited to, variable optical attenuators (VOAs), PIN diodes, and Mach-Zehnder modulators. Examples of suitable optical attenuators can be found in U.S. Patent Application Serial No. 17 / 396,616, filed on August 6, 2021, entitled "Carrier Injector Having Increased Compatibility," the entire text of which is incorporated herein by reference.

[0105] Suitable for use as Figures 1A to 1C The chirp rate identifier for chirp rate identifier 70 as shown includes a signal separator configured to split a common optical signal into a first optical signal and a second optical signal. The chirp rate identifier further includes a signal combiner configured to combine the light from the first optical signal and the light from the second optical signal to form a combined signal that beats at a beat frequency. The chirp rate identifier further includes a signal combiner configured to combine the light from the first optical signal and the light from the second optical signal to form a combined signal that beats at a beat frequency. The electronic device may include a beat frequency identifier that identifies the beat frequency of the combined signal; and a chirp rate generator that calculates the chirp rate of the common optical signal based on the beat frequency of the combined signal.

[0106] Figures 3F to 3H An example of a chirp rate identifier suitable for use as Figures 1A to 1C chirp rate identifier 70 as shown is shown. Figure 3F is a schematic diagram of an example of a suitable optoelectronic conversion component for chirp rate identifier 70. Common waveguide 68 carries a common signal into signal separator 282 included in chirp rate identifier 70. Signal separator 282 splits the common signal into an accelerated signal received on accelerated waveguide 284 and a delayed signal received on delayed waveguide 286. Signal separator 282 can be a wavelength-independent separator. For example, signal separator 282 can be configured such that the delayed signal and the accelerated signal carry the same or substantially the same wavelength selection. Suitable signal separators 282 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0107] The delay waveguide 286 carries the delayed signal to the signal combiner 288. The acceleration waveguide 284 carries the acceleration signal to the signal combiner 288. The delay waveguide 286 includes a delay section 289 that can be used to increase the length of the delay waveguide 286 to exceed the length of the acceleration waveguide 284. Although Figure 3F not shown, the delay section 289 can be or include a helically arranged delay waveguide 286. The longer length of the delay waveguide 286 creates a difference or delay between the time required for the delayed signal to travel between the signal splitter 282 and the signal combiner 288 and the time required for the acceleration signal to travel between the signal splitter 282 and the signal combiner 288.

[0108] The signal combiner 288 combines the delayed signal and the acceleration signal into a combined signal. Due to the delay between the delayed signal and the acceleration signal, the combined signal beats at a beat frequency. The signal combiner 288 also splits the combined signal onto a first sensor waveguide 290 and a second sensor waveguide 291. The first sensor waveguide 290 carries a first portion of the combined signal to a first optical sensor 292 that converts the first portion of the second composite signal into a first sensor output signal as an electrical signal. The second sensor waveguide 291 carries a second portion of the combined signal to a second optical sensor 293 that converts the second portion of the second composite signal into a second sensor output signal as an electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0109] An example of a suitable signal combiner 288 is a multimode interference (MMI) device, such as a 2×2 MMI device. Other suitable signal combiners 288 include, but are not limited to, adiabatic splitters and directional couplers. In some cases, the functions of the illustrated signal combiner 288 are performed by more than one optical component or a combination of optical components.

[0110] The first optical sensor 292 and the second optical sensor 293 can be connected as a balanced detector that converts the optical signal into an electrical signal. Figure 3G A schematic diagram of the relationship between the electronic device 62 and Figure 3F the optoelectronic conversion components in Figure 3G is provided. The symbol of a photodiode is used to represent the first optical sensor 292 and the second optical sensor 293, but one or more of these sensors can have other configurations. In some cases, Figure 3G all of the components shown in the schematic diagram of

[0111] The electronic device 62 connects the first optical sensor 292 and the second optical sensor 293 to form a balanced detector. In particular, the first optical sensor 292 and the second optical sensor 293 are connected in series. The series connection in the balanced detector communicates with the data line 294, which carries the output from the balanced detector as a data signal. This data signal is an electrical data signal carrying a representation of the combined signal. Thus, this data signal includes contributions from the first waveform and the second waveform.

[0112] The electronic device 62 includes Figures 3A to 3E the data processor 237 disclosed in the context of. The data processor 237 includes a beat frequency identifier 295, which is configured to identify the beat frequency of the combined signal. The beat frequency identifier 295 includes an analog-to-digital converter (ADC) 296, which receives the data signal from the data line 294. The analog-to-digital converter (ADC) 296 converts the data signal from analog form to digital form and outputs a digital data signal. The digital data signal is a digital representation of the data signal.

[0113] The beat frequency identifier 295 includes a mathematical transformer 297 that receives the data signal. For example, the mathematical transformer 297 receives the digital data signal from the first analog-to-digital converter (ADC) 296 as an input. The mathematical transformer 297 is configured to perform a mathematical transformation on the digital data signal to convert from the time domain to the frequency domain. This mathematical transformation can be a real transformation, such as a real fast Fourier transform (FFT).

[0114] The mathematical transformer 297 may include a peak finder (not shown), which is configured to identify peaks in the output of the mathematical transformer 297. The peak finder may be configured to identify the frequency peaks associated with the chirp rate identifier. For example, the frequency peaks associated with the chirp rate identifier may fall within a frequency range. The peak finder may identify the frequency peaks within the frequency range associated with the chirp rate identifier. The frequency of the identified frequency peaks represents the beat frequency of the combined signal.

[0115] The data processor 237 includes a chirp rate generator 299, which receives the beat frequency of the combined signal from the peak finder. In addition, the chirp rate generator 299 is configured to calculate the chirp rate (α n ) based on the beat frequency of the combined signal. For example, the chirp rate generator 299 may calculate the magnitude of the chirp rate (α n =f p / τ p ), where mα n represents the magnitude of the chirp rate (α n ), f n represents the beat frequency of the combined signal generated by the data period with period index n, and τ p represents pRepresents the difference or delay between the time required for the delay signal to travel between the signal splitter 282 and the signal combiner 288 and the time required for the acceleration signal to travel between the signal splitter 282 and the signal combiner 288. τ p The value of can be stored by the chirp rate generator 299 for calculating the chirp rate (α n ). The chirp rate generator 299 can assign the direction of the target chirp rate (tα n ) of the data period with period index n to the magnitude of the chirp rate (mα n ), thereby providing a chirp rate (α n ) with magnitude and direction.

[0116] The chirp rate generator 299 can generate the value of the chirp rate (α n ) for the data period with period index n. Thus, all or some of the data periods can be associated with different chirp rates (α n ), where the different chirp rates (α n ) are each generated by the chirp rate generator 299.

[0117] Figure 3G The illustrated electronic device 62 and data processor 237 include Figure 3B , Figure 3D or Figure 3E the components shown in the data processor 237, but for simplicity of illustration, only some of the components are shown. For example, Figure 3G shows the electronic device 62 and data processor 237, which include Figures 3A to 3E the LIDAR data generator 270 and beat frequency identifier 238 disclosed in the context of Figure 3B . Thus, the LIDAR data generator 270 receives from Figure 3D or Figure 3E the beat frequency of any frequency peak associated with one or more objects located outside the LIDAR system from the beat frequency identifier 238 shown. For example, the LIDAR data generator 270 can receive the beat frequency of any frequency peak associated with one or more objects located outside the LIDAR system from the peak finder included in the beat frequency identifier 238. In addition, the LIDAR data generator 270 receives different chirp rates (α n ) from the chirp rate generator 299. The LIDAR data generator 270 combines the chirp rate (α n ) associated with the sample region with the beat frequency generated by irradiating the same sample region, thereby calculating the LIDAR data of the sample region, as disclosed in the context of Figure 3C . The LIDAR data generator 270 receives the chirp rate (α n) and the beat frequency generated by irradiating the sample area. As a result, the LIDAR data generator 270 calculates the LIDAR data for the series of sample areas.

[0118] In Figures 3F to 3H 's exemplary chirp rate identifier, the common signal carried by the common waveguide 68 acts as the common optical signal, and the common waveguide 68 acts as the common waveguide. Additionally, the delay signal acts as the second optical signal, where the delay waveguide acts as the first waveguide. The acceleration signal acts as the first optical signal, where the acceleration waveguide acts as the first waveguide.

[0119] Figures 1A to 1C The chirp branches shown can be optional. For example, Figures 1A to 1C the components of the core can act as Figures 3F to 3H the components of the chirp rate identifier disclosed in the context of Figure 1A . For example, one or more optical components located after one of the splitters 24 in the LIDAR system can act as chirp rate detection components. Suitable chirp rate detection components can receive an optical signal including light from the outgoing LIDAR signal and cause a portion of the optical signal to be reflected as a reflected signal that travels along the optical path including one of the splitters 24. In a LIDAR core constructed according to Figure 1A , examples of chirp rate detection components include but are not limited to the signal director 14, the port 18, the waveguide facet, and components external to the chip, such as optical fibers, optical connectors, lenses, collimators, polarizers, polarization rotators, Faraday rotators, beam scanning mirrors, and / or other beam scanning devices. In a LIDAR constructed according to Figure 1B or Figure 1C , examples of chirp rate detection components include but are not limited to the port 18, the waveguide facet, the port 18, and components external to the chip, such as optical fibers, optical connectors, lenses, collimators, polarizers, polarization rotators, Faraday rotators, beam scanning mirrors, and / or other beam scanning devices. In a LIDAR constructed according to Figure 1B or Figure 1C , the alternating waveguide can transmit the reflected signal to one of the splitters 24.

[0120] In some cases, chirp rate detection components can be added to a LIDAR system constructed according to Figures 1A to 1C . For example, a perturbation region can be added to Figure 1A 's utility waveguide 12 to cause a portion of the outgoing LIDAR signal traveling along the utility waveguide to be reflected back towards the splitter 24. Alternatively, a perturbation region can be added to the Figures 1B to 1Ceach of the alternating waveguides 16 such that a portion of the outgoing LIDAR signal traveling along each of the alternating waveguides 16 is reflected back by one of the splitters 24. Examples of suitable perturbation regions include, but are not limited to, recesses extending into the waveguide, Bragg gratings, offset waveguides, waveguide tapers, and waveguide bends.

[0121] In Figures 1A to 1C the core of, the splitter 24 may move a portion of the reflected signal from the utility waveguide 12 onto the comparison waveguide 26, or move a portion of the reflected signal from one of the alternating waveguides 16 onto one of the comparison waveguides 26. As described above, the splitter 24 also moves a portion of the incoming LIDAR signal from the utility waveguide 12 onto the comparison waveguide 26 as a comparison signal. The portion of the reflected signal on the comparison waveguide 26 may act as a chirp detection signal. The chirp detection signal is combined with the comparison signal on the comparison waveguide 26. The comparison waveguide 26 carries the chirp detection signal and the comparison signal to the signal processor 28 for further processing.

[0122] The signal processor 28 combines the comparison signal, the chirp detection signal, and a reference signal to form a composite signal that carries LIDAR data for a sample region in the field of view. For example, as described above, the signal processor 28 includes one or more optical signal combiners that combine the comparison signal, the chirp detection signal, and the reference signal to form the composite signal. Thus, 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) for the sample region.

[0123] Figures 3A to 3E the signal processor 28 disclosed in the context of Figure 3G the chirp rate generator 299 disclosed in the context of Figure 3H illustrates Figure 3B modified to include Figure 3G the chirp rate generator 299 of. The chirp rate generator 299 receives the output from the mathematical transducer 268. As described above, the composite signal includes contributions from.

[0124] The output from the mathematical transducer 268 will include the frequency peaks from the chirp detection component. For example, the output from the mathematical transducer 268 will include the frequency peaks generated by the beating of the chirp detection signal against the reference signal. Additionally, when one or more objects located outside the LIDAR system reflect the system output signal, the output from the mathematical transducer 268 will include the frequency peaks from the one or more objects. Thus, the output from the mathematical transducer 268 can also include one or more frequency peaks generated by the differential beating of the comparison signal against the reference signal. Since the delay between the reference signal and the comparison signal for one or more objects is longer than the delay between the reference signal and the chirp detection signal, the frequency peaks from the chirp rate detection component will occur at a lower frequency than the frequency peaks from the one or more objects.

[0125] The chirp rate generator 299 can include a peak finder (not shown) configured to identify the frequency peaks in the output of the mathematical transducer 297. The peak finder can be configured to identify the frequency peaks associated with the chirp rate detection component as well as any frequency peaks associated with the one or more objects. For example, the frequency peaks associated with the chirp rate detection component can be located in a different frequency range than the frequency peaks associated with the one or more objects. Thus, the peak finder can associate the frequency peaks within the range associated with the chirp rate detection component as the frequency peaks generated by the chirp rate detection component. Additionally, the peak finder can associate any frequency peaks within the range associated with the one or more objects as the frequency peaks generated by the one or more objects.

[0126] The chirp rate generator 299 receives from the peak finder the frequency of the frequency peaks generated by the chirp rate detection component. Additionally, the chirp rate generator 299 is configured to calculate the chirp rate (α n ) based on the frequency peaks generated by the chirp rate detection component. For example, the chirp rate generator 299 can calculate the magnitude of the chirp rate (α n = f p / τ p , where mα n represents the magnitude of the chirp rate (α n ), f n represents the frequency of the frequency peaks generated by the chirp rate detection component during the data period with cycle index n, and τ p represents the delay between the time it takes for the reference signal to reach the optical signal combiner (optical signal combiner 211 and second optical signal combiner 212) from the separator and the time it takes for the chirp detection signal to reach the optical signal combiner (optical signal combiner 211 and second optical signal combiner 212) from the separator. The τ p of a particular chirp rate detection component pThe value can be known and stored by the chirp rate generator 299 for calculating the chirp rate. The chirp rate generator 299 can assign the direction corresponding to the target chirp rate (tα n ) to the magnitude of the chirp rate (mα n ), thereby providing a chirp rate (α n ) with magnitude and direction

[0127] In some cases, the value of τ p may be unknown or indeterminable. In these cases, the chirp rate generator 299 can estimate the value of τ pest according to τ pinit = |f n |, where τ p represents the estimated value of τ pest , tα p represents the target chirp rate of the data period associated with the period index n, and f n represents the frequency of the frequency peak generated by the chirp rate detection component during the data period associated with the period index n and appearing near the start or startup of the LIDAR system operation. When the LIDAR system operation starts, the error level between the actual chirp rate (α pinit ) and the target chirp rate (tα n ) decreases. Therefore, the combination of tα n and f n can provide an accurate estimate of the τ pinit value. In some cases, the value of f p represents the frequency at the frequency peak generated by the chirp rate detection component during the data period associated with the period index n and appearing within the first 1, 10, or 100 cycles after starting or starting the LIDAR system operation to generate LIDAR data. Since the value of τ pinit can be estimated, it is not necessary to know the actual identity of the chirp rate detection component. p

[0128] The chirp rate generator 299 can estimate a single value of τ pest using one of the data periods and set τ p to the value of τ pest (τ p = τ pest ). Alternatively, the chirp rate generator 299 can estimate different τ pest values for different data periods. Therefore, the final value of τ p can be a function of multiple different τ p values. For example, the chirp rate generator 299 can average multiple different τ pest values to generate τ p ​value. When the chirp rate generator 299 estimates τ p value, the chirp rate generator 299 can, as described above, according to α n = f p / τ p calculate the chirp rate (α n ).

[0129] The LIDAR data generator 270 receives the chirp rate (α n ) from the beat frequency identifier 238 and the frequency of any frequency peaks associated with one or more objects located outside the LIDAR system. For example, the LIDAR data generator 270 receives the chirp rate (α n ) from the chirp rate generator 299 and the frequency of any frequency peaks associated with one or more objects located outside the LIDAR system. Thus, the LIDAR data generator 270 combines the chirp rate (α n ) associated with the sample area with any beat frequencies generated by irradiating the same sample area, thereby calculating the LIDAR data for the sample area, as Figure 3C disclosed in the context of. The LIDAR data generator 270 receives, for a series of sample areas, the chirp rate (α n ) associated with the sample area and the beat frequencies generated by irradiating the sample area. Thus, the LIDAR data generator 270 calculates the LIDAR data for the series of sample areas.

[0130] Figure 3H shows Figure 3B a schematic diagram modified to include the chirp rate generator 299; however, Figure 3D and Figure 3E schematic diagrams can be modified to include Figure 3I and Figure 3J the chirp rate generator 299 shown in. Figure 3I and Figure 3J The chirp rate generator 299 and the LIDAR data generator 270 in Figure 3H are constructed and operate in the manner disclosed in the context of.

[0131] When the kernel constructed according to Figures 1A to 1C has as Figures 3H to 3JWhen the signal processor is constructed in the manner disclosed in the context, the components of the core act as a chirp rate identifier. As described above, the chirp rate identifier includes a signal separator configured to divide a common optical signal into a first optical signal and a second optical signal. The separator 24 acts as the signal separator of the chirp rate identifier, where the outgoing LIDAR signal acts as the common optical signal. Additionally, the reference signal acts as the first optical signal, and the reference waveguide acts as the first waveguide. A portion of the outgoing LIDAR output signal output from the separator 24, combined with the resulting reflected signal and the resulting chirp detection signal, acts as the second optical signal. For example, the portion of the outgoing LIDAR signal that is present in the chirp detection signal and also present in the reflected signal acts as the second optical signal. The chirp rate identifier further includes a signal combiner configured to combine the light from the first optical signal and the light from the second optical signal, thereby forming a combined signal that beats at a beat frequency. The optical signal combiner 211 and / or the second optical signal combiner 212 act as the signal combiner of the chirp rate identifier. For example, the optical signal combiner 211 and / or the second optical signal combiner 212 combine the comparison signal, the chirp detection signal, and the reference signal to form a composite signal. The chirp detection signal and the reference signal beat within the composite signal and thus act as the combined signal of the chirp rate identifier. The beat frequency identifier 238 identifies the beat frequency of the combined signal, and the chirp rate generator 270 calculates the chirp rate of the common optical signal.

[0132] Figures 3A to 3J The illustrated electronic device 62 includes only some of the components in the electronic device. For example, the electronic device 62 shown in FIG. 62 may further include a guider controller 15 and a light source controller 63 that communicate with the data processor 237.

[0133] Although the mathematical transformer 268 is disclosed as performing a complex transform on a complex signal, the complex transform can be replaced with a real transform performed on a real signal. Thus, Figure 3A the optoelectronic conversion component of can be simplified to not include the second optical combination component 212, the comparison waveguide 206, the second separator 202, the second reference waveguide 208, the first auxiliary optical sensor 218, the second auxiliary optical sensor 220, and Figure 3B , Figure 3D and Figure 3E the related components shown.

[0134] Suitable platforms for LIDAR chips include, but are not limited to, silicon dioxide, indium phosphide, and silicon-on-insulator wafers. Figure 4is a cross-section of a silicon-on-insulator wafer. The silicon-on-insulator (SOI) wafer includes a buried layer 300 located between a substrate 302 and an optical transmission medium 304. In a silicon-on-insulator wafer, the buried layer 300 is silicon dioxide, and the substrate 302 and the optical transmission medium 304 are silicon. A substrate of an optical platform such as an SOI wafer can serve as a base for a LIDAR chip. For example, in some cases, Figures 1A to 1C the optical components shown in can be positioned on top of and / or on and / or above the same substrate. Thus, a substrate of an optical platform such as an SOI wafer can serve as base 305.

[0135] Figure 4 The portion of the LIDAR chip shown in includes a waveguide structure that is 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 flat region 308 of the optical transmission medium 304. An optical signal is confined between the top of the ridge and the buried layer 300. Thus, the ridge 306 at least partially defines a waveguide.

[0136] The dimensions of the ridge waveguide are marked in Figure 4 . For example, the ridge has a width marked as w and a height marked as h. The thickness of the flat region is marked as t. For LIDAR applications, these dimensions may be more important than in other applications because higher levels of optical power than those used in other applications are required. The ridge width (marked as w) is greater than 1 μm and less than 4 μm, the ridge height (marked as h) is greater than 1 μm and less than 4 μm, and the flat region thickness is greater than 0.5 μm and less than 3 μm. These dimensions can be applicable to straight or substantially straight portions of the waveguide, curved portions of the waveguide, and tapered portion(s) of the waveguide. Thus, these portions of the waveguide will be single-mode. However, in some cases, these dimensions are applicable to straight or substantially straight portions of the waveguide. Additionally or alternatively, a curved portion of the waveguide can have a reduced plate thickness to reduce optical losses in the curved portion of the waveguide. For example, a curved portion of the waveguide can have a ridge that extends away from a flat region having a thickness greater than or equal to 0.0 μm and less than 0.5 μm. Although the above dimensions will generally provide straight or substantially straight portions of the waveguide with a single-mode structure, they may result in multimode tapered portion(s) and / or curved portion(s). A taper that does not substantially excite higher-order modes can be used to achieve coupling between a multimode geometry and a single-mode geometry. Thus, the waveguide can be constructed such that even when the signal carried in the waveguide is carried in a portion of the waveguide having multimode dimensions, the signal carried in the waveguide is carried in single mode. Figure 4 The waveguide structure of is suitable for all or part of the waveguide on a LIDAR chip constructed according to Figures 1A to 1C .

[0137] Suitable signal directors 14 for use with a LIDAR chip include, but are not limited to, optical switches such as cascaded Mach-Zehnder interferometers and microring resonator switches. In one example, the signal director 14 includes a cascaded Mach-Zehnder interferometer using thermal or free carrier injection phase shifters. Figure 5A and Figure 5B shows an example of an optical switch including a cascaded Mach-Zehnder interferometer 416. Figure 5A is a top view of the optical switch. Figure 5B is along Figure 5A the line marked B in Figure 5A the cross-section of the optical switch shown in.

[0138] 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 alternating 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 414. The director controller 15 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 alternating waveguides 16.

[0139] Each Mach-Zehnder interferometer 416 includes two branch waveguides 418, each of which receives a portion of the outgoing LIDAR signal from the utility waveguide 12 or the interconnect waveguide 414. Each Mach-Zehnder interferometer 416 includes a direction component 420 that receives two portions of the outgoing LIDAR signal from the branch waveguides 418. The direction component 420 steers the outgoing LIDAR signal into one of two interconnect waveguides 414 configured to receive the outgoing LIDAR signal from the direction component 420. The interconnect waveguide 414 to which the outgoing LIDAR signal is directed varies according to the phase difference between two different portions of the outgoing LIDAR signal received by the direction component 420. Although Figure 5A a directional coupler is shown operating as the direction component 420, other direction components 420 can also be used. Suitable alternative direction components 420 include, but are not limited to, multimode interference (MMI) devices and tapered couplers.

[0140] Each Mach-Zehnder interferometer 416 includes a phase shifter 422 positioned along one of the branch waveguides 418. The output component includes conductors 424 in electrical communication with the phase shifter 422. The conductors 424 are shown as dashed lines so that they can be easily distinguished from the underlying features. Each of the conductors 424 terminates at a contact pad 426. The contact pads 426 can be used to provide electrical communication between the conductors 424 and the electronic device. Thus, the conductors 424 provide electrical communication between the electronic device and the phase shifter 422 and allow the electronic device to operate the phase shifter 422. Suitable conductors 424 include, but are not limited to, metal traces. Suitable materials for the conductors include, but are not limited to, titanium, aluminum, and gold.

[0141] The electronic device can operate each phase shifter 422 to control the phase difference between portions of the outgoing LIDAR signal received by the steering component 420. In one example, the phase shifter 422 can be operated to change the refractive index of at least a portion of a portion of the branch waveguide 418. Changing the refractive index of a portion of the branch waveguide 418 in the Mach-Zehnder interferometer 416 changes the effective length of that branch waveguide 418 and thus changes the phase difference between portions of the outgoing LIDAR signal received by the steering component 420. The ability of the electronic device to change the phase difference allows the electronic device to select the interconnect waveguide 414 that receives the outgoing LIDAR signal from the steering component 420.

[0142] Figure 5B An example of a suitable configuration of the phase shifter 422 on the branch waveguide 418 is shown. The branch waveguide 418 is at least partially defined by a ridge 306 of the optical transmission medium 304 that extends away from a planar region 308 of the optical transmission medium 304. Doped regions 428 extend into the planar region 308, where one of the doped regions includes an n-type dopant and one of the doped regions 428 includes a p-type dopant. A first cladding 430 is located between the optical transmission medium 304 and the conductors 424. Each of the conductors 424 extends through an opening in the first cladding 430 and contacts one of the doped regions 428. A second cladding 432 is optionally located above the first cladding 430 and above the conductors 424. The electronic device can apply a forward bias to the conductors 424 to generate a current through the branch waveguide 418. The resulting carrier injection into the branch waveguide 418 causes free carrier absorption, thereby changing the refractive index in the branch waveguide 418.

[0143] Figure 5BThe first cladding 430 and / or the second cladding 432 shown in FIG. may each represent one or more layers of material. The materials for the first cladding 430 and / or the second cladding 432 may be selected to provide electrical isolation of the conductor 424, a lower refractive index relative to the optical transmission medium 304, stress reduction, and mechanical and environmental protection. Suitable materials for the first cladding 430 and / or the second cladding 432 include, but are not limited to, silicon nitride, tetraethyl orthosilicate (TEOS), silica, silicon nitride, and alumina. One or more of the materials for the first cladding 430 and / or the second cladding 432 may be doped or undoped.

[0144] In the case where the LIDAR system includes multiple cores, the LIDAR system may include multiple signal directors 76, and different signal directors 76 may receive LIDAR output signals from different selections of the signal directors 76. For example, Figure 6 is shown Figure 2 a LIDAR system that is modified to have multiple signal directors 76, each signal director receiving a LIDAR output signal from a different one of the cores.

[0145] Figures 1A to 1C Each core including a different light source 10 is shown. However, multiple cores, all cores, or some of the cores may receive the outgoing LIDAR signal from a common light source. In some cases, the cores are arranged in groups, where each core in a group receives the outgoing LIDAR signal from the same common light source, and the cores in different groups receive the outgoing LIDAR signal from different common light sources. In some cases, a group of cores may include a single core. For example, Figure 7 is shown Figure 2 a LIDAR system in which the light source 10 is located outside the core, and each core receives the outgoing LIDAR signal from the light source.

[0146] 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 different cores 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 divides the preliminary signal into multiple separated signals, each separated signal being received on a different one of the second optical links 444. Each utility waveguide 12 receives a separated signal from a different one of the optical links 444. The portion of the separated signal entering the utility waveguide acts as the outgoing LIDAR signal.

[0147] The LIDAR system may optionally include an amplifier 446 positioned along the first optical link 440 to amplify the power of the preliminary signal. Suitable amplifiers 446 for use along the optical link include, but are not limited to, SOAs, erbium-doped fiber amplifiers (EDFAs), and praseodymium-doped fiber amplifiers (PDFAs).

[0148] When it is desired that different outgoing LIDAR signals have the same or substantially the same wavelength distribution, suitable signal splitters 442 include, but are not limited to, wavelength-independent signal combiners, such as optical couplers, y-junctions, MMIs, cascaded attenuated optical couplers, and cascaded y-junctions. When it is desired that different outgoing LIDAR signals have different wavelength distributions, suitable signal splitters 442 include, but are not limited to, wavelength-dependent signal splitters 442, including optical demultiplexers, such as arrayed waveguide gratings (AWGs) and ladder gratings.

[0149] In some cases where multiple different cores receive the outgoing LIDAR signal from a common light source, only one core that receives its outgoing LIDAR signal from the common light source includes a control branch. Thus, other cores that receive the outgoing LIDAR signal from the same common light source may not include Figures 1A to 1C the directional coupler 66, common waveguide 68, and control branch shown in

[0150] From Figure 1A and Figure 1B it is apparent that the LIDAR system may optionally include one or more optical signal amplifiers 446. For example, the amplifier 446 may optionally be positioned along a utility waveguide, as shown in the LIDAR system of Figure 1A In another example, the amplifier 446 is optionally positioned along all or a portion of the alternate waveguide 16, as shown in the LIDAR system of Figure 1B The electronics may operate the amplifier 446 to amplify the power of the outgoing LIDAR signal, and thus the power of the system output signal. The electronics may operate each amplifier 446 to amplify the power of the outgoing LIDAR signal. Suitable amplifiers 446 for use on the LIDAR chip include, but are not limited to, semiconductor optical amplifiers (SOAs).

[0151] Figure 1A and Figure 1B The amplifier 446 shown in is respectively located before one of the splitters 24. In some cases, this location of the amplifier 446 may cause 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 to saturate. For example, the amplifier 446 may increase the power level of the reference signal to a level at which saturation occurs. A beam collector may be used to reduce the power level of the reference signal to a level at which saturation is reduced or eliminated.

[0152] From Figure 3B 、 Figure 3D and Figure 3E it can be clearly seen that the LIDAR system can optionally include one or more electrical signal amplifiers 447. Each amplifier 447 is positioned to provide amplification of a first data signal traveling between a first optical sensor (e.g., first balanced detector 225) and an analog-to-digital converter, or a second data signal traveling between a second optical sensor (e.g., second balanced detector 226) and an analog-to-digital converter. Although Figure 3D each electrical signal amplifier 447 is shown positioned along the first data line 228 or the second data line 232, the electrical signal amplifier 447 can be positioned along the common data line 273 or the second common data line 275. Although Figure 3E each electrical signal amplifier 447 is shown positioned along the common data line 273 or the second common data line 275, the electrical signal amplifier 447 can be positioned along the first data line 228 or the second data line 232. Suitable electrical signal amplifiers 447 include, but are not limited to, transimpedance amplifiers (TIAs).

[0153] Figure 8 shows a portion of the LIDAR chip that includes a reference waveguide 32, which is used in combination with a beam collector configured to reduce the power level of a reference signal carried on the reference waveguide 32. The reference waveguide 32 carries the reference signal to a splitter 448 that moves a portion of the reference signal from the reference waveguide 32 onto a collection waveguide 450 as a collection signal. The collection waveguide 450 carries the collection signal to a beam collector 452.

[0154] The beam collector 452 is configured to scatter the collection signal without reflecting a significant amount of light from the collection signal back into the collection waveguide 450. For example, the beam collector 452 can be a recess 454 etched into an optical transmission medium of a silicon-on-insulator wafer, the depth of which is such that the collection signal impinges on one or more sides of the recess 454. The recess 454 can be shaped to cause the collection signal to scatter. For example, the recess 454 can have a star shape, or can include any number of irregularly positioned sides. In some cases, the recess 454 can extend through the optical transmission medium to a lower layer, such as a buried layer of a silicon-on-insulator wafer.

[0155] The separator 448 can be configured to control the percentage of the reference signal power transmitted to the collection waveguide. Increasing the percentage of the reference signal power transmitted to the collection waveguide increases the attenuation of the reference signal power, thereby reducing the power of the signals 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. The decrease in the optical signal power received by all or some of the optical sensors reduces the likelihood of saturation. Suitable separators 448 include, but are not limited to, 1×2 separators, including optical couplers, y-junctions, and MMIs. In some cases, the separator 448 is configured such that the percentage of the reference signal power transmitted to the collection waveguide 450 is greater than or equal to 0.1%, 0.5%, or 1% and less than or equal to 2%, 10%, or 20%.

[0156] The optical sensors that dock with the waveguides on the LIDAR chip can be components that are separated from the chip and then attached to the chip. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, InGaAs PIN photodiodes manufactured by Hamamatsu located in Hamamatsu, Japan, or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu located in Hamamatsu, Japan. These optical sensors can be located at the center of the LIDAR chip. Alternatively, all or part of the waveguides that terminate at the optical sensors can terminate at a facet located at the edge of the chip, and the optical sensor can be attached to the chip edge above the facet such that the optical sensor receives the light passing through the facet. Using optical sensors as components separated from the chip is applicable to all or some of the optical sensors selected from the group consisting of the first optical sensor and the second optical sensor.

[0157] As an alternative to optical sensors as separated components, all or some of the optical sensors can be integrated with the chip. For example, examples of optical sensors that dock with ridge waveguides on a chip composed of a silicon-on-insulator wafer 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. 6,108,8472, issued on August 22, 2000, each of which is incorporated herein by reference in its entirety. Using optical sensors integrated with the chip is applicable to all or some of the optical sensors selected from the group consisting of the first optical sensor and the second optical sensor.

[0158] As described above, the electronic devices of the operating system include electronic devices 62 and component controller 280. Each of the electronic devices 62 is associated with one of the cores (i.e., local electronic devices). In contrast, the component controller 280 can be associated with multiple cores (i.e., common electronic devices). Although the electronic devices 62 and component controller 280 shown in the figure are located at different positions, the electronic devices 62 and component controller 280 can be located in a common location and / or a common package. In addition, the electronic devices 62 and component controller 280 for each core can be integrated, rather than necessarily referring to discrete or different electronic components. For example, the electronic devices 62 associated with different cores can optionally be combined with the component controller 280. The combined component controller 280 can be located on the LIDAR chip or support 77. The component controller 280 or the combined component controller 280 can collect or generate LIDAR data results from different cores, and / or can coordinate the LIDAR data results from different cores to assemble the LIDAR data results of the field of view of the LIDAR system.

[0159] Suitable electronic devices 62 for use in a LIDAR system can include, but are not limited to, a controller that comprises or consists of an analog circuit, a digital circuit, a processor, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a computer, a microcomputer, or a combination suitable for performing the above-described operations, monitoring, and control functions. In some cases, the controller can access a memory that includes instructions for the controller to execute during the performance of the operations, control, and monitoring functions. Although the electronic device is shown as a single component in a single location, the electronic device can include multiple different components that are independent of each other and / or placed in different locations. In addition, as described above, all or part of the disclosed electronic devices can be included on a chip, including electronic devices integrated with the chip.

[0160] Examples of suitable booting controllers 15 use firmware, hardware, software, or a combination thereof to perform attributed functions. Examples of suitable light source controllers 63 use firmware, hardware, software, or a combination thereof to perform attributed functions. Examples of suitable data processors 237 use firmware, hardware, software, or a combination thereof to perform attributed functions. Examples of suitable component controllers 280 use firmware, hardware, software, or a combination thereof to perform attributed functions.

[0161] 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 portion of the wafer on which the LIDAR chip is fabricated. The wafer that can serve as a platform for the LIDAR chip can include multiple layers of material. At least a portion of the different layers can be different materials. For example, a silicon-on-insulator wafer includes a buried layer 300 between a substrate 302 and an optical transmission medium 304, as Figure 4 shown. 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 flat plate 318 that defines a waveguide and a stop recess can be formed in a desired region of the wafer using different etches of the wafer. Thus, the LIDAR chip includes a portion of the wafer, and the integrated on-chip components can each include or consist of a portion of the wafer. Additionally, the integrated on-chip components can be configured such that an optical signal traveling through the component travels through one or more layers initially included in the wafer. For example, Figure 4 the waveguide of

[0162] guides the optical signal through the optical transmission medium 304 in the wafer. The integrated components can optionally include materials in addition to the materials present on the wafer. For example, the integrated components can include reflective materials and / or cladding. Digital labels (such as first, second, third, etc.) are used to distinguish different features and components and do not indicate the order or presence of lower-numbered features. For example, a second component can be present without a first component and / or a third step can be performed before a first step. Each of the optical signals disclosed above includes, consists of, or consists essentially of light from one or more previous optical signals from which the optical signal is derived. For example, an incoming LIDAR signal includes, consists of, or consists essentially of light from the LIDAR input signal.

[0163] Although it is disclosed that the LIDAR system uses complex signals such as complex data signals, the LIDAR system can also use real signals. Thus, the mathematical transform can be a real transform, and components related to the generation and use of orthogonal components can be removed from the LIDAR system. Accordingly, the LIDAR system can use a single signal combiner. Additionally or alternatively, a single optical sensor can replace each balanced detector.

[0164] Although the imaging system and the LIDAR system are disclosed as having steerable system output signals, the imaging system and the LIDAR system can also be used in applications where the (one or more) system output signals are not steered. Thus, the optical component assembly 75 is optional.

[0165] In view of these teachings, other embodiments, combinations, and modifications of the present invention will be readily apparent to those of ordinary skill in the art. Accordingly, the present invention is limited only by the appended claims, which, when viewed in light of the foregoing specification and drawings, include all such embodiments and modifications.

Claims

1. A LIDAR system, comprising: a signal splitter configured to split a common optical signal into a first optical signal and a second optical signal; a signal combiner configured to combine light from the first optical signal and light from the second optical signal to form a combined signal that beats at a beat frequency; and an electronic device including a beat frequency identifier configured to identify the beat frequency of the combined signal, wherein the electronic device includes a chirp rate generator configured to calculate a chirp rate of the common optical signal based on the beat frequency of the combined signal.

2. The system according to claim 1, wherein, The chirp rate generator is configured to calculate the chirp rate, including: the chirp rate generator is configured to calculate the magnitude of the chirp rate according to mα n = f p / τ p where mα n represents the magnitude of the chirp rate, f p represents the beat frequency of the combined signal, and τ p represents the delay between the time required for the first optical signal to travel between the signal splitter and the signal combiner and the time required for the second optical signal to travel between the signal splitter and the signal combiner.

3. The system according to claim 1, wherein, the electronic device includes a LIDAR data generator configured to calculate LIDAR data based on the chirp rate calculated by the chirp rate generator, the LIDAR data indicating a radial velocity and / or distance between an imaging system and an object external to the imaging system.

4. The system according to claim 1, wherein, the signal combiner is further configured to combine light from the first optical signal with light from a comparison signal to form a composite signal that beats at a composite signal beat frequency, the light from the comparison signal includes light from the common signal that has left the imaging system, has been reflected by an object located external to the imaging system, and has returned to the imaging system.

5. The system according to claim 4, wherein, the beat frequency identifier is configured to identify the composite signal beat frequency.

6. The system according to claim 5, wherein, the electronic device includes a LIDAR data generator configured to calculate LIDAR data based on the chirp rate calculated by the chirp rate generator and further based on the composite signal beat frequency identified by the beat frequency identifier, the LIDAR data indicating a radial velocity and / or distance between the imaging system and an object external to the imaging system.

7. The system according to claim 1, further comprising: a chirp rate detection component that reflects the second optical signal but transmits light from the common signal and included in the comparison signal.

8. The system according to claim 1, wherein, the signal splitter and the signal combiner are included in a photonic circuit on a semiconductor chip.

9. The system according to claim 1, wherein, a second signal splitter taps the common signal from the outgoing LIDAR signal.

10. The system according to claim 1, wherein, the chirp rate generator is configured to calculate an approximate duration of a delay between a time required for the first optical signal to travel between the signal splitter and the signal combiner and a time required for the second optical signal to travel between the signal splitter and the signal combiner.

11. A method of operating a LIDAR system, comprising: dividing a common optical signal into a first optical signal and a second optical signal; Combine light from the first optical signal and light from the second optical signal to form a combined signal that beats at a beat frequency; Identify the beat frequency of the combined signal; and Calculate the chirp rate of the common optical signal based on the beat frequency of the combined signal.

12. The method according to claim 11, further comprising: Calculate LIDAR data based on the calculated chirp rate, the LIDAR data indicating the radial velocity and / or distance between the imaging system and an object external to the imaging system.

13. The method according to claim 11, wherein, Calculating the chirp rate includes, according to mα n = f p / τ p Calculating the magnitude of the chirp rate, where mα n represents the magnitude of the chirp rate, f p represents the beat frequency of the combined signal, and τ p represents the delay between the time required for the first optical signal to travel between the signal splitter and the signal combiner and the time required for the second optical signal to travel between the signal splitter and the signal combiner.

14. The method according to claim 11, further comprising: Calculate LIDAR data based on the calculated chirp rate, the LIDAR data indicating the radial velocity and / or distance between the imaging system and an object external to the imaging system.

15. The method according to claim 11, further comprising: Combine light from the first optical signal with light from a comparison signal to form a composite signal that beats at a composite signal beat frequency, The light from the comparison signal includes light from the common signal that has left the imaging system, has been reflected by an object located external to the imaging system, and has returned to the imaging system.

16. The method according to claim 15, further comprising: Identify the composite signal beat frequency.

17. The method according to claim 16, further comprising: Calculate LIDAR data based on the chirp rate calculated by the chirp rate generator and also based on the composite signal beat frequency identified by the beat frequency identifier, the LIDAR data indicating the radial velocity and / or distance between the imaging system and an object external to the imaging system.

18. The method according to claim 11, wherein, The chirp rate detection component reflects the second optical signal but transmits light from the common signal and included in the comparison signal.

19. The method according to claim 11, further comprising: Calculate an approximate duration of a delay between a time required for the first optical signal to travel between a signal splitter and a signal combiner and a time required for the second optical signal to travel between the signal splitter and the signal combiner; The signal splitter is configured to split the common optical signal into the first optical signal and the second optical signal; and The signal combiner is configured to combine light from the first optical signal and light from the second optical signal.

Images