Use of a common chirp period in the generation of LIDAR data

Abstract

The LIDAR system is configured to output a system output signal that travels away from the LIDAR system and can be reflected by objects located outside the LIDAR system. The system output signal has a frequency versus time pattern with a repeating period. Each period of the frequency versus time pattern has a plurality of data periods configured to chirp the system output signal differently for different data periods. The LIDAR system also has electronic circuitry configured to generate a plurality of different sets of LIDAR data. Each set of LIDAR data indicates a radial velocity and / or separation between the LIDAR system and one or more objects located outside the LIDAR system. Each set of LIDAR data is generated from light contained in the system output signal during a group of a plurality of data periods. The groups of data periods each have one or more common data periods contained in two or more different groups of data periods.

Description

Related Applications

[0001] This application claims the benefit of U.S. Patent Application No. 16 / 867,537, filed May 5, 2020, entitled "Use of a Common Chirp Period in the Generation of LIDAR Data," which is incorporated herein by reference in its entirety.

Technical Field

[0002] The present invention relates to optical devices. In particular, the present invention relates to LIDAR systems.

Background Art

[0003] The performance requirements placed on LIDAR systems are increasing as these systems support an increasing number of applications. LIDAR systems generally generate LIDAR data regarding a series of sample regions that are continuously illuminated by a system output signal. The LIDAR data regarding the sample regions indicates the radial velocity and / or distance between the LIDAR system and one or more objects disposed within the sample regions. The LIDAR system can scan the system output signal across a plurality of different sample regions. The sample regions can be joined together to form the field of view for the LIDAR system. As a result, the LIDAR data from the different sample regions provides LIDAR data regarding the objects within the field of view.

[0004] By increasing the rate at which LIDAR data can be generated for different sample regions, the frequency at which the field of view can be scanned can be increased and / or the resolution of the field of view can be increased. As a result, increasing the LIDAR data generation rate can increase the number of applications for which the LIDAR system can be well applied. However, increasing the LIDAR data generation rate often increases the complexity and / or cost of the LIDAR system. As a result, an improved LIDAR system is needed.

Summary of the Invention

[0005] The LIDAR system has one or more optical components configured to output a system output signal that travels away from the LIDAR system and can be reflected by an object disposed outside the LIDAR system. The system output signal has a frequency - versus - time pattern having a repetition period. Each period of the frequency - versus - time pattern has a plurality of data periods configured such that the system output signal is chirped differently in different data periods. Also, the LIDAR system has an electronic circuit configured to generate a plurality of different sets of LIDAR data. Each set of LIDAR data indicates a radial velocity and / or separation between the LIDAR system and one or more objects located outside the LIDAR system. Each set of LIDAR data is generated from the light included in the system output signal among a group of a plurality of data periods. All or some of the groups of data periods have one or more common data periods respectively included in two or more different groups of data periods.

[0006] A method of operating a LIDAR system includes outputting a system output signal from the LIDAR system such that the system output signal travels away from the LIDAR system and can be reflected by an object disposed outside the LIDAR system. The system output signal has a frequency - versus - time pattern having a repetition period. Each period of the frequency - versus - time pattern has a plurality of data periods configured such that the system output signal is chirped differently in different data periods. Also, the method includes generating a plurality of different sets of LIDAR data. Each set of LIDAR data indicates a radial velocity and / or separation between the LIDAR system and one or more objects located outside the LIDAR system. Each set of LIDAR data is generated from the light included in the system output signal among a group of a plurality of data periods. The group of data periods has one or more common data periods respectively included in two or more different groups of data periods.

Brief Description of the Drawings

[0007] Figure 1A is a schematic plan view of a LIDAR system including or comprising a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal in a common waveguide.

[0008] Figure 1B is a schematic plan view of a LIDAR system including or comprising a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal in different waveguides.

[0009] Figure 1C is a schematic plan view of another embodiment of a LIDAR system including or comprising a LIDAR chip that outputs a LIDAR output signal and receives a plurality of LIDAR input signals in different waveguides.

[0010] Figure 2 is a plan view of an example of a LIDAR adapter suitable for use with the LIDAR chip of Figure 1B.

[0011] Figure 3 is a plan view of an example of a LIDAR adapter suitable for use with the LIDAR chip of Figure 1C.

[0012] Figure 4 is a plan view of an example of a LIDAR system having the LIDAR chip of Figure 1A and the LIDAR adapter of Figure 2 on a common support.

[0013] Figure 5A shows an example of a processing component suitable for use with a LIDAR system.

[0014] Figure 5B provides a schematic of an electronic circuit section suitable for use with a processing component configured according to Figure 5A.

[0015] Figure 5C is a graph of frequency versus time for a system output signal.

[0016] Figure 5D is another graph of frequency versus time for a system output signal.

[0017] Figure 5E is another graph of frequency versus time for the system output signal.

[0018] Figure 5F is another graph of frequency versus time for the system output signal.

[0019] Figure 6 is a partial cross-sectional view of a LIDAR chip having a waveguide on a silicon-on-insulator platform. DETAILED DESCRIPTION OF THE INVENTION EXAMPLE

[0020] The LIDAR system outputs a system output signal that continuously irradiates a series of sample regions. The system output signal can be reflected by one or more objects disposed within the sample region during the time that the system output signal irradiates the sample region. The system is configured to receive at least a portion of the reflected light. The system has an electronic circuit section that uses the reflected light to generate a plurality of sets of LIDAR data indicating the radial velocity and / or distance between the LIDAR system and an object located within the illuminated sample region, respectively.

[0021] The system output signal has a frequency-versus-time pattern having a repetition period. Each period has a plurality of data periods configured to be chirped differently in different data periods. Each set of LIDAR data is generated from the light included in the system output signal during a group of a plurality of data periods. Different groups of data periods can each have a common data period included in two or more different groups of data periods. As a result, a single data period can be used in generating LIDAR data for two or more different sample regions.

[0022] When generating LIDAR data for two or more different sample regions, the ability to use a single data period reduces the total time period required to generate LIDAR for these sample regions. As a result, the LIDAR data generation speed is improved. Further, when generating LIDAR data for multiple sample regions, using a single data period can be done with basic modifications to existing electronic circuitry. As a result, an increased LIDAR generation speed can be achieved without substantially increasing the cost or complexity of the LIDAR system.

[0023] FIG. 1A is a schematic plan view of a LIDAR chip that can function as a LIDAR system or can be included in a LIDAR system having additional components in addition to the LIDAR chip. The LIDAR chip can have a photonic integrated circuit (PIC) and can be a photonic integrated circuit chip. The LIDAR chip has a light source 4 that outputs a preliminary emitted LIDAR signal. Suitable light sources 4 include, but are not limited to, semiconductor lasers such as external cavity lasers (ECLs), distributed feedback lasers (DFBs), discrete mode (DM) lasers, and distributed Bragg reflector lasers (DBRs).

[0024] The LIDAR chip has a utility waveguide 12 that receives the emitted LIDAR signal from the light source 4. The utility waveguide 12 terminates at the facet 14 and conveys the emitted LIDAR signal to the facet 14. The emitted LIDAR signal moving through the facet 14 exits the LIDAR chip, and the facet 14 can be arranged so that it functions as the LIDAR output signal. For example, the facet 14 can be arranged at the edge of the chip so that the emitted LIDAR signal moving through the facet 14 exits the chip and functions as the LIDAR output signal. In some cases, a portion of the LIDAR output signal exiting the LIDAR chip can also be regarded as the system output signal. As an example, when the exit of the LIDAR output signal from the LIDAR chip is also the exit of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be regarded as the system output signal.

[0025] The LIDAR output signal travels away from the LIDAR system through the free space in the atmosphere where the LIDAR system is located. The LIDAR output signal can be reflected by one or more objects within the path of the LIDAR output signal. When the LIDAR output signal is reflected, at least a portion of the reflected light travels back towards the LIDAR chip as the LIDAR input signal. In some examples, the LIDAR input signal can also be regarded as the system return signal. As an example, when the exit of the LIDAR output signal from the LIDAR chip is also the exit of the LIDAR output signal from the LIDAR system, the LIDAR input signal can also be regarded as the system return signal.

[0026] The LIDAR input signal can enter the utility waveguide 12 through the facet 14. A portion of the LIDAR input signal entering the utility waveguide 12 functions as the incident LIDAR signal. The utility waveguide 12 conveys the incident LIDAR signal to a splitter 16 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 to the comparison waveguide 18 as a comparison signal. The comparison waveguide 18 conveys the comparison signal to a processing component 22 for further processing. Although FIG. 1A shows a directional coupler operating as the splitter 16, other signal tap components can be used as the splitter 16. Suitable splitters 16 include, but are not limited to, directional couplers, optical couplers, y-junctions, taper couplers, and multimode interference (MMI) devices.

[0027] The utility waveguide 12 also conveys the outgoing LIDAR signal to the splitter 16. The splitter 16 moves a portion of the outgoing LIDAR signal from the utility waveguide 12 to the reference waveguide 20 as a reference signal. The reference waveguide 20 conveys the reference signal to the processing component 22 for further processing.

[0028] The ratio of the light transferred from the utility waveguide 12 by the splitter 16 can be fixed or substantially fixed. For example, the splitter 16 can be configured such that the power of the reference signal transferred to the reference waveguide 20 is the emission rate of the power of the emitted LIDAR signal, or the power of the comparison signal transferred to the comparison waveguide 18 is the incidence rate of the power of the incident LIDAR signal. In many splitters 16, such as directional couplers and multimode interferometers (MMIs), the emission rate is equal to or substantially equal to the incidence rate. In some examples, the emission rate is greater than 30%, 40%, or 49%, and / or less than 51%, 60%, or 70%, and / or the incidence rate is greater than 30%, 40%, or 49%, and / or less than 51%, 60%, or 70%. Splitters 16 such as multimode interferometers (MMIs) generally provide an emission rate and an incidence rate of 50% or about 50%. However, multimode interferometers (MMIs) can be more easily fabricated on platforms such as silicon-on-insulator platforms than some alternatives. In one example, the splitter 16 is a multimode interferometer (MMI), and the emission rate and the incidence rate are 50% or substantially 50%. As will be described in more detail below, the processing component 22 combines the comparison signal with the reference signal to form a composite signal that carries LIDAR data regarding the sample region in the field of view. Accordingly, the composite signal can be processed to extract LIDAR data (radial velocity and / or distance between the LIDAR system and an object external to the LIDAR system) regarding the sample region.

[0029] The LIDAR chip can include a control branch for controlling the operation of the light source 4. The control branch has a splitter 26 that moves a portion of the emitted LIDAR signal from the utility waveguide 12 to the control waveguide 28. A portion of the combined emitted LIDAR signal functions as a tap signal. FIG. 1A shows a directional coupler operating as a splitter 26, but other signal tap components can be used as the splitter 26. Suitable splitters 26 include, but are not limited to, directional couplers, optical couplers, y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0030] The control waveguide 28 conveys the tap signal to a control component 30. The control component can communicate electrically with the electronic circuitry 32. During operation, the electronic circuitry can use the output from the control component 30 in a control loop configured to control a processing variable of one, two, or three loop-controlled optical signals selected from the group consisting of the tap signal, the system output signal, and the emitted LIDAR signal. Examples of suitable processing variables include the frequency of the loop-controlled optical signal and / or the phase of the loop-controlled optical signal.

[0031] The LIDAR system can be modified to carry the incident LIDAR signal and the outgoing LIDAR signal through different waveguides. For example, FIG. 1B is a plan view of the LIDAR chip of FIG. 1A modified to carry the incident LIDAR signal and the outgoing LIDAR signal through different waveguides. The outgoing LIDAR signal exits the LIDAR chip through facet 14 and also functions as the LIDAR output signal. When the light from the LIDAR output signal is reflected by an object outside the LIDAR system, at least a part of the reflected light returns to the LIDAR chip as the first LIDAR input signal. The first LIDAR input signal enters the comparison waveguide 18 through facet 35 and functions as a comparison signal. The comparison waveguide 18 conveys the comparison signal to the processing component 22 for further processing. As described in connection with FIG. 1A, the reference waveguide 20 conveys the reference signal to the processing component 22 for further processing. As will be described in more detail below, the processing component 22 combines the comparison signal with the reference signal to form a composite signal that conveys LIDAR data regarding a sample region in the field of view.

[0032] The LIDAR chip can be modified to receive a plurality of LIDAR input signals. For example, FIG. 1C shows the LIDAR chip of FIG. 1B modified to receive two LIDAR input signals. The splitter 40 is configured to direct a part of the reference signal conveyed to the reference waveguide 20 to the first reference waveguide 42 and another part of the reference signal to the second reference waveguide 44. Thereby, the first reference waveguide 42 conveys the first reference signal and the second reference waveguide 44 conveys the second reference signal. The first reference waveguide 42 conveys the first reference signal to the first processing component 46 and the second reference waveguide 44 conveys the second reference signal to the second processing component 48. Examples of suitable splitters 40 include, but are not limited to, y - couplers, optical couplers, and multimode interference couplers (MMIs).

[0033] The emitted LIDAR signal exits the LIDAR chip via facet 14 and functions as the LIDAR output signal. When the light from the LIDAR output signal is reflected by one or more objects disposed outside the LIDAR system, at least a portion of the reflected light returns to the LIDAR chip as the first LIDAR input signal. The first LIDAR input signal enters the comparison waveguide 18 via facet 35 and functions as the first comparison signal. The comparison waveguide 18 conveys the first comparison signal to the first processing component 46 for further processing.

[0034] In addition, when the light from the LIDAR output signal is reflected by one or more objects disposed outside the LIDAR system, at least a portion of the reflected signal returns to the LIDAR chip as the second LIDAR input signal. The second LIDAR input signal enters the second comparison waveguide 50 via facet 52 and functions as the second comparison signal conveyed by the second comparison waveguide 50. The second comparison waveguide 50 conveys the second comparison signal to the second processing component 48 for further processing.

[0035] Although the light source 4 is shown to be disposed on the LIDAR chip, the light source 4 can be disposed outside the LIDAR chip. For example, the utility waveguide 12 can terminate with a second facet through which the emitted LIDAR signal can enter the utility waveguide 12 from a light source 4 disposed outside the LIDAR chip.

[0036] In some examples, a LIDAR chip constructed according to FIG. 1B or FIG. 1C is used with a LIDAR adapter. In some examples, the LIDAR adapter can be physically and optically positioned between the LIDAR chip and one or more reflective objects and / or the field of view such that an engineering path for a first LIDAR input signal and / or a LIDAR output signal to move out of the field of view from the LIDAR chip passes through the LIDAR adapter. Further, the LIDAR adapter can be configured to manipulate the first LIDAR input signal and the LIDAR output signal such that the first LIDAR input signal and the LIDAR output signal travel different optical paths between the LIDAR adapter and the LIDAR chip while traveling the same optical path between the LIDAR adapter and a reflective object within the field of view.

[0037] An example of a LIDAR adapter suitable for use with the LIDAR chip of FIG. 1B is shown in FIG. 2. The LIDAR adapter has a plurality of components located on a base. For example, the LIDAR adapter has a circulator 100 disposed on a base 102. The illustrated optical circulator 100 has three ports and is configured such that light entering one port exits the next port. For example, the illustrated optical circulator has a first port 104, a second port 106, and a third port 108. The LIDAR output signal enters the first port 104 from the utility waveguide 12 of the LIDAR chip and exits from the second port 106.

[0038] The output of the LIDAR output signal from the second port 106 can also configure the LIDAR adapter so that it can function as the output of the LIDAR output signal from the LIDAR adapter and thus from the LIDAR system. As a result, the LIDAR output signal can be output from the LIDAR adapter so that it travels towards the sample region within the field of view. Thus, in some examples, a portion of the LIDAR output signal exiting the LIDAR adapter can also be considered a system output signal. As an example, if the exit of the LIDAR output signal from the LIDAR adapter is also the exit of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0039] The LIDAR output signal output from the LIDAR adapter has, consists of, or is essentially composed of light from the LIDAR output signal received from the LIDAR chip. Thus, the LIDAR output signal output from the LIDAR adapter will be the same as, or substantially the same as, the LIDAR output signal received from the LIDAR chip. However, there may be differences between the LIDAR output signal output from the LIDAR adapter and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal can experience optical loss as the LIDAR output signal travels through the LIDAR adapter, and / or the LIDAR adapter can optionally include an amplifier configured to amplify the LIDAR output signal as the LIDAR output signal travels through the LIDAR adapter.

[0040] When one or more objects in the sample region reflect the LIDAR output signal, at least a portion of the reflected light travels back to the circulator 100 as a system return signal. The system return signal enters the circulator 100 through the second port 106. FIG. 2 shows the LIDAR output signal and the system return signal traveling along the same optical path between the LIDAR adapter and the sample region.

[0041] The system return signal exits the circulator 100 through the third port 108 and is directed towards the comparison waveguide 18 on the LIDAR chip. Thus, all or part of the system return signal can function as the first LIDAR input signal, and the first LIDAR input signal has or consists of light from the system return signal. Thus, the LIDAR output signal and the first LIDAR input signal travel along different optical paths between the LIDAR adapter and the LIDAR chip.

[0042] As is apparent from FIG. 2, the LIDAR adapter can have optical components in addition to the circulator 100. For example, the LIDAR adapter can have components that direct and control the optical paths of the LIDAR output signal and the system return signal. As an example, the adapter of FIG. 2 has a selective amplifier 110 that is arranged to receive and amplify the LIDAR output signal before the LIDAR output signal enters the circulator 100. The electronic circuit section 32 can operate the amplifier 110 so that the electronic circuit section 32 can control the power of the LIDAR output signal.

[0043] FIG. 2 also shows a LIDAR adapter having a selective first lens 112 and a selective second lens 114. The first lens 112 can be configured to couple the LIDAR output signal to a desired location. In some cases, the first lens 112 is configured to focus or collimate the LIDAR output signal at the desired location. In one example, when the LIDAR adapter does not have the amplifier 110, the first lens 112 is configured to couple the LIDAR output signal to the first port 104. As another example, when the LIDAR adapter has the amplifier 110, the first lens 112 can be configured to couple the LIDAR output signal to the input port of the amplifier 110. The second lens 114 can be configured to couple the LIDAR output signal to a desired location. In some cases, the second lens 114 can be configured to focus or collimate the LIDAR output signal at the desired location. For example, the second lens 114 can be configured to couple the LIDAR output signal to the facet 35 of the comparison waveguide 18.

[0044] The LIDAR adapter can also have one or more direction-changing components such as a mirror. FIG. 2 shows a LIDAR adapter having a mirror as a direction-changing component 116 that redirects the system return signal from the circulator 100 to the facet 20 of the comparison waveguide 18.

[0045] The IDAR chip has one or more waveguides that constrain the optical paths of one or more optical signals. The LIDAR adapter has waveguides, while the optical paths through which the system return signal and the LIDAR output signal travel between components of the LIDAR adapter and / or between the LIDAR chip and the components of the LIDAR adapter can be free space. For example, the system return signal and / or the LIDAR output signal can travel through the environment in which the LIDAR chip, the LIDAR adapter, and / or the base 102 are disposed when traveling between different components of the LIDAR adapter and / or between the components of the LIDAR adapter and the LIDAR chip. As a result, using optical components such as lenses and beam-steering components, the characteristics of the optical paths through which the system return signal and the LIDAR output signal travel on, toward, and from the LIDAR adapter can be controlled.

[0046] Suitable bases 102 for the LIDAR adapter include, but are not limited to, substrates, platforms, and plates. Suitable substrates include, but are not limited to, glass, silicon, and ceramic. The components can be discrete components attached to the substrate. Suitable techniques for attaching the discrete components to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamps. In one example, one or more of the components are integrated components, and the remaining components are discrete components. In another example, the LIDAR adapter has one or more integrated amplifiers, and the remaining components are discrete components.

[0047] A LIDAR system can be configured to compensate for polarization. The light from the laser light source is typically linearly polarized, and thus the LIDAR output signal is also typically linearly polarized. The reflection from an object may change the polarization angle of the return light. Therefore, the system return signal may contain light in different linear polarization states. For example, the first part of the system return signal may have light in a first linear polarization state, and the second part of the system return signal may have light in a second linear polarization state. The intensity of the resulting composite signal is proportional to the square of the cosine of the angle between the comparison signal polarization field and the reference signal polarization field. If the angle is 90 degrees, the LIDAR data may be lost in the resulting composite signal. However, the LIDAR system can be modified to compensate for changes in the polarization state of the LIDAR output signal.

[0048] Figure 3 shows a modified LIDAR system in which the LIDAR adapter is suitable for use with the LIDAR chip of Figure 1C. The LIDAR adapter has a beam splitter 120 that receives the system return signal from the circulator 100. The beam splitter 120 splits the system return signal into a first part of the system return signal and a second part of the system return signal. Suitable beam splitters include, but are not limited to, Wollaston prisms and MEMS-based beam splitters.

[0049] The first part of the system return signal is directed to the comparison waveguide 18 on the LIDAR chip and functions as the first LIDAR input signal described in connection with Figure 1C. The second part of the system return signal is directed to the polarization rotator 122. The polarization rotator 122 is directed to the second input waveguide 76 on the LIDAR chip. Also, a second LIDAR input signal that functions as the second LIDAR input signal is output.

[0050] The beam splitter 120 can be a polarization beam splitter. An example of a polarization beam splitter is configured such that the first portion of the system return signal has a first polarization state but does not have, or substantially does not have, a second polarization state, and the second portion of the system return signal has a second polarization state but does not have, or substantially does not have, a first polarization state. The first polarization state and the second polarization state can be linear polarization states, and the second polarization state is different from the first polarization state. For example, the first polarization state can be TE and the second polarization state can be TM, or the first polarization state can be TM and the second polarization state can be TE. In some cases, the laser light source can be linearly polarized such that the LIDAR output signal has a first polarization state. Suitable beam splitters include, but are not limited to, Wollaston prisms and MEMS-based polarization beam splitters.

[0051] A polarization rotator can be configured to change the polarization state of the first portion of the system return signal and / or the second portion of the system return signal. For example, the polarization rotator 122 shown in FIG. 3 can be configured to change the polarization state of the second portion of the system return signal from the second polarization state to the first polarization state. As a result, the second LIDAR input signal has a first polarization state but does not substantially have, or does not have, a second polarization state. Thus, the first LIDAR input signal and the second LIDAR input signal each have the same polarization state (the first polarization state in this example). Despite carrying light of the same polarization state, the first LIDAR input signal and the second LIDAR input signal are associated with different polarization states as a result of the use of the polarization beam splitter. For example, the first LIDAR input signal carries light reflected in the first polarization state, and the second LIDAR input signal carries light reflected in the second polarization state. As a result, the first LIDAR input signal is associated with the first polarization state, and the second LIDAR input signal is associated with the second polarization state.

[0052] Since the first LIDAR input signal and the second LIDAR carry light of the same polarization state, the comparison signal resulting from the first LIDAR input signal has the same polarization angle as the comparison signal resulting from the second LIDAR input signal.

[0053] Suitable polarization rotators include, but are not limited to, rotation of a polarization-maintaining fiber, a Faraday rotator, a half-wave plate, a MEMS-based polarization rotator, and an integrated optical polarization rotator using an asymmetric y-branch, a Mach-Zehnder interferometer, and a multimode interference coupler.

[0054] Since the output LIDAR signal is linearly polarized, the first reference signal can have the same linear polarization state as the second reference signal. Also, the components of the LIDAR adapter can be selected so that the first reference signal, the second reference signal, the comparison signal, and the second comparison signal each have the same polarization state. In the example disclosed in connection with FIG. 3, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can each have light of a first polarization state.

[0055] With the above configuration, the first composite signal generated by the first processing component 46 and the second composite signal generated by the second processing component 48 are each the result of combining a reference signal and a comparison signal in the same polarization state, and also provide a desired beat between the reference signal and the comparison signal. For example, the composite signal is the result of combining a first reference signal and a first comparison signal in a first polarization state, and also excludes, or substantially excludes, light in a second polarization state, or is the result of combining a first reference signal and a first comparison signal in a second polarization state, and also excludes, or substantially excludes, light in a first polarization state. Similarly, the second composite signal has a second reference signal, and the second comparison signal in the same polarization state thus provides a desired beat between the reference signal and the comparison signal. For example, the second composite signal is the result of combining a second reference signal and a second comparison signal in a first polarization state, and also excludes, or substantially excludes, light in a second polarization state, or the second composite signal combines a second reference signal and a second comparison signal in a second polarization state, and also excludes, or substantially excludes, light in a first polarization state.

[0056] The above configuration results in LIDAR data for a single sample region of the field of view generated from a plurality of different composite signals (i.e., the first composite signal and the second composite signal) from the sample region. In some examples, determining the LIDAR data for the sample region includes an electronic circuit that combines the LIDAR data from different composite signals (i.e., the composite signal and the second composite signal). Combining the LIDAR data can include taking the average, median, or mode of the LIDAR data generated from different composite signals. For example, the electronic circuit can average the distance between the LIDAR system and the reflective object determined from the composite signal having a distance determined from the second composite signal, and / or the electronic circuit can average the radial velocity between the LIDAR system and the reflective object determined from the composite signal having a radial velocity determined from the second composite signal.

[0057] In some examples, determining LIDAR data for a sample region includes an electronic circuit that identifies one or more composite signals (i.e., a composite signal and / or a second composite signal) as a source of the most representative LIDAR data (representative LIDAR data). The electronic circuit can then utilize the LIDAR data from the identified composite signal as representative LIDAR data for further processing. For example, the electronic circuit can identify a signal (a composite signal or a second composite signal) with a larger amplitude as having representative LIDAR data, and utilize the LIDAR data from the identified signal for further processing by the LIDAR system. In some examples, the electronic circuit combines identifying a composite signal with representative LIDAR data with combining LIDAR data from different LIDAR signals. For example, the electronic circuit can identify each composite signal with an amplitude exceeding an amplitude threshold as having representative LIDAR data, and if two or more composite signals are identified as having representative LIDAR data, the electronic circuit can combine the LIDAR data of each identified composite signal. When one composite signal is identified as having representative LIDAR data, the electronic circuit can utilize the LIDAR data from that composite signal as representative LIDAR data. If none of the composite signals are identified as having representative LIDAR data, the electronic circuit can discard the LIDAR data for the sample region associated with those composite signals.

[0058] FIG. 3 is described in connection with components arranged such that the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal each have a first polarization state. However, the composite signal is the result of combining a reference signal and a comparison signal in the same linearly polarized state, and other configurations of the components in FIG. 3 can be arranged such that the second composite signal is the result of combining a reference signal and a comparison signal in the same linearly polarized state. For example, the beam splitter 120 can be configured such that the second portion of the system return signal has a first polarization state and the first portion of the system return signal has a second polarization state, and the polarization rotator receives the first portion of the system return signal, and the outgoing LIDAR signal can have a second polarization state. In this example, the first LIDAR input signal and the second LIDAR input signal each have a second polarization state.

[0059] The above system configuration results in a first portion of the system return signal and a second portion of the system return signal that are directed to different composite signals. As a result, the first portion of the system return signal and the second portion of the system return signal are each associated with a different polarization state, but since the electronic circuit unit can process each composite signal, the LIDAR system compensates for changes in the polarization state of the LIDAR output signal in response to reflections of the LIDAR output signal.

[0060] The LIDAR adapter of FIG. 3 can have additional optical components including passive optical components. For example, the LIDAR adapter can have an optional third lens 126. The third lens 126 can be configured to couple the second LIDAR output signal at a desired location. In some cases, the third lens 126 focuses or collimates the second LIDAR output signal at a desired location. For example, the third lens 126 can be configured to focus or collimate the second LIDAR output signal at the facet 52 of the second comparison waveguide 50. The LIDAR adapter also has one or more direction conversion components 124 such as mirrors and prisms. FIG. 3 shows a LIDAR adapter having a mirror as a direction conversion component 124 that redirects the second portion of the system return signal from the circulator 100 to the facet 52 of the second comparison waveguide 50 and / or the third lens 1266.

[0061] When the LIDAR system has a LIDAR chip and a LIDAR adapter, the LIDAR chip, the electronic circuit unit, and the LIDAR adapter can be arranged on a common mount. Suitable common mounts include, but are not limited to, glass plates, metal plates, silicon plates, and ceramic plates. As an example, FIG. 4 is a plan view of a LIDAR system having the LIDAR chip of FIG. 1A, the electronic device 32, and the LIDAR adapter of FIG. 2 on a common support 140. Although the electronic circuit unit 32 is shown as being arranged on the common support, all or part of the electronic circuit unit can be arranged outside the common support. When the light source 4 is arranged outside the LIDAR chip, the light source can be arranged on the common support 240 or outside the common support 140. Suitable approaches for attaching the LIDAR chip, the electronic circuit unit, and / or the LIDAR adapter to the common support include, but are not limited to, epoxy, solder, and mechanical clamps.

[0062] The LIDAR system can have components with additional passive and / or active optical components. A portion of the LIDAR output signal from one or more components can function as the system output signal. For example, the LIDAR system can receive the LIDAR output signal from a LIDAR chip or from a LIDAR adapter and have one or more beam steering components that output all or a portion of the LIDAR output signal that functions as the system output signal. For example, FIG. 4 shows a beam steering component 142 that receives the LIDAR output signal from a LIDAR adapter. FIG. 4 shows the beam steering component disposed on a common support 140, but the beam steering component can be disposed on the LIDAR adapter, on the LIDAR chip, or outside the common support 140. Suitable beam steering components include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), and actuators that move the LIDAR chip, the LIDAR adapter, and / or the common support.

[0063] The electronic circuit can operate one or more beam steering components 142 and steer the system output signal to different sample regions 144. The sample regions can extend away from the LIDAR system to a maximum distance configured to provide reliable LIDAR data from the LIDAR system. The sample regions can be stitched together to define a field of view. For example, the field of view for the LIDAR system includes or constitutes the space occupied by the combination of the sample regions.

[0064] Figures 5A through 5C illustrate examples of suitable processing components for use as all or part of a group consisting of processing component 22, first processing component 46, and second processing component 48. The processing component receives a comparison signal from comparison waveguide 196 and a reference signal from reference waveguide 198. The comparison waveguide 18 and reference waveguide 20 shown in FIGS. 1A and 1B can function as comparison waveguide 196 and reference waveguide 198, the comparison waveguide 18 and first reference waveguide 42 shown in FIG. 1C can function as comparison waveguide 196 and reference waveguide 198, or the second comparison waveguide 50 and second reference waveguide 44 shown in FIG. 1C can function as comparison waveguide 196 and reference waveguide 198.

[0065] The processing component includes a second splitter 200 that splits the comparison signal carried on comparison waveguide 196 into a first comparison waveguide 204 and a second comparison waveguide 206. The first comparison waveguide 204 carries a first portion of the comparison signal to an optical coupling component 211. The second comparison waveguide 208 carries a second portion of the comparison signal to a second optical coupling component 212.

[0066] The processing component includes a first splitter 202 that splits the reference signal carried on reference waveguide 196 into a first reference waveguide 204 and a second reference waveguide 206. The first reference waveguide 204 carries a first portion of the reference signal to an optical coupling component 211. The second reference waveguide 208 carries a second portion of the reference signal to a second optical coupling component 212.

[0067] The second optical coupling component 212 combines the second portion of the comparison signal and the second portion of the reference signal into a second composite signal. Due to the frequency difference between the second portion of the comparison signal and the second portion of the reference signal, the second composite signal beats between the second portion of the comparison signal and the second portion of the reference signal.

[0068] The second optical coupling component 212 also splits the resulting second composite signal into a first auxiliary detection waveguide 214 and a second auxiliary detection waveguide 216. The first auxiliary detection waveguide 214 conveys a first portion of the second composite signal to a first auxiliary optical sensor 218 that converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detection waveguide 216 conveys a second portion of the second composite signal to a second auxiliary optical sensor 220 that converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0069] In some cases, the second optical coupling component 212 splits the second composite signal such that a portion of the comparison signal (i.e., a part of the second portion of the comparison signal) included in the first portion of the second composite signal has a phase shifted by 180° with respect to a portion of the comparison signal (i.e., a part of the second portion of the comparison signal) in the second portion of the second composite signal, while a portion of the reference signal (i.e., a part of the second portion of the reference signal) in the second portion of the second composite signal has no phase shift with respect to a portion of the reference signal (i.e., a part of the second portion of the reference signal) in the first portion of the second composite signal. Alternatively, the second optical coupling component 212 splits the second composite signal such that a portion of the reference signal (i.e., a part of the second portion of the reference signal) in the first portion of the second composite signal has a phase shifted by 180° with respect to a portion of the reference signal (i.e., a part of the second portion of the reference signal) in the second portion of the second composite signal, while a portion of the comparison signal (i.e., a part of the second portion of the comparison signal) in the first portion of the second composite signal has no phase shift with respect to a portion of the comparison signal (i.e., a part of the second portion of the comparison signal) in the second portion of the second composite signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0070] The first optical coupling component 211 combines the first portion of the comparison signal and the first portion of the reference signal into a first composite signal. Due to the frequency difference between the first portion of the comparison signal and the first portion of the reference signal, the first composite signal beats between the first portion of the comparison signal and the first portion of the reference signal.

[0071] The first optical coupling component 211 also splits the first composite signal into a first detection waveguide 221 and a second detection waveguide 222. The first detection waveguide 221 conveys a first portion of the first composite signal to a first optical sensor 223 that converts a first portion of the second composite signal into a first electrical signal. The second detection waveguide 222 conveys a second portion of the second composite signal to a second optical sensor 224 that converts the second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0072] In some cases, the optical coupling component 211 splits the first composite signal such that the portion of the comparison signal (i.e., a part of the first portion of the comparison signal) included in the first portion of the composite signal has a phase shifted by 180° with respect to the portion of the comparison signal (i.e., a part of the first portion of the comparison signal) in the second portion of the composite signal, while the portion of the reference signal (i.e., a part of the first portion of the reference signal) in the first portion of the composite signal has no phase shift with respect to the portion of the reference signal (i.e., a part of the first portion of the reference signal) in the second portion of the composite signal. Alternatively, the optical coupling component 211 splits the composite signal such that the portion of the reference signal (i.e., a part of the first portion of the reference signal) in the first portion of the composite signal has a phase shifted by 180° with respect to the portion of the reference signal (i.e., a part of the first portion of the reference signal) in the second portion of the composite signal, while the portion of the comparison signal (i.e., a part of the first portion of the comparison signal) in the first portion of the composite signal has no phase shift with respect to the portion of the comparison signal (i.e., a part of the first portion of the comparison signal) in the second portion of the composite signal.

[0073] When the second optical coupling component 212 divides the second composite signal such that the portion of the comparison signal in the first portion of the second composite signal has a phase shifted by 180° with respect to the portion of the comparison signal in the second portion of the second composite signal, the optical coupling component 211 also divides the composite signal such that the portion of the comparison signal included in the first portion of the composite signal has a phase shifted by 180° with respect to the portion of the comparison signal in the second portion of the composite signal. When the second optical coupling component 212 divides the second composite signal such that the portion of the reference signal in the first portion of the second composite signal has a phase shifted by 180° with respect to the portion of the reference signal in the second portion of the second composite signal, the optical coupling component 211 also divides the composite signal such that the portion of the reference signal in the first portion of the composite signal has a phase shifted by 180° with respect to the portion of the reference signal in the second portion of the composite signal.

[0074] The first reference waveguide 210 and the second reference waveguide 208 are configured to provide a phase shift between the first portion of the reference signal and the second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 can be configured to provide a 90-degree phase shift between the first portion of the reference signal and the second portion of the reference signal. As an example, one portion of the reference signal can be made the in-phase component, and the other can be made the quadrature component. Thus, one portion of the reference signal can be made a sine function, and the other portion of the reference signal can be made a cosine function. In one example, the first reference waveguide 210 and the second reference waveguide 208 are constructed such that the first portion of the first reference signal is a cosine function and the second portion of the second reference signal is a sine function. Thus, the portion of the reference signal in the second composite signal is phase-shifted with respect to the portion of the reference signal in the first composite signal, but the portion of the comparison signal in the first composite signal is not phase-shifted with respect to the portion of the comparison signal in the second signal.

[0075] The first optical sensor 223 and the second optical sensor 224 can be connected as a balanced detector, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 can also be connected as a balanced detector. For example, FIG. 5B provides an overview of the relationship between the electronic circuit section, the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220. Symbols for photodiodes are used to represent the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220, but one or more of these sensors can have other configurations. In some cases, all of the components shown in the schematic of FIG. 5B are included in the LIDAR chip. In some cases, the components shown in the schematic of FIG. 5B are distributed between the LIDAR chip and an electronic circuit section disposed outside the LIDAR chip.

[0076] The electronic circuit unit connects the first optical sensor 223 and the second optical sensor as the first balanced detector 225, and also connects the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 as the second balanced detector 226. In particular, the first optical sensor 223 and the second optical sensor 224 are connected in series. Also, the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 are connected in series. The series connection in the first balanced detector communicates with the first data line 228 that carries the output from the first balanced detector as the first data signal. The series connection in the second balanced detector communicates with the second data line 232 that carries the output from the second balanced detector as the second data signal. The first data signal electrically represents the first composite signal, and the second data signal electrically represents the second composite signal. Therefore, the first data signal includes contributions from the first waveform and the second waveform, and the second data signal is a composite of the first waveform and the second waveform. A part of the first waveform in the first data signal is phase-shifted with respect to the part of the first waveform in the first data signal, but a part of the second waveform in the first data signal is in phase with the part of the second waveform in the first data signal. For example, the second data signal has a part of the reference signal that is phase-shifted with respect to different parts of the reference signal included in the first data signal. In addition, the second data signal has a part of the comparison signal that is in phase with different parts of the comparison signal included in the first data signal. The first data signal and the second data signal are the result of the beat between the comparison signal and the reference signal, that is, the beat in the first composite signal and the beat in the second composite signal.

[0077] The electronic circuit unit 32 has a conversion mechanism 238 configured to perform a mathematical transformation on the first data signal and the second data signal. For example, the mathematical transformation can be a complex Fourier transform that takes the first data signal and the second data signal as inputs. Since the first data signal is the in-phase component and the second data signal is the quadrature component, both the first data signal and the second data signal act as a complex data signal where the first data signal is the real component of the input and the second data signal is the imaginary component of the input.

[0078] The conversion mechanism 238 has a first analog-to-digital conversion converter (ADC) 264 that receives a first data signal from the first data line 228. The first analog-to-digital conversion converter (ADC) converts the first data signal from an analog format to a digital format and outputs a first digital data signal. The conversion mechanism 238 has a second analog-to-digital conversion converter (ADC) 266 that receives a second data signal from the second data line 232. The second analog-to-digital conversion converter (ADC) 226 converts the second data signal from an analog format to a digital format and outputs a second digital data signal. The first digital data signal represents the first data signal in digital form, and the second digital data signal represents the second data signal in digital form. Therefore, the first digital data signal and the second digital data signal together act as a complex signal in which the first digital data signal acts as the real component of the complex signal and the second digital data signal acts as the imaginary component of the complex data signal.

[0079] The conversion mechanism 238 has a conversion component 268 that receives a complex data signal. For example, the conversion component 268 receives, as an input, a first digital data signal from a first analog-to-digital converter (ADC) 264 and also receives, as an input, a second digital data signal from a second analog-to-digital converter (ADC) 266. The conversion component 268 can be configured to perform a mathematical conversion on the complex signal so as to convert from the time domain to the frequency domain. The mathematical conversion can be a complex conversion such as a complex fast Fourier transform (FFT). A complex conversion such as a complex fast Fourier transform (FFT) provides a clear solution for the frequency shift of the LIDAR input signal relative to the LIDAR output signal caused by the radial velocity between the reflecting object and the LIDAR chip. The electronic circuit section utilizes one or more frequency peaks output from the conversion component 268 for further processing to generate LIDAR data (the distance between the reflecting object and the LIDAR chip, and / or the radial velocity, and / or the LIDAR system). The conversion component 268 can execute an attributed function using firmware, hardware, or software, or a combination thereof.

[0080] FIG. 5A shows an optical coupling component that couples a portion of a reference signal to a portion of a comparison signal, but the processing component can have a single optical coupling component that couples the reference signal and the comparison signal to form a composite signal. As a result, at least a portion of the reference signal and at least a portion of the comparison signal can be combined to form a composite signal. The combined portion of the reference signal can be the entire reference signal or a portion of the reference signal, and the combined portion of the comparison signal can be the entire comparison signal or a portion of the comparison signal.

[0081] The electronic circuit section adjusts the frequency of the system output signal over time. The system output signal has a frequency - versus - time pattern in the repetition period. FIG. 5C shows an example of a suitable frequency - versus - time pattern for the system output signal. FIG. 5C shows the frequency of the system output signal for a sequence of two periods labeled period j and period j + 1. The base frequency (f0) of the system output signal can be the frequency of the system output signal at the start of the period. The plurality of periods shown do not have a rearrangement period, and / or the placement period is not placed between periods of the number of scans. As a result, FIG. 5C shows the result of a continuous scan.

[0082] Each of the plurality of periods has M data periods, each of which is associated with a period index m and labeled with DPm. In the example of FIG. 5C, each period has two data periods labeled with DPm for m = 1 and m = 2. In some cases, as shown in FIG. 5C, the frequency - versus - time pattern is the same for corresponding data periods in different periods. Corresponding data periods are data periods having the same period index. As a result, each of the data periods DP1 can be regarded as a corresponding data period, and the associated frequency - versus - time pattern is the same in FIG. 5C. At the end of the period, the electronic circuit section returns the frequency to the same frequency level as when the previous period started.

[0083] LIDAR data is generated for a series of sample regions irradiated by the system LIDAR signal. The field of view for the LIDAR system includes or is composed of the space occupied by the combination of sample regions. For example, the sample regions can be stitched together to define the field of view.

[0084] Figure 5C labels sample regions, each associated with a sample region index k and labeled SRk. Figure 5C labels sample regions SRk−1 through SRk+3. Each sample region is illuminated by the system output signal during a data period as indicated by Figure 5C's association with the sample region. For example, sample region SRk+1 is illuminated by the system output signal during the data period labeled DP2 in period j and during the data period labeled DP1 in period j+1. Thus, the sample region labeled SRk+1 is associated with the data period labeled DP2 in period j and the data period labeled DP1 in period j+1.

[0085] As is clear from Figure 5C, one data period can be associated with one or more sample regions. For example, the data period labeled DP2 in period j is associated with the sample region labeled SRk+1 and the sample region labeled SRk. Thus, different groups of data periods can share a common data period. However, a group sharing a common data period can have one or more data periods not shared by the group. Since sample regions are illuminated by the system output signal during associated data periods and different sample regions can be associated with the same data period, different sample regions can overlap each other.

[0086] The system output signal can be chirped during at least some data periods of the same period. The chirp can be constant and continuous while the data period continues. For example, between the data period labeled DP1 and the data period labeled DP2, the electronic circuit section operates the light source such that the frequency of the system output signal changes at a linear rate α. The direction of the frequency change in data period DP1 is opposite to the direction of the frequency change in data period DP2. Thus, the chirp of the system output signal can be different for different data periods within the same period.

[0087] The frequencies output from the complex Fourier transform represent the Doppler frequencies of complex signals each having a comparison signal that is Doppler shifted with respect to a reference signal. LIDAR data regarding a sample region can be generated from the Doppler frequencies (fLDP) from a group of data periods associated with the sample region. Thus, the electronic circuit unit generates a set of LIDAR data regarding the sample region from the light included in the system output signal among groups of a plurality of data periods. For example, the Doppler frequency determined from DP1 of period j can be combined with the Doppler frequency determined from DP2 of period j to determine LIDAR data regarding the sample region labeled with SRk. Thus, the electronic circuit unit generates a set of LIDAR data regarding the sample region SRk from the group data periods having data periods labeled with DP1 and DP2 of period j.

[0088] As an example of a method for determining LIDAR data regarding a sample area from a group of data periods, in a data period during which the electronic circuit unit increases the frequency of the emitted LIDAR signal as seen in data period DP1 of period j in FIG. 5C, the following equation is applied. fub = -fd + ατ, where fub is the frequency provided by the conversion component 268 (here, fLDP determined from DP1), fd represents the Doppler shift (fd = 2νfc / c), where fc represents the optical frequency (f0), c represents the speed of light, ν represents the radial velocity between the reflecting object and the LIDAR system, v is the radial velocity between the reflecting object and the LIDAR system, where the direction from the reflecting object towards the LIDAR system is assumed to be the positive direction, and c is the speed of light. In a data period during which the electronic circuit unit decreases the frequency of the emitted LIDAR signal as seen in data period DP2 of period j in FIG. 5C, the following equation is applied. fdb = -fd - ατ, where fdb is the frequency provided by the conversion component 268 (here, fi.LDP determined from DP2). In these two equations, fd and τ are unknowns. The electronic circuit unit solves these two equations regarding the two unknowns fd and τ. Then, the radial velocity regarding the sample area can be quantified from the Doppler shift (ν = c×fd / (2fc)), and / or the separation distance regarding the sample area can be quantified from c×fd / 2.

[0089] The above example discloses generating LIDAR data for a sample region (SRk) from a group of data periods that fall within the same cycle (cyclej). However, it is possible to generate LIDAR data for a sample region from a group of data periods having data periods from different cycles. For example, using the associated data periods, LIDAR data can be generated for the sample region labeled SRk+1. For example, as described above, using the value of fdb from the data period labeled DP2 within cycle j and the value of fub from the data period labeled DP1 within cycle j+1, LIDAR data for the sample region labeled SRk+1 can be generated.

[0090] In some examples, one or more objects are present in the sample region. Different objects need not be physically distinct objects and can be different surfaces of the same object. If one or more objects are present within the sample region, the transformation can output one or more frequencies and each frequency can be associated with a different object. Frequencies arising from the same object in different data periods of the same cycle can be considered corresponding frequency pairs. LIDAR data can be generated for each corresponding frequency pair output by the transformation. As a result, different LIDAR data can be generated for each object in the sample region.

[0091] The period of FIG. 5C can have two or more data periods. For example, FIG. 5D shows an example of the relationship between the frequency, time, period, and data period of the system output signal, and each period has two or more data periods. The data period labeled as DP 3 in FIG. 5C makes it possible to combine the frequencies belonging to the same corresponding frequency pair. For example, during the feedback period of DP1 of period 2 and during the feedback period of DP2 of period 2, one or more frequency pairs can also be combined. In these situations, it may not be clear which frequency peak from which DP2 corresponds to which frequency peak from which DP1. As a result, it may not be clear which frequencies need to be used together to generate LIDAR data for an object in the sample area. As a result, 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 corresponding frequencies can be found using the data period labeled as DP3. LIDAR data can be generated for each pair of corresponding frequencies and considered and / or processed as LIDAR data for different reflecting objects in the sample area.

[0092] For a specific example of identifying corresponding frequencies, as shown in FIG. 5D, a LIDAR system having three data periods (DP1, DP2, DP3) in a period is used. If there are two objects in the sample area irradiated by the system output signal, the conversion component 268 outputs two different frequencies related to fub: fu1 and fu2 during DP1, and also outputs two other different frequencies related to fdb: fd1 and fd2 during DP2. In this case, the possible frequency pairs are (fd1, fu1); (fd1, fu2); (fd2, fu1); and (fd2, fdu2). The values of fd and τ can be calculated for each of the possible frequency pairs. Substitute each pair of values of fd and τ into f3 = -fd + α3τ0 to generate the theoretical f3 for each possible frequency pair. The value of α3 is different from the value of α used in DP1 and DP2. In FIG. 5D, the value of α3 is zero. In this case, the conversion component 268 also outputs two values related to f3, each of which is associated with one object in the sample area. Consider the frequency pair having the theoretical f3 value closest to each of the actual f3 values as the corresponding pair. As described above, LIDAR data can be generated for each of the corresponding pairs, and considered and / or processed as being related to different single reflecting objects in the sample area. Each of the corresponding frequency pairs can be used in the above formula to generate LIDAR data. The generated LIDAR data will be related to one object in the sample area. As a result, a plurality of different LIDAR data values can be generated for the sample area, and each of the different LIDAR data values corresponds to a different single object in the sample area.

[0093] The frequency - versus - time pattern shown in FIG. 5D shows three sample regions associated with a single data period. Further, FIG. 5D shows three data periods associated with each sample region. However, a different number of data periods can be associated with each sample region than the number of sample regions associated with each data period. For example, FIG. 5E shows the frequency - versus - time pattern of FIG. 5D configured such that three data periods are associated with each sample region, but only two sample regions are associated with each data period.

[0094] FIGS. 5C through 5E show that the duration of each data period appears to be the same, but the durations of different data periods can be different. For example, the duration of the data period labeled DP3 in FIG. 5D can be different from the data period labeled DP2. FIGS. 5C through 5E also show at least two data periods of the same cycle having the same frequency change rate (α); however, different data periods of the same cycle can have different frequency change rates. For example, FIG. 5F shows an example of the relationship between the frequency, time, cycle, and data period of a system output signal, and different data periods of the same cycle have different frequency change rates. When different data periods within the same cycle have different frequency change rates and / or different durations, suitable approaches for LIDAR data generation are not limited, but are approaches disclosed in U.S. Patent Application Serial No. 16 / 848,829, filed April 14, 2020, titled "Reduction of Sampling Rate in LIDAR Systems," and incorporated herein by reference in its entirety, and also approaches disclosed in U.S. Patent Application Serial No. 16 / 848,818, filed April 14, 2020, titled "Simultaneous LIDAR Measurements of Regions within a Field of View," and incorporated herein by reference in its entirety.

[0095] Suitable platforms for LIDAR chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. FIG. 6 is a cross-section of a portion of a chip composed of a silicon-on-insulator wafer. An SOI (Silicon-On-Insulator) wafer has a buried layer 310 between a substrate 312 and an optically transparent medium 314. In a silicon-on-insulator wafer, the buried layer 310 is silica, while the substrate 312 and the optically transparent medium 314 are silicon. The substrate 31 of an optical platform such as an SOI wafer can function as the base of the entire LIDAR chip. For example, the optical components shown in the LIDAR chips of FIGS. 1A through 1C can be placed in contact with, or on, the upper surface and / or side surfaces of the substrate 312.

[0096] FIG. 6 is a cross-sectional view of a portion of a LIDAR chip including a waveguide structure suitable for use in a LIDAR chip composed of a silicon-on-insulator wafer. A ridge 316 of the optical transmission medium extends away from a slab region 318 of the optical transmission medium. An optical signal is confined between the apex of the ridge 316 and the buried oxide layer 310.

[0097] In FIG. 6, the dimensions of the ridge waveguide are labeled. For example, the ridge has a width labeled w and a height labeled h. The thickness of the slab region is labeled T. In LIDAR applications, these dimensions may be more important than other dimensions because they need to use a higher level of optical power than those used in other applications. The ridge width (labeled w) is greater than 1 μm and less than 4 μm, the ridge height (labeled h) is greater than 1 μm and less than 4 μm, and the slab region thickness is greater than 0.5 μm and less than 3 μm. These dimensions are applicable to straight or substantially straight portions of the waveguide, curved portions of the waveguide, and tapered portions of the waveguide. Thus, these portions of the waveguide will be single mode. However, in some cases, these dimensions apply to straight or substantially straight portions of the waveguide. Additionally, or alternatively, the curved portion of the waveguide can have a reduced slab thickness to reduce optical loss in the curved portion of the waveguide. For example, the curved portion of the waveguide can have a ridge extending away from a slab region with a thickness greater than or equal to 0.0 μm and less than 0.5 μm. The above dimensions generally provide a straight or substantially straight portion of the waveguide having a single mode structure, while they can result in a tapered portion and / or a curved portion that is multimode. A taper that does not substantially excite higher order modes can be used to effect a coupling from the multimode geometry to the single mode geometry. Thus, the waveguide can be configured such that the signal carried in the waveguide is carried in single mode even when it is carried in a portion of the waveguide having multimode dimensions. The waveguide structure disclosed in connection with FIG. 6 is suitable for all or part of the waveguide of the LIDAR chip constructed in accordance with FIGS. 1A through 1C.

[0098] An optical sensor connected to a waveguide in a LIDAR chip can be made into a component that is separated from the chip and then attached to the chip. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, 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 centrally arranged on the LIDAR chip. Alternatively, all or part of the waveguide terminated by the optical sensor can be terminated with a facet arranged at the end of the chip, and the optical sensor can be attached beyond the facet to the end of the chip so that the optical sensor receives the light passing through the facet. The use of an optical sensor as a component separated from the chip is suitable for all or part of the optical sensors 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.

[0099] Instead of an optical sensor as a separated component, all or part of the optical sensor can be integrated into the chip. For example, examples of optical sensors connected to the ridge waveguide of a chip composed of a silicon-on-insulator wafer can be found in Optics Express Vol. 15, No. 21, 13965 - 13971 (2007), which is incorporated herein by reference in its entirety; U.S. Patent No. 8,093,080, issued on January 10, 2012; U.S. Patent No. 8,242,432, issued on August 14, 2012; and U.S. Patent No. 6,108,472, issued on August 22, 2000. The use of an optical sensor integrated into the chip is suitable for all or part of the optical sensors selected from the group consisting of the auxiliary optical sensor 218, the second auxiliary optical sensor 220, the first optical sensor 223, and the second optical sensor 224.

[0100] The light source 4 connected to the utility waveguide 12 can be separated from the LIDAR chip and can be a laser chip attached to the LIDAR chip. For example, the light source 4 can be a laser chip attached to the chip using a flip-chip arrangement. The use of a flip-chip arrangement is suitable when the light source 4 is connected to the ridge waveguide of a chip composed of a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 can have an optical grating (not shown), such as a Bragg grating, that acts as a reflector for an external resonator laser. In these examples, the light source 4 can be separated from the LIDAR chip and can have a gain element attached to the LIDAR chip in a flip-chip arrangement. Examples of suitable interfaces between a silicon-on-insulator wafer-derived silicon-on-insulator wafer-derived element and a ridge waveguide can be found in U.S. Patent No. 9,700,278, issued July 11, 2017, and U.S. Patent No. 5,991,484, issued November 23, 1999, which are incorporated herein by reference in their entirety. When the light source 4 is a gain element or a laser chip, the electronic circuit section 32 can change the frequency of the emitted LIDAR signal by changing the level of the current applied through the gain element or the laser cavity.

[0101] Suitable electronic circuit units 32 can include, but are not limited to, analog electrical circuits, digital electrical circuits, processors, microprocessors, digital signal processors (DSPs), field programmable gate arrays (FPGAs), computers, microcomputers, or control units having or configured with a suitable combination for performing the above-described operations, monitoring, and control functions. In some examples, the control unit accesses a memory having instructions executed by the control unit during performance of the operation, control, and monitoring functions. Although the electronic circuit unit is illustrated as a single component in a single location, the electronic circuit unit can have multiple different components that are independent of each other and / or located in different locations. Additionally, as described above, all or a portion of the disclosed electronic circuit unit can be included in a chip having an integrated electronic circuit unit of the chip.

[0102] The above-described LIDAR system has a plurality of optical components such as a LIDAR chip, a LIDAR adapter, a light source, an optical sensor, a waveguide, and an amplifier. In some examples, the LIDAR system has one or more passive optical components in addition to or in place of the illustrated optical components. The passive optical component can be a solid state component excluding movable parts. Suitable passive optical components include, but are not limited to, lenses, mirrors, optical gratings, reflective surfaces, splitters, demultiplexers, multiplexers, polarizers, polarization splitters, and polarization rotators. In some examples, the LIDAR system has one or more active optical components in addition to or in place of the illustrated optical components. Suitable active components include, but are not limited to, optical switches, phase tuners, attenuators, steerable mirrors, steerable lenses, tunable demultiplexers, and tunable multiplexers.

[0103] Other embodiments, combinations, and modifications of the present invention will be readily made by those skilled in the art in view of these teachings. Accordingly, the present invention is limited only by the following claims, which, when viewed in conjunction with the above specification and the accompanying drawings, include all such embodiments and modifications.

Claims

**Claim 1** One or more components configured to advance away from a LIDAR system and output a system output signal that can be reflected by an object disposed outside the LIDAR system, and an electronic circuit configured to generate a plurality of different sets of LIDAR data, a LIDAR system having, wherein the system output signal has a frequency-versus-time pattern with a repetition period, each period of the frequency-versus-time pattern having a plurality of data periods configured such that the system output signal is chirped differently in different data periods, each set of LIDAR data indicating a radial velocity and / or a separation between the LIDAR system and one or more objects, generated from light included in the system output signal between different groups of the plurality of data periods, the groups of data periods having one or more common data periods, and one or more of the common data periods being included in two or more different groups of data periods, a LIDAR system. **Claim 2** The system of claim 1, wherein the shared group has at least one common data period and at least one data period not common to the shared group. **Claim 3** The system of claim 2, wherein each data period included in at least a portion of the shared group is common to at least one other of the groups. **Claim 4** The system of claim 1, wherein each data period included in each of the groups is common to at least one other of the groups. **Claim 5** The system of claim 1, wherein each data period included in each group occurs sequentially. **Claim 6** The system of claim 1, wherein each group has at least one data period during which the frequency of the system output signal increases linearly with respect to time while the data period continues. **Claim 7** The system of claim 6, wherein each group has at least one data period during which the frequency of the system output signal decreases linearly with respect to time while the data period continues. **Claim 8** The system of claim 1, wherein each group of data periods is associated with a sample region illuminated by the system output signal between the groups of data periods. **Claim 9** The LIDAR chip is configured to output a LIDAR output signal, and the system output signal has light from the LIDAR output signal, and the LIDAR chip has a photonic integrated circuit (PIC), the system according to claim 1.

10. The system according to claim 9, wherein the LIDAR chip is built on a silicon-on-insulator wafer.

11. Output the system output signal from the LIDAR system such that the system output signal travels away from the LIDAR system and can be reflected by an object located outside the LIDAR system, the system output signal has a frequency-versus-time pattern having a repetition period, each period of the frequency-versus-time pattern has a plurality of the data periods configured such that the system output signal is chirped differently in different data periods, and generate a plurality of different sets of LIDAR data, each set of LIDAR data indicates a radial velocity and / or a separation between the LIDAR system and one or more objects, each set of LIDAR data is generated from light included in the system output signal between a group of a plurality of data periods, the group of data periods has one or more common data periods, and the one or more common data periods are included in two or more different groups of data periods, a method of operating a LIDAR system.

12. The method according to claim 11, wherein the common group has at least one common data period and at least one data period that is not common to the common group.

13. The method according to claim 12, wherein each data period included in at least a portion of the common group is common to at least one other group.

14. The method according to claim 11, wherein each data period included in each of the groups is common to at least one other group.

15. The method according to claim 11, wherein each data period included in each group occurs sequentially.

16. The method according to claim 11, wherein each group has at least one data period during which the frequency of the system output signal increases linearly with respect to time while the data period continues.

17. The method of claim 16, wherein each group has at least one data period during which the frequency of the system output signal decreases linearly with time while the data period persists. **Claim 18** The method of claim 11, wherein each group of data periods is associated with a sample region illuminated by the system output signal between the groups of data periods. **Claim 19** The method of claim 11, wherein the system output signal has light from a LIDAR output signal, and the LIDAR output signal is output from a LIDAR chip having a photonic integrated circuit (PIC). **Claim 20** The method of claim 19, wherein the LIDAR chip is constructed on a silicon-on-insulator wafer.

Images