Improving the signal-to-noise ratio in LIDAR systems

Abstract

The LIDAR system includes a light source configured to output light. A portion of this light is included in a LIDAR signal that travels on a LIDAR path from the light source to an object external to the LIDAR system, from the object to a filter, and from the filter to a processing unit. The processing unit is configured to convert the light signal that includes the LIDAR signal into an electrical signal. A portion of this light is also included in one or more misguided signals. Each of the misguided signals travels on a misguided path from the light source to the filter. Each of the misguided paths is a different path from the LIDAR path. The system also includes a filter configured to filter out the LIDAR signal from the misguided signals. The system also includes electronics that generate LIDAR data from the electrical signals.

Description

Related applications

[0001] This application is a continuation of U.S. Patent Application No. 17 / 067,623, filed on October 9, 2020, entitled "Improving the signal-to-noise ratio in LiDAR systems," and incorporates the entirety of that application.

[0002] This invention relates to an optical device. In particular, this invention relates to a LIDAR system. Background

[0003] The performance requirements imposed on LIDAR systems are increasing as the number of applications they support grows. A LIDAR system typically generates an optical signal used to illuminate one or more sample areas within its field of view. When an object within a sample area reflects light, the reflected light can return to the LIDAR system. The LIDAR system can use this reflected light to generate LIDAR data for each sample area. The LIDAR data for a sample area indicates the line-of-sight velocity and / or distance between the LIDAR system and one or more objects within the sample area.

[0004] LiDAR systems convert reflected light into electrical signals. Electronic devices use these electrical signals to generate LiDAR data. However, the processing of optical signals by LiDAR systems can become a source of noise in the electrical signals. This noise can reduce the reliability of LiDAR data. As a result, improvements to LiDAR systems are needed. Overview

[0005] A LIDAR system includes a light source configured to emit light. A portion of this light is included in a LIDAR signal traveling along a LIDAR path from the light source to an object outside the LIDAR system, from the object to a filter, and from the filter to a processing unit. The processing unit is configured to convert the optical signal, including the LIDAR signal, into an electrical signal. A portion of this light is also included in one or more misinduced signals. Each of these misinduced signals travels along a misinduced path from the light source to the filter. Each of these misinduced paths is different from the LIDAR path. The system also includes a filter configured to filter out the LIDAR signal from the misinduced signals. The system also includes electronic equipment that generates LIDAR data from the electrical signals. [Brief explanation of the drawing]

[0006] Figure 1 is a schematic top view of a LIDAR chip for use in a LIDAR system.

[0007] Figure 2 is a schematic top view of a LIDAR chip for use in a LIDAR system, according to another embodiment.

[0008] Figure 3 is a top view of an example of a LiDAR adapter suitable for use with the LiDAR chip shown in Figure 1.

[0009] Figure 4 is a top view of an example of a LiDAR adapter suitable for use with the LiDAR chip shown in Figure 1.

[0010] Figure 5 is a top view of a LiDAR system including the LiDAR chip from Figure 1 and the LiDAR adapter from Figure 3 on a common mount.

[0011] Figure 6 is a top view of a LiDAR system including the LiDAR chip from Figure 2 and the LiDAR adapter from Figure 4 on a common mount.

[0012] Figure 7A is a schematic diagram of an example of a processing unit suitable for use in a LIDAR system.

[0013] Figure 7B is a schematic diagram of the relationship between the electronic device and the optical sensor during processing.

[0014] Figure 7C shows an example of a frequency pattern suitable for the system output signal.

[0015] Figure 8A shows an example of the output from the mathematical calculation element when the misguided signal is not excluded from the LIDAR signal.

[0016] Figure 8B is the LiDAR system from Figure 5, labeled to show examples of possible sources of misdirection within the LiDAR system and the polarization state of the signal at different locations.

[0017] Figure 8C shows an example of the output from the mathematical calculation element when a misguided signal is excluded from the LIDAR signal.

[0018] Figure 9 is a cross-sectional view of a portion of a LiDAR chip, including waveguides, on a silicon-on-insulator platform.

[0019] A LIDAR system includes a light source configured to emit light. A portion of this light is contained in a LIDAR signal traveling along a LIDAR path from the light source to an object outside the LIDAR system, from the object to a filter, and from the filter to a processing unit. The processing unit is configured to convert the optical signal, including the LIDAR signal, into an electrical signal. Electronic equipment can generate LIDAR data from this electrical signal. This LIDAR data may indicate the line-of-sight velocity and / or distance between the LIDAR system and one or more objects located in a sample area outside the LIDAR system.

[0020] A portion of the light from the light source is also included in one or more spurious signals. Each of the spurious signals travels on a different path from the light source to the source of the spurious signal and then to the filter. Each source of the spurious signal is a feature of the LIDAR path that causes one of the spurious signals to deviate from the full length of the LIDAR path. The inventor has discovered that these spurious signals can be a source of noise in the electrical signal from which the LIDAR data is generated. The system includes an optical filter configured to exclude at least one spurious signal from the LIDAR signal. As a result, the noise in the electrical signal is reduced. The reduction in the noise level improves the reliability of the LIDAR data.

[0021] FIG. 1 is a schematic top view of a LIDAR chip that can function as a LIDAR system or can be included in a LIDAR system that includes components in addition to the LIDAR chip. The LIDAR chip can include an optical integrated circuit (PIC) and can be an optical integrated circuit chip. The LIDAR chip includes a light source 10 that outputs a light source signal. Suitable light sources 10 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).

[0022] The LIDAR chip includes a utility waveguide 12 that receives the light source signal from the light source 10. The utility waveguide 12 includes a splitter 22 that receives the light source signal. The splitter outputs a transmitted LIDAR signal on the utility waveguide 12.

[0023] The utility waveguide 12 terminates at the facet 14 and conveys the transmitted LIDAR signal to the facet 14. The facet 14 can be arranged such that the transmitted LIDAR signal moving through the facet 14 exits the LIDAR chip and functions as a LIDAR output signal. For example, the facet 14 can be arranged at the end of the chip such that the transmitted LIDAR signal moving through the facet 14 exits the chip and functions as a LIDAR output signal. In some cases, a portion of the LIDAR output signal exiting the LIDAR chip can also be regarded as a 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 a system output signal.

[0024] The light from the LIDAR output signal moves away from the LIDAR system in the system output signal. The system output signal can pass through the free space in the atmosphere where the LIDAR system is located. The system output signal can be reflected by one or more objects in the path of the system output signal. When the system output signal is reflected, at least a portion of the reflected light returns towards the LIDAR chip as a system input signal.

[0025] The light from the system feedback signal can be conveyed within the first LIDAR input signal received by the LIDAR chip. In some cases, a portion of the system feedback signal can function as the first LIDAR input signal. The first LIDAR input signal is incident on the comparison waveguide 16 through the facet 18 and functions as a first comparison signal. The comparison waveguide 16 conveys the first comparison signal to a processing unit 20 configured to convert the optical signal into an electrical signal in which the line-of-sight velocity and / or distance between the LIDAR system and one or more objects located outside the LIDAR system are generated.

[0026] The splitter 22 moves a portion of the light source signal from the utility waveguide 12 onto the reference waveguide 24 as a first reference signal. The reference waveguide 24 then transports the first reference signal to the processing unit 20 for further processing.

[0027] The percentage of light transferred from the utility waveguide 12 by the splitter 22 can be fixed or substantially fixed. For example, the splitter 22 can be configured such that the power of the first reference signal transferred to the reference waveguide 24 is a ratio of the power of the light source signal. In some cases, the ratio is greater than 5%, 10%, or 20%, and / or less than 50% or 60%. Suitable splitters 22 include, but are not limited to, optical couplers, y-junctions, tapered couplers, and composite-mode interference (MMI) devices.

[0028] The LIDAR chip may include a control branch for controlling the operation of the light source 10. This control branch includes a divider 26 that moves a portion of the light source signal from the utility waveguide 12 onto the control waveguide 28. The coupled portion of the light source signal functions as a tapped signal. Figure 1 shows a directional coupler acting as divider 26, but other signal interception elements can be used as divider 26. Suitable divider 26s include, but are not limited to, directional couplers, optical couplers, y-junctions, tapered couplers, and composite-mode interference (MMI) devices.

[0029] The control waveguide 28 carries the tapped signal to the control unit 30, which can communicate with the electronic equipment 32. All or part of the control unit 30 may be included in the electronic equipment 32. During operation, the electronic equipment can use the output from the control unit 30 to control process variables of one, two, three, four, or five controlled optical signals selected from the group consisting of the tapped signal, system output signal, emitting LIDAR signal, system output signal, and LIDAR output signal. Examples of appropriate process variables include the frequency and / or phase of the controlled optical signals.

[0030] Figure 2 is a schematic top view of a LiDAR chip that can function as a LiDAR system or be included in a LiDAR system that includes components other than the LiDAR chip. The LiDAR chip in Figure 2 shows the LiDAR chip in Figure 1 modified to process multiple LiDAR input signals. As mentioned above, if light from the system output signal is reflected by an object located outside the LiDAR system, at least some of the reflected light can be returned to the LiDAR chip in the system feedback signal.

[0031] Light from the system feedback signal can be carried within a second system LIDAR input signal received by the LIDAR chip. In some cases, a portion of the system feedback signal can function as the second LIDAR input signal. The LIDAR chip includes a second comparison waveguide 36 terminated at facet 38. The second LIDAR input signal enters the second comparison waveguide 36 through facet 38 and functions as the second comparison signal. The second comparison waveguide 36 carries the second comparison signal to a second processing unit 40 configured to convert the optical signal into an electrical signal that generates LIDAR data (line-of-sight velocity and / or distance between the LIDAR system and one or more objects located outside the LIDAR system).

[0032] The reference waveguide 24 carries the first reference signal to the divider 42. The divider 42 moves a portion of the transmitted LIDAR signal from the reference waveguide 24 onto the second reference waveguide 44 as a second reference signal. The second reference waveguide 44 carries the second reference signal to the second processing unit 40 for further processing.

[0033] As will be described in more detail below, the first processing unit 20 and the second processing unit 40 each combine a comparison signal with a reference signal to form a composite signal that carries LIDAR data of a sample area in the field of view. Thus, the composite signal can be processed to extract LIDAR data of the sample area (one or more data selected from the group consisting of material labels of one or more reflective objects, line-of-sight velocities between the LIDAR system and objects outside the LIDAR system, and distances between the LIDAR system and the objects).

[0034] In some cases, a LIDAR chip constructed according to Figure 1 or Figure 2 is used with a LIDAR adapter. In some cases, the LIDAR adapter can be physically and optically positioned between the LIDAR chip and one or more reflective objects, and / or in the field of view, through which the optical path of the first LIDAR input signal and / or LIDAR output signal travels from the LIDAR chip to the field of view passes. Alternatively, the LIDAR adapter can operate with a system feedback signal and a LIDAR output signal, thereby configuring the first LIDAR input signal and LIDAR output signal to travel on different optical paths between the LIDAR adapter and the LIDAR chip, but on the same optical path between the LIDAR adapter and the reflective objects in the field of view. Furthermore, or instead, the LIDAR adapter can operate with a system feedback signal and a LIDAR output signal, thereby configuring the second LIDAR input signal and LIDAR output signal to travel on different optical paths between the LIDAR adapter and the LIDAR chip, but on the same optical path between the LIDAR adapter and the reflective objects in the field of view.

[0035] An example of a LiDAR adapter suitable for use with the LiDAR chip in Figure 1 is shown in Figure 3. The LiDAR adapter includes multiple elements arranged on a base. For example, the LiDAR adapter includes a circulator 100 arranged on a base 102. The illustrated optical circulator 100 includes three ports, configured such that light incident on one port exits from the next port. For example, the illustrated optical circulator includes a first port 104, a second port 106, and a third port 108. The LiDAR output signal is incident on the first port 104 from the utility waveguide 12 of the LiDAR chip and exits from the second port 106 as an assembly output signal.

[0036] The assembly output signal includes, consists of, or essentially consists of, light from the LIDAR output signal received from the LIDAR chip. Therefore, the assembly output signal may 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 assembly output signal and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal may experience light loss as it travels through the LIDAR adapter. Moreover / or the LIDAR adapter may optionally include an amplifier 110 configured to amplify the LIDAR output signal as it travels through the LIDAR adapter.

[0037] When one or more objects within the sample region reflect light from the assembly output signal, at least a portion of the reflected light returns to the circulator 100 as the assembly feedback signal. At least a portion of the light from the assembly feedback signal enters the circulator 100 through the second port 106. Figure 3 shows the LIDAR output signal and the assembly feedback signal traveling between the LIDAR adapter and the sample region along the same optical path.

[0038] The assembly feedback signal is emitted from the circulator 100 through the third port 108. The LIDAR adapter includes a polarization divider 116 that receives the assembly feedback signal from the circulator 100.

[0039] The polarization divider 116 divides the assembly feedback signal into a first feedback signal and a second feedback signal. Here, the first feedback signal has a first polarization state but does not have, or substantially does not have, a second polarization state. The second feedback signal has a second polarization state but does not have, or substantially does not have, a first polarization state. The first and second polarization states may be linear polarization states, but the second polarization state may be different from the first polarization state. For example, the first polarization state may be TE and the second polarization state may be TM, or the first polarization state may be TM and the second polarization state may 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 polarization dividers include, but are not limited to, Wollaston prisms and MEM-based polarization beam dividers.

[0040] The second feedback signal may not be used or may be discarded. The first feedback signal is induced in a polarization rotor 118. The polarization rotor 118 outputs a first LIDAR input signal induced in a comparison waveguide 16 on the LIDAR chip. In some cases, the polarization rotor 118 is configured to rotate the polarization state of the first LIDAR input signal by m*90° (where m is an odd number) to the first feedback signal. As a result, if the first feedback signal has a first polarization state of TE and the second feedback signal has a second polarization state of TM, the first LIDAR input signal has a second polarization state of TM. Alternatively, if the first feedback signal has a second polarization state of TM and the second feedback signal has a first polarization state of TE, the first LIDAR input signal has a first polarization state of TE. The polarization rotor may be a mutual or mutual polarization rotor. Suitable polarization rotors 118 include, but are not limited to, polarization-holding fiber rotors, Faraday rotors, half-wave plates, MEM-based polarization rotors, and integrated optical polarization rotors using asymmetric y-bifurcation, Mach-Zehnder interferometers, and composite-mode interference couplers.

[0041] Since the polarization splitter 116 outputs all or essentially all of the assembly feedback signal as the first feedback signal, all or part of the assembly feedback signal can function as the first LIDAR input signal, and the first LIDAR input signal includes or is composed of light from the system feedback signal. Thus, the LIDAR output signal and the first LIDAR input signal travel between the LIDAR adapter and the LIDAR chip along different optical paths.

[0042] As is clear from Figure 3, the LIDAR adapter may include optical components in addition to the circulator 100. For example, the LIDAR adapter may include elements for guiding and controlling the optical paths of the LIDAR output signal and the system feedback signal. As an example, the adapter in Figure 2 includes an optional amplifier 110 positioned to receive and amplify the LIDAR output signal before it enters the circulator 100. The amplifier 110 is operated by an electronic device 32, which allows the electronic device 32 to control the power of the LIDAR output signal.

[0043] Figure 3 also shows a LiDAR adapter including an optional first lens 112 and an optional second lens 114. The first lens 112 can be configured to couple the LiDAR output signal at a desired position. In some cases, the first lens 112 is configured to focus or sight the LiDAR output signal at a desired position. In one example, if the LiDAR adapter does not include an amplifier 110, the first lens 112 is configured to couple the LiDAR output signal on the first port 104. In another example, if the LiDAR adapter includes an amplifier 110, the first lens 112 can be configured to couple the LiDAR output signal to the amplifier 110 at the inlet port. The second lens 114 can be configured to couple the LiDAR output signal at a desired position. In some cases, the second lens 114 is configured to focus or sight the LiDAR output signal at a desired position. For example, the second lens 114 can be configured to couple the LiDAR output signal on facet 18 of the comparison waveguide 16.

[0044] A suitable base 102 for a LiDAR adapter includes, but is not limited to, a substrate, a platform, and a plate. Suitable substrates include, but are not limited to, glass, silicon, and ceramic. These components may be individual components mounted on the substrate. Suitable techniques for mounting individual components to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamps. In one example, one or more components are an integrated component, and the remaining components are individual components. In another example, the LiDAR adapter includes one or more integrated amplifiers, and the remaining components are individual components.

[0045] Figure 4 shows the LiDAR system of Figure 3, modified so that the LiDAR adapter is suitable for use with the LiDAR chip of Figure 2. The LiDAR adapter includes a polarization divider 116 that receives an assembly feedback signal from the circulator 100. The polarization divider 116 divides the assembly feedback signal into a first feedback signal and a second feedback signal.

[0046] The polarization divider 116 may also be a polarization beam divider. An example of a polarization beam divider is configured such that the first feedback signal has a first polarization state but does not have or substantially has a second polarization state, and the second feedback signal has a second polarization state but does not have or substantially has a first polarization state. The first and second polarization states may be linear polarization states, but the second polarization state is different from the first polarization state. For example, the first polarization state may be TE and the second polarization state may be TM, or the first polarization state may be TM and the second polarization state may 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 dividers include, but are not limited to, Wollaston prism and MEM-based polarization beam dividers.

[0047] A first feedback signal is induced in a polarization rotor 118. The polarization rotor 118 outputs a first LIDAR input signal induced in a comparison waveguide 16 on the LIDAR chip. In some cases, the polarization rotor 118 is configured to rotate the polarization state of the first LIDAR input signal by m*90° (where m is an odd number) to the first feedback signal. As a result, if the first feedback signal has a first polarization state of TE and the second feedback signal has a second polarization state of TM, the first LIDAR input signal has a second polarization state of TM. Alternatively, if the first feedback signal has a second polarization state of TM and the second feedback signal has a first polarization state of TE, the first LIDAR input signal has a first polarization state of TE. Suitable polarization rotors 118 include, but are not limited to, polarization-holding fiber rotors, Faraday rotors, half-wave plates, MEM-based polarization rotors, and integrated optical polarization rotors using asymmetric y-bifurcation, Mach-Zehnder interferometers, and composite-mode interference couplers.

[0048] Since the polarization splitter 116 outputs all or essentially all of the assembly feedback signal as the first feedback signal, all or part of the assembly feedback signal can function as the first LIDAR input signal, and the first LIDAR input signal includes or is composed of light from the system feedback signal. Thus, the LIDAR output signal and the first LIDAR input signal travel between the LIDAR adapter and the LIDAR chip along different optical paths.

[0049] The second feedback signal is induced in the second comparison waveguide 36 on the LIDAR chip and functions as the second LIDAR input signal as described in the context of Figure 2. Since the polarization divider 116 outputs all or essentially all of the assembly feedback signal as the second feedback signal, all or part of the assembly feedback signal can function as the second LIDAR input signal, and the second LIDAR input signal includes or consists of light from the system feedback signal. Thus, the LIDAR output signal and the second LIDAR input signal travel between the LIDAR adapter and the LIDAR chip along different optical paths.

[0050] Therefore, all or part of the assembly feedback signal can function as a second LIDAR input signal, and the second LIDAR input signal includes or is composed of light from the system feedback signal. Thus, the LIDAR output signal and the second LIDAR input signal travel between the LIDAR adapter and the LIDAR chip along different optical paths.

[0051] The polarization divider 116 may also be a polarization beam divider. An example of a polarization beam divider is configured such that the first feedback signal has a first polarization state but does not have or substantially has a second polarization state, and the second feedback signal has a second polarization state but does not have or substantially has a first polarization state. The first and second polarization states may be linear polarization states, but the second polarization state may be different from the first polarization state. For example, the first polarization state may be TE and the second polarization state may be TM, or the first polarization state may be TM and the second polarization state may 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 dividers include, but are not limited to, Wollaston prism and MEM-based polarization beam dividers.

[0052] A polarization rotor can be configured to change the polarization state of the first and / or second feedback signals. For example, the polarization rotor 118 shown in Figure 4 can be configured to change the polarization state of the second feedback signal from a second polarization state to a first polarization state. As a result, the second LIDAR input signal has a first polarization state but does not have a second polarization state, or does not substantially have one. Thus, the first and second LIDAR input signals each have the same polarization state (the first polarization state in this example). Despite carrying light of the same polarization state, the first and second LIDAR input signals are associated with different polarization states as a result of using a 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.

[0053] Since the first LIDAR input signal and the second LIDAR input signal carry light in the same polarization state, the comparison signal generated from the first LIDAR input signal has the same polarization angle as the comparison signal generated from the second LIDAR input signal.

[0054] Suitable polarization rotors include, but are not limited to, rotations of polarization-holding fibers, Faraday rotors, half-wave plates, MEM-based polarization rotors, and integrated optical polarization rotors using asymmetric y-bifurcation, Mach-Zehnder interferometers, and composite-mode interference couplers.

[0055] Since the transmitted LIDAR signal is linearly polarized, the first reference signal can have the same linear polarization state as the second reference signal. Furthermore, 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 relation to Figure 4, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can each have light in a first polarization state.

[0056] As a result of the above configuration, the first composite signal generated by the first processing unit 20 and the second composite signal generated by the second processing unit 40 are each generated by combining a reference signal and a comparison signal in the same polarization state, and therefore provide a desired pulse between the reference signal and the comparison signal. For example, the composite signal is generated by combining a first reference signal and a first comparison signal in the first polarization state, thereby excluding or substantially excluding light in the second polarization state. Alternatively, the composite signal is generated by combining a first reference signal and a first comparison signal in the second polarization state, thereby excluding or substantially excluding light in the first polarization state. Similarly, the second composite signal includes a second reference signal and a second comparison signal in the same polarization state, and therefore provides a desired pulse between the reference signal and the comparison signal. For example, the second composite signal is generated by combining a second reference signal and a second comparison signal in the first polarization state, thereby excluding or substantially excluding light in the second polarization state. Alternatively, the second composite signal is generated by combining the second reference signal and the second comparison signal in the second polarization state, thereby excluding or substantially excluding the light in the first polarization state.

[0057] The LIDAR adapter in Figure 4 may include other optical components, including passive optical components. For example, the LIDAR adapter may include an optional third lens 126. The third lens 126 may be configured to couple the second LIDAR output signal at a desired position. In some cases, the third lens 126 focuses or sights the second LIDAR output signal at a desired position. For example, the third lens 126 may be configured to focus or sight the second LIDAR output signal onto facet 36 of the second reference waveguide 38. The LIDAR adapter may also include one or more redirection elements 124, such as mirrors and prisms. Figure 4 shows a LIDAR adapter including a mirror as a redirection element 124 that redirects the second feedback signal from the circulator 100 to facet 38 and / or the third lens 126 of the second reference waveguide 36.

[0058] A LIDAR chip includes one or more waveguides that restrict the optical path of one or more optical signals. A LIDAR adapter may include waveguides, but the optical path through which a signal travels between components on the LIDAR adapter and / or between the LIDAR chip and components on the LIDAR adapter may be free space. For example, when the signal travels between different components on the LIDAR adapter and / or between components on the LIDAR adapter and the LIDAR chip, it can travel through the free space through which the LIDAR chip, LIDAR adapter, and / or base 102 are located. As a result, the components on the adapter may be individual optical elements mounted on the base 102.

[0059] If a LIDAR system includes a LIDAR chip and a LIDAR adapter, the LIDAR chip, LIDAR adapter, and all or part of the electronic components can be included in a LIDAR assembly, which is mounted on a common mount 128. Suitable common mounts 128 include, but are not limited to, glass plates, metal plates, silicon plates, and ceramic plates. As an example, Figure 5 is a plan view of a LIDAR system including the LIDAR chip and electronic components 32 of Figure 1 and the LIDAR adapter of Figure 3 on a common mount 128. As another example, Figure 6 is a plan view of a LIDAR system including the LIDAR chip and electronic components 32 of Figure 2 and the LIDAR adapter of Figure 4 on a common mount 128.

[0060] Figures 5 and 6 show electronic equipment 32 positioned on a common mount 128, but all or part of the electronic equipment may be positioned away from the common mount 128. If the light source 10 is positioned away from the LIDAR chip, the light source may be positioned on or away from the common mount 128. Suitable methods for mounting the LIDAR chip, electronic equipment, and / or LIDAR adapter on the common mount 128 include, but are not limited to, epoxy, solder, and mechanical clamps.

[0061] The LIDAR systems in Figures 5 and 6 may include one or more system components located at least partially away from the common mount 128. Suitable system components include, but are not limited to, optical links, beam shaping elements, polarization state rotors, beam steering elements, optical dividers, optical amplifiers, and optical attenuators. For example, the LIDAR systems in Figures 5 and 6 may include one or more beam shaping elements 130 that receive an assembly output signal from an adapter and output a shaping signal. One or more beam shaping elements 130 may be configured to give the shaping signal a desired shape. For example, one or more beam shaping elements 130 may be configured to output a focused, divergent, or sighted shaping signal. In Figures 5 and 6, one or more beam shaping elements 130 are lenses configured to output a sighted shaping signal.

[0062] The LIDAR systems in Figures 5 and 6 may include one or more polarizing rotors 132 that receive a shaping signal and output a rotation signal. In some cases, one or more polarizing rotors 132 are configured to rotate the polarization state of the shaping signal by n*90°+45° (where n is 0 or an even integer). Suitable polarizing rotors 132 include, but are not limited to, non-reciprocal polarizing rotors such as Faraday rotors.

[0063] The LIDAR systems in Figures 5 and 6 may optionally include one or more beam steering elements 134 that receive rotation signals from one or more polarizing rotors 132 and output system output signals. For example, Figures 5 and 6 show beam steering elements 134 that receive rotation signals from polarizing rotors 132. Electronic equipment can operate one or more beam steering elements 134 to steer the system output signals to different sample regions 135. These sample regions can be extended away from the LIDAR system to the maximum distance at which the LIDAR system is configured to provide reliable LIDAR data. The sample regions can be joined together to define a field of view. For example, the field of view of a LIDAR system includes or is composed of the space occupied by the combination of sample regions.

[0064] Suitable beam steering elements include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), optical gratings, working optical gratings, and drivers for moving LiDAR chips, LiDAR adapters, and / or common mounts 128.

[0065] When the system output signal is reflected by the LIDAR system and an object 136 located outside the LIDAR, at least a portion of the reflected light is returned to the LIDAR system as a system feedback signal. If the LIDAR system includes one or more beam steering elements 134, one or more beam steering elements 134 can receive at least a portion of the system feedback signal from the object 136. One or more polarizing rotors 132 can receive at least a portion of the system feedback signal from the object 136 or from one or more beam steering elements 134. One or more polarizing rotors 132 can output a rotated feedback signal. One or more beam shaping elements 130 receive the rotated feedback signal from one or more polarizing rotors 132 and output an assembly feedback signal received by the adapter.

[0066] If one or more polarization rotors 132 are configured to rotate the polarization state of the molding signal by n*90°+45° (where n is 0 or an even integer), and the one or more polarization rotors 132 are not reciprocal, then the one or more polarization rotors 132 rotate the polarization state of the system feedback signal such that the rotated polarization state of the feedback signal is rotated by n*90°-45° relative to the polarization state of the system feedback signal. As a result, the polarization state of the rotated feedback signal is changed by n*180°+90° (where n is 0 or an even integer) relative to the polarization state of the molding signal. Therefore, the polarization state of the assembly feedback signal is increased by n*180°+90° (where n is 0 or an even integer) relative to the polarization state of the assembly output signal. For example, if the assembly output signal has a first polarization state of TE, the assembly feedback signal has a second polarization state of TM. Or, if the assembly output signal has a second polarization state of TM, the assembly feedback signal has a first polarization state of TE.

[0067] The LiDAR systems in Figures 5 and 6 include an optional optical link 138 that carries optical signals from an adapter, from a LiDAR chip, and / or from one or more components on a common mount to one or more system components. For example, the LiDAR systems in Figures 5 and 6 include an optical fiber configured to carry the assembly output signal to a beamforming element 130. The use of the optical link 138 makes it possible to place the source of the system output signal away from the LiDAR chip. The illustrated optical link 138 is an optical fiber, but other optical links 138 can be used. Suitable optical links 138 include, but are not limited to, free-space optical links and waveguides. If the LiDAR system eliminates the optical link, one or more beamforming elements 130 can receive the assembly output signal directly from the adapter.

[0068] Figures 7A and 7B show an example of a processing unit 138 suitable for use as processing unit 20 and / or processing unit 40 in the above-described LIDAR system. The processing unit 138 receives a comparison signal contribution from the comparison waveguide 150 and a reference signal contribution from the reference waveguide 152. The comparison waveguide 150 in Figure 7A can represent the comparison waveguide 16 in Figure 1, while the reference waveguide 152 in Figure 7A is the reference waveguide 24 in Figure 1. Alternatively, the comparison waveguide 150 in Figure 7A can represent the comparison waveguide 16 in Figure 2, while the reference waveguide 152 in Figure 7A is the reference waveguide 24 in Figure 2. Thus, the processing unit 138 can receive a first comparison signal as a comparison signal contribution and a first reference signal as a reference signal contribution. Alternatively, the comparison waveguide 150 in Figure 7A can represent the second comparison waveguide 36 in Figure 2, while the reference waveguide 152 in Figure 7A can represent the second reference waveguide 44 in Figure 2. Therefore, the processing unit 138 can receive the second comparison signal as a comparison signal contribution and the second reference signal as a reference signal contribution.

[0069] The comparison waveguide 150 carries the comparison signal contribution to the optical coupling element 154. The reference waveguide 152 carries the reference signal contribution to the optical coupling element 154. The optical coupling element 154 couples the comparison signal contribution and the reference signal contribution into a composite signal. Due to the frequency difference between the comparison signal contribution and the reference signal contribution, the composite signal pulsates between the comparison signal contribution and the reference signal contribution.

[0070] The optical coupling element 154 also splits the resulting composite signal into a first detector waveguide 156 and a second detector waveguide 158. The first auxiliary detector waveguide 156 carries the first portion of the composite signal to a first photosensor 160, which converts the first portion of the composite signal into a first electrical signal. The second detector waveguide 158 carries the second portion of the composite signal to a second photosensor 162, which converts the second portion of the composite signal into a second electrical signal. Examples of suitable photosensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0071] In some cases, the optical coupling element 154 splits the composite signal such that the comparison signal contribution in the first part of the composite signal is phase-shifted by 180° relative to the comparison signal contribution in the second part of the composite signal, but the reference signal contribution in the second part of the composite signal is in phase with the reference signal contribution in the first part of the composite signal. Alternatively, the optical coupling element 154 splits the composite signal such that the reference signal contribution in the first part of the composite signal is phase-shifted by 180° relative to the reference signal contribution in the second part of the composite signal, but the comparison signal contribution in the first part of the composite signal is in phase with the comparison signal portion in the second part of the composite signal. Suitable examples of optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0072] Figure 7B provides a schematic diagram of the relationship between electronic equipment and optical sensors in the processing unit 138. The symbols for photodiodes are used to represent the first optical sensor 160 and the second optical sensor 162, although one or more of these sensors may have other structures. In some cases, all components shown in the schematic diagram of Figure 7B are contained within the LIDAR chip. In some cases, the components shown in the schematic diagram of Figure 7B are distributed between the LIDAR chip and electronic equipment located away from the LIDAR chip.

[0073] The electronic device 62 can be configured as a balance detector 164 by connecting the first photosensor 160 with the second photosensor 162. For example, the electronic device can connect the first photosensor 160 in series with the second photosensor 162, as shown in Figure 7B. The series connection between the first photosensor 160 and the second photosensor 162 carries the output from the balance detector as a data signal. This data signal is carried on the sensor output line 166 and can also function as an electrical representation of a composite signal.

[0074] The electronic device 62 includes a conversion mechanism 168 configured to perform mathematical transformations on a data signal. The conversion mechanism 168 includes an analog-to-digital converter (ADC) 170 that receives the data signal from a sensor output line 166. The analog-to-digital converter (ADC) 170 converts the data signal from analog to digital and outputs a digital data signal. The digital data signal is a digital representation of the data signal.

[0075] The conversion mechanism 168 includes a mathematical operation element 172 configured to receive the digital data signal. The mathematical operation element 172 is configured to perform mathematical operations on the received digital data signal. Suitable mathematical operations include, but are not limited to, mathematical transformations such as the Fourier transform. In one example, the mathematical operation element 172 performs a Fourier transform on the digital signal to convert it from the time domain to the frequency domain. The mathematical transformation may be an actual transformation such as an actual Fast Fourier Transform (FFT). The actual Fast Fourier Transform (FFT) can provide an output in which the amplitude is expressed as a function of frequency. As a result, a peak in the output of the Fast Fourier Transform may occur and / or indicate the correct beat frequency of the beat signal. The mathematical operation element 172 can perform the assigned function using firmware, hardware, software, or a combination thereof.

[0076] The electronic device includes a LiDAR data generator 174 that receives the output from the conversion element 168. The LiDAR data generator 174 can perform peak detection on the output of the conversion element 168 to identify peaks in frequency of the output of the conversion element 168. The LiDAR data generator 174 treats the frequencies at the identified peaks as the pulsating frequencies of the pulsating signals, which result from all or part of the comparison signal pulsating relative to all or part of the reference signal. The LiDAR data generator 174 can use the identified pulsating frequencies in combination with the frequency patterns of the LiDAR output signal and / or the system output signal to generate LiDAR data.

[0077] As shown in Figure 7B, the sensor output line 166 carrying the data signal may optionally include an amplifier 176. A suitable amplifier 176 includes, but is not limited to, a transimpedance amplifier (TIA).

[0078] Figure 7C has a solid line showing an example of a suitable frequency pattern for the LIDAR output signal and the resulting system output signal. Therefore, the solid line also represents the frequency pattern of the reference signal. Figure 7C is cycle j and cycle j+1 This shows a series of frequency-versus-time patterns spanning two cycles, labeled as such. In some cases, the frequency-versus-time pattern is repeated in each cycle, as shown in Figure 7C. The illustrated cycles do not include a relocation period, and / or the relocation period is not placed between cycles. As a result, Figure 7C shows the results of a continuous scan of the system output signal across multiple different sample regions in the field of view.

[0079] Each cycle is associated with a period exponent k, and DP k It contains K data periods labeled as such. In the example in Figure 7C, each cycle contains two data periods (k=1 and k=2). In some cases, the frequency-to-time patterns are the same for corresponding data periods in different cycles, as shown in Figure 7C. Corresponding data periods are data periods with the same period exponent. As a result, each data period DP1 can be considered a corresponding data period with the same channel exponent (i), and the associated frequency-to-time pattern is the same as in Figure 7C. At the end of the cycle, the electronic equipment returns the frequency to the same frequency level as when the previous cycle began.

[0080] During each data period, the frequency of the system output signal changes at a constant rate. The rate may be zero, but during at least a portion of the data period of each cycle, the system output signal changes at a non-zero rate. The direction and / or rate of the frequency change varies with the change in the data period from the same cycle. For example, between data period DP1 and data period DP2, the electronic device operates the light source such that the frequency of the system output signal changes at a linear rate α. The direction of the frequency change during data period DP1 is opposite to the direction of the frequency change during data period DP2.

[0081] The beat frequencies (f LDP ) from two or more different data periods within the same cycle can be combined to generate LIDAR data. For example, the beat frequency measured from DP1 in FIG. 7C can be combined with the beat frequency measured from DP2 in FIG. 7C to measure the LIDAR data of the sample region. As an example, during a data period in which the frequency of the transmitted LIDAR signal is increased such that the electronic device generates during data period DP1 of FIG. 7C, the following equation applies: f ub = -f d +ατ (where f ub is the beat frequency measured from the output of the mathematical operation element 172, f d represents the Doppler shift (f d = 2νf c / c), where f c represents the optical frequency (f o ), c represents the speed of light, ν is the line-of-sight velocity between the reflecting object and the LIDAR system assuming the direction from the reflecting object towards the LIDAR system as the positive direction, and also, c is the speed of light). During a data period in which the frequency of the transmitted LIDAR signal is decreased such that the electronic device generates during data period DP2 of FIG. 7C, the following equation applies: f db = -f d -ατ (where f db is the beat frequency measured from the output of the mathematical operation element 172). In these two equations, f dand τ are unknowns. The electronic device solves these two equations for these two unknowns. Next, the line of sight velocity of the sample region is the Doppler shift ((ν = c*f d / (2f c The separation distance of the sample region is measured from and / or c*f d Measurements can be taken from / 2. Since LIDAR data can be generated for each corresponding frequency pair output by the conversion, separate LIDAR data can be generated for each object within the sample area. Thus, electronic devices can measure multiple line-of-sight velocities and / or multiple line-of-sight separation distances from a single sample of a single sample area in the field of view.

[0082] Figure 8A shows an example of output from a mathematical operation element 172 that can be generated when a LIDAR system eliminates the polarization rotor 118, the polarization splitter 116, and one or more polarization rotors 132. In particular, Figure 8A shows the amplitude-versus-frequency function that can be output by a mathematical operation element 172 that performs a Fourier transform on a digital data signal in a LIDAR system that eliminates the polarization rotor 118 and one or more polarization rotors 132. The amplitude-versus-frequency function in this figure includes peaks labeled as system peaks and target peaks. Each of the target peaks occurs at a pulsating frequency associated with the reflection of the system output signal by an object outside the LIDAR system. In the example shown, the sample region includes two different objects, each of which reflects the system output signal. As a result, each target peak originates from one of the different objects.

[0083] The aforementioned system peak occurs as a result of mis-induced light from the outgoing LIDAR signal being included in the composite signal, without passing through the LIDAR path designed for the signal to pass through the LIDAR system. Light from the outgoing LIDAR signal that does not pass through the LIDAR path can be considered a mis-induced signal. In some cases, the mis-induced signal does not leave the LIDAR assembly or LIDAR system. Therefore, light from the mis-induced signal is often not included in the system output signal. As a result, light from the mis-induced light is often not reflected by objects in the sample area.

[0084] Examples of sources of mis-induced signals (sources of mis-induction) include, but are not limited to, reflections, crosstalk between optical components within the LIDAR system, and light scattered by components of the LIDAR system. Figure 8B is the LIDAR system of Figure 5 and is shown to illustrate examples of undesirable light reflections, each of which can function as a source of mis-induction. For example, Figure 8B includes a dashed line labeled SPB. This dashed line may represent a reflection of the assembly output signal in one or more beamforming elements 130. The reflected signal can pass through the LIDAR system and return as if it were light from a properly reflected system feedback signal. As a result, the reflected signal can be transported to the processing unit 20 and included in the comparison signal. This reflected signal can then be the source of the system peak labeled SPB in Figure 8A.

[0085] Figure 8B also includes an arrow labeled SPA, which shows part of the path of another mis-induced signal. The arrow labeled SPA may represent crosstalk between the LIDAR output signal and the assembly feedback signal. The circulator 100 may be the source of this crosstalk. The resulting crosstalk signal can function as a mis-induced signal passing through the LIDAR system as if it were light from a properly reflected system feedback signal. The reflected signal is then transported to the processing unit 20 and can be included in the comparison signal. The mis-induced signal may then be the source of the system peak labeled SPA in Figure 8A.

[0086] As is clear from Figure 8A, the system peak represents noise at the output of the conversion mechanism 168. Furthermore, the target peak labeled TPA in Figure 8A is caused by an object located closer to the LIDAR system than the target peak labeled TPB in Figure 8B. As a result, the system peak can reduce the signal-to-noise ratio (SNR) at the output of the conversion mechanism 168 for objects close to the LIDAR system.

[0087] One or more polarization rotors 132 and polarization dividers 116 are arranged to increase the signal-to-noise ratio (SNR) at the output of the conversion mechanism 168. As is clear from the above discussion, the LIDAR system is designed so that a portion of the light from the light source signal acts as a LIDAR signal traveling along a LIDAR path from the light source to a reflecting object located outside the LIDAR system, from the reflecting object to the polarization divider 116, and from the polarization divider 116 to the processing unit 20. The LIDAR path may include a utility waveguide 12, a comparison waveguide, and paths on which signals such as the LIDAR output signal, assembly output signal, system output signal, system feedback signal, assembly feedback signal, and LIDAR input signal travel.

[0088] Furthermore, one or more mis-induced portions of light from a light source signal can each function as a mis-induced signal. Each mis-induced optical signal can travel along a different mis-induced path extending from the light source to one of the sources of mis-induction, and then to the polarization splitter 116. As is evident from the labels SPA and SPB in Figure 8B, each source of mis-induction is a feature of the LIDAR path in which one of the mis-induced signals traveling along the LIDAR path is converted from traveling along the entire length of the LIDAR path. In some cases, the LIDAR system is constructed such that at least one of the mis-induced signals is reflected by the surface to which the LIDAR signal is transmitted, as indicated by the arrow labeled SPB in Figure 8B, and / or at least one of the mis-induced signals carries crosstalk between different components in the LIDAR system, as indicated by the arrow labeled APS in Figure 8B.

[0089] The optical signals described in the context of Figures 1 to 6 may have contributions from different parts of the LIDAR signal and one or more misinducible signals. For example, the outgoing LIDAR signal may carry contributions from the LIDAR signal and one or more misinducible signals. Similarly, the assembly feedback signal may have contributions from the LIDAR signal and one or more misinducible signals.

[0090] One or more polarizing rotors 132 are positioned along the comparison signal path after one or more sources of misinduced light. As a result, the LIDAR signal encounters one or more sources of misinduction before encountering one or more polarizing rotors 132. In contrast, the misinduced signal does not encounter one or more polarizing rotors 132 as a result of being misinduced by one of the sources of misinduction.

[0091] The above-described LIDAR system shows a LIDAR signal that is received multiple times by one or more polarizing rotors 132, but the LIDAR system can be configured so that the comparison portion of the light is received at once by one or more polarizing rotors 132. For example, one or more beam steering elements 134 can be configured so that the system feedback signal is guided to one or more beam shaping elements 130 without being received by one or more polarizing rotors 132. As a result, one or more polarizing rotors 132 can be configured to change the polarization state of the LIDAR signal once or more times.

[0092] A portion of the LiDAR signal that travels from the last of one or more polarization rotors 132 to the polarization divider 116 and receives the LiDAR signal can function as a rotated LiDAR signal. Thus, the polarization divider 116 receives a rotated LiDAR signal. A portion of the misinduced signal that travels from the source of misinduction to the polarization divider 116 can function as a noise signal. Thus, the polarization divider 116 receives a noise signal.

[0093] One or more polarization rotors 132 are selected so that the rotated LiDAR signal has a different polarization state from the noise signal. A polarization splitter 116 uses the difference in polarization states to separate the rotated sample from the noise signal. As shown in Figure 8B, the rotated LiDAR signal is passed to the processing unit 20, while the noise signal may be left unused or discarded.

[0094] In the above-described LIDAR system, the polarization rotor 118 receives the rotated LIDAR signal from the polarization divider 116. The polarization rotor 118 can be selected so that the comparison signal portion and the reference signal portion, which are combined to form a composite signal, have the same polarization state. For example, the polarization rotor 118 can be selected to further rotate the rotated LIDAR signal so that the comparison signal and the reference signal have the same polarization state when received by the processing unit 20.

[0095] An example of possible polarization states is shown in Figure 8B. In Figure 8B, each arrow indicating a signal moving in a single direction is marked with the polarization state primarily carried by that signal. In Figure 8B, arrows indicating signals moving in multiple directions are marked with arrows indicating the polarization state primarily carried by the signal moving in the indicated direction. In some cases, the polarization state primarily carried by a signal is the only polarization state carried by that signal.

[0096] Light from a laser is typically linearly polarized. As a result, the emitted LIDAR signal is also usually linearly polarized. Consequently, in the example in Figure 8B, the light source 10 can output a light source signal with a polarization state of TM, but it outputs a light source signal with a first polarization state of TE. The LIDAR signal passes through the polarization rotor 132 twice, and the sum of their rotations changes the polarization state of the LIDAR signal from TE to TM.

[0097] This rotation of the polarization state of the LIDAR signal occurs after the source of misinduction (SPA and SPB), so the polarization divider 116 receives the LIDAR signal with a different polarization state (TM) than the noise signal (both misinduction signals with TE). As a result, the polarization divider 116 acts as a filter to remove the noise signal (misinduction signal) from the LIDAR signal used to generate the LIDAR data. The polarization rotor 118 also changes the polarization state of the LIDAR signal to match the polarization state (TE) of the reference signal.

[0098] Figure 8C shows the output from the mathematical calculation element 172 when the LIDAR system includes a polarization rotor 118, a polarization splitter 116, and one or more polarization rotors 132. As a result, Figure 8C shows the output from the mathematical calculation element 172 when all or part of the misinduced signals are excluded from the LIDAR signal. As is clear from Figure 8A, the system peak can have a higher amplitude than the target peak. As a result, since amplitude is proportional to signal power, the misinduced signals can each have a higher power than the LIDAR signal. This may be a result of misinduced signals remaining within the LIDAR system while the LIDAR signal leaves the LIDAR system and returns to the LIDAR system as a result of diffuse reflection by an object. As shown in Figure 8C, by excluding the misinduced signals from the LIDAR signal, the amplitude of the misinduced signals can be reduced to below the amplitude of the LIDAR signal. As a result, by this exclusion, the power of the misinduced signals can be reduced to below the power of the LIDAR signal. Figure 8C shows some amplitude from the system peak. This is because the polarization state of a portion of the misinduced signal can change due to sources of misinduction such as reflection. This change in polarization state allows a portion of the misinduced signal to reach the processing unit.

[0099] The LIDAR system in Figure 6 includes a second processing unit 40. The second processing unit 40 receives the noise signal portion of the misinduced signal, which was described as not being used or discarded in the context of Figure 8B. However, the second processing unit 40 can also receive a portion of the LIDAR signal. For example, reflection of the system output signal by an object can change the polarization angle of all portions of the system feedback signal. Thus, the LIDAR signal can carry light in different polarization states away from the reflective object. For example, the first portion and the second portion of the LIDAR signal may contain light in different polarization states. As a result, the polarization splitter 116 can split the LIDAR signal into a first portion and a second portion. The first portion of the LIDAR signal is induced to the first processing unit 20, and the second portion of the LIDAR signal is induced to the second processing unit 40. As a result, the second processing unit 40 can receive a portion of the LIDAR signal, and can also receive noise signals. In contrast, processing unit 20 receives a portion of the LIDAR signal but does not receive any noise signal, or it receives a level of noise signal lower than that received by the second processing unit 40. In some cases, the power of the noise signal received by the second processing unit 40 is more than 5, 10, or 100 times greater than the power of the noise signal received by processing unit 20.

[0100] The portion of the LIDAR signal received by the first processing unit 20 can function as a first comparison signal, and the portion of the LIDAR signal received by the second processing unit 40 can function as a second comparison signal. The electronic device 62 can use the output from the second processing unit 40 to generate LIDAR data. As a result, the electronic device can generate a first LIDAR data result from the output of the first processing unit 20 and a second LIDAR data result from the output of the second processing unit 40. Consequently, in the LIDAR system configuration of Figure 6, LIDAR data for a single sample region within the field of view can be generated from multiple different composite signals (i.e., a first composite signal and a second composite signal) from the sample region.

[0101] In some cases, measuring LIDAR data in a sample region involves electronic equipment that combines LIDAR data results from different composite signals (i.e., a first composite signal and a second composite signal). Combining LIDAR data may include taking the mean, median, or mode of the LIDAR data generated from different composite signals. For example, the electronic equipment may average the distance between the LIDAR system and the reflective object measured from the composite signal with the distance measured from the second composite signal, and / or the electronic equipment may average the line-of-sight velocity between the LIDAR system and the reflective object measured from the composite signal with the line-of-sight velocity measured from the second composite signal.

[0102] In some cases, measuring LIDAR data in a sample region involves an electronic device identifying one or more composite signals (i.e., a first composite signal and / or a second composite signal) as the source of the most realistic LIDAR data (representative LIDAR data). The electronic device can then use the LIDAR data from the identified composite signals as representative LIDAR data for further processing. For example, an electronic device may identify a signal with a larger amplitude (either the first or second composite signal) as having representative LIDAR data, and the LIDAR data from the identified signal can be used for further processing by the LIDAR system. In some cases, the electronic device combines identifying composite signals with representative LIDAR data with combining LIDAR data from different LIDAR signals. For example, an electronic device may identify each composite signal with an amplitude exceeding an amplitude threshold as having representative LIDAR data, and if three or more composite signals are identified as having representative LIDAR data, the electronic device can combine LIDAR data from each of the identified composite signals. If one composite signal is identified as having representative LIDAR data, the electronic device can use 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 device can discard the LIDAR data of the sample regions associated with those composite signals.

[0103] Suitable platforms for LIDAR chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. Figure 9 is a cross-sectional view of a portion of a chip constructed from a silicon-on-insulator wafer. A silicon-on-insulator (SOI) wafer includes a bridging layer 310 between a substrate 312 and a light-transmitting medium 314. In a silicon-on-insulator wafer, the bridging layer 310 is silica, while the substrate 312 and light-transmitting medium 314 are silicon. The substrate 312 of an optical platform such as an SOI wafer can serve as the base for the entire LIDAR chip. For example, the optical components shown on the LIDAR chip in Figures 1-2 can be placed on or on the top and / or sides of the substrate 312.

[0104] Figure 9 is a cross-sectional view of a portion of a LiDAR chip, including a waveguide structure suitable for use in a LiDAR chip constructed from a silicon-on-insulator wafer. The ridge 316 of the light-transmitting medium extends away from the slab region 318 of the light-transmitting medium. The optical signal is confined between the top of the ridge 316 and the embedded oxide layer 310.

[0105] The dimensions of a ridge waveguide are shown in Figure 9. For example, the ridge has a width denoted as w and a height denoted as h. The thickness of the slab region is denoted as T. These dimensions can be more important than others because LIDAR applications require the use of higher levels of optical power than those used in other applications. The width of the ridge (denoted as w) is greater than 1 μm and less than 4 μm, the height of the ridge (denoted as h) is greater than 1 μm and less than 4 μm, and the thickness of the slab region is greater than 0.5 μm and less than 3 μm. These dimensions can apply to the straight or substantially straight sections of the waveguide, the curved sections of the waveguide, and the tapered sections of the waveguide. Thus, these sections of the waveguide are single-mode. However, in some cases, these dimensions apply to the straight or substantially straight sections of the waveguide. Furthermore, or instead, the curved sections of the waveguide may have a reduced slab thickness to reduce optical loss in the curved sections of the waveguide. For example, the curved portion of the waveguide may have a ridge extending away from a slab region with a thickness of 0.0 μm or more and less than 0.5 μm. The above dimensions generally provide a straight or substantially straight portion of the waveguide as a single-mode structure, but can result in a tapered and / or curved portion of a composite mode. Coupling between the composite mode geometry and the single-mode geometry can be achieved using a taper that substantially does not excite higher-order modes. Thus, the waveguide can be configured so that the signal carried in the waveguide is carried in a single mode, even when carried in a waveguide section having composite mode dimensions. The waveguide structure disclosed in the context of Figure 9 is suitable for all or part of a waveguide on a LIDAR chip constructed according to Figures 1 and 2.

[0106] A photosensor interfaced with a waveguide on a LIDAR chip may be a component that is separated from the chip and then mounted on the chip. For example, the photosensor may be a photodiode or an avalanche photodiode. Examples of suitable photosensor components include, but are not limited to, InGaAs PIN photodiodes manufactured by Hamamatsu in Hamamatsu, Japan, or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu in Hamamatsu, Japan. These photosensors may be located in the center of the LIDAR chip. Alternatively, all or part of the waveguide terminating with the photosensor may be terminated at a facet located at the edge of the chip, and the photosensor may be mounted at the edge of the chip on the facet so that the photosensor receives light passing through the facet. The use of a photosensor as a component separate from the chip is suitable for all or part of photosensors selected from the group consisting of first photosensors and second photosensors.

[0107] As an alternative to a separate component, an optical sensor can be integrated with a chip, in whole or in part. For example, examples of optical sensors interfaced with ridge waveguides on a chip constructed from 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 January 10, 2012); U.S. Patent No. 8,242,432 (issued August 14, 2012); and U.S. Patent No. 6,108,472 (issued August 22, 2000), each of which is incorporated herein in whole. The use of an optical sensor integrated with a chip is suitable for all or part of an optical sensor selected from the group consisting of first optical sensors and second optical sensors.

[0108] The light source 10 interfaced with the utility waveguide 12 may be a laser chip isolated from the LIDAR chip and subsequently mounted on the LIDAR chip. For example, the light source 10 may be a laser chip mounted on the chip using a flip-chip configuration. The use of a flip-chip configuration is suitable when the light source 10 interfaces with a ridge waveguide on a chip constructed from a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 may include an optical grating (not shown), such as a Bragg grating, which functions as a reflector for an external cavity laser. In these examples, the light source 10 may include a gain element isolated from the LIDAR chip and subsequently mounted on the LIDAR chip in a flip-chip configuration. Examples of suitable interfaces between flip-chip gain elements and ridge waveguides on chips constructed from silicon-on-insulator wafers can be found in U.S. Patent No. 9,705,278 (issued July 11, 2017) and U.S. Patent No. 5,991,484 (issued November 23, 1999), each of which is incorporated herein by reference in whole. When the light source 10 is a gain element or laser chip, the electronic equipment can change the frequency of the emitted LIDAR signal by changing the level of current applied through the gain element or laser cavity.

[0109] Appropriate electronic equipment may include, but is not limited to, analog electrical circuits, digital electrical circuits, processors, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), computers, microcomputers, or any combination suitable for performing the operations, monitoring, and control functions described above. In some cases, a controller may have access to memory containing instructions executed by the controller while performing the operations, control, and monitoring functions. Although electronic equipment is shown as a single component in a single location, electronic equipment may include multiple different components that are independent of each other and / or located in different locations. Also, as described above, all or part of the disclosed electronic equipment may be included on a chip, including electronic equipment integrated with the chip.

[0110] Although the light source 10 is shown as being located on the LIDAR chip, the light source can be located outside the LIDAR chip. For example, the LIDAR chip can receive transmitted LIDAR signals from an optical fiber.

[0111] Other embodiments, combinations, and modifications of the present invention will be readily conceivable to those skilled in the art in consideration of these teachings. Accordingly, the present invention should be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.

Claims

1. A light source configured to emit light, A portion of the light is included in the LIDAR signal traveling along the LIDAR path from the light source to the object, from the object to the filter, and from the filter to the processing unit. The object is placed outside the LIDAR system, The processing unit is configured to convert an optical signal into an electrical signal, and the optical signal includes the LIDAR signal. A portion of the light is included in the misguided signal, the misguided signal travels along the misguided path from the light source to the filter, and the misguided path is different from the LIDAR path. A filter configured to filter the LIDAR signal from the misguided signal, The LIDAR path includes a non-reciprocal polarization rotor configured to change the polarization state of the LIDAR signal before it is received by the filter, The non-reciprocal polarization rotor is positioned behind the source of misinduction on the LIDAR path such that the LIDAR signal passes through the non-reciprocal polarization rotor twice. The source of the misinduction is the reflection of at least one of the misinductioned signals in the lens, and Electronic equipment that generates LIDAR data from the aforementioned electrical signals. A LIDAR system, including a LiDAR system.

2. The system according to claim 1, wherein the filter is configured to split an optical signal into different output signals such that different output signals have different polarization states.

3. The LIDAR signal primarily carries light in the first polarization state, and the misinduced signal primarily carries light in the second polarization state. The filter receives the LIDAR signal and the misguided signal, and The system according to claim 1, wherein the filter is configured to split the LIDAR signal and the misinduced signal into different output signals such that one output signal carries light in a first polarization state and the other output signal carries light in a second polarization state.

4. The system according to claim 1, wherein the filter is a Wollaston prism.

5. The system according to claim 1, wherein the LIDAR system includes a LIDAR chip, the LIDAR chip includes one or more waveguides that define a portion of an optical path and at least a portion of one or more misguided paths.

6. The system according to claim 1, wherein the misguided path does not extend outside the LIDAR system.

7. The system according to claim 1, wherein the lens includes a surface through which at least one of the misguided signals is reflected, but through which the LIDAR signal is transmitted.

8. The system according to claim 1, wherein the non-reciprocal polarization rotor is configured to change the polarization state of the LIDAR signal before the LIDAR signal is received by the filter.

9. The system according to claim 8, wherein each of the misguided paths extends from the light source to the source of the misguided induction and from the source of the misguided induction to the filter.

10. The system according to claim 8, wherein the non-reciprocal polarization rotor is configured to receive the LIDAR signal and output the LIDAR signal in a polarization state that is 45° different from the polarization state of the LIDAR signal when it was received by the non-reciprocal polarization rotor.

11. The system according to claim 1, wherein the non-reciprocal polarization rotor receives the LIDAR signal before the LIDAR signal is reflected by the object and after the LIDAR signal is reflected by the object.

12. The system according to claim 8, wherein the second polarization rotor is configured to change the polarization state of the LIDAR signal after the LIDAR signal has been received by the filter.

13. The system according to claim 8, wherein the processing unit receives a reference signal in addition to receiving the LIDAR signal.

14. The system according to claim 12, wherein the polarization state of the reference signal when the reference signal is received by the processing unit matches the polarization state of the LIDAR signal when the LIDAR signal is received by the processing unit.

15. The system according to claim 12, wherein the second polarization rotor is configured to change the polarization state of the LIDAR signal after the LIDAR signal has been received by the filter.

16. The system according to claim 1, wherein the processing unit, in addition to receiving the LIDAR signal, also receives a reference signal, the reference signal includes light from the light source.

17. The system according to claim 1, wherein the lens is configured to output a sighted molding signal.

18. The system according to claim 17, wherein the non-reciprocal polarizing rotor is configured to receive the molding signal and output a rotation signal.

19. The system according to claim 18, wherein the non-reciprocal polarization rotor is configured to rotate the polarization state of the shaping signal by n*90°+45° (where n is 0 or an even integer).

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