Manipulation of output signals in LIDAR systems

Abstract

A LIDAR system includes a demultiplexer that separates an outgoing LIDAR signal into multiple LIDAR output signals, each LIDAR output signal carrying a different channel, each at a different wavelength. The system also includes a beam splitter that receives each LIDAR output signal. The beam splitter directs the received LIDAR output signals such that the different LIDAR output signals travel away from the beam splitter in different directions.

Description

[0001] Related applications

[0002] This application is a continuation of U.S. patent application serial number 62 / 797,126, filed on January 25, 2019, and entitled “Optical Sensor System,” and is incorporated herein in its entirety. Technical Field

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

[0004] LIDAR technology is being used in a variety of applications. LIDAR specifications typically specify that LIDAR data be generated for a minimum number of sample areas in the field of view. To generate LIDAR data for different sample areas, the LIDAR output signal is typically scanned from one sample area to another. Various mechanisms are used to scan the LIDAR output signal. However, these mechanisms typically utilize moving parts, such as mirrors in MEMs devices. These devices are generally not suitable for providing the high frequency, repeatability, and long life required for LIDAR systems. Consequently, there is a need for improved mechanisms for manipulating LIDAR output signals. Summary of the Invention

[0005] A LIDAR system includes a demultiplexer that separates an outgoing LIDAR signal into multiple LIDAR output signals, each LIDAR output signal carrying a different channel. The different channels are at different wavelengths. The system also includes a beam splitter that receives each LIDAR output signal. The beam splitter directs the received LIDAR output signals so that the different LIDAR output signals travel away from the beam splitter in different directions.

[0006] Another embodiment of a LIDAR system includes a demultiplexer that separates an outgoing LIDAR signal into a plurality of LIDAR output signals, each LIDAR output signal being received at an output side of the demultiplexer. Each LIDAR output signal carries a different channel, and the different channels are each at a different wavelength. The system also includes a beam splitter that receives each LIDAR output signal. The beam splitter directs the received LIDAR output signals so that the different LIDAR output signals travel away from the beam splitter in different directions. In some cases, the beam splitter includes, consists of, or consists essentially of a lens or a mirror.

[0007] A LIDAR system includes a LIDAR chip including multiple channel waveguides. Each channel waveguide is configured to guide a LIDAR output signal. Different LIDAR output signals carry different channels. A beam splitter simultaneously receives the LIDAR output signals from the channel waveguides. The beam splitter receives the LIDAR output signals such that each LIDAR output signal is incident on the beam splitter at a different angle of incidence. The beam splitter directs the received LIDAR output signals such that different LIDAR output signals travel away from the beam splitter in different directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A It is a schematic diagram of the LIDAR system.

[0009] Figure 1B is a schematic diagram of another embodiment of a LIDAR system.

[0010] Figure 2 is a schematic diagram of another embodiment of a LIDAR system.

[0011] Figure 3 is a schematic diagram of another embodiment of a LIDAR system.

[0012] Figure 4 Illustrated are multiple light sources configured to generate outgoing light signals carrying multiple channels.

[0013] Figure 5 A light source comprising a plurality of laser sources is illustrated.

[0014] Figure 6 One example of a structure configured to generate an optical signal including a plurality of channels is illustrated.

[0015] Figure 7A An example of a processing unit is illustrated.

[0016] Figure 7B Provides a Figure 7A Schematic diagram of the electronics used in conjunction with the constructed processing unit.

[0017] Figure 8 The diagram shows an example of reusing components.

[0018] Figures 9A to 9C Pictured Figure 8 A demultiplexing component is modified to provide a scan of the LIDAR output signal. Figure 9A illustrates a demultiplexing component tuned to a first configuration, and Figure 9B The demultiplexing component is illustrated tuned to a second configuration. Figure 9CA beam splitter is illustrated that receives a LIDAR output signal at an incident angle that changes in response to tuning a demultiplexing component between a first configuration and a second configuration.

[0019] Figure 10A and Figure 10B Pictured Figure 9A and Figure 9B A demultiplexing component is modified to include a mechanism for tuning, wherein an outgoing optical signal is received at an input side of the demultiplexer. Figure 10A illustrates a demultiplexing component tuned to a first configuration, and Figure 10B The demultiplexing component is illustrated tuned to a second configuration.

[0020] Figure 11 FIG1 is a top view of an arrayed waveguide grating demultiplexer used as a demultiplexer in a demultiplexing component.

[0021] Figure 12A and Figure 12B The diagram shows the Figures 10A to 10B The construction of the optical switch used in the demultiplexing component. Figure 12A is a schematic diagram of an optical switch. Figure 12B It is applicable to Figure 12A Schematic diagram of the Mach-Zehnder interferometer used in optical switches. DETAILED DESCRIPTION

[0022] The LIDAR system includes a demultiplexer that separates the outgoing LIDAR signal into a plurality of different LIDAR output signals, each associated with a different channel. The LIDAR system also includes a beam splitter (such as a lens) that simultaneously receives the LIDAR output signals and directs them to different sample areas in the field of view.

[0023] In some cases, the demultiplexer is tuned to change the path that each LIDAR output signal travels away from the demultiplexer. Changing the path that each LIDAR output signal travels away from the demultiplexer causes a change in the direction that the LIDAR output signal travels away from the beam splitter. As a result, the path that each LIDAR output signal travels away from the demultiplexer is tuned to scan the LIDAR output signal to different sample areas in the field of view.

[0024] A variety of mechanisms are suitable for tuning the path that each LIDAR output signal takes away from the demultiplexer. For example, mechanisms such as optical switches and temperature tuning can be integrated into an optical platform such as a silicon-on-insulator platform and can be solid-state mechanisms. Consequently, a solid-state mechanism for manipulating LIDAR output signals is disclosed.

[0025] Figure 1Ais a schematic diagram of a LIDAR system. The system includes a light source 10, such as a laser, that outputs an outgoing optical signal. The outgoing optical signal carries a plurality of different channels, each at a different wavelength. The wavelengths of the channels can be periodically spaced such that the increase in wavelength from one channel to the next is constant or substantially constant. Suitable light sources 10 for generating multiple channels with periodically spaced wavelengths include, but are not limited to, comb lasers; multiple single-wavelength lasers multiplexed into a single optical waveguide; and sources such as described in U.S. patent application Ser. No. 11 / 998,846, filed Nov. 30, 2017, entitled “Multi-Channel Optical Device,” and incorporated herein in its entirety.

[0026] The LIDAR system also includes a utility waveguide 12 that receives the outgoing optical signal from the light source 10. A modulator 14 is optionally positioned along the utility waveguide 12. Modulator 14 is configured to modulate the power of the outgoing optical signal and, accordingly, modulate the LIDAR output signal(s). Electronics can operate modulator 14. Thus, the electronics can modulate the power of the outgoing LIDAR signal and, accordingly, modulate the LIDAR output signal(s). Suitable modulators 14 include, but are not limited to, PIN diode carrier injection devices, Mach-Zehnder modulator devices, and electro-absorption modulator devices. When the modulator 14 is constructed on a silicon-on-insulator platform, a suitable modulator is disclosed in U.S. Patent Application Serial No. 617,810, filed on September 21, 1993, entitled Integrated Silicon PIN Diode Electro-Optic Waveguide, which is incorporated herein in its entirety.

[0027] An amplifier 16 is optionally positioned along the utility waveguide 12. Since the power of the outgoing optical signal is distributed among multiple channels, it may be desirable for the amplifier 16 to provide a desired power level for each channel on the utility waveguide 12. Suitable amplifiers include, but are not limited to, semiconductor optical amplifiers (SOAs).

[0028] The utility waveguide 12 carries the outgoing optical signal from the modulator 14 to a signal-directing component 18. The signal-directing component 18 can direct the outgoing optical signal to a LIDAR branch 20 and / or a data branch 22. The LIDAR branch outputs a LIDAR output signal and receives a LIDAR input signal. The data branch processes the LIDAR input signal to generate LIDAR data (the distance and / or radial velocity between the LIDAR system and a reflecting object located outside the LIDAR system).

[0029] The LIDAR branch includes a LIDAR signal waveguide 24, which receives at least a portion of the outgoing optical signal from the signal-directing component 18. The LIDAR signal waveguide 24 carries at least a portion of the outgoing optical signal to a demultiplexing component 26. If the outgoing optical signal carries multiple different channels at different wavelengths, the demultiplexing component 26 separates the outgoing optical signal into multiple LIDAR output signals, each at a different wavelength (channel) and directed toward a different sample area in the field of view. The demultiplexing component 26 outputs the LIDAR output signals, which can be reflected by reflective objects (not shown) located outside the LIDAR system. The reflected LIDAR output signals return to the demultiplexing component 26 as the LIDAR input signals. The demultiplexing component 26 combines the LIDAR input signals and outputs the result as the incoming optical signal on the LIDAR signal waveguide 24.

[0030] In some cases, demultiplexing component 26 also includes beam steering functionality. In these cases, demultiplexing component 26 can be in electrical communication with electronics (not shown) that can operate demultiplexing component 26 to steer the LIDAR output signals to different sample areas in the field of view. Demultiplexing component 26 and / or electronics can be configured so that different LIDAR output signals are steered independently or simultaneously.

[0031] Although the demultiplexing component 26 is illustrated as a single component, the demultiplexing component 26 may include multiple optical and / or electrical components. Suitable demultiplexing components 26 include, but are not limited to, optical phased arrays (OPAs), transmissive diffraction gratings, reflective diffraction gratings, and diffractive optical elements (DOEs). Suitable demultiplexing components 26 with beam steering capabilities include, but are not limited to, optical phased arrays (OPAs) with active phase control elements on arrayed waveguides.

[0032] LIDAR signal waveguide 24 carries the incoming optical signal to signal guiding component 18. Signal guiding component 18 guides the incoming optical signal to utility waveguide 12 and / or comparison signal waveguide 28. The portion of the incoming optical signal directed to comparison signal waveguide 28 serves as a comparison incoming optical signal.

[0033] Comparison signal waveguide 28 carries the incoming comparison optical signal to comparison demultiplexer 30. When the comparison optical signal carries multiple channels, comparison demultiplexer 30 divides the incoming comparison optical signal into different comparison signals, each carrying a different one of the channels. Comparison demultiplexer 30 outputs the comparison signals on different comparison waveguides 32. Each of comparison waveguides 32 carries a comparison signal to a different processing component 34.

[0034] Signal guiding component 18 is configured such that when signal guiding component 18 directs at least a portion of the incoming optical signal to comparison signal waveguide 28, signal guiding component 18 also directs at least a portion of the outgoing optical signal to reference signal waveguide 36. The portion of the outgoing optical signal received by reference signal waveguide 36 serves as the reference optical signal.

[0035] Reference signal waveguide 36 carries the reference optical signal to reference demultiplexer 38. When the reference optical signal carries multiple channels, reference demultiplexer 38 divides the reference optical signal into different reference signals, each carrying a different channel. Reference demultiplexer 38 outputs each of the reference signals on a different reference waveguide 40. Each reference waveguide 40 carries a reference signal to a different one of processing components 34.

[0036] The comparison waveguide 32 and the reference waveguide 40 are configured such that the comparison signal and the corresponding reference signal are received at the same processing component 34. For example, the comparison waveguide 32 and the reference waveguide 40 are configured such that the comparison signal and the corresponding reference signal carrying the same channel (same wavelength) are received at the same processing component 34.

[0037] As will be described in more detail below, each of the processing components 34 combines the comparison signal with a corresponding reference signal to form a composite signal carrying LIDAR data for a sample area in the field of view. Thus, the composite signal can be processed to extract LIDAR data for the sample area.

[0038] Signal guiding component 18 may be an optical coupler. When signal guiding component 18 is an optical coupler, signal guiding component 18 guides a first portion of the outgoing optical signal to LIDAR signal waveguide 24 and a second portion of the outgoing optical signal to reference signal waveguide 36, and further guides a first portion of the incoming optical signal to utility waveguide 12 and a second portion of the incoming optical signal to comparison signal waveguide 28. Thus, the second portion of the incoming optical signal may serve as a comparison incoming optical signal, and the second portion of the outgoing optical signal may serve as a reference optical signal.

[0039] Signal directing component 18 may be an optical switch, such as a crossbar switch. Suitable crossbar switches can operate in either crossbar mode or pass-through mode. In pass-through mode, the outgoing optical signal is directed to LIDAR signal waveguide 24, and the incoming optical signal is directed to utility waveguide 12. In crossbar mode, the outgoing optical signal is directed to reference signal waveguide 36, and the incoming optical signal is directed to comparison signal waveguide 28. Thus, the incoming optical signal, or a portion of the incoming optical signal, can serve as the comparison optical signal, and the outgoing optical signal, or a portion of the outgoing optical signal, can serve as the reference optical signal.

[0040] An optical switch, such as a crossbar switch, can be controlled by electronics. For example, the electronics can control the operation of the switch so that it operates in either a crossbar mode or a pass-through mode. When LIDAR output signals are being transmitted from the LIDAR system, the electronics operate the switch so that it operates in the pass-through mode. When the LIDAR system is receiving LIDAR input signals, the electronics operate the switch so that it operates in the crossbar mode. The use of a switch can provide lower optical loss levels than those associated with the use of an optical coupler as the signal guide component 18.

[0041] In the above description of the operation of signal directing component 18, the comparison optical signal and the reference optical signal are simultaneously directed to data branch 22. As a result, processing components 34 can each combine the comparison signal with a reference signal carrying the same channel (corresponding reference signal).

[0042] In some cases, an optical amplifier 42 is optionally positioned along the LIDAR signal waveguide 24 and configured to provide amplification of the outgoing optical signal and / or the incoming optical signal. Thus, the effects of optical losses at the signal guiding component 18 can be reduced.

[0043] Figure 1B Pictured Figure 1A The LIDAR system is modified to include an optical circulator as the signal guiding component 18. The optical circulator is configured such that the outgoing optical signal is guided to the LIDAR signal waveguide 24 and the incoming optical signal is guided to the comparison signal waveguide 28. The comparison signal waveguide 28 carries the comparison incoming optical signal to the comparison demultiplexer 30. Additionally, a tapping component 44 is positioned along the utility waveguide 12. The tapping component 44 is configured to tap a first portion of the outgoing optical signal such that the first portion of the outgoing optical signal is received on the reference signal waveguide 36. The first portion of the outgoing optical signal received by the reference signal waveguide 36 serves as a reference optical signal. The reference signal waveguide 36 carries the reference optical signal to the reference demultiplexer 38. Thus, as in Figure 1A As disclosed in the context of Figure 1B LIDAR system. Suitable optical circulators include, but are not limited to, fiber optic circulators based on Faraday rotators and integrated optical circulators. Figure 1B The signal guiding component 18 is disclosed as an optical circulator, but Figure 1B The signal guiding component 18 may be an optical coupler or an optical switch.

[0044] Light from a laser source is typically linearly polarized, and therefore the LIDAR output signal is also typically linearly polarized. Reflections from a target can change the polarization angle of the returning light. Therefore, the LIDAR input signal can include light with different linear polarization states. For example, the first portion of the LIDAR input signal can include light with a first linear polarization state, and the second portion of the LIDAR input signal can include light with 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 and the reference signal polarization. If the angle is 90 degrees, LIDAR data may be lost in the resulting composite signal. As a result, the LIDAR system can be modified to compensate for changes in the polarization state of the LIDAR output signal.

[0045] Figure 2 yes Figure 1A and / or Figure 1B Schematic diagram of a LIDAR system modified to compensate for polarization changes in the LIDAR output signal. A tapping component 44 is positioned along the utility waveguide 12. The tapping component 44 is configured to tap a first portion of the outgoing optical signal, such that the first portion of the outgoing optical signal is received on a first reference signal waveguide 46. The first portion of the outgoing optical signal received by the first reference signal waveguide 46 serves as a first reference optical signal. The tapping component 44 is also configured to tap a second portion of the outgoing optical signal, such that the second portion of the outgoing optical signal is received on a second reference signal waveguide 48. The second portion of the outgoing optical signal received by the second reference signal waveguide 48 serves as a second reference optical signal.

[0046] First reference signal waveguide 46 carries the first reference optical signal to first reference demultiplexer 50. When the first reference optical signal includes multiple channels, first reference demultiplexer 50 divides the first reference optical signal into different first reference signals, each having a different wavelength. First reference demultiplexer 50 outputs the first reference signals on different first reference waveguides 52. Each first reference waveguide 52 carries one of the first reference signals to one of several first processing components 54.

[0047] Second reference signal waveguide 48 carries the second reference optical signal to second reference demultiplexer 56. When the second reference optical signal includes multiple channels, second reference demultiplexer 56 divides the second reference optical signal into different second reference signals, each having a different wavelength. Second reference demultiplexer 56 outputs the second reference signals on different second reference waveguides 58. Each of second reference waveguides 58 carries one of the second reference signals to a different one of several second processing components 60.

[0048] The utility waveguide 12 carries the outgoing optical signal to the signal guiding component 18. The signal guiding component 18 guides the outgoing optical signal to the LIDAR signal waveguide 24. The LIDAR signal waveguide 24 receives the incoming optical signal from the demultiplexing component 26 and carries the incoming optical signal to the signal guiding component 18. The signal guiding component 18 guides the incoming optical signal to the intermediate waveguide 62. Suitable signal guiding components 18 include, but are not limited to, circulators, 2x2 optical couplers, 1x2 optical couplers, and switches.

[0049] Intermediate waveguide 62 carries the received portion of the incoming optical signal to beam splitter 64. Beam splitter 64 splits the optical beam into a precursor comparison incoming signal and a second comparison incoming signal. The precursor comparison incoming signal is received on precursor comparison signal waveguide 65, and the second comparison incoming signal is received on second comparison signal waveguide 66. Predecessor comparison signal waveguide 65 carries the precursor comparison incoming signal to polarization rotator 67. Polarization rotator 67 outputs the first comparison incoming signal received on first comparison signal waveguide 69. First comparison signal waveguide 69 carries the first comparison incoming signal to a first comparison demultiplexer 68, and second comparison signal waveguide 66 carries the second comparison incoming signal to a second comparison demultiplexer 70.

[0050] When the first comparison incoming optical signal carries multiple channels, the first comparison demultiplexer 68 divides the first comparison incoming optical signal into different first comparison signals, each having a different wavelength. The first comparison demultiplexer 68 outputs the first comparison signals on different first comparison waveguides 72. Each first comparison waveguide 72 carries one of the first comparison signals to a different first processing component 54.

[0051] When the second comparison optical signal includes multiple channels, the second comparison demultiplexer 70 divides the first comparison incoming optical signal into different second comparison signals, each having a different wavelength. The second comparison demultiplexer 70 outputs the second comparison signals on different second comparison waveguides 74. Each second comparison waveguide 74 carries one of the second comparison signals to a different second processing component 60.

[0052] The first comparison waveguide 72 and the first reference waveguide 52 are configured such that the comparison signal and the corresponding reference signal are received at the same first processing component 54. For example, the first comparison waveguide 72 and the first reference waveguide 52 are configured such that the first comparison signal and the first reference signal of the same wavelength are received at the same first processing component 54.

[0053] The second comparison waveguide 74 and the second reference waveguide 58 are configured such that the comparison signal and the reference signal carrying the same channel are received at the same second processing component 60. For example, the second comparison waveguide 74 and the second reference waveguide 58 are configured such that the second comparison signal and the second reference signal of the same wavelength are received at the same second processing component 60.

[0054] Each first processing component 54 combines the first comparison signal with a corresponding first reference signal to form a first composite signal carrying LIDAR data for a sample area in the field of view. Each second processing component 60 combines the second comparison signal with a corresponding second reference signal to form a second composite signal carrying LIDAR data for the sample area in the field of view.

[0055] The LIDAR system is configured such that the first comparison signal has the same polarization state angle as the corresponding second comparison signal. For example, the beam splitter 64 can be a polarization beam splitter. One example of a polarization beam splitter is configured such that a channel in the precursor comparison incoming signal has a first polarization state but no or substantially no second polarization state, and a channel in the second comparison incoming signal has a second polarization state but no or substantially no first polarization state. For example, the polarization beam splitter can route a portion of the incoming optical signal with the first polarization state to the precursor comparison signal waveguide 65 and a portion of the incoming optical signal with the second polarization state to the second comparison signal waveguide 66. The first polarization state and the second polarization state can be linear polarization states, and the second polarization state can be 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. Suitable beam splitters include, but are not limited to, Wollaston prisms, MEMs-based polarization beam splitters, integrated optics polarization beam splitters using asymmetric y-branches, Mach-Zehnder interferometers, and multimode interference couplers.

[0056] The polarization state rotator can be configured to change the polarization state of a channel in the precursor comparison incoming signal from a first polarization state to a second polarization state. As a result, the channel in the first comparison incoming signal has the second polarization state, but does not have or substantially does not have the first polarization state. Therefore, the channel in the first comparison incoming signal and the corresponding channel in the second comparison incoming signal each have the same polarization state (the second polarization state in this discussion). The first comparison signal caused by the first comparison incoming signal has the same polarization state angle as the corresponding second comparison signal caused by the second comparison incoming signal. Suitable polarization state rotators include, but are not limited to, rotation of polarization-maintaining fiber, Faraday rotators, half-wave plates, MEMs-based polarization rotators and integrated optical polarization rotators using asymmetric y-branches, Mach-Zehnder interferometers, and multimode interference couplers.

[0057] Because the LIDAR output signal(s) are linearly polarized, the first reference signal can have the same linear polarization angle as the corresponding second reference signal. For example, the first reference signal and the second reference signal can each have the same polarization angle as the first comparison incoming signal and the second comparison incoming signal. Therefore, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can each have the same polarization angle. In this example, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can each have light of the second polarization state.

[0058] As a result of the above configuration, each of the first composite signals is caused by combining a reference signal and a comparison signal of the same polarization state, and will accordingly provide a desired beat between the reference signal and the comparison signal. For example, each of the first composite signals is caused by combining a reference signal and a comparison signal of the first polarization state, and excludes or substantially excludes light of the second polarization state, or each of the first composite signals is caused by combining a reference signal and a comparison signal of the second polarization state, and excludes or substantially excludes light of the first polarization state. Similarly, each of the second composite signals includes a reference signal and a comparison signal of the same polarization state, and will accordingly provide a desired beat between the reference signal and the comparison signal. For example, each of the second composite signals is caused by combining a reference signal and a comparison signal of the first polarization state, and excludes or substantially excludes light of the second polarization state, or each of the first composite signals is caused by combining a reference signal and a comparison signal of the second polarization state, and excludes or substantially excludes light of the first polarization state.

[0059] The above configuration results in LIDAR data for a single sample area in the field of view appearing in multiple different composite signals (i.e., a first composite signal and a second composite signal) generated for the sample area. In some cases, determining the LIDAR data for the sample area includes electronics combining LIDAR data from the different composite signals (i.e., the first composite signal and the second composite signal). Combining the LIDAR data may include taking an average, median, or modulus of the LIDAR data generated from the multiple different composite signals. For example, the electronics may average a distance between the LIDAR output signal source and a reflecting object determined from the first composite signal with a distance determined from the second composite signal, and / or the electronics may average a radial velocity between the LIDAR output signal source and a reflecting object determined from the first composite signal with a radial velocity determined from the second composite signal.

[0060] In some cases, determining LIDAR data for a sample area includes the electronics identifying one or more composite signals (i.e., the first composite signal and / or the second composite signal) as the source of LIDAR data that best represents reality (representative LIDAR data). The electronics may then use the LIDAR data from the identified composite signals as representative LIDAR data for additional processing. For example, the electronics may identify the signal with the larger amplitude (the first composite signal or the second composite signal) as representative LIDAR data and use the LIDAR data from the identified signal for further processing by the LIDAR system. In some cases, the electronics combines the composite signal identified as representative LIDAR data with LIDAR data from different LIDAR signals. For example, the electronics may identify each composite signal with an amplitude above an amplitude threshold as representative LIDAR data, and if more than two composite signals are identified as representative LIDAR data, the electronics may combine the LIDAR data from each identified composite signal. When a composite signal is identified as having representative LIDAR data, the electronic device may use the LIDAR data from the composite signal as the representative LIDAR data. When no composite signal is identified as having representative LIDAR data, the electronic device may discard the LIDAR data for the sample areas associated with those composite signals.

[0061] although Figure 2 is described in the context of components being arranged so that the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal each have a second polarization state, but Figure 2 Other configurations of the components in can be arranged such that the first composite signal is the result of combining the reference signal and the comparison signal of the same linear polarization state, and the first composite signal is the result of combining the reference signal and the comparison signal of the same linear polarization state. For example, the polarization state rotator can be positioned along the first reference signal waveguide 46 instead of between the precursor comparison signal waveguide 65 and the first comparison signal waveguide 69. As another example, when the first reference signal and the second reference signal each have the first polarization state, the polarization state rotator can be positioned along the second comparison signal waveguide 66.

[0062] The above system configuration causes the first portion of the LIDAR input signal (the portion having the first polarization state) and the first portion of the LIDAR input signal (the portion having the second polarization state) to be directed into different composite signals. For example, the system configuration may cause the first composite signal to include more power from the first portion of the LIDAR input signal than the first composite signal, and the second composite signal to include more power from the second portion of the LIDAR input signal than the first composite signal. Alternatively, the system configuration may cause the first composite signal to include more power from the second portion of the LIDAR input signal than the first composite signal, and the second composite signal to include more power from the first portion of the LIDAR input signal than the first composite signal. In some cases, the first portion of the LIDAR input signal has zero power or substantially zero power, or the second portion of the LIDAR input signal has zero power or substantially zero power.

[0063] The above LIDAR system may include more than one data branch associated with the LIDAR branch. For example, Figure 3 The LIDAR system of FIG. 1 illustrates a LIDAR system in which a plurality of light sources 10 provide channels to a LIDAR branch, and a plurality of data branches receive light signals from the LIDAR branch.

[0064] Although the LIDAR system is illustrated above as having a single light source 10, the LIDAR system may have multiple light sources 10, such as Figure 4 As shown in FIG. , the light source 10 includes M light sources 10, each light source 10 generating N channels. Each channel is received on a channel waveguide 80. The channel waveguide carries the channel to a channel multiplexer 82, which combines the channels to form an outgoing optical signal received on the utility waveguide 12.

[0065] exist Figure 4 In the , each channel is marked as , where i is the number of light sources 10 and is from 1 to M, and j is the number of channels of light source 10j and is from 1 to N. As noted above, the light sources 10 can be configured such that the wavelengths of the channels are periodically spaced such that the wavelength increases from one channel to the next ( ) is constant or substantially constant. In some cases, the light source 10 is configured so that channels with adjacent wavelengths are generated by different light sources 10. For example, the light source 10 can be configured so that Suitable light sources 10 for this configuration include, but are not limited to, comb lasers. In this configuration, the channel multiplexer may be a cyclic multiplexer designed to have a wavelength spacing equal to a multiple of the free spectral range (FSR) of the channel multiplexer ( Therefore, the channel multiplexer can be designed to be able to transmit signals in the wavelength range ( ) within the loop. Suitable loop multiplexers include, but are not limited to, the "colorless" AWG from Gemfire (8-channel looping arrayed waveguide grating, 2018).

[0066] Suitable values ​​for the number of light sources 10 (M) include, but are not limited to, values ​​greater than or equal to 2, 4, or 8 and / or less than 16, 32, or 64. Suitable values ​​for the number of channels provided by the light source 10 (N) include, but are not limited to, values ​​greater than or equal to 2, 4, or 8 and / or less than 16, 32, or 64. Suitable values ​​for the increase in wavelength from one channel to the next ( ) include, but are not limited to, values ​​greater than or equal to 0.2 nm, 0.4 nm, or 0.6 nm and / or less than 0.8 nm, 1.0 nm, or 1.5 nm. Suitable values ​​for the wavelength of the channel with the shortest wavelength include, but are not limited to, values ​​greater than or equal to 1.3 , 1.4 or 1.5 and / or less than 1.6 , 1.7 or 1.8 In one example, the LIDAR system includes M greater than or equal to 2, 4, or 8 and / or less than 16, 32, or 64; N greater than or equal to 2, 4, or 8, and / or less than 16, 32, or 64; and N greater than or equal to 0.2 nm, 0.4 nm, or 0.6 nm and / or less than 0.8 nm, 1 nm, or 1.5 nm. .

[0067] In some cases, the light source 10 is configured such that at least a portion of the light sources 10 each generate two or more channels having adjacent wavelengths. For example, the light source 10 can be configured such that Suitable light sources 10 for this configuration include, but are not limited to, comb lasers. In this configuration, the channel multiplexer may be a laser having at least Suitable broadband multiplexers include, but are not limited to, arrayed waveguide gratings (AWGs) and thin film filters.

[0068] As indicated above, one or more of the light sources 10 may be comb lasers. However, other configurations of the light sources 10 are possible. For example, Figure 5 An example of a light source 10 including a plurality of laser sources 84 is illustrated. Figure 5The light source 10 shown in FIG. 1 includes a plurality of laser sources 84, each of which outputs one channel on a source waveguide 86. The source waveguide 86 carries the channels to a laser multiplexer 88, which combines the channels to form the optical signal received on the channel waveguide or utility waveguide 12. The electronics can operate the laser sources 84 so that they output each channel simultaneously. Figure 5 Suitable lasers for use with the constructed light source 10 include, but are not limited to, external cavity lasers, distributed feedback lasers (DFB), and Fabry-Perot (FP) lasers. External cavity lasers are advantageous in this embodiment due to their generally narrow linewidth, which can reduce noise in the detection signal.

[0069] Figure 6 Another example of a possible light source 10 configuration is shown. Light source 10 includes a gain element 90, such as a semiconductor laser. A gain waveguide 92 is optically aligned with the gain element to receive an optical signal from the gain element. In some cases, the gain waveguide excludes the gain medium contained in the gain element. For example, the gain waveguide can be a ridge waveguide on a silicon-on-insulator chip. A plurality of partial return devices 94 are positioned along the gain waveguide so that the partial return devices interact with the optical signal.

[0070] During operation, the electronics operate the gain element, causing the gain medium to transmit an optical signal. Each of the partial return devices 94 passes a portion of the optical signal. The portion of the optical signal received by the utility waveguide 12 from the partial return device serves as the outgoing optical signal. The partial return device also returns a portion of the optical signal to the gain element, allowing the returned portion of the optical signal to travel through the gain element. The gain element may include a fully reflective layer or a partially reflective layer that receives the returned portion of the optical signal from the gain element and reflects it back to the gain element, allowing it to be amplified and emitted as lasing light. Thus, the light source 10 may be an external cavity laser.

[0071] The partial return devices can be configured so that each returns light of a different wavelength. For example, the partial return devices can be configured so that at least one partial return device returns the wavelength of each channel to be output by light source 10. As a result, each desired channel will lase and appear in the outgoing optical signal. Suitable partial return devices include, but are not limited to, Bragg gratings.

[0072] 7A to 7BAn example of a suitable processing component for use in the above LIDAR system is shown. A first splitter 102 divides the reference signal carried on reference waveguide 40, 52, or 58 into a first reference waveguide 110 and a second reference waveguide 108. First reference waveguide 110 carries a first portion of the reference signal to an optical combining component 111. Second reference waveguide 108 carries a second portion of the reference signal to a second optical combining component 112.

[0073] Second splitter 100 divides the comparison signal carried on comparison waveguide 30, 72, or 74 into first comparison waveguide 104 and second comparison waveguide 106. First comparison waveguide 104 carries a first portion of the comparison signal to optical combination component 111. Second comparison waveguide 108 carries a second portion of the comparison signal to second optical combination component 112.

[0074] Second optical combining component 112 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 oscillates between the second portion of the comparison signal and the second portion of the reference signal. Optical combining component 112 also splits the resulting second composite signal onto first auxiliary detector waveguide 114 and second auxiliary detector waveguide 116.

[0075] The first auxiliary detector waveguide 114 carries the first portion of the second composite signal to a first auxiliary photosensor 118, which converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 116 carries the second portion of the second composite signal to a second auxiliary photosensor 120, which converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable photosensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0076] First optical combination component 111 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 oscillates between the first portion of the comparison signal and the first portion of the reference signal. Optical combination component 111 also splits the first composite signal onto first detector waveguide 121 and second detector waveguide 122.

[0077] First detector waveguide 121 carries the first portion of the first composite signal to first photosensor 123, which converts the first portion of the second composite signal into a first electrical signal. Second detector waveguide 122 carries the second portion of the second composite signal to second auxiliary photosensor 124, which converts the second portion of the second composite signal into a second electrical signal. Examples of suitable photosensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0078] The first reference waveguide 110 and the second reference waveguide 108 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 110 and the second reference waveguide 108 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 reference signal portion can be an in-phase component and the other a quadrature component. Thus, one of the reference signal portions can be a sine function and the other a cosine function. In one example, the first reference waveguide 110 and the second reference waveguide 108 are configured such that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Thus, the reference signal portion in the second composite signal is phase-shifted relative to the reference signal portion in the first composite signal, whereas the comparison signal portion in the first composite signal is not phase-shifted relative to the comparison signal portion in the second composite signal.

[0079] The first light sensor 123 and the second light sensor 124 can be connected as a balanced detector, and the first auxiliary light sensor 118 and the second auxiliary light sensor 120 can also be connected as a balanced detector. Figure 7B A schematic diagram is provided of the relationship between the electronics, the first light sensor 123, the second light sensor 124, the first supplemental light sensor 118, and the second supplemental light sensor 120. The symbol of a photodiode is used to represent the first light sensor 123, the second light sensor 124, the first supplemental light sensor 118, and the second supplemental light sensor 120, but one or more of these sensors may have other configurations. In some cases, Figure 7B All components shown in the schematic diagram are included in the LIDAR system. In some cases, Figure 7B The components illustrated in the schematic diagram of FIG. 5 are distributed between the LIDAR system and electronics located outside the LIDAR system.

[0080] The electronics connect the first and second light sensors 123 and 124 as a first balanced detector 125, and connect the first and second auxiliary light sensors 118 and 120 as a second balanced detector 126. Specifically, the first and second light sensors 123 and 124 are connected in series. Additionally, the first and second auxiliary light sensors 118 and 120 are connected in series. The serial connection in the first balanced detector communicates with a first data line 128, which carries the output from the first balanced detector as a first data signal. The serial connection in the second balanced detector communicates with a second data line 132, which carries the output from the first balanced detector as a second data signal. The first and second data signals are pulsating due to the pulsation between the comparison signal and the reference signal, i.e., the pulsation in the first and second composite signals.

[0081] The first data line 128 carries the first data signal to the first switch 134. The first switch can be in a first configuration, in which the first data signal is carried to the distance branch 136, or in a second configuration, in which the first data signal is carried to the speed branch 138. Figure 7B , the first switch 134 is shown in a first configuration. The second data line 132 carries the second data signal to the second switch 140. The second switch can be in a first configuration, in which the second data signal is carried to the distance branch 136, or in a second configuration, in which the second data signal is carried to the speed branch 138. Figure 7B , the second switch 140 is shown in a first configuration. Suitable switches for use as the first switch and / or the second switch include, but are not limited to, electromechanical switches and solid-state MOSFET or PIN diode switches.

[0082] The electronic device operates the first switch and the second switch so that they are in the same configuration during the first time period and during the second time period. For example, the electronic device may operate the first switch and the second switch so that the first switch and the second switch are both in the first configuration during the first time period and are both in the second configuration during the second time period. In this example, the first data signal and the second data signal are carried to the distance branch 136 during the first time period and to the speed branch 138 during the second time period.

[0083] During operation of a LIDAR system, LIDAR data generation is divided into a series of cycles, where LIDAR data is generated for each cycle. In some cases, each cycle corresponds to a different sample area in the field of view. Thus, different cycles can generate LIDAR data for different areas in the field of view.

[0084] The loop can be executed such that the time of each loop can be divided into different time periods, including a distance time period (a first time period) and a velocity time period (a second time period). The distance between the reflecting object and the LIDAR chip can be determined in the distance time period, and the radial velocity between the reflecting object and the LIDAR chip can be determined in the velocity time period.

[0085] The electronics are configured to determine, or at least approximate, a distance between the LIDAR system and a reflecting object using the first data signal and the second data signal. For example, during a first time period, the electronics may operate the modulator 14 to add a chirp to the outgoing LIDAR signal, and accordingly, the amplitude of the LIDAR output signal. Adding the chirp to the amplitude may include modulating the amplitude of the outgoing LIDAR signal such that the amplitude of the outgoing LIDAR signal is a function of a sinusoid. In one example, the amplitude of the outgoing LIDAR signal is modulated such that the amplitude of the outgoing LIDAR signal is the square root of a function including a sinusoid and / or is the square root of a sinusoid. For example, the outgoing LIDAR signal may be modulated to produce a modulated outgoing LIDAR signal and mathematically represented by Equation 1: The LIDAR output signal is represented by, where M, N, C, D and F are constants, t represents time, M>0, N>0 and , in order to prevent the square root from becoming negative, As will become apparent below, F can be the LIDAR output signal frequency (f c ). In equation 1, F and C can be chosen so that .

[0086] The distance branch includes a first distance branch line 142. During a first period, the first distance branch line 142 carries the first data signal to the first multiplier 144. Figure 7B In the first period, the first multiplier 144 is configured to square the amplitude of the first data signal and output a first multiplied data signal. The distance branch includes a second distance branch line 146. During the first period, the second distance branch line 146 carries the second data signal to the second multiplier 148. Figure 7B In the embodiment of the present invention, the second multiplier 148 is configured to square the amplitude of the second data signal and output a second multiplied data signal. Suitable first multipliers and / or second multipliers include, but are not limited to, RF mixers, such as Gilbert cell mixers.

[0087] The distance branch includes an adder 150 that adds the first multiplied data signal and the second multiplied data signal. The adder outputs the added data signal. Suitable adders include, but are not limited to, RF combiners, including resistive or hybrid combiners. The distance branch includes a low-pass filter 152 that receives the added data signal and outputs a flapping data signal. The low-pass filter is selected to remove high-frequency contributions to the added data signal that are artifacts of mixing of the reference signal and the return signal. The low-pass filter can be selected to have a value greater than or equal to: bandwidth, where represents the maximum level of Doppler shift of the LIDAR input signal relative to the LIDAR input signal for which the LIDAR system will provide reliable results, represents the maximum delay between the transmission of the LIDAR output signal and the reception of the LIDAR input signal, and represents the rate of change of the chirp frequency added to the modulated outgoing LIDAR signal amplitude during the duration of the sampling period (i.e., the first period). In some cases, it is determined based on B / T , where B represents the change in chirp frequency added to the modulated outgoing LIDAR signal amplitude during the duration of the sampling period, and T is the duration of the sampling period. In some cases, T is determined according to the following formula: ,in represents the wavelength of the outgoing LIDAR signal, : represents the velocity resolution, and B can be determined according to the following formula: , where c represents the speed of light, and In some cases, the filter has a bandwidth greater than 0.1 GHz, 0.2 GHz, or 0.3 GHz and / or less than 0.4 GHz, 0.5 GHz, or 1 GHz. The corresponding value of the scanning period (T) can be 10 , 8 , 4 , 3 , 2 and 1 .

[0088] The range branch includes an analog-to-digital converter (ADC) 154 that receives the flap data signal from the filter. The ADC 154 converts the flap data signal from analog form to digital form and outputs the result as a digital LIDAR data signal. As discussed above, the conversion of the flap data signal includes sampling the flap data signal at a sampling rate. Adding a chirp to the amplitude of the LIDAR output signal significantly reduces or removes the effects of the radial velocity of the flap from the composite signal and the resulting electrical signal. For example, the frequency shift (“frequency shift”) of the LIDAR output signal relative to the LIDAR input signal ) can be written as ,in represents the frequency change due to Doppler shift, and The outgoing LIDAR signal may be modulated to produce a modulated outgoing LIDAR signal and a correspondingly modulated LIDAR output signal, wherein the frequency change due to the Doppler shift ( ) is less than 10%, 5%, 1%, or even 0.1% of the Doppler shift that would occur from a sinusoidal LIDAR output signal that acts as a LIDAR and has a constant amplitude and the same frequency as the modulated outgoing LIDAR signal and / or LIDAR output signal. For example, the outgoing LIDAR signal and / or LIDAR output signal may be modulated to produce a modulated outgoing LIDAR signal and / or LIDAR output signal, wherein the frequency change due to the Doppler shift ( ) is less than 10%, 5%, 1%, or even 0.1% of the Doppler shift that would occur from a continuous wave that serves as the LIDAR output signal and has the same frequency as the modulated outgoing LIDAR signal and / or LIDAR output signal. In another example, the outgoing LIDAR signal and / or LIDAR output signal is modulated to produce a modulated outgoing LIDAR signal and / or LIDAR output signal, wherein the frequency change due to the Doppler shift ( ) is less than 10%, 5%, 1%, or even 0.1% of the Doppler shift that would occur from the outgoing LIDAR signal before modulation (the unmodulated outgoing LIDAR signal) that serves as the LIDAR output signal. These results can be achieved by increasing the value of the variable F in Equation 1 relative to C. For example, F can be expressed as , and C can be expressed as ,in Indicates the fundamental frequency of the frequency chirp in the modulated outgoing LIDAR signal amplitude. Therefore, by increasing the LIDAR output signal frequency ( ) relative to the linear FM fundamental frequency ( ) value, you can increase F relative to C. As an example, and can be chosen so that In some cases, choosing and , making : The ratio is greater than 2:1, 10:1, 1x10 4 ∶1,5xl0 4 or 1x10 5 :1 and / or less than 5x10 5 、lxl0 6 、5xl0 6 or 5x10 8 Therefore, for the ratio F:C, the variables F and C may also have these same values. The frequency change due to Doppler shift is reduced and / or removed from the frequency shift ( ) reduces the beat frequency and correspondingly reduces the required sampling rate.

[0089] The range branch includes a transform module 156 that receives the digital LIDAR data signal from the analog-to-digital converter (ADC) 154. The transform module 156 is configured to perform a real transform on the digital LIDAR data signal to convert from the time domain to the frequency domain. This transform provides a definite resolution of the frequency offset of the LIDAR input signal relative to the offset of the LIDAR input signal caused by the distance between the reflecting object and the LIDAR system. A suitable real transform is a Fourier transform, such as a fast Fourier transform (FFT). Classifying the transform as a real transform distinguishes it from a complex transform, such as a complex Fourier transform. The transform module can perform the attribute function using firmware, hardware, or software, or a combination thereof.

[0090] Since the frequency provided by the transformation module has no input from the frequency shift due to relative motion, or no substantial input from the frequency shift due to relative motion, the determined frequency shift can be used to approximate the distance between the reflecting object and the LIDAR system. For example, the electronics can use Equation 3: to approximate the distance between the reflecting object and the LIDAR system (R0), where can be approximated as the peak frequency output from the transform module, and c is the speed of light.

[0091] The velocity branch can be configured to determine or at least approximate the radial velocity of the LIDAR system and the reflecting object using the first data signal and the second data signal. Figures 1A to 2The LIDAR output signal disclosed in the context of having a frequency as a function of time may be replaced by a LIDAR output signal, wherein the frequency of the LIDAR output signal is not a function of time. For example, the LIDAR output signal may be a continuous wave (CW). For example, during the second time period, the modulated outgoing LIDAR signal and the corresponding LIDAR output signal may be a continuous wave (CW) that is not chirped. As an example, the modulated outgoing LIDAR signal and the corresponding LIDAR output signal may be represented by Equation 2: , where G and H are constants, and t represents time. In some cases, G represents the square root of the outgoing LIDAR signal power, and / or H represents the constant F from Equation 1. In cases where the output of the light source has the desired waveform for the modulated outgoing LIDAR signal, the electronics need not operate the modulator 14 to modify the outgoing LIDAR signal. In these cases, the output of the light source(s) can serve as the modulated outgoing LIDAR signal, and accordingly, the LIDAR output signal. In some cases, the electronics operate the modulator 14 to generate a modulated outgoing LIDAR signal having the desired form.

[0092] Because the frequency of the LIDAR output signal is constant during the second time period, changing the distance between the reflecting object and the LIDAR system does not cause the frequency of the LIDAR input signal to change. As a result, the separation distance does not contribute to the shift in the frequency of the LIDAR input signal relative to the frequency of the LIDAR output signal. Therefore, the effect of the separation distance is removed or substantially removed from the shift in the frequency of the LIDAR input signal relative to the frequency of the LIDAR output signal.

[0093] The velocity branch includes a first velocity branch line 160 and a second velocity branch line 160. During the second period, first velocity branch line 160 carries the first data signal to an analog-to-digital converter (ADC) 164, which converts the first data signal from analog to digital form and outputs a first digital data signal. As discussed above, the conversion of the first data signal is accomplished by sampling the first data signal at the sampling rate. Using a continuous wave as the LIDAR output signal substantially removes the effect of the distance between the reflecting object and the LIDAR system on the composite signal and the resulting electrical signal. This reduces the flapping effect and lowers the required sampling rate.

[0094] Second velocity branch line 162 carries the second data signal to analog-to-digital converter (ADC) 166, which converts the second data signal from analog to digital form and outputs a second digital data signal. As discussed above, the conversion of the second data signal includes sampling the second data signal at a sampling rate. Using a continuous wave as the LIDAR output signal substantially reduces or eliminates the effect of the distance between the reflecting object and the LIDAR system on the jitter of the second composite signal and the resulting electrical signal. Consequently, jitter is reduced, and the required sampling rate is lowered.

[0095] The sampling rate of analog-to-digital converter (ADC) 164 may be the same as or different from the sampling rate of analog-to-digital converter (ADC) 166 .

[0096] The velocity branch includes a transform module 168, which receives a first digital data signal from analog-to-digital converter (ADC) 164 and a second digital data signal from analog-to-digital converter (ADC) 166. Because the first data signal is an in-phase component and the second data signal is a quadrature component, the first and second data signals together function as a complex velocity data signal, where the first data signal is a real component and the second data signal is an imaginary component. Consequently, the first digital data signal can be the real portion of the digital velocity data signal, and the second data signal can be the imaginary portion of the digital velocity data signal. Transform module 168 can be configured to perform a complex transform on the digital velocity data signal to convert from the time domain to the frequency domain. This transform provides an unambiguous resolution of the frequency offset of the LIDAR input signal relative to the LIDAR input signal caused by the radial velocity between the reflecting object and the LIDAR system. A suitable complex transform is a Fourier transform, such as a complex fast Fourier transform (FFT). The transform module can perform the attribute function using firmware, hardware, or software, or a combination thereof.

[0097] Because the frequency shift provided by transform module 168 has no input from the frequency shift due to the separation distance between the reflecting object and the LIDAR system, and due to the complex nature of the velocity data signal, the output of transform module 168 can be used to approximate the radial velocity between the reflecting object and the LIDAR system. For example, the electronics can use Equation 4: to approximate the radial velocity (v) between the reflecting object and the LIDAR system, where is approximately the peak frequency output from the transform module 168, c is the speed of light, and Indicates the frequency of the LIDAR output signal.

[0098] Can Figure 7BAdditional components may be added to the schematic diagram. For example, when the LIDAR system generates multiple LIDAR output signals or is used with other LIDAR systems that generate LIDAR output signals (i.e., using frequency division or wavelength division multiplexing, FDM / WMD), the LIDAR system may include one or more filters to remove interfering signals from the real and / or imaginary components of the flap data signal and / or velocity data signal. Thus, in addition to the components shown, the LIDAR system may include one or more filters. Suitable filters include, but are not limited to, low-pass filters. In the case of an optical design, if the frequency of the interfering component falls outside the bandwidth of the balanced detector(s), additional filtering may not be necessary, as it can be effectively provided by the balanced detector(s).

[0099] The sampling rate used during the first period and the second period may be selected to have a value greater than or equal to the larger of two values ​​selected from the group consisting of a minimum sampling rate for the first period and a minimum sampling rate for the second period. For example, during the first period, the first period sampling rate (f s1 ) can be determined by OK, among them represents the maximum amount of time between the transmission of the LIDAR output signal and the reception of the LIDAR input signal. During the second period, the second period sampling rate (f s2 ) can be determined by OK, among them represents the maximum level of Doppler shift of the LIDAR input signal relative to the LIDAR input signal for which the LIDAR system will provide reliable results. The maximum value is determined by the maximum level for which the LIDAR system will provide reliable results. Therefore, the maximum distance generally corresponds to the field of view distance set in the LIDAR specification, and the maximum Doppler shift generally corresponds to the Doppler shift that occurs at the maximum radial velocity value set in the specification. These two equations show that the minimum sampling rate for the first period is , and the minimum sampling rate of the second period is As a result, the sampling rate is chosen to have a value greater than or equal to and In other words, the sampling rate used during the first period and the second period ( )yes In some cases, the sampling rate used during the first period and the second period ( ) greater than or equal to 0.1 GHz, 0.2 GHz or 0.5 GHz and / or less than 1 GHz, 2 GHz or 4 GHz.

[0100] The above description of the LIDAR system's operation assumes the presence of a modulator on the utility waveguide 12; however, the modulator is optional. In these cases, the electronics can operate the light source(s) 10 to increase the frequency of the outgoing LIDAR signal during a first period, and during a second period, the electronics can decrease the frequency of the outgoing LIDAR signal. Suitable methods for extracting LIDAR data from the resulting composite signal are disclosed in U.S. patent application Ser. No. 62 / 671,913, filed May 15, 2018, entitled "Optical Sensor Chip," which is incorporated herein in its entirety.

[0101] Figure 8 An example of a suitable demultiplexing component 26, optionally including beam steering capabilities, is illustrated. Demultiplexing component 26 includes a demultiplexer 184 that receives the outgoing optical signal from LIDAR signal waveguide 24. The illustrated demultiplexer 184 includes an input side 186 through which the outgoing optical signal is received, although other configurations are possible. Demultiplexer 184 separates the outgoing optical signal into different channel signals, each associated with a channel. The illustrated demultiplexer 184 includes an output side 188 through which the channel signals exit the demultiplexer 184, although other configurations are possible. Each channel signal is received on a different channel waveguide 190. For example, in the illustrated demultiplexer, the channel signals may exit the demultiplexer 184 through an optical port in output side 188 and each be received on a different channel waveguide 190 connected to output side 188. Each channel waveguide 190 terminates in a facet 192 through which the channel signal exits the channel waveguide 190. The channel signal exiting the channel waveguide 190 serves as one of the LIDAR output signals. Since embodiments of the demultiplexer 184 can be constructed without the channel waveguide 190, the channel waveguide 190 is optional.

[0102] As noted above, the LIDAR output signal is reflected by an object positioned away from the LIDAR system. The reflected LIDAR output signal serves as the LIDAR input signal(s) that enter the channel waveguide 190, or, when the channel waveguide 190 is not present, enters the demultiplexer 184 through the output side 188. In each case, the demultiplexer 184 receives the LIDAR input signal(s) and combines them into an incoming LIDAR signal. The incoming LIDAR signal is received on the LIDAR signal waveguide 24. Thus, the incoming LIDAR signal may include, consist of, or consist essentially of light from both the LIDAR input signal and the LIDAR output signal.

[0103] Suitable demultiplexers for use with LIDAR systems include, but are not limited to, arrayed waveguide gratings (AWGs), echelle gratings, and reflection gratings. Suitable demultiplexers for integration into optical platforms such as silicon-on-insulator wafers include, but are not limited to, arrayed waveguide gratings (AWGs), echelle gratings, and reflection gratings. Demultiplexer 184 separates the outgoing optical signal into different channel signals, each associated with a channel. Suitable demultiplexers for integration into optical platforms such as silicon-on-insulator wafers include, but are not limited to, arrayed waveguide gratings (AWGs) and reflection gratings. Suitable demultiplexers for integration into optical platforms such as silicon-on-insulator wafers include, but are not limited to, arrayed waveguide gratings (AWGs) and reflection gratings. Examples of suitable demultiplexers for integration into optical platforms such as silicon-on-insulator wafers can be found in U.S. Patent No. 5,002,350, filed on February 26, 1990, with patent application serial number 485,014, entitled Optical Multiplexer / Demultiplexer, and incorporated herein in its entirety; and D. Chowdhury, “Design of Low-Loss and Polarization-Insensitive Reflection Grating-Based Planar Demultiplexers,” in IEEE Journal of Selected Topics in Quantum Electronics, Vol. 6, March / April 2000.

[0104] The LIDAR system also includes a beam splitter 200 that receives the LIDAR output signal and redirects at least a portion of the LIDAR output signal so that different LIDAR output signals are distributed to different sample areas in the field of view. For example, a suitable beam splitter can receive the LIDAR output signal and redirect at least a portion of the LIDAR output signal so that the LIDAR output signal travels away from the beam splitter in different directions, so that different LIDAR output signals can be directed to different sample areas in the field of view. Figure 8 The beam splitter shown in is a lens. Figure 8 The paths of light rays parallel to the optical axis of the lens incident on different positions of the beam splitter 200 are shown. Examples of suitable beam splitters include, but are not limited to, passive components such as focusing mirrors and lenses. The beam splitter 200 may include or be composed of a combination of different beam splitters. For example, a suitable beam splitter 200 may include one or more lenses and one or more mirrors.

[0105] In some cases, it may be desirable to scan the LIDAR output signal(s) to different sample areas in the field of view. Figure 9A and Figure 9B Pictured Figure 8 The demultiplexer 184 is modified to provide a scan of the LIDAR output signal(s). The demultiplexer 184 includes channel waveguides 190 arranged in one or more active groups, wherein each active group includes one or more channel waveguides 190. Figure 9A and Figure 9B , the channel waveguides 190 in the first active group are labeled A, while the channel waveguides 190 in the second active group are labeled B. Different active groups include different selections of channel waveguides; however, one or more channel waveguides 190 may belong to more than one active group.

[0106] When the demultiplexer 184 is tuned to a configuration, the channel waveguides in one of the active groups may each receive one of the channel signals, while the channel waveguides in one or more other active groups do not receive the channel signal. Figure 9A The demultiplexer 184 is shown tuned to a first configuration, wherein each channel waveguide in a first active group receives one of the channel signals, while no channel waveguide in a second active group receives one of the channel signals. When the demultiplexer 184 is tuned to another configuration, the channel waveguides in another of the active groups may each receive one of the channel signals, while the channel waveguides in one or more other active groups do not receive a channel signal. For example, Figure 9B The demultiplexer 184 is shown tuned to a second configuration in which each channel waveguide in the second active group receives one of the channel signals, while no channel waveguide in the first active group receives one of the channel signals.

[0107] As from Figure 9A and Figure 9B Obviously, the channel waveguides can be arranged so that for all or part of the channel signals, when the channel waveguide receiving the channel signal changes, the area of ​​the beam splitter 200 receiving the channel signal (LIDAR output signal) changes. To illustrate this, the LIDAR output signal of the first configuration is Figure 9A and Figure 9B The LIDAR output signal of the second configuration is marked as CSA to CSC. Figure 9B The LIDAR output signals marked as CSA' to CSC' in the figure carry the same channel. The LIDAR output signals marked as CSB and CSB' carry the same channel. The LIDAR output signals marked as CSC and CSC' carry the same channel. As a result, Figure 9BThe direction in which each LIDAR output signal travels is compared when the LIDAR system is in the first configuration and when the LIDAR system is in the second configuration.

[0108] exist Figure 9A and Figure 9B In the embodiment, light parallel to the optical axis of the lens is incident on different positions of the beam splitter 200 when in different configurations. Figure 9C The entire path of the LIDAR output signals CSB and CSB' is illustrated, not just the rays parallel to the optical axis. A solid line is used to illustrate the path of the LIDAR output signal CSB', and a dashed line is used to illustrate the path of the LIDAR output signal CSB. Each illustrated path also includes a center ray. As is apparent from comparing the paths of the LIDAR output signals CSB and CSB', the channel waveguide 190 is configured so that the path of the LIDAR output signal and the angle at which the center ray is incident on the beam splitter 200 change in different configurations. As a result, the direction in which the LIDAR output signal travels away from the LIDAR system changes in response to the tuning of the demultiplexer 184. For example, Figure 9C The LIDAR output signals in FIG are shown as originating from different regions of the focal plane of beam splitter 200 and traveling away from the LIDAR system in different directions in response to the tuning of demultiplexer 184. Thus, the sample region to which all or a portion of the LIDAR output signal is directed changes in response to the tuning of demultiplexer 184. Thus, demultiplexer 184 can be tuned to scan the LIDAR output signal from one sample region to another. Figure 9C The channel waveguides 190 are illustrated as being arranged such that the beam splitter receives all or a portion of different LIDAR output signals at different regions of the beam splitter; however, the channel waveguides 190 can be arranged such that the beam splitter receives all or a portion of different LIDAR output signals at the same or substantially the same region of the beam splitter.

[0109] A variety of mechanisms can be used to tune the demultiplexer to adjust the path that each LIDAR output signal takes away from the demultiplexer. In some cases, the tuning mechanism tunes where the outgoing optical signal is incident on the output side of the demultiplexer 184. Suitable mechanisms include, but are not limited to, heating and / or cooling all or a portion of the demultiplexer 184 and phase tuning of the arrayed waveguides in the demultiplexer, such as an arrayed waveguide grating (AWG). For example, phase shifting devices (such as PIN diodes) can be used on all or a portion of the arrayed waveguides in the AWG. Mechanical movement of the input waveguides 24 to tune where the channel signals are incident on the input side of the demultiplexer 184 can also be used to tune where the channel signals are incident on the output side of the demultiplexer 184.

[0110] Another mechanism for tuning the path that each LIDAR output signal takes away from the demultiplexer is to tune the path that the channel signal takes through the demultiplexer. For example, the location at which the channel signal is incident on the input side 186 of the demultiplexer 184 can be tuned to tune the path that the channel signal takes through the demultiplexer. Figure 10A Pictured Figure 9A and Figure 9B The demultiplexing component of the demultiplexer 184 is modified to include a mechanism for tuning where the outgoing optical signal is received on the input side 186 of the demultiplexer 184. The LIDAR signal waveguide 24 directs the outgoing optical signal to the optical switch 220. The electronics operate the optical switch 220 so that the outgoing optical signal is directed to one of several input waveguides 222. Each input waveguide 222 is configured to carry the outgoing optical signal to a different area on the input side 186 of the demultiplexer 184. Thus, the electronics can tune where the outgoing optical signal is received on the input side 186 of the demultiplexer 184. As with Figure 9A and Figure 9B Like the demultiplexing components of the CMOS process, demultiplexer 184 separates the outgoing optical signal into different channel signals, each associated with one of the channels. Each channel signal exiting demultiplexer 184 is received on a different channel waveguide 190. Each channel waveguide terminates at a facet 192, through which the channel signal exits the channel waveguide. Each channel signal exiting the channel waveguide serves as one of the LIDAR output signals. Since embodiments of demultiplexer 184 can be constructed without channel waveguide 190, channel waveguide 190 is optional.

[0111] The optical switch 220 can be configured to operate in two directions. For example, when the LIDAR output signal is reflected by an object located far from the LIDAR system, the reflected LIDAR output signal serves as the LIDAR input signal(s), which enter the demultiplexer 184 through the output side 188. The demultiplexer 184 receives the LIDAR input signal(s) and combines the LIDAR input signal(s) into an incoming LIDAR signal received on one of the input waveguides. The input waveguide 222 carries the incoming LIDAR signal to the optical switch 220. The optical switch directs the incoming LIDAR signal to the LIDAR signal waveguide 24.

[0112] As in Figure 9A and Figure 9B As disclosed in the context of , the channel waveguides 190 are arranged in a plurality of different active groups, wherein each active group includes one or more channel waveguides 190. Figure 10A and Figure 10B, the channel waveguides in the first active group are labeled A, the channel waveguides in the second active group are labeled B, and the channel waveguides in the third active group are labeled C.

[0113] As from Figure 10A and Figure 10B As will be apparent, the input waveguides 222 are arranged such that when the optical switch 220 directs the LIDAR input signal to one of the input waveguides, the channel waveguides in one of the active groups may each receive one of the channel signals, while the channel waveguides in one or more other active groups do not receive the channel signal. Figure 10A The optical switch 220 is shown directing the LIDAR input signal to a first one of the input waveguide optical switches 220, and each channel waveguide in the second active group receives one of the channel signals, while no channel waveguide in the first active group and the third active group receives one of the channel signals. When the optical switch 220 directs the LIDAR input signal to another input waveguide, the channel waveguides in the other active group may each receive one of the channel signals, while the channel waveguides in one or more other active groups do not receive the channel signals. For example, Figure 10B Optical switch 220 is shown directing the LIDAR input signal to a second one of the input waveguides, wherein each channel waveguide in the third active group receives one of the channel signals, while no channel waveguides in the first and second active groups receive one of the channel signals.

[0114] As in Figure 9A and Figure 9B As described in the context of [ 1 ], changing the active group receiving the channel signal changes the direction in which the channel signal (LIDAR output signal) travels away from the LIDAR system. Thus, the sample area across the field of view to which all or a portion of the LIDAR output signal is directed changes in response to the optical switch changing the input waveguide receiving the outgoing LIDAR signal. Thus, the electronics can operate the optical switch to sweep the LIDAR output signal from one sample area to another.

[0115] A number of mechanisms for tuning where the channel signals are incident on the output side of a demultiplexer are disclosed above. A demultiplexing component may utilize more than one mechanism for tuning where the channel signals are incident on the output side of a demultiplexer. For example, a demultiplexing component may be configured as follows: Figure 10A and Figure 10B and also includes Figure 9A and Figure 9B The tuning mechanism is disclosed in the context of .

[0116] exist Figures 8 to 10BIn LIDAR systems, the beam splitter 200 can optionally be fixed relative to the demultiplexer. For example, the beam splitter 200 and the demultiplexer can be integrated on the same LIDAR chip. Alternatively, the beam splitter 200 and the demultiplexer can be fixed on a common platform. In these cases, the above mechanism for manipulating the LIDAR output signal provides a solid-state manipulation solution.

[0117] In some cases, the beam splitter 200 is movable relative to the demultiplexer. For example, the electronics can operate actuators of the beam splitter 200 and / or the demultiplexer relative to each other to change where the channel signals are incident on the beam splitter 200. This change in position changes the direction of the LIDAR output signal and can be used to manipulate the LIDAR output signal in addition to or instead of other mechanisms disclosed for manipulating the LIDAR output signal.

[0118] Suitable for use as Figures 8 to 10B An example of a demultiplexer is an arrayed waveguide grating demultiplexer. Figure 11 1 is a top view of an arrayed waveguide grating (AWG) demultiplexer suitable for integration with silicon-on-insulator wafers. The demultiplexer includes an arrayed waveguide grating 230 that provides an optical path between a first optical distributor 232 and a second optical distributor 234. The LIDAR signal waveguide 24 interfaces with one side of the first optical distributor, which serves as the input side 186 of the demultiplexer. Alternatively, the input waveguide 222 ( Figure 11 The channel waveguide 190 is connected to one side of the first optical distributor serving as the input side of the demultiplexer. The channel waveguide 190 is connected to one side of the second optical distributor serving as the output side 188 of the demultiplexer. Suitable components for the first optical distributor and the second optical distributor include, but are not limited to, star couplers. Figure 11 Suitable methods for tuning the position of the output side 188 of the demultiplexer include, but are not limited to, temperature tuning, such as thermo-optical tuning. Another suitable method for tuning the position of the channel signal incident on the output side 188 of the demultiplexer includes phase tuning all or part of the waveguides in the arrayed waveguide grating 230 with the aid of a heater or a PIN diode. Figure 11 An example of a constructed tunable demultiplexer can be found in “Modeling and Validation of High Performance and Athermal AWGsfor the Silicon Photonics Platform” (Proceedings SPIE Vol. 9891 (2016)).

[0119] Used for use as Figure 10ASuitable optical switches for the optical switch 220 include, but are not limited to, those operating on principles based on thermo-optical, electro-optical, and magneto-optical effects. Figure 12A and Figure 12B The diagram illustrates the construction of a cascaded optical switch suitable for integration with a silicon-on-insulator wafer. Figure 12A is a schematic diagram of an optical switch 220 that includes a plurality of 1x2 optical switches 240 cascaded to provide a 1x3 optical switch 220. The 1x2 optical switches 240 are each configured to switch an optical signal received on a switch input waveguide 242 between different switch output waveguides 244. Figure 12A As is apparent in FIG, the LIDAR signal waveguide 24 can serve as one of the switch input waveguides 242, and / or the output waveguide 244 can serve as the switch input waveguide 242 of another 1x2 optical switch. Furthermore, in some cases, the switch output waveguide 244 can serve as the input waveguide 222.

[0120] Various optical switches are suitable for use as a 1x2 optical switch. Examples of suitable 1x2 optical switches for integration into a silicon-on-insulator platform include, but are not limited to, a Mach-Zehnder interferometer, a tunable coupler, and a splitter with an attenuator. Figure 12B is a schematic diagram of a suitable Mach-Zehnder interferometer. The switch includes a first switch waveguide 260 connecting a switch input waveguide 242 and a switch output waveguide 244. A second switch waveguide 262 is connected to another switch output waveguide 244. The first switch waveguide 260 and the second switch waveguide 262 are included in a first optical coupler 264 and a second optical coupler 266. A phase shifter 268 is positioned between the first optical coupler 264 and the second optical coupler 266, along the second switch waveguide 262 or the first switch waveguide 260. Suitable phase shifters include, but are not limited to, a PIN diode, a PN junction operating in a carrier depletion mode, and a thermal heater.

[0121] The above LIDAR system can be integrated on a single chip. A variety of platforms can be used for a chip including the above LIDAR system. Suitable platforms include, but are not limited to, silicon-on-insulator wafers. One or more of the above components and / or portions of the above components can be integrated with the chip, or can be placed on the chip using techniques such as flip-chip bonding. For example, the light source 10 can include a gain element and one or more other components, such as a waveguide. The waveguide can be integrated with the chip, and the gain element can be a component separate from the chip but attached to the chip using flip-chip bonding. Alternatively, the above LIDAR system can be constructed using discrete components. For example, all or part of the waveguide can be an optical fiber connecting discrete components. Alternatively, one or more parts of the LIDAR system can be integrated on the chip, while other parts are discrete components. For example, the utility waveguide 12 can be or include an optical fiber that provides optical communication between the light source 10 and the optical chip that includes the rest of the LIDAR system.

[0122] In view of these teachings, other embodiments, combinations and modifications of the present invention will be readily apparent to those skilled in the art. Therefore, the present invention will be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above description and drawings.

Claims

1. A LIDAR system comprising: a demultiplexer that separates the outgoing LIDAR signal into multiple LIDAR output signals, each carrying a different channel; and a plurality of input waveguides, each configured to carry an outgoing LIDAR signal to a different region of an input side of the demultiplexer; A beam splitter receives each of the LIDAR output signals and directs the received LIDAR output signals such that different LIDAR output signals travel away from the beam splitter in different directions.

2. The system according to claim 1, wherein: The beam splitter is a lens.

3. The system according to claim 1, further comprising: A tuning mechanism for tuning where the LIDAR output signal is received on the output side of the demultiplexer.

4. The system according to claim 3, wherein: The tuning mechanism includes an optical switch configured to direct the outgoing LIDAR signal to one of the input waveguides.

5. The system according to claim 1, wherein A plurality of channel waveguides each receive a different one of the LIDAR output signals from the demultiplexer, and a beam splitter receives the LIDAR output signals from the channel waveguides.

6. The system according to claim 5, wherein: The demultiplexer and channel waveguides are positioned on the LIDAR chip.

7. The system according to claim 6, wherein: The LIDAR chip is constructed on a silicon-on-insulator platform.

8. The system according to claim 7, wherein: The demultiplexer is selected from the group consisting of an arrayed waveguide grating and an echelle grating.

9. The system according to claim 5, wherein: The channel waveguides are arranged in a plurality of active groups such that when the LIDAR system is tuned to a first configuration, at least a portion of the LIDAR output signals are each directed to one of the channel waveguides in a first of the active groups, but no LIDAR output signals are directed to a channel waveguide in a second of the active groups.

10. The system according to claim 9, wherein: When the LIDAR system is tuned to a first configuration, all LIDAR output signals are each directed to one of the channel waveguides in the first active set.

11. The system according to claim 9, wherein: When the LIDAR system is tuned to the second configuration, at least a portion of the LIDAR output signals are each directed to one of the channel waveguides in the second active set.

12. The system according to claim 11, wherein When the LIDAR system is tuned to the second configuration, all LIDAR output signals are each directed to one of the channel waveguides in the second active set.

13. The system according to claim 12, wherein: The beam splitter is configured such that when the LIDAR system is tuned to a first configuration, the beam splitter receives the LIDAR output signal at a different angle of incidence than when the LIDAR system is tuned to a second configuration.

14. The system according to claim 13, wherein: When the LIDAR system is tuned to the second configuration, none of the LIDAR output signals are directed to the channel waveguides in the first set.

15. The system of claim 1, wherein: The demultiplexer and beam splitter are solid-state components.

16. The system of claim 1, wherein: The beam splitter receives each of the LIDAR output signals simultaneously.

17. A LIDAR system comprising: A LIDAR chip including multiple channel waveguides, each channel waveguide guiding a LIDAR output signal carrying a different channel; and A beam splitter that simultaneously receives the LIDAR output signal from the channel waveguide, The beam splitter receives the LIDAR output signal so that each LIDAR output signal is incident on the beam splitter at a different incident angle, and The beam splitter directs the received LIDAR output signals so that different LIDAR output signals travel away from the beam splitter in different directions; an optical switch configured to direct an outgoing LIDAR signal to one of a plurality of input waveguides, the outgoing LIDAR signal carrying each of the channels; and electronics configured to operate the optical switch to change the input waveguide that receives the outgoing LIDAR signal; The direction in which the LIDAR output signal travels away from the beam splitter changes in response to a change in the input waveguide that receives the outgoing LIDAR signal.

18. The system according to claim 17, wherein: The beam splitter is positioned outside the LIDAR chip.

19. The system according to claim 17, wherein: Each of the channel waveguides receives one of the LIDAR output signals from the same demultiplexer.

Images