Scanning multiple LIDAR system output signals

Abstract

The LIDAR system includes a switch configured to direct a switch signal to one of a plurality of different alternate waveguides, whereby the alternate waveguide to which the switch directs the switch signal receives the switch signal from the switch. The switch signal carries a plurality of different channels. The system also includes an optical grating that receives a plurality of different channel output signals, each channel output signal containing light from the switch signal and carrying a different one of the channels. The optical grating outputs the channel output signals such that the direction in which each channel output signal travels away from the optical grating changes in response to changes in the alternate waveguide to which the switch directs the switch signal.

Description

Related Applications

[0001] This application is a continuation of U.S. Patent Application No. 18 / 104,770, filed February 1, 2023 ("Scanning Multiple LIDAR System Output Signals"), which is incorporated herein in its entirety.

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

[0003] There is growing commercial demand for LIDAR systems that can be deployed in applications such as ADAS (Advanced Driver Assistance Systems) and AR (Augmented Reality). LIDAR systems typically scan the system output signal over multiple different sample areas within the LIDAR system's field of view. The LIDAR system generates LIDAR data for the sample areas within the field of view. The LIDAR data for the sample areas indicates the line-of-sight velocity and / or distance between the LIDAR system and objects within the sample areas.

[0004] A solid-state mechanism for scanning the system output signal in a LIDAR system can improve the reliability of LIDAR data and the speed at which LIDAR data is generated. However, as the number of sample areas and the size of the field of view increase, the effectiveness of solid-state scanning mechanisms decreases. Therefore, improvements in LIDAR systems are needed.

[0005] The LIDAR system includes a switch configured to direct a switch signal to one of a plurality of different alternate waveguides. The alternate waveguides to which the switch directs the switch signal receive the switch signal from the switch. The switch signal carries a plurality of different channels. The system also includes an optical grating that receives a plurality of different channel output signals. Each channel output signal includes light from the switch signal and carries one of the different channels. The optical grating outputs the channel output signals such that the direction in which each channel output signal travels away from the optical grating changes in response to changes in the alternate waveguide to which the switch directs the switch signal.

[0006] A method for operating a LIDAR system includes directing a switch signal to one of a plurality of different alternative waveguides. The alternative waveguide along which the switch signal is directed receives a switch signal from a switch. The switch signal carries a plurality of different channels. The method also includes receiving a plurality of different channel output signals from an optical grating. Each of the different channel output signals includes light from the switch signal and carries one of the different channels. The method further includes changing the alternative waveguide along which the switch directs the switch signal. The direction in which each channel output signal travels away from the optical grating changes in response to changing the alternative waveguide along which the switch directs the switch signal. [Brief explanation of the drawings]

[0007] FIG. 1A is a top view of the LIDAR chip.

[0008] FIG. 1B shows a light source that includes multiple laser sources.

[0009] FIG. 2 is a top view of the LIDAR chip.

[0010] FIG. 3 is a top view of the LIDAR chip.

[0011] FIG. 4 is a top view of the LIDAR chip.

[0012] FIG. 5 is a top view of a LIDAR assembly including a LIDAR adapter in optical communication with the LIDAR chip.

[0013] FIG. 6A is a top view of a system including a scanning tip used with an adapter constructed in accordance with FIG.

[0014] FIG. 6B is a top view of a system with a scanning tip used in combination with a signal director and a transmission optical grating.

[0015] FIG. 6C is a top view of a system with a scanning tip used in combination with a signal director and a reflective optical grating.

[0016] FIG. 7A is a top view of a LIDAR system including the LIDAR chip disclosed in connection with FIG. 1A, the LIDAR adapter disclosed in connection with FIG. 5, and the scanning chip, signal director, and optical grating disclosed in connection with FIG. 6B.

[0017] FIG. 7B is a top view of a portion of another embodiment of a LIDAR system that combines the LIDAR system of FIG. 7A with multiple maneuvers.

[0018] FIG. 8 is a cross-sectional view of a portion of a suitable reflective optical grating.

[0019] FIG. 9A shows an example of a processing unit applied to the LIDAR system.

[0020] FIG. 9B shows a schematic diagram of the electronics applied to the processing unit constructed according to FIG. 7A.

[0021] FIG. 9C is a graph of frequency versus time of the system output signal using triangular frequency regulation.

[0022] FIG. 9D shows another example of a processing unit applied to the LIDAR system.

[0023] FIG. 9E shows a schematic diagram of the electronics applied to the processing unit constructed according to FIG. 7D.

[0024] Figures 10A and 10B show an example of a controller suitable for use as all or part of the controller disclosed in the context of Figures 1A-4. Figure 10A shows an interface between optical components and a light sensor that can be located on a LIDAR chip.

[0025] FIG. 10B is a schematic diagram of the relationship between the electronics and light sensors that may be included on the LIDAR chip.

[0026] FIG. 10C is a graph showing the amplitude of the in-phase and quadrature components of the signal on the same time axis as the frequency of the system output signal.

[0027] FIG. 10D shows an example of a process variable identifier applied to the electronics of a LIDAR system.

[0028] FIG. 10E illustrates another example of a process variable identifier applied to the electronics of a LIDAR system.

[0029] FIG. 11 is a top view of a portion of a waveguide including a spiral waveguide.

[0030] Figure 12A is a cross-sectional view of a portion of a LIDAR chip containing a waveguide on a silicon-on-insulator platform.

[0031] Figures 12B-12D show an example of a feedback device built on a silicon-on-insulator platform and suitable for use on a LIDAR chip constructed according to Figures 2 and 4. Figure 12B is a top view of a portion of a LIDAR chip equipped with the feedback device.

[0032] FIG. 12C is a cross-sectional view of the feedback device taken along the line labeled C in FIG. 12B.

[0033] FIG. 12D is a cross-sectional view of the feedback device taken along the line labeled C in FIG. 12B.

[0034] FIG. 13A is a top view of a portion of a LIDAR chip including an echelle grating.

[0035] Figure 13B is a cross-sectional view of the echelle grating through a signal redirection portion included on the LIDAR chip of Figure 13A, taken along the line labeled E in Figure 13A.

[0036] FIG. 13C is a cross-sectional view of another embodiment of an echelle grating.

[0037] FIG. 13D is an enlarged top view of a portion of the return surface.

[0038] FIG. 14 is a top view of an example of an optical switch.

[0039] FIG. 15A shows a modification of the control assembly of FIG. 4 so that the control unit receives a series of different channels simultaneously.

[0040] FIG. 15B shows a modification of the control assembly of FIG. 15A so that the branch signal is tapped from the reference waveguide rather than the source waveguide.

[0041] FIG. 16 is a top view of the LIDAR system excluding the LIDAR adapter.

[0042] A solid-state scanner for use in a LIDAR system includes a signal redirector, such as a lens. The signal redirector receives a plurality of channel output signals from a portion of the channel output waveguides included in a switch system. The switch system is operable to change a selection of the channel output waveguides through which the redirector receives the channel output signals. The signal redirector is configured to redirect the channel output signals such that the direction in which each channel output signal travels away from the signal redirector changes in response to the change in the selection of the channel output waveguides through which the redirector receives the system output signals.

[0043] It is often desirable to increase the number of channel output signals to increase the number of sample areas that can be scanned per unit. In many LIDAR systems, a desired sample area scanning rate is achieved by using 16 or more output signals. The angular resolution of a LIDAR system can also be improved by decreasing the distance between the channel output waveguides. However, decreasing this distance reduces the size of the field of view that can be scanned. An optical grating receives the channel output signals from the signal redirector and outputs at least a portion of each channel output signal. The optical grating can provide additional dispersion of the channel output signals beyond that provided by the signal redirector. The dispersion level is selected to expand the field of view to a desired size. Thus, a LIDAR system can have a large number of output channels that provide a desired sample area scanning rate and improved angular resolution while also providing a field of view with a desired size.

[0044] FIG. 1A is a top view of a LIDAR chip configured to generate composite signals, each pulsating at a pulsating frequency that can be used by electronics to generate LIDAR data. The LIDAR chip includes a photonic integrated circuit. The photonic integrated circuit can include a light source 10 that outputs an outgoing LIDAR signal. The outgoing LIDAR signal includes one or more different channels, each at a different wavelength. The wavelengths of the channels can be periodically spaced such that the wavelength increase from one channel to the next (channel spacing) is constant or substantially constant. In some cases, the channel spacing is constant and is greater than 0.5 nm, 1 nm, 3 nm, or 5 nm, and / or less than 10 nm, 15 nm, or 20 nm. In some cases, the number of channels N is greater than 2, 4, or 8, and / or less than 16, 32, or 64. Light sources 10 for generating multiple channels with periodically spaced wavelengths include, but are not limited to, comb lasers, and one or more single wavelength lasers and / or multi-wavelength lasers with one or more outputs multiplexed into the outgoing LIDAR signal.

[0045] The LIDAR chip also includes a utility waveguide 12 that receives the outgoing LIDAR signal from the light source 10. The utility waveguide 12 terminates at a facet 14 and transmits the outgoing LIDAR signal to the facet 14. The facet 14 can be positioned such that the outgoing LIDAR signal traveling through the facet 14 exits the chip and serves as the LIDAR output signal. For example, the facet 14 can be positioned at the end of the chip, such that the outgoing LIDAR signal traveling through the facet 14 exits the chip and serves as the LIDAR output signal.

[0046] The LIDAR output signal travels away from the chip and may be reflected by an object in the path of the LIDAR output signal. The reflected signal travels away from the object. When the LIDAR output signal is reflected, at least a portion of the light from the reflected signal returns to an input waveguide 16 on the LIDAR chip as a LIDAR input signal. The input waveguide 16 includes a facet 18 through which the LIDAR input signal can enter the input waveguide 16. The portion of the LIDAR input signal that is incident on the input waveguide 16 can be considered the incident LIDAR signal. The input waveguide 16 transmits the incident LIDAR signal to a comparison demultiplexer 30. If the incident LIDAR signal contains multiple channels, the comparison demultiplexer 30 splits the incident LIDAR signal into different comparison signals, each carrying a different channel. The comparison demultiplexer 30 outputs the comparison signals on different comparison waveguides 32. Each comparison waveguide 32 transmits one of the comparison signals to a different processing unit 34.

[0047] The LIDAR chip includes a splitter 36 that transfers a portion of the outgoing LIDAR signal from the utility waveguide 12 to a reference waveguide 37 as a reference signal. Suitable splitters 36 include, but are not limited to, optical couplers, Y-junctions, and MMIs.

[0048] The reference waveguide 37 transmits the reference optical signal to a reference demultiplexer 38. If the reference optical signal includes multiple channels, the reference demultiplexer 38 splits the reference optical signal into different reference signals, each having a different wavelength. The reference demultiplexer 38 outputs the reference signals onto different reference waveguides 40. Each of the reference waveguides 40 transmits one of the reference signals to a different one of the processing units 34.

[0049] The comparison waveguide 32 and the reference waveguide 40 are configured so that a comparison signal and a corresponding reference signal are received by the same processing unit 34. For example, the comparison waveguide 32 and the reference waveguide 40 are configured so that a comparison signal and a reference signal transmitting the same wavelength and / or the same channel are received by the same processing unit 34.

[0050] As described in more detail below, each processing unit 34 combines the comparison signal with a corresponding reference signal to form a composite signal conveying LIDAR data for a sample area on the field of view, which can then be processed to extract LIDAR data for the sample area (such as line-of-sight velocity and / or distance between the LIDAR system and objects external to the LIDAR system).

[0051] The LIDAR chip can include a control assembly for controlling the operation of the light source 10 and / or one or more characteristics of the system output signal. The control assembly includes a splitter 50 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 to a control waveguide 52. The combined portion of the outgoing LIDAR signal functions as a branch signal. The splitter 50 can be a wavelength-independent splitter, such as a directional coupler, an optical coupler, a Y-junction, a tapered coupler, and a multi-mode interference (MMI) device.

[0052] The control waveguide 52 transmits the drop signal to a differential delay mechanism 54, which may be the primary source of delay between the delay path signal and the priority path signal. The delay mechanism 54 includes a splitter 60 that receives the drop signal and splits it into a delay signal and a priority signal. The splitter 60 may be a wavelength-independent splitter. For example, the splitter 60 may be configured so that the delay signal and the priority signal carry the same or substantially the same wavelength selection. Thus, the delay signal and the priority signal may each carry multiple channels. In some cases, the delay signal and the priority signal each carry a respective channel. Suitable splitters 60 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and multi-mode interference (MMI) devices.

[0053] The delay waveguide 62 transmits the delayed signal to a first divider 64. The priority waveguide 66 transmits the priority signal to a second divider 67. The delay waveguide 62 may include a delay section 70 that can be used to increase the length of the delay waveguide beyond the length of the priority waveguide 66. For example, the delay section 70 shown in FIG. 1A may represent a spiral arrangement of the delay waveguide 62. The longer the length of the delay waveguide 62, the more delay there is between the delayed signal and the priority signal.

[0054] The first divider 64 divides the delayed signal into delayed channel signals, each transmitted through a different delay channel waveguide 72. The first divider 64 may be a wavelength-dependent divider. For example, the first divider 64 may be configured so that each delayed channel signal transmits a different wavelength selection. As an example, the first divider 64 may be configured so that each delayed channel signal transmits a different channel. Each delay channel waveguide 72 transmits one of the delayed channel signals to a different control unit 74. As a result, each control unit 74 receives a delayed channel signal transmitting a different channel. Thus, each control unit 74 may be associated with a different channel. Suitable first dividers 64 include, but are not limited to, demultiplexers such as arrayed waveguide gratings, echelle gratings, and ring resonator-based devices.

[0055] The second splitter 67 splits the priority signal into priority sub-signals, each of which is transmitted through a different priority sub-waveguide 76. The second splitter 67 may be a wavelength-dependent splitter. For example, the second splitter 67 may be configured so that each priority sub-signal transmits the same or substantially the same wavelength selection. Thus, each priority sub-signal may transmit multiple channels. In some cases, each priority sub-signal transmits each channel. Each priority sub-waveguide 76 transmits one of the priority sub-signals to a different one of the control units 74. As a result, each control unit 74 may receive a priority sub-signal that transmits the channel associated with that control unit 74 and also transmits one or more other channels. Thus, each control unit 74 may receive a priority sub-signal and a delayed channel signal that transmit the same channel. Suitable second splitters 67 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and multi-mode interference (MMI) devices.

[0056] In some cases, the second divider 67 is a wavelength-dependent divider. The wavelength-dependent divider functioning as the second divider 67 can be configured so that each priority sub-signal carries a different channel. Additionally, the priority sub-waveguide 76 can be configured so that the priority sub-signal received by each control unit 74 carries the channel associated with that control unit 74. As a result, each control unit 74 can receive a priority sub-signal carrying the same channel as the delayed channel signal received by that control unit 74.

[0057] As is clear from the above description, light from the branch signal travels from the splitter 60 to the combiner in one of the control units 74 on one of a plurality of different delay paths. Each delay path is primarily defined by the delay waveguide 62, the first splitter 64, and one of the delay channel waveguides 72. A delay path signal that combines the delay signal and one of the delay channel signals travels in each delay path. Light from the branch signal travels from the splitter 60 to the control unit 74 on one of a plurality of different priority paths. Each priority path is primarily defined by the priority sub-waveguide 76, the second splitter 67, and one of the priority sub-waveguides 76. A priority path signal that combines the priority signal and one of the priority sub-signals travels in each priority path.

[0058] Each delay path has a common portion and an isolated portion. The common portion of each delay path is shared among multiple delay paths. Meanwhile, the isolated portions of a delay path are not shared with other delay paths. An optical signal passing through the common portion can carry multiple different channels. An optical signal passing through the isolated portions can carry different channels. For example, delay waveguide 62 is common to each delay path and functions as a common portion. Meanwhile, each delay channel waveguide 72 is isolated from the other delay channel waveguides 72 and functions as an isolated portion.

[0059] Each priority path has a common portion and a separate portion. The common portion of each priority path is shared among multiple priority paths. Meanwhile, the separate portions of a priority path are not shared with other priority paths. Optical signals passing through the common portion can carry multiple different channels. Optical signals passing through the separate portions can each carry a different channel. For example, the priority waveguide 66 is common to each delay path and functions as the common portion. Meanwhile, each priority sub-waveguide 76 is separate from the other priority sub-waveguides 76 and can function as a separate portion.

[0060] The priority path and delay path are configured so that each control unit 74 receives a delay path signal and a priority path signal that carry the same channel (common channel). The priority path and delay path can be configured so that different control units 74 each receive a delay path signal and a priority path signal that carry a different common channel. The delay path and priority path can also be configured so that the delay path signal and / or priority path signal received at each control unit 74 carries only one of the channels or substantially only one of the channels.

[0061] The components defining the delay path and the priority path are configured so that, of the priority path signal and the delay path signal arriving at the same control unit 74, the delay path signal arrives at the control unit 74 later than the priority path signal.

[0062] Because the delay path signal and the priority path signal comprise different portions of the branch signal, each control unit 74 receives both the delayed portion of the branch signal and the priority portion of the branch signal. The delayed portion is delayed relative to the branch portion. The components defining the delay path and the priority path can be configured to impart a delay between the branch portion and the priority portion reaching the control unit 74. For example, the waveguides defining the delay path and the waveguides defining the priority path can be configured so that the delay path is longer than the priority path by an amount that imparts the desired delay at each control unit 84. The length of the delay unit 70 can be a major source of length differences between the delay path and the priority path leading to the same control unit 74. As can be seen from FIG. 1A, delayed signals carrying different channels pass through the same delay unit 70. As a result, the same delay unit 70 is common to each delay path and each channel.

[0063] Additional details regarding the construction and operation of the control assembly are described in U.S. Patent Application No. 17 / 244,869, entitled "Signal Reduction for LIDAR System Control Assembly," filed April 29, 2021, which is incorporated herein in its entirety.

[0064] Although the light source 10 is shown as being located on the LIDAR chip, all or part of the light source 10 may be located off-chip. FIG. 1B shows an example of a light source 10 including multiple laser light sources 68. The light sources in FIG. 1B may be located off-chip, on-chip, or integrated on-chip. In some cases, each laser light source 68 outputs a channel signal on a light source waveguide 69. Each channel signal can carry one or more channels. For example, FIG. 1B shows one possible arrangement, where the light source waveguide 69 guiding the channel signal carrying channel i is designated λ. i where i represents the wavelength channel index, and the wavelength channels are associated with wavelength channel indexes i=1 to i=N, respectively.

[0065] Each optical source waveguide 69 transmits a channel signal to a laser multiplexer 71. The laser multiplexer 71 combines the channel signals to form an optical signal that is received at the channel waveguide or utility waveguide 12. Suitable laser multiplexers 72 include, but are not limited to, arrayed waveguide grating (AWG) multiplexers, echelle grating multiplexers, and star couplers. The electronics can operate the laser sources 68 so that they output each channel simultaneously. The electronics can operate the laser sources 68 so that they output each channel simultaneously.

[0066] In some cases, each laser source 68 outputs one of the channels onto a source waveguide 69. The total number of laser sources 68 included in light source 10 may be equal to or greater than the number of LIDAR output signals simultaneously directed to the sample region. In some cases, the total number of laser sources 68 included in light source 10 is equal to the number of LIDAR output signals simultaneously directed to the sample region. As a result, each laser source 68 can be the source of a different one of the LIDAR output signals simultaneously directed to the sample region.

[0067] The electronics 62 can independently operate the multiple laser sources 68. For example, the electronics can operate the laser sources 68 to provide a particular LIDAR output signal with a particular frequency versus time waveform. Because the electronics can independently operate the multiple laser sources 68, and each laser source 68 can be the source of a different LIDAR output signal, the electronics can operate the laser sources 68 so that the different LIDAR output signals have different frequency versus time waveforms.

[0068] 2 shows the LIDAR chip of FIGS. 1A and 1B modified to reduce the length of the delay section 70. A splitter 78 receives the branch signal from the control waveguide 52 and splits the branch signal into a priority signal and a first delayed signal. The priority signal is received on the priority waveguide 66 as described in FIG. 1. Suitable splitters 78 include, but are not limited to, a multimode interference coupler (MMI) and a directional coupler.

[0069] The first delay waveguide 80 receives the first delayed signal from the splitter 78. The first delay waveguide 80 transmits the first delayed signal to a feedback device 82. The feedback device 82 is configured to feed the first delayed signal back to the first delay waveguide 80, such that the first delayed signal is fed back from the feedback device 82 to the splitter 78 via the first delay waveguide 80. As a result, the first delayed signal passes through the first delay waveguide 80 twice. For example, the first delayed signal may pass through the first delay waveguide 80 once in each direction, as shown by arrow A in FIG. 2 . Suitable feedback devices 82 include, but are not limited to, mirrors and reflective surfaces.

[0070] Splitter 78 receives the first delayed signal from first delay waveguide 80 and outputs the first delayed signal to delay waveguide 62. The portion of the first delayed signal received on delay waveguide 62 functions as the second delayed signal transmitted on delay waveguide 62. Delay waveguide 62 transmits the second delayed signal to first splitter 64. Thus, light from the branch signal passes from splitter 78 through first delay waveguide 80 twice and through delay waveguide 62 once before being received by first splitter 64. As a result, both the first delayed signal and the second delayed signal effectively function as the delayed signals disclosed in connection with FIG. 1A .

[0071] First delay waveguide 80 includes delay section 70. The second pass of light through first delay waveguide 80 increases the effective path length that the delayed signal travels between splitter 78 and first splitter 64. This increase in effective path length allows the length of delay section 70 to be reduced to provide the desired delay between the delayed signal and the priority signal.

[0072] As is apparent from the above description of FIG. 2, light from the branch signals travels on one of several different delay paths from splitter 78 to one of control sections 74. Each delay path is primarily defined by first delay waveguide 80, splitter 60, delay waveguide 62, first splitter 64, and one of delay channel waveguides 72. Each delay path carries a delay path signal that combines one of the first delay signal, second delay signal, and delay channel signal. Light from the branch signals also travels on one of several different priority paths from splitter 78 to one of control sections 74. Each priority path is primarily defined by priority waveguide 66, second splitter 67, and one of priority sub-waveguides 76.

[0073] Each delay path has a common portion and an isolated portion. The common portion of each delay path is shared among multiple delay paths. Meanwhile, the isolated portions of a delay path are not shared with other delay paths. An optical signal passing through the common portion can carry multiple different channels. An optical signal passing through the isolated portions can each carry a different channel. For example, the first delay waveguide 80 and the delay waveguide 62 are common to each delay path and function as a common portion. Meanwhile, each delay channel waveguide 72 is isolated from the other delay channel waveguides 72 and function as an isolated portion.

[0074] Each priority path has a common portion and a separation portion. The common portion of each priority path is shared among multiple priority paths. Meanwhile, the separation portion of a priority path is not shared with other priority paths. Optical signals passing through the common portion can carry multiple different channels. Optical signals passing through the separation portions can each carry a different channel. For example, the priority waveguide 66 is common to each delay path and functions as the common portion. Meanwhile, each priority sub-waveguide 76 is separated from the other priority sub-waveguides 76 and functions as a separation portion.

[0075] Each priority path carries a priority path signal that combines a priority signal and one of the priority sub-signals. The priority path and delay path are configured so that each control unit 74 receives a delay path signal and a priority path signal that transmit the same channel (common channel). The priority path and delay path can be configured so that different control units 74 each receive a delay path signal and a priority path signal that transmit a different common channel. The delay path and priority path can also be configured so that the delay path signal and / or the priority path signal received by each control unit 74 transmits only one of the channels, or essentially transmits only one of the channels.

[0076] The components defining the delay path and the priority path are configured so that, of the priority path signal and the delay path signal arriving at the same control unit 74, the delay path signal arrives at the control unit 74 later than the priority path signal.

[0077] Because the delay path signal and the priority path signal represent different portions of the branch signal, each control unit 74 receives both a delayed portion of the branch signal and a priority portion of the branch signal. The delayed portion is delayed relative to the branch portion. The components defining the delay path and the priority path can be configured to impart a delay between the branch portion and the priority portion reaching the control unit 74. For example, the waveguides defining the delay path and the waveguides defining the priority path can be configured so that the delay path is longer than the priority path by a length that imparts the desired delay at each control unit 84. The length of the delay unit 70 can be a major source of difference in length between the delay path and the priority path leading to the same control unit 74. As can be seen from FIG. 2, first delayed signals carrying different channels pass through the same delay unit 70. As a result, the same delay unit 70 is common to each delay path.

[0078] As mentioned above, in some cases, the second splitter 67 can be a wavelength-dependent splitter configured so that each of the priority sub-signals carries a different channel. While FIGS. 1A and 2 show these priority sub-signals separated from the common signal (priority signal), the priority sub-signals, each carrying a different channel, can be branched off from the light source waveguides 69. For example, FIG. 3 shows the LIDAR system of FIG. 1A modified to include a light source 10 constructed according to FIG. 1B. Each light source waveguide 69 includes a splitter 60 configured to transfer a portion of the channel signal from the light source waveguide 69 to one of the priority sub-waveguides 76. The portion of the channel signal received by the priority sub-waveguide 76 serves as one of the priority sub-signals. Each of the priority sub-signals carries a different channel. Each of the priority sub-waveguides 76 transmits one of the priority sub-signals to one of the controllers 74, as described above. Because the priority sub-signal is not separated from the branch signal, the delay waveguide 62 can receive a delayed signal from the splitter 50 as shown in FIG. 3. For example, the delay waveguide 62 can receive a portion of the outgoing LIDAR signal from the splitter 50. The portion of the outgoing LIDAR signal received by the delay waveguide 62 can function as the delayed signal. Suitable splitters 60 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and wavelength-independent splitters such as multi-mode interference (MMI) devices.

[0079] The priority sub-signals and delayed channel signals received by the same control unit 74 each contain light from the same optical source waveguide 69, and therefore from the same channel signal. Light from each channel signal travels one of several different delay paths from splitter 60 on optical source waveguide 69 to one of the control units 74. Each delay path is primarily defined by the portion of optical source waveguide 69 after splitter 60, laser multiplexer 71, the portion of utility waveguide 12 between laser multiplexer 71 and splitter 50, splitter 50, delay waveguide 62, first splitter 64, and one of the delay channel waveguides 72.

[0080] Each delay path has a common portion and multiple separate portions. The common portion of each delay path is shared by multiple delay paths. Meanwhile, the separate portions of a delay path are not shared with other delay paths. An optical signal passing through the common portion can carry multiple different channels. An optical signal passing through the separate portions can each carry a different channel. For example, the portion of utility waveguide 12 and delay waveguide 62 between laser multiplexer 71 and splitter 50 are common to each delay path and function as the common portion. Meanwhile, the portion of optical source waveguide 69 and delay channel waveguide 72 after splitter 60 are each separated from the other delay channel waveguides 72 and function as separate portions.

[0081] In the LIDAR system of Figure 3, each delay path carries a delay path signal that combines one of the channel signals, the outgoing LIDAR signal, the delay signal, and the delayed channel signal. Light from each channel signal travels on a different priority path from the splitter 60 on the light source waveguide 69 to one of the controllers 74. These priority paths do not share a common portion. Each priority path is primarily defined by a priority sub-waveguide 76. Each priority sub-signal functions as a priority path signal traveling on one priority path.

[0082] The priority path and delay path are configured so that each control unit 74 receives a delay path signal and a priority path signal that carry the same channel (common channel). The priority path and delay path can be configured so that different control units 74 each receive a delay path signal and a priority path signal that carry a different common channel. Also, the delay path and priority path can be configured so that the delay path signal and / or priority path signal received at each control unit 74 carries only one of the channels or essentially only one of the channels.

[0083] The components defining the delay path and the priority path are configured so that, of the priority path signal and the delay path signal arriving at the same control unit 74, the delay path signal arrives at the control unit 74 later than the priority path signal.

[0084] Because the delay path signal and the priority path signal contain different portions of the common signal (channel signal), each control unit 74 receives both a delayed portion of the common signal and a priority portion of the common signal. The delayed portion is delayed relative to the branch portion. The components defining the delay path and the priority path can be configured to impart a delay between the branch portion and the priority portion arriving at the control unit 74. For example, the waveguides defining the delay path and the waveguides defining the priority path can be configured so that the delay path is longer than the priority path by a length that imparts the desired delay at each control unit 84. The length of the delay unit 70 can be a major source of length differences between the delay path and the priority path leading to the same control unit 74. As can be seen from FIG. 3, delayed signals carrying different channels pass through the same delay unit 70. As a result, the same delay unit 70 is common to each delay path and each channel.

[0085] FIG. 3 illustrates a LIDAR system in which the light in the priority signal is not separated from a common signal carrying multiple channels, but the light in the delayed signal is separated from the common signal. However, this LIDAR system can also be configured so that the light in the priority signal is not separated from the common signal, and the light in the delayed signal is not separated from the common signal. For example, FIG. 4 illustrates the LIDAR system of FIG. 3 modified so that the light in the priority signal and the delayed signal is not separated from the common signal. Each light source waveguide 69 includes a splitter 50 and a differential delay mechanism 54, as disclosed in connection with FIG. 2. As a result, each splitter 50 is configured to transfer a portion of the channel signal from the light source waveguide 69 onto the control waveguide 52. The portion of the channel signal received by the control waveguide 52 can function as a drop signal. Each channel signal carries a different channel, and therefore the light in each drop signal carries a different channel.

[0086] Each branch signal is received at a different splitter 78. Each splitter 78 splits the branch signal into a priority signal and a first delayed signal. The priority signals are each received on a priority waveguide 66. Suitable splitters 78 include, but are not limited to, multi-mode interference couplers (MMIs) and directional couplers.

[0087] Each of the first delay waveguides 80 receives a first delayed signal from a divider 78. The first delay waveguides 80 transmit the first delayed signal to a feedback device 82. The feedback device 82 is configured to feed the first delayed signal back to the first delay waveguide 80, such that the first delayed signal is fed back from the feedback device 82 to the divider 78 via the first delay waveguide 80. As a result, the first delayed signal passes through the first delay waveguide 80 twice. Each divider 78 receives a first delayed signal from the first delay waveguide 80 and outputs the first delayed signal onto a delay waveguide 62. The portion of the first delayed signal received at the delay waveguide 62 functions as a second delayed signal transmitted by the delay waveguide 62. A first delayed signal and its associated second delayed signal can together effectively function as a delay signal.

[0088] When the channel signals each carry a single channel, the resulting first and second delay signals also carry a single channel. As a result, the second delay signal is not a common signal, and the first divider 64 disclosed in connection with FIGS. 1A-3 is not required. Furthermore, because the second delay signals carry a single channel, each of them can effectively function as one of the delayed channel signals disclosed in connection with FIGS. 1A-3. As a result, each delay waveguide 62 can function as the delay channel waveguide 72 of FIGS. 1A-3 by transmitting the second delay signal, which functions as a delayed channel signal, to one of the controllers 74.

[0089] If each channel signal carries a single channel, the resulting priority signal also carries a single channel. As a result, each of the resulting priority signals is not a common signal, and the second divider 67 disclosed in connection with FIGS. 1A-3 is not required. Furthermore, because each priority signal carries a single channel, each can effectively function as one of the priority sub-signals disclosed in connection with FIGS. 1A-3. As a result, each priority waveguide 66 can function as a priority sub-waveguide 76 by transmitting a priority signal that functions as a priority sub-signal to one of the controllers 74.

[0090] The priority sub-signals and delayed channel signals received by the same control section 74 each contain light from the same optical source waveguide 69, and therefore from the same channel signal. Light from each channel signal travels on one of a number of different delay paths from the splitter 50 on the optical source waveguide 69 to one of the control sections 74. Each delay path is primarily defined by the control waveguide 52, the splitter 78, the first delay waveguide 80, and the delay waveguide 62. Each priority path and each delay path is disjoint.

[0091] In the LIDAR system of FIG. 4 , each delay path carries a delay path signal that combines a control signal, a first delay signal, and a second delay signal. Light from each channel signal travels along a different priority path from the splitter 50 on the light source waveguide 69 to one of the control units 74. Each priority path is primarily defined by the control waveguide 52, the splitter 78, and the priority waveguide 66. Each priority path carries a priority path signal that combines the control signal, the splitter 78, and a priority sub-signal. The priority path and delay path are configured so that each control unit 74 receives a delay path signal and a priority path signal that transmit the same channel. The components defining the delay path and priority path are configured so that, of the priority path signal and delay path signal that arrive at the same control unit 74, the delay path signal arrives at the control unit 74 later than the priority path signal.

[0092] Because the delay path signal and the priority path signal comprise different portions of the common signal (one of the channel signals), each control unit 74 receives both a delayed portion of the common signal and a priority portion of the common signal. The delayed portion is delayed relative to the branch portion. The components defining the delay path and the priority path can be configured to impart a delay between the branch portion and the priority portion arriving at the control unit 74. For example, the waveguides defining the delay path and the waveguides defining the priority path can be configured so that the delay path is longer than the priority path by a length that imparts the desired delay at each control unit 84. The length of the delay unit 70 can be a major source of length differences between the delay path and the priority path leading to the same control unit 74. As can be seen from FIG. 4, first delayed signals carrying different channels pass through different delay units 70.

[0093] In some cases, the LIDAR assembly includes or consists of a LIDAR chip and a LIDAR adapter configured to separate an output signal carrying light exiting the LIDAR system from a return signal containing light that has already exited the LIDAR system and returned to the LIDAR system. In some cases, the LIDAR adapter can be physically optically positioned between the LIDAR chip and one or more reflective objects and / or the field of view, where the optical path along which the first LIDAR input signal and / or LIDAR output signal travel from the LIDAR chip to the field of view passes through the LIDAR adapter. The LIDAR adapter can also be configured to operate on the LIDAR input signal and the LIDAR output signal, whereby the LIDAR input signal and the LIDAR output signal travel on different optical paths between the LIDAR adapter and the LIDAR chip but on the same optical path between the LIDAR adapter and reflective objects in the field of view.

[0094] FIG. 5 shows an example of a LIDAR adapter applied to the LIDAR chip of FIGS. 1A to 4. The LIDAR adapter includes multiple components arranged on a base. For example, the LIDAR adapter includes a circulator 100 arranged on a base 102. The illustrated optical circulator 100 has three ports, configured so that light entering one port exits the next port. For example, the illustrated optical circulator includes a first port 104, a second port 106, and a third port 108. A LIDAR output signal enters the first port 104 from the utility waveguide 12 of the LIDAR chip and exits from the second port 106.

[0095] The LIDAR adapter can be configured such that the output of the LIDAR output signal from the second port 106 also serves as the output of the LIDAR output signal from the LIDAR adapter, and thus from the LIDAR assembly, such that the LIDAR output signal output from the LIDAR adapter and / or the LIDAR chip can serve as the assembly output signal.

[0096] The assembly output signal includes, consists of, or consists essentially of light from the LIDAR output signal received from the LIDAR chip. Thus, the assembly output signal may be the same as or substantially the same as the LIDAR output signal received from the LIDAR chip. However, there may be differences between the assembly output signal and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal may experience optical loss as it passes through the LIDAR adapter. And / or the LIDAR adapter may optionally include an amplifier configured to amplify the LIDAR output signal as it passes through the LIDAR adapter.

[0097] When one or more objects within the sample volume reflect the assembly output signal, at least a portion of the reflected light returns to the circulator 100 as an assembly return signal. The assembly return signal enters the circulator 100 through the second port 106. Figure 5 shows the assembly output signal traveling away from the LIDAR assembly along the same path that the assembly return signal takes back to the LIDAR assembly.

[0098] The assembly return signal exits the circulator 100 through a third port 108 and is directed to a comparison waveguide 18 on the LIDAR chip. Thus, all or a portion of the assembly return signal can serve as a first LIDAR input signal, which can include or consist of light from the assembly return signal. Thus, the LIDAR output signal and the first LIDAR input signal travel on different optical paths between the LIDAR adapter and the LIDAR chip.

[0099] As is evident from FIG. 5 , the LIDAR adapter can include optical components in addition to the circulator 100. For example, the LIDAR adapter can include components for directing and controlling the optical paths of the LIDAR output signal and the assembly return signal. As an example, the adapter of FIG. 5 includes an optional amplifier 110 positioned to receive and amplify the LIDAR output signal before it enters the circulator 100. The amplifier 110 can be operated by the electronics 62, allowing the electronics 62 to control the power of the LIDAR output signal. Suitable amplifiers 110 include, but are not limited to, optical fiber amplifiers configured to operate at wavelengths other than 1550 nm, such as erbium-doped optical fiber amplifiers (EDFAs), semiconductor optical amplifiers (SOAs), and praseodymium optical amplifiers (PDFAs).

[0100] FIG. 5 also illustrates a LIDAR adapter including an optional first lens 112 and an optional second lens 114. The first lens 112 can be configured to couple the LIDAR output signal to a desired location. In some cases, the first lens 112 is configured to focus or collimate the LIDAR output signal to a desired location. In one example, if the LIDAR adapter does not include an amplifier 110, the first lens 112 is configured to couple the LIDAR output signal to the first port 104. As another example, if the LIDAR adapter includes an amplifier 110, the first lens 112 can be configured to couple the LIDAR output signal on the input port to the amplifier 110. The second lens 114 can be configured to couple the LIDAR output signal to a desired location. In some cases, the second lens 114 is configured to focus or collimate the LIDAR output signal to a desired location. For example, the second lens 114 can be configured to couple the LIDAR output signal to facet 35 of the comparison waveguide 18.

[0101] The LIDAR adapter may also include one or more redirecting components, such as a mirror. Figure 5 shows a LIDAR adapter including a mirror as a redirecting component 116 that redirects the assembly return signal from the circulator 100 to the facet 20 of the comparison waveguide 18.

[0102] The LIDAR chip includes one or more waveguides that restrict the optical path of one or more optical signals. While the LIDAR adapter can include waveguides, the optical paths along which the assembly return signals and LIDAR output signals travel between components on the LIDAR adapter and / or between the LIDAR chip and components on the LIDAR adapter can be free space. For example, the assembly return signals and / or LIDAR output signals can travel through the air in which the LIDAR chip, LIDAR adapter, and / or base 102 are located as they travel between different components on the LIDAR adapter and / or between components on the LIDAR adapter and the LIDAR chip. As a result, optical components such as lenses and redirecting components can be used to control the characteristics of the optical paths along which the assembly return signals and LIDAR output signals travel on, to, and from the LIDAR adapter.

[0103] Suitable bases 102 for LIDAR adapters include, but are not limited to, substrates, platforms, and plates. Suitable substrates include, but are not limited to, glass, silicon, and ceramic. These components may be discrete components attached to a substrate. Suitable techniques for attaching discrete components to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamps. In one example, one or more of the components are integrated components and the remaining components are discrete components. In another example, the LIDAR adapter includes one or more integrated amplifiers and the remaining components are discrete components.

[0104] Suitable circulators 100 for use with the adapter include, but are not limited to, the circulators disclosed in U.S. patent application Ser. No. 16 / 726,235, filed Dec. 23, 2019 ("LIDAR System with Signal Separation by Polarization Angle"), and U.S. patent application Ser. No. 17 / 221,770, filed Apr. 2, 2021 ("Use of a Circulator in a LIDAR System"), both of which are incorporated herein in their entireties.

[0105] The LIDAR assembly can be used in combination with a scanning chip. Electronics can operate the scanning chip to steer the direction in which the system output signals travel away from the LIDAR system. The electronics can steer each system output signal to multiple different sample areas within the field of view. FIG. 6A is a top view of an example scanning chip used with an adapter constructed according to FIG. 5. The scanning chip includes an optical integrated circuit. The optical integrated circuit includes a common waveguide 117 that receives the assembly output signals from the adapter. The common waveguide 117 transmits the assembly output signals to an optical switch 118. Although not shown in FIG. 6A, other optical components, such as amplifiers, lenses, or optical fibers, can be disposed on the optical path between the circulator 106 and the optical switch 118. As a result, other optical components can operate on the assembly output signals before they are received by the optical switch 118. The portion of the assembly output signal received by the optical switch 118 can function as a switch signal. The optical switch 118 directs the switch signal to one of multiple alternative waveguides 119. The optical switch 118 can be operated by electronics 62. For example, the electronics can operate the optical switch 118 to control which alternative waveguide 119 receives the switch signal. In some cases, the optical switch 118 directs the switch signal to one of multiple alternative waveguides 119. Each alternative waveguide 119 is associated with an alternative waveguide index m = 1 to M.

[0106] The scanning chip includes a splitter 120 in optical communication with an alternate waveguide 119 and a plurality of channel output waveguides 121. The alternate waveguide 119 functions as a first splitter waveguide, and the channel output waveguides 121 function as second splitter waveguides. The alternate waveguide 119, which receives the switch signal, directs light from the switch signal to the splitter 120. Thus, the splitter 120 receives the switch signal from the alternate waveguide 119, which received the switch signal from the optical switch 118. The splitter 120 is configured to split the switch signal into a plurality of different channel output signals, each received at the channel output waveguides 121. Because the switch signal includes or is composed of light from the outgoing LIDAR signal, the switch signal can be a common channel carrying multiple channels carried by the outgoing LIDAR signal. The splitter 120 can be a wavelength-dependent splitter. As a result, each channel output signal can carry one of the different channels. Suitable splitters 120 include, but are not limited to, demultiplexers such as arrayed waveguide gratings, echelle gratings, and ring resonator-based devices.

[0107] The splitter 120 is configured so that some of the channel output waveguides 121 each receive one of the channel output signals. The selection of which output waveguide 121 receives one of the channel output signals can change in response to changes in which of the alternative waveguides 119 receives the switch signal. For example, the channel output waveguides 121 in FIG. 6A are C i,m where i represents the channel index and m represents the alternate waveguide index. When the alternate waveguide 119 with alternate waveguide index m receives the switch signal, C i,m Each channel output waveguide 121 in a selection of channel output waveguides 121, labeled C, receives one of the channel output signals. As an example, when the alternate waveguide 119 with alternate waveguide index 2 receives the switch signal, C i,2 Each channel output waveguide in a selection of channel output waveguides 121, labeled C, receives one of the channel output signals. 1,2 , C 2,2 , and C N,2Each of the channel output waveguides 121, labeled C, receives one of the channel output signals. 1,1 , C 2,1 , C N,1 , C 1,2 , C 1,M , C 2,M , and C N,M The channel output waveguide 121 labeled C does not receive one of the channel output signals. In contrast, when the alternate waveguide 119 with alternate waveguide index M receives a switch signal, C i,M Each of the channel output waveguides 121, labeled , receives one of the channel output signals.

[0108] The electronics can operate the optical switch 118 to control which of the alternative waveguides 119 receive the switch signal, and the portion of the channel output waveguides 121 that receive one of the channel output signals changes depending on which of the alternative waveguides 119 receive the switch signal, so the electronics can operate the optical switch 118 to control which of the channel output waveguides 121 receive one of the channel output signals.

[0109] The LIDAR system also includes a signal redirector configured to receive the channel output signals from any one of the channel output waveguides 121 and direct the received channel output signals such that different channel output signals travel in different directions away from the signal redirector. The signal redirector also directs the received channel output signals such that the direction in which each outgoing LIDAR signal travels away from the signal redirector is a function of the selection of the channel output waveguide 121 from which the signal redirector receives the outgoing LIDAR signal.

[0110] As a result of the channel output signals traveling in different directions away from the signal redirector, they travel in different directions away from the LIDAR system.

[0111] The different directions of the channel output signals can be a function of the channel output waveguides 121. The direction in which each channel output signal leaves the signal redirection section changes with changes in the selection of the channel output waveguides 121 from which the signal redirection section receives the channel output signals. In some cases, the signal redirection section is configured so that none of the different directions are parallel to one another. For example, the signal redirection section can be configured so that different channel output signals travel away from the signal redirection section at different transmission angles, and the transmission angles change as the signal redirection section receives the channel output signals from different channel output waveguides 121. The transmission angles are measured relative to the signal redirection section.

[0112] In Figure 6A, a lens functions as a signal redirector 122. The lens is positioned to receive channel output signals from channel output waveguides 121. The lens and channel output waveguides 121 are positioned such that the channel output signals from different channel output waveguides 121 are incident on different regions on the input side of the lens and / or have different angles of incidence on the input side of the lens. As a result, the channel output signals from different channel output waveguides 121 travel in different directions away from the lens. For example, Figure 6A shows an example in which signal redirector 122 is C i,m The transmission angle of the channel output signal received from the channel output waveguide 121 is expressed as θ i,m where i represents the channel index and m represents the alternative waveguide index.

[0113] Figure 6A shows the C i,M and C N,M The transmission angle of the channel output signal output from the channel output waveguide 121 is expressed as θ i,m If the switch signal is guided to an alternative waveguide, denoted m=M, then C 1,M The channel output signal output from the channel output waveguide 121 is expressed as 1,M C N,M The channel output signal output from the channel output waveguide 121 is expressed as N,M The transmission angle θ 1,M is the transmission angle θN,M , the signal redirection unit 122 can simultaneously output channel output signals carrying different channels and traveling in different directions away from the signal redirection unit 122.

[0114] FIG. 6A shows the output of the channel output waveguide 121 and the C N,1 and C N,M The transmission angle label (θ i,m ) is also shown. When the switch signal is directed to an alternate waveguide labeled m=1, the channel output signal carrying channel N is transmitted through a transmission angle θ N,1 When the alternate waveguide receiving the switch signal is changed to an alternate waveguide denoted m=M, the transmission angle of the channel output signal carrying channel N is θ N,M As is clear from FIG. 6A, the transmission angle θ N,1 is the transmission angle θ N,M As a result, the direction in which the channel output signal travels away from the signal redirection portion 122 changes in response to a change in the alternate waveguide that receives the switch signal.

[0115] The transmission angle is measured relative to the signal redirection portion 122. For example, the transmission angle between the optical axis of the lens and the LIDAR output signal can be measured. As can be seen from FIG. 6A, the angle θ i,m is different for different channel output waveguides 121. Because the channel output signals from different channel output waveguides 121 travel in different directions away from the lens, the electronics can control the direction of the channel output signals by operating a switch to direct a switch signal to an alternate waveguide 119 that provides the desired direction for the channel output signal. The degree of change in direction from one alternate waveguide 119 to another alternate waveguide 119 can be a function of the lens structure. Thus, by changing the lens structure, the degree of change in direction between the alternate waveguides can be increased or decreased.

[0116] The LIDAR system may include an optical grating positioned to receive the channel output signals from the signal redirector. The optical grating outputs at least a portion of each channel output signal received by the optical grating. The optical grating may provide additional dispersion of the channel output signals beyond that provided by the signal redirector. The dispersion level may be selected to expand the field of view to a desired size. FIG. 6B illustrates a scanning chip used in combination with the signal redirector 122 and the optical grating 123. The optical grating 123 is positioned such that the optical path of each channel output signal traveling from the splitter 120 to the optical grating 123 passes through a lens.

[0117] The optical grating 123 is arranged to receive the channel output signals from the signal redirection portion and to output at least a portion of each channel output signal received by the optical grating. The illustrated optical grating 123 is a transmission grating. Suitable transmission gratings include, but are not limited to, ruled diffraction gratings, holographic diffraction gratings, and digital planar holographic diffraction gratings.

[0118] Each channel output signal has a different angle of incidence on the optical grating 123 and may reside in a different region of the optical grating 123. Each channel output signal carries one of the wavelength channels (i=1 to N). Each channel output signal travels in a different direction away from the optical grating 123. The direction in which each channel output signal travels away from the optical grating changes as the switch changes the alternate waveguide through which the switch directs the switch signal. For example, changing the alternate waveguide 119 through which the switch signal is received changes the direction of the channel λ i The channel output waveguide 121 that outputs the output signal carrying the channel λ i , the channel λ on the optical grating 123. i The angle of incidence of the output signal transmitted through channel λ is changed. i The direction in which the output signal traveling away from the optical grating 123 changes.

[0119] In some cases, the channel output signals traveling away from the optical grating 123 also travel away from the LIDAR system. As a result, the channel output signals traveling away from the optical grating 123 and the LIDAR system can function as system output signals. Thus, each system output signal can travel away from the LIDAR system in a different direction, and the direction in which each system output signal travels away from the optical grating changes depending on the alternate waveguide through which the switch directs the switch signal. Each system output signal illuminates a sample area within the field of view. As a result, the electronics can scan each system output signal through a different sample area within the field of view by changing the alternate waveguide 119 through which the switch signal is received. The LIDAR system can be configured to generate LIDAR data for each sample area.

[0120] In some cases, the electronics delay switching of the alternate waveguide 119 receiving the switch signal for a period of sample area illumination having a sample area duration. As a result, each system output signal illuminates a different sample area for the sample area duration. The sample area duration can be selected to allow at least enough time for the system output signal to travel from the LIDAR system to an object at a maximum operating distance from the LIDAR system and return to the LIDAR system.

[0121] If an object is present within the sample region illuminated by the system output signal, the object may reflect light from the system output signal. The reflected light is returned to the LIDAR system in a system return signal. Each system return signal may carry a different channel. The system return signals are received by optical grating 123. Optical grating 123 may be configured to output at least a portion of each system output signal. The portion of each system output signal output from optical grating 123 may serve as a channel return signal. Optical grating 123 outputs the channel return signal, thereby transmitting the wavelength channel i(λ i) is transmitted through wavelength channel i(λ i ) travels in the opposite direction along the same or substantially the same path as the channel output signal carrying wavelength channel i. Also, the channel return signal carrying wavelength channel i (λ i ) travels in the reverse direction through signal redirection portion 122 along the same or substantially the same path as the channel output signal carrying the

[0122] The scanning chip can receive a channel return signal that includes or is composed of light from a different one of the system return signals. For example, the scanning chip can receive the channel return signal from signal redirection 122. As an example, channel output waveguide 121 receives a channel return signal that carries the same wavelength channel as the channel output signal output from channel output waveguide 121. For example, during illumination of the sample area, channel λ i The channel feedback signal carrying the channel λ during illumination of the sample area. i Some of the channel output waveguides 121 do not output channel output signals during illumination of the sample area, so some of the channel output waveguides 121 do not receive channel feedback signals during illumination of the sample area, but may receive channel feedback signals during illumination of a different sample area.

[0123] The channel output waveguides 121 transmit the received channel return signals to the splitter 120. The splitter 120 combines the channel return signals into the assembly return signal received on one alternate waveguide 119. Thus, the splitter 120 can operate as a demultiplexer / multiplexer. The alternate waveguide 119 that receives the assembly return signal transmits the assembly return signal to the optical switch 118. The optical switch 118 directs the assembly return signal to the common waveguide 117. The common waveguide transmits the assembly return signal to an output port through which the assembly return signal exits the scanning tip and is received by the LIDAR adapter as described above. In some cases, the output port is a facet of the common waveguide 117.

[0124] In Figure 6A, R represents the radius of the channel output signal at the input side of the lens. R' represents the radius of the lens, and s represents the object distance from the lens. The value of R' can be selected to increase the amount of divergent light captured by the lens. The R / s ratio can be used to approximate the required value of R' and can be a function of the divergence angle of the light from the waveguide facet. To increase the capture of divergent light, a doubling of the divergence half angle φ can be used. In that case, R / s can be equal to at least tan(2φ). For example, if the lateral dimension of the waveguide facet is 10 μm, the lateral divergence half angle φ is approximately 6°. In that case, R / s can be equal to at least tan(12°) = 1 / 5. R' represents the lens radius and can be larger than the half-width (R) of the LIDAR output signal to accommodate the change in position of the LIDAR output signal on the lens due to switching between alternative waveguides. In some cases, R' is greater than or equal to R, 1.3R, or 1.6R and / or less than or equal to 4R or 6R, where R is greater than or equal to s*tan(2φ).

[0125] The center-to-center distance between the facets of the channel output waveguides 121 is denoted by d in FIG. 6A. Reducing d can improve angular resolution. In some cases, the center-to-center distance between each pair of adjacent facets is constant. However, the center-to-center distance may vary from one pair of facets to another. Suitable center-to-center distances between facets 18 include, but are not limited to, distances greater than 5, 10, or 50 μm and / or less than 100, 1,000, or 10,000 μm.

[0126] The maximum value of N*M can be the nearest integer value of (1 + 2(R'-R) / d), where R is the diameter of the channel output signal at the input side of the lens and R' is the radius of the lens. Thus, a scanning chip can include a number of channel output waveguides 121 up to the nearest integer value of (1 + 2(R'-R) / d). In some cases, N*M is equal to or greater than 5, 10, or 50 and / or less than 100, 500, or 1000. The angular range (2θ) that can be scanned by sequentially directing the LIDAR output signal to each alternate waveguide 119 can be determined by the following equation: N,M ) can be enlarged by increasing N or M. Therefore, the resolution can be improved by reducing d, and the scanning range can be enlarged by increasing N or M within the limits of the optical system.

[0127] The lenses can be configured to collimate the LIDAR output signals from the different channel output waveguides 121. Additionally or alternatively, the lenses can be positioned such that one or more facets are located at the focal point of the lens.

[0128] Although FIG. 6B shows the signal redirector 122 and the optical grating 123 located away from the scanning tip, the signal redirector 122 can be included on the scanning tip, or the optical grating 123 and the signal redirector 122 can be included on the scanning tip.

[0129] Although Figure 6C shows the optical grating 123 as a transmission grating, the optical grating 123 may also be a reflection grating as shown in Figure 6C. Suitable reflection gratings 123 include, but are not limited to, ruled diffraction gratings, holographic diffraction gratings, and digital planar holographic diffraction gratings.

[0130] The LIDAR system can include electronics, a LIDAR chip, a LIDAR adapter, a scanning chip, a signal redirector, and an optical grating. For example, Figure 7A is a top view of a LIDAR system including the LIDAR chip disclosed in connection with Figure 1A, the LIDAR adapter disclosed in connection with Figure 5, and the scanning chip, signal redirector, and optical grating disclosed in connection with Figure 6A. To form a solid-state LIDAR system, the LIDAR chip, LIDAR adapter, scanning chip, signal redirector, and optical grating can be solid state.

[0131] 6A-6C, the channel output signals output from optical grating 123 travel away from the LIDAR system and therefore function as system output signals, each carrying a different channel. As a result, each system output signal includes or is made up of light from the channel output signals.

[0132] The direction in which each channel output signal travels away from the optical grating 123 changes in response to a change in the channel output waveguide 121 through which the signal redirector receives the channel output signal. As a result, the direction in which each system output signal travels away from the LIDAR system changes in response to a change in the alternate waveguide 119 through which the switch signal is received. Thus, by changing the alternate waveguide 119 through which the switch signal is received, the electronics can scan each system output signal through different sample areas within the field of view.

[0133] Light from the system output signal can be reflected by an object illuminated by the system output signal. This reflected light can return to the LIDAR system as a system return signal. Different system return signals each carry a different channel. Each system return signal received by the LIDAR system can function as a channel return signal.

[0134] In the LIDAR systems of FIGS. 6A-7A, the channel output signals function as system output signals, but the LIDAR systems may include one or more other components that operate on the channel output signals output from the signal redirector. Examples of components that can operate on the channel output signals output from the signal redirector include steering units. For example, FIG. 7B is a top view of a LIDAR system including a steering unit 124 that receives the channel output signals output from the signal redirector 122 in the LIDAR system of FIG. 7A. The one or more steering units can be operated by electronics to steer the channel output signals, or the one or more steering units may be fixed. The one or more steering units 124 shown in FIG. 7B are mirrors that receive and reflect the channel output signals. The channel output signals traveling away from the one or more steering units 124 travel away from the LIDAR system and can function as system output signals. However, other suitable steering units include, but are not limited to, fixed and / or steerable optical gratings and solid-state steering devices.

[0135] In FIG. 7B , one of the controls 124 is fixed and the other is movable. The movable control can be operated by electronics to steer the channel output signal within a field of view. For example, as shown by arrow A in FIG. 7B , the electronics can control the movement of one or more of the controls 124 to steer the system output signal within a field of view. The electronics can operate one or more of the controls 124 to steer the system output signal outside of a field of view provided solely by operation of the optical switch. For example, operation of the optical switch can steer the movement of the system output signal within a substantially two-dimensional or planar field of view. In contrast, the electronics can operate one or more of the controls 124 to steer the channel output signal outside of the substantially two-dimensional steering range provided by the optical switch 118. As a result, the electronics can operate the optical switch 118 and one or more controls 124 to steer the system output signal to a sample area within a three-dimensional field of view.

[0136] The scan rate provided by the operation of the scan switches can be higher than the scan rate provided by the one or more controls 124. For example, the scan rate provided by the operation of the scan switches can be at least 5, 10, or 100 times higher than the scan rate provided by the one or more controls 124. The scan rate can be the rate of angular change of all or a portion of the system output signal. For example, the scan rate provided by the operation of the scan switches can be the average rate of change of the transmission angle of all or a portion of the system output signal resulting from the operation of the scan switches.

[0137] The light may be reflected by an object illuminated by the system output signal. The reflected light may return toward the LIDAR system and thus function as a system return signal. Different system return signals each transmit a different channel. The system return signals received by the LIDAR system may function as channel return signals. For example, each of the system return signals received by one or more of the control units 124 may function as a channel return signal.

[0138] The LIDAR system of Figures 7A and 7B shows the LIDAR chip, electronics, LIDAR adapter, and scanning chip disposed on a common support 126. Although the electronics 62 are shown disposed on the common support 126, all or a portion of the electronics can be disposed remotely from the common support 126. While Figure 7B shows the signal redirector 122 and one or more steering units 124 disposed remotely from the common support 126, one or more components selected from the group consisting of the signal redirector 122 and one or more steering units 124 can also be disposed on the common support 126. Suitable methods for attaching components such as the LIDAR chip, electronics, scanning chip, LIDAR adapter, signal redirector, and one or more steering units to the common support include, but are not limited to, epoxy, solder, and mechanical clamps.

[0139] 7A and 7B show the LIDAR adapter components disposed on base 102 and the base disposed on common support 126, all or some of the LIDAR adapter components can be disposed on common support 126. As a result, base 102 is optional.

[0140] FIG. 8 shows a portion of a suitable reflective optical grating 123 including multiple grooves 130. The dispersion level of the optical grating 123 is a measure of the degree to which different channels separate as they travel away from the grating and can be expressed as dβ / dλ, where λ represents the wavelength and β represents the angle of reflection, as shown in FIG. 8. At wavelengths and distances used in many LIDAR applications, suitable dispersion levels include, but are not limited to, dispersion levels greater than 0.05° / nm or 0.1° / nm and / or less than 0.15° / nm or 0.2° / nm. The dispersion level increases with increasing grating order, decreasing grating spacing (denoted as dn in FIG. 8), and increasing angle of incidence (α). Additionally, the grating efficiency increases as the blaze angle (denoted as δ) increases. In some cases, the grating has all or some of the characteristics selected from the group consisting of an order greater than 10, 20, or 50 and / or less than 100, 200, or 300; a grating spacing (dn) greater than 5 μm, 10 μm, or 20 μm and / or less than 25 μm, 30 μm, or 40 μm; an angle of incidence maintained in the range of 40° to 60° or 20° to 40°; and a blaze angle greater than 10°, 20°, or 30° and / or less than 40°, 50°, or 60°; and receives LIDAR input signals transmitting multiple channels having wavelengths less than 1640 nm, 1600 nm, or 1550 nm and greater than 1450 nm, 1350 nm, or 1250 nm. In one example, the grating has an order of 20, a grating spacing (d) of 21 μm, an incidence angle of 40°, a blaze angle (δ) of 48°, and receives a LIDAR input signal carrying multiple channels having wavelengths less than 1570 nm and greater than 1538 nm.

[0141] The number of wavelength channels (N), the center-to-center distance (d) between the facets of the channel output waveguides, and the dispersion are selected to provide the desired sample area scanning speed, angular resolution, and field of view of the desired size. The size of the field of view (FOV) is often referred to as the FOV angle (θ in Figure 6B), which indicates the total angular range over which the system output signal is scanned during scanning of the field of view. FOV In some cases, the FOV angle (θ FOV) is shown in Figure 6B, C 1,1 and C N,M The angular difference between the system output signals transmitting at least 16 wavelength channels (N) can be expressed as the angular difference between the system output signals transmitting at least 16 wavelength channels (N) when the center-to-center distance (d) between the facets of the channel output waveguides is less than 100 μm and greater than 5 μm, the dispersion of the optical grating is 0.1 degrees / nm, and the wavelengths of the at least 16 system output signals are in the range of 1535 nm to 1565 nm. > 16) can be used to achieve a FOV angle of over 25° and a scanning speed of 2 to 2.5 million sample areas per second.

[0142] 9A-9C show an example of a processing unit suitable for use as all or part of processing unit 34. Processing unit 34 receives a comparison signal from one of comparison waveguides 32 and a reference signal from one of reference waveguides 40. The processing unit includes a second splitter 200 that splits the comparison signal transmitted in comparison waveguide 32 to a first comparison waveguide 204 and a second comparison waveguide 206. First comparison waveguide 204 transmits a first portion of the comparison signal to optical coupling unit 211. Second comparison waveguide 208 transmits a second portion of the comparison signal to second optical coupling unit 212.

[0143] The processing unit includes a first splitter 202 that splits a reference signal transmitted on the reference waveguide 40 into a first reference waveguide 204 and a second reference waveguide 206. The first reference waveguide 204 transmits a first portion of the reference signal to an optical combiner 211. The second reference waveguide 208 transmits a second portion of the reference signal to a second optical combiner 212.

[0144] The second optical combiner 212 combines the second portion of the comparison signal with the second portion of the reference signal to generate 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 pulsates between the second portion of the comparison signal and the second portion of the reference signal.

[0145] The second optical combiner 212 also splits the resulting second composite signal into a first auxiliary detector waveguide 214 and a second auxiliary detector waveguide 216. The first auxiliary detector waveguide 214 transmits a first portion of the second composite signal to a first auxiliary optical sensor 218, which converts the first portion of the second composite signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 216 transmits a second portion of the second composite signal to a second auxiliary optical sensor 220, which converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0146] In some cases, the second optical combiner 212 splits the second composite signal such that the portion of the comparison signal included in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the second composite signal, but the portion of the reference signal in the second portion of the second composite signal (i.e., the second portion of the reference signal) is not phase-shifted relative to the portion of the reference signal in the first portion of the second composite signal. Alternatively, the second optical combiner 212 splits the second composite signal such that the portion of the reference signal in the first portion of the second composite signal (i.e., the second portion of the reference signal) is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the second composite signal, but the portion of the comparison signal in the first portion of the second composite signal (i.e., the second portion of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second portion of the second composite signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0147] The first optical combiner 211 combines the first portion of the comparison signal and the first portion of the reference signal to generate 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 pulsates between the first portion of the comparison signal and the first portion of the reference signal.

[0148] The first optical combiner 211 splits the first composite signal into a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 transmits a first portion of the first composite signal to a first optical sensor 223, which converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 transmits a second portion of the second composite signal to a second optical sensor 224, which converts the second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include a germanium photodiode (PD) and an avalanche photodiode (APD).

[0149] In some cases, the optical combiner 211 splits the first composite signal such that the portion of the comparison signal included in the first portion of the composite signal (i.e., the first portion of the comparison signal) is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal), but the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is not phase-shifted relative to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal). Alternatively, the optical combiner 211 splits the composite signal such that the portion of the reference signal in the first portion of the composite signal (i.e., the first portion of the reference signal) is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the composite signal (i.e., the first portion of the reference signal), but the portion of the comparison signal in the first portion of the composite signal (i.e., the first portion of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second portion of the composite signal (i.e., the first portion of the comparison signal).

[0150] When the second optical coupler 212 splits the second composite signal such that the portion of the comparison signal in the first portion of the second composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the second composite signal, the optical coupler 211 also splits the composite signal such that the portion of the comparison signal in the first portion of the composite signal is phase-shifted by 180° relative to the portion of the comparison signal in the second portion of the composite signal. When the second optical coupler 212 splits the second composite signal such that the portion of the reference signal in the first portion of the second composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the second composite signal, the optical coupler 211 also splits the composite signal such that the portion of the reference signal in the first portion of the composite signal is phase-shifted by 180° relative to the portion of the reference signal in the second portion of the composite signal.

[0151] Suitable optical coupling portions 211 and second optical coupling portions 212 include, but are not limited to, multi-mode interference couplers, directional couplers, and tapered couplers.

[0152] The first reference waveguide 210 and the second reference waveguide 208 are constructed to provide a phase shift between the first portion of the reference signal and the second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 can be constructed 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 portion can be a quadrature component. Thus, one of the reference signal portions can be a sine function and the other reference signal portion can be a cosine function. As an example, the first reference waveguide 210 and the second reference waveguide 208 are constructed so that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Thus, the portion of the reference signal in the second composite signal is phase-shifted relative to the portion of the reference signal in the first composite signal, but the portion of the comparison signal in the first composite signal is not phase-shifted relative to the portion of the comparison signal in the second composite signal.

[0153] The first optical sensor 223 and the second optical sensor 224 can be connected as a balanced detector, and the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 can also be connected as a balanced detector. For example, FIG. 9B shows a schematic diagram of the relationship between the electronics, the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220. Although photodiode symbols are used to represent the first optical sensor 223, the second optical sensor 224, the first auxiliary optical sensor 218, and the second auxiliary optical sensor 220, one or more of these sensors may have other configurations. In some cases, all of the components shown in the schematic diagram of FIG. 9B are included on the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 9B are distributed between the LIDAR chip and electronics that are off the LIDAR chip.

[0154] The electronics 62 connects the first optical sensor 223 and the second optical sensor 224 as a first balance detector 225, and connects the first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 as a second balance detector 226. Specifically, the first optical sensor 223 and the second optical sensor 224 are connected in series. The first auxiliary optical sensor 218 and the second auxiliary optical sensor 220 are also connected in series. The series connection in the first balance detector communicates with a first data line 228, which carries the output from the first balance detector as a first data signal. The series connection in the second balance detector communicates with a second data line 232, which carries the output from the second balance detector as a second data signal. The first data signal is an electrical representation of the first composite signal, and the second data signal is an electrical representation of the second composite signal. Thus, the first data signal includes contributions from the first waveform and the second waveform, and the second data signal is a combination of the first waveform and the second waveform. A portion of a first waveform in the first data signal is phase-shifted relative to a portion of the first waveform in the first data signal, while a portion of a second waveform in the first data signal is in phase with a portion of the second waveform in the first data signal. For example, the second data signal includes a portion of a reference signal that is phase-shifted relative to a different portion of the reference signal included in the first data signal. Also, the second data signal includes a portion of a comparison signal that is in phase with a different portion of the comparison signal included in the first data signal. The first and second data signals are pulsating as a result of the pulsation between the comparison signal and the reference signal, i.e., the pulsation in the first and second composite signals.

[0155] The electronics 62 includes a transform mechanism 238 configured to perform a mathematical transform on the first and second data signals. For example, the mathematical transform may be a complex Fourier transform with the first and second data signals as inputs. Because the first data signal is the in-phase component and the second data signal is the quadrature component, the first and second data signals act together as a complex data signal, with the first data signal being the real component of the input and the second data signal being the imaginary component of the input.

[0156] The conversion mechanism 238 includes a first analog-to-digital converter (ADC) 264 that receives the first data signal from the first data line 228. The first analog-to-digital converter (ADC) 264 converts the first data signal from analog format to digital format and outputs a first digital data signal. The conversion mechanism 238 includes a second analog-to-digital converter (ADC) 266 that receives the second data signal from the second data line 232. The second analog-to-digital converter (ADC) 266 converts the second data signal from analog format to digital format and outputs a second digital data signal. The first digital data signal is a digital representation of the first data signal, and the second digital data signal is a digital representation of the second data signal. Thus, the first digital data signal and the second digital data signal together function as a complex signal, where the first digital data signal functions as the real component of the complex signal and the second digital data signal functions as the imaginary component of the complex data signal.

[0157] The conversion mechanism 238 includes a mathematical converter 268 that receives the complex data signal. For example, the mathematical converter 268 receives as an input a first digital data signal from a first analog-to-digital converter (ADC) 264 and a second digital data signal from a second analog-to-digital converter (ADC) 266. The mathematical converter 268 can be configured to perform a mathematical transform on the complex signal to convert it from the time domain to the frequency domain. The mathematical transform can be a complex transform, such as a complex Fast Fourier Transform (FFT). A complex transform, such as a complex Fast Fourier Transform (FFT), provides an explicit solution to the shift in frequency of the LIDAR input signal relative to the LIDAR output signal caused by the line-of-sight velocity between a reflecting object and the LIDAR tip.

[0158] The mathematical transformer 268 may include a peak detector (not shown) configured to identify peaks in the output of the mathematical transformer 268. The peak detector may be configured to identify frequency peaks associated with reflections of the system output signal by one or more objects located outside the LIDAR system. For example, frequency peaks associated with reflections of the system output signal by one or more objects located outside the LIDAR system may fall within a frequency range. The peak detector may identify frequency peaks within the frequency range associated with reflections of the system output signal by one or more objects located outside the LIDAR system. The frequencies of the identified frequency peaks represent the beat frequencies of the composite signal. The mathematical transformer 268 may perform the attribute functions using firmware, hardware, software, or a combination thereof.

[0159] The data processor 237 includes a LIDAR data generator 270 that receives the pulsating frequency of the composite signal from the peak detector and processes the pulsating frequency of the composite signal to generate LIDAR data (distance and / or radial velocity between a reflecting object and the LIDAR tip or LIDAR system).

[0160] 9C shows an example of the relationship between frequency, time, cycle, and data period of a system output signal. The frequency versus time patterns are shown for two system output signals carrying different channels. The system output signal carrying channel i has a period λ. i where i represents the channel index. The base frequency (fo) of the system output signal may be the lowest frequency of the system output signal during a cycle.

[0161] The frequency vs. time pattern is a cycle j and cycle j+1 9C. In some cases, the frequency versus time pattern is repeated in each cycle, as shown in FIG. 9C.

[0162] Each cycle is associated with a period index k, and the DP k In the example of FIG. 9C, each cycle contains K data periods, denoted as DP k 9C, where k = 1 and 2. In some cases, the frequency versus time patterns of corresponding data periods in different cycles are the same, as shown in FIG. 9C. Corresponding data periods are data periods with the same cycle index. As a result, each data period DP1 can be considered a corresponding data period, and the associated frequency versus time patterns are the same in FIG. 9C. At the end of the cycle, the electronics returns the frequency to the same frequency level as at the start of the previous cycle.

[0163] During the data periods DP1 and DP2, the electronic device transmits data to the channel λ i whereby the frequency of the system output signal increases at a linear rate α i where i represents the channel index. The direction of the frequency change in data period DP1 is opposite to the direction of the frequency change in data period DP2.

[0164] During each cycle, the system output signal carrying channel i is SR k,i where k represents the sample area index and i represents the channel index. For example, during the cycle represented as j in FIG. 9C, the sample area SR k,i is the channel λ i The sample area SR is illuminated by the system output signal k,i+1 is the channel λ i+1 The sample area index k can be assigned with respect to time. For example, the sample areas can be illuminated by the system output signal in the order indicated by the index k. As a result, the sample area SR 10,1 is the sample area SR 9,1 After and sample area SR 11,1 is irradiated before

[0165] The sample region illumination period, denoted SRP, can be equal to the time of each cycle. As a result, the sample region duration can be equal to the duration of each cycle. In some cases, the electronics do not switch the alternate waveguide 119 that receives the switch signal during the sample region illumination period. As a result, during each sample region illumination period, the system output signal does not shift in response to a change in the alternate waveguide 119 that receives the switch signal.

[0166] In some cases, moving the system output signal to a different sample region includes changing an alternate waveguide 119 that receives a switch signal. The change in alternate waveguide 119 that receives a switch signal can occur between cycles. In some cases, there may be a delay associated with changing an alternate waveguide 119 that receives a switch signal. This delay is possible but is not shown in FIG. 9C.

[0167] When the electronics manipulate one or more controls 124 to steer the system output signal within a field of view, the steering of the system output signal by the one or more controls 124 may be continuous. This continuous motion is in contrast to the stop-and-go motion provided by changing alternate waveguides 119 that receive the switch signal.

[0168] LIDAR systems are typically configured to provide reliable LIDAR data when an object is within an operating distance range from the LIDAR system. The operating distance range can range from a minimum operating distance to a maximum operating distance. The maximum round trip time is the time required for the system output signal to leave the LIDAR system, travel the maximum operating distance to the object, and return to the LIDAR system, which is shown in FIG. 9C as τ M It is written as follows.

[0169] Because there is a delay between when the system output signal is transmitted and when it returns to the LIDAR system, the composite signal does not include a contribution from the LIDAR signal until the system return signal returns to the LIDAR system. Because a contribution from the system return signal is required for a beat frequency to appear in the composite signal, the electronics measure the beat frequency resulting from the system return signal returning to the LIDAR system during a data window within the data period. In Figure 9C, the data window is labeled "W." The contribution from the LIDAR signal to the composite signal is delayed by a maximum operating time delay (τ M ) occurs at a time longer than the maximum operating time delay (τ M ) and extend to the end of the data period.

[0170] Although FIG. 9C shows the frequency versus time patterns for two channels, the frequency versus time patterns disclosed in FIG. 9C can be applied to each channel.

[0171] As is apparent from the above description, each processing unit 34 receives a reference signal traveling on the same channel as the comparison signal. As a result, the frequency output from the complex Fourier transform associated with a processing unit 34 represents the beat frequency of a composite signal that includes the comparison signal beating relative to the reference signal when the comparison signal and the reference signal travel on the same channel. By combining beat frequencies from the same processing unit 34 with beat frequencies from two or more different data periods, LIDAR data for one of the sample regions can be generated. For example, a comparison signal and channel λ i The processing unit 34 receives the reference signal transmitting the cycle j Beat frequency and cycles generated from DP1 j Combine the beating frequencies generated from DP2 and sample the SR k,i As an example, during a data period where the electronics increase the frequency of the outgoing LIDAR signal during the data period, such as occurs during data period DP1 in FIG. 9C, the following formula applies: f ub = -f d +α kτ, where f ub is the frequency provided by the mathematical converter 268, and f d is the Doppler shift (f d = 2υf c / c), where f c is the base frequency (f o ), c is the speed of light, υ is the line-of-sight velocity between the reflecting object and the LIDAR system (where the direction from the reflecting object towards the LIDAR system is assumed to be the positive direction), c is the speed of light, τ is the time it takes for the system output signal to leave the LIDAR system, be reflected by an object outside the LIDAR system, and return to the LIDAR system as the system return signal (round trip time). k represents the chirp rate in the data period with period index k. For example, α1 is calculated by the mathematical transformer f ub represents the chirp rate in the same data period DP1 that was generated. As a result, α k and f ub has the same data period DP k is associated with.

[0172] During a data period in which the electronics reduces the frequency of the emitted LIDAR signal, such as data period DP2 in FIG. 9C, the following formula applies: f db = -f d -α k *τ, where f db is the frequency provided by the mathematical converter 268. In these two equations, f d and τ are unknowns. These two equations (f db = -f d -α n τ and f ub = -f d +α n In τ), f d and τ are unknowns. These equations can be solved for these two unknowns. The LIDAR data generator calculates the Doppler shift (ν = c*f d / (2f c)) can be used to calculate the radial velocity of the sample area, and c*τ / 2 can be used to calculate the distance away from that sample area. For example, if the system output signal has the frequency vs. time pattern shown in Figure 9C, the distance (r) between the LIDAR system and an object outside the LIDAR system can be calculated as r = c(f ub -f db ) / (2(α1-α2)), and the line-of-sight velocity between the LIDAR system and the object is υ = c(α2f ub -α1f db ) / (2f c The resulting LIDAR data (r and / or υ) can be calculated from the channel λ i The LIDAR data represents LIDAR data for a sample area illuminated by a system output signal carrying a channel. Because multiple different sample areas may be simultaneously illuminated by system output signals carrying different channels, LIDAR data may be generated for each different sample area simultaneously illuminated by one of the system output signals. Also, different LIDAR data results may be generated in parallel using different processing units 34. Alternatively, different LIDAR data results may be generated serially using different processing units 34, depending on the configuration of the electronics.

[0173] In some cases, multiple objects exist within the sample volume. When multiple objects exist within the sample volume, the transform outputs multiple frequencies, each associated with a different object. Frequencies originating from the same object in different data periods of the same cycle can be considered as corresponding frequency pairs. For each corresponding frequency pair output by the transform, LIDAR data can be generated. As a result, individual LIDAR data can be generated for each object within the sample volume.

[0174] 9A-9B show an optical combiner combining a portion of the reference signal and a portion of the comparison signal, the processing unit may include a single optical combiner combining the reference signal and the comparison signal to form a composite signal. As a result, at least a portion of the reference signal and at least a portion of the comparison signal may be combined to form the composite signal. The combined portion of the reference signal may be the entire reference signal or a portion of the reference signal, and the combined portion of the comparison signal may be the entire comparison signal or a portion of the comparison signal.

[0175] As an example of a processing unit that combines the reference signal and the comparison signal to form a composite signal, Figures 9D-9E show an example of the processing unit of Figures 9A-9B modified to include a single optical combining unit. Comparison waveguide 196 transmits the comparison signal directly to first optical combining unit 211, and reference waveguide 198 transmits the reference signal directly to first optical combining unit 211.

[0176] The first optical combiner 211 combines the comparison signal and the reference signal to generate a composite signal. Due to the frequency difference between the comparison signal and the reference signal, the first composite signal pulsates between the comparison signal and the reference signal. The first optical combiner 211 also splits the composite signal into a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 transmits a first portion of the composite signal to a first optical sensor 223, which converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 transmits a second portion of the second composite signal to a second optical sensor 224, which converts the second portion of the second composite signal into a second electrical signal.

[0177] FIG. 9E shows a schematic diagram of the relationship between the electronics, first optical sensor 223, and second optical sensor 224. Although a photodiode symbol is used to represent first optical sensor 223 and second optical sensor 224, one or more of these sensors may have other configurations. In some cases, all of the components shown in the schematic diagram of FIG. 9E are included on the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 9E are distributed between the LIDAR chip and electronics located off the LIDAR chip.

[0178] The electronics connects a first photosensor 223 and a second photosensor 224 as a first balance detector 225. In particular, the first photosensor 223 and the second photosensor 224 are connected in series. The series connection of the first balance detector is in communication with a first data line 228 that carries the output from the first balance detector as a first data signal. The first data signal is an electrical representation of the composite signal.

[0179] The electronics 62 includes a transform mechanism 238 configured to perform a mathematical transform on the first data signal. This mathematical transform may be a real Fourier transform with the first data signal as an input. The LIDAR data generator 270 may use the frequencies output from this transform to extract LIDAR data, as described above.

[0180] 9A-9E can be replaced with a single optical sensor. As a result, the processing unit can include one or more optical sensors, each receiving at least a portion of the composite signal, which can be the entire composite signal or a portion of the composite signal.

[0181] As described in connection with Figure 9C, the electronics 62 adjust the frequency of the system output signal. One way to generate this frequency chirp is to modulate the current applied by the electronics to the light source. In semiconductor lasers, which can be used as light sources in LIDAR systems, current modulation achieves frequency modulation via strongly nonlinear carrier / photon coupling.

[0182] 1A-4. As described above, each of the control sections 74 receives a delay path signal from a delay channel waveguide 72 and a priority path signal from a forward sub-waveguide 76. The delay path signal and the priority path signal received at the control section 74 are coupled to each other via a λ i The same channel is transmitted, denoted by .

[0183] The delay channel waveguide 72 conveys the delay path signal to a first divider 274. The forward sub-waveguide 76 conveys the priority path signal to a second divider 278. Dividers suitable for use as the first divider 274 and the second divider 278 include, but are not limited to, directional couplers, optical couplers, Y-junctions, tapered couplers, and wavelength-independent dividers such as multimode interference (MMI) devices.

[0184] The first divider 274 divides the delay path signal into a first portion of the delay signal and a second portion of the delay signal. The first delay waveguide 280 transmits the first portion of the delay signal to the first optical combiner 282. The second delay waveguide 284 transmits the second portion of the delay signal to the second optical combiner 286.

[0185] The second divider 278 divides the priority signal into a first portion of the priority signal and a second portion of the priority signal. The first priority waveguide 290 transmits the first portion of the priority signal to the first optical combiner 282. The second priority waveguide 292 transmits the second portion of the priority signal to the second optical combiner 286.

[0186] The first light combiner 282 combines a first portion of the priority signal with a first portion of the delayed signal to generate a first pulsating signal, and the second light combiner 286 combines a second portion of the priority signal with a second portion of the delayed signal to generate a second pulsating signal, such that each delay path extends from a splitter to a light combiner that combines light from one of the delayed path signals with light from one of the priority path signals.

[0187] As described above, the length of the delay path exceeds the length of the priority path. As a result, the second portion of the delayed signal is delayed relative to the second portion of the priority signal. Because the electronics can adjust the frequency of the outgoing LIDAR signal, this delay causes the second portion of the delayed signal to have a different frequency than the second portion of the priority signal. Due to the frequency difference between the second portion of the priority signal and the second portion of the delayed signal, the second pulsating signal pulsates between the second portion of the priority signal and the second portion of the delayed signal.

[0188] The second optical coupling portion 286 also splits the second pulsatile signal into a first auxiliary detector waveguide 294 and a second auxiliary detector waveguide 296. The first auxiliary detector waveguide 294 transmits a first portion of the second pulsatile signal to a first auxiliary optical sensor 298, which converts the first portion of the second pulsatile signal into a first auxiliary electrical signal. The second auxiliary detector waveguide 296 transmits a second portion of the second pulsatile signal to a second auxiliary optical sensor 300, which converts the second portion of the second pulsatile signal into a second auxiliary electrical signal. Examples of suitable optical sensors include a germanium photodiode (PD) and an avalanche photodiode (APD).

[0189] In some cases, the second optical coupling unit 286 splits the second pulsating signal so that the portion of the priority signal included in the first portion of the second pulsating signal (i.e., the second portion of the priority signal) is phase shifted by 180 degrees relative to the portion of the priority signal in the second portion of the second pulsating signal (i.e., the second portion of the priority signal), but the portion of the delayed signal in the second portion of the second pulsating signal (i.e., the second portion of the delayed signal) is not phase shifted relative to the portion of the delayed signal in the first portion of the second pulsating signal (i.e., the second portion of the delayed signal).

[0190] As described above, the length of the delay path exceeds the length of the priority path. As a result, the first portion of the delayed signal is delayed relative to the first portion of the priority signal. Due to this delay, the first portion of the delayed signal has a different frequency than the first portion of the priority signal. Due to the frequency difference between the first portion of the priority signal and the first portion of the delayed signal, the first pulsating signal pulsates between the second portion of the priority signal and the second portion of the delayed signal.

[0191] The first optical coupling portion 282 also splits the first pulsatile signal into a first detector waveguide 302 and a second detector waveguide 304. The first detector waveguide 302 transmits a first portion of the first pulsatile signal to a first optical sensor 306, which converts the first portion of the second pulsatile signal into a first electrical signal. The second detector waveguide 304 transmits a second portion of the second pulsatile signal to a second optical sensor 308, which converts the second portion of the second pulsatile signal into a second electrical signal. Examples of suitable optical sensors include a germanium photodiode (PD) and an avalanche photodiode (APD).

[0192] In some cases, the first optical coupling unit 282 splits the first pulsating signal so that the portion of the priority signal included in the first portion of the pulsating signal (i.e., the first portion of the priority signal) is phase shifted by 180° relative to the portion of the priority signal in the second portion of the pulsating signal (i.e., the first portion of the priority signal), but the portion of the delayed signal in the first portion of the pulsating signal (i.e., the first portion of the delayed signal) is not phase shifted relative to the portion of the delayed signal in the second portion of the pulsating signal (i.e., the first portion of the delayed signal).

[0193] When the second optical coupling unit 286 divides the second pulsation signal so that the portion of the priority signal in the first portion of the second pulsation signal is phase shifted by 180° relative to the portion of the priority signal in the second portion of the second pulsation signal, the first optical coupling unit 282 also divides this pulsation signal so that the portion of the priority signal in the first portion of the pulsation signal is phase shifted by 180° relative to the portion of the priority signal in the second portion of the pulsation signal.

[0194] The first delay waveguide 280, the second delay waveguide 284, the first priority waveguide 80, and the second priority waveguide 292 can be configured such that the first pulsating signal and the second pulsating signal together function as the in-phase and quadrature components of the optical process variable signal, where the first pulsating signal is the in-phase component of the optical process variable signal and the second pulsating signal is the quadrature component of the optical process variable signal. Alternatively, the second pulsating signal is the in-phase component of the optical process variable signal and the first pulsating signal is the quadrature component of the optical process variable signal. For example, the first delay waveguide 280 and the second delay waveguide 284 can be configured to impart a phase shift between the first portion of the delayed signal and the second portion of the delayed signal. Meanwhile, the first priority waveguide 280 and the second priority waveguide 292 are configured such that the first portion of the priority signal and the second portion of the priority signal are in phase. As an example, the first delay waveguide 280 and the second delay waveguide 284 can be constructed to provide a 90° phase shift between the first portion of the delayed signal and the second portion of the delayed signal. Thus, one of the delayed signal portions can be a sine function, and the other delayed signal portion can be a cosine function operating with the same argument as the sine function. In one example, the first delay waveguide 280 and the second delay waveguide 284 are constructed so that the first portion of the delayed signal is a cosine function and the second portion of the delayed signal is a sine function. In this example, the delayed signal portion in the second pulsating signal is phase-shifted relative to the delayed signal portion in the first pulsating signal, but the priority signal portion in the first pulsating signal is not phase-shifted relative to the priority signal portion in the second pulsating signal.

[0195] In another example, the first delay waveguide 280 and the second delay waveguide 284 are constructed so that the first portion of the delayed signal and the second portion of the delayed signal are in phase, while the first priority waveguide 280 and the second priority waveguide 292 are constructed to impart a phase shift between the first portion of the priority signal and the second portion of the priority signal. As an example, the first priority waveguide 280 and the second priority waveguide 292 can be constructed to impart a 90° phase shift between the first portion of the priority signal and the second portion of the priority signal. Thus, one of the priority signal portions can be a sine function and the other priority signal portion can be a cosine function operating with the same argument as the sine function. In one example, the first priority waveguide 280 and the second priority waveguide 292 are constructed so that the first portion of the priority signal is a cosine function and the second portion of the priority signal is a sine function operating with the same argument as the cosine function. In this example, the portion of the priority signal in the second beat signal is phase shifted relative to the portion of the priority signal in the first beat signal, but the portion of the delayed signal in the first beat signal is not phase shifted relative to the portion of the delayed signal in the second beat signal.

[0196] The first optical sensor 306 and the second optical sensor 308 can be connected as a balanced detector, and the first auxiliary optical sensor 298 and the second auxiliary optical sensor 300 can also be connected as a balanced detector. For example, FIG. 10B shows a schematic diagram of the relationship between the electronics 62, the first optical sensor 306, the second optical sensor 308, the first auxiliary optical sensor 298, and the second auxiliary optical sensor 300. Although photodiode symbols are used to represent the first optical sensor 306, the second optical sensor 308, the first auxiliary optical sensor 298, and the second auxiliary optical sensor 300, one or more of these sensors may have other configurations. In some cases, all of the components shown in the schematic diagram of FIG. 10B are included on the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 10B are distributed between the LIDAR chip and the electronics that are off the LIDAR chip.

[0197] The electronics 62 connects the first optical sensor 306 and the second optical sensor 308 as a first balance detector 312, and connects the first auxiliary optical sensor 298 and the second auxiliary optical sensor 300 as a second balance detector 314. Specifically, the first optical sensor 306 and the second optical sensor 308 are connected in series. The first auxiliary optical sensor 298 and the second auxiliary optical sensor 300 are connected in series. The series connection in the first balance detector communicates with a first data line 316 that carries the output from the first balance detector as a first process variable signal. The series connection in the second balance detector communicates with a second data line 318 that carries the output from the second balance detector as a second process variable signal.

[0198] The first process variable signal is an electrical representation of the first pulsating signal, and the second process variable signal is an electrical representation of the second pulsating signal. Thus, the first process variable signal is pulsating. The second process variable signal is pulsating. The first process variable signal and the second process variable signal can each carry a different component selected from the group consisting of an in-phase component of the process variable signal and a quadrature component of the process variable signal. For example, the first process variable signal can include contributions from a first waveform and a second waveform, and the second process variable signal can include contributions from the first waveform and the second waveform. A portion of the first waveform in the first process variable signal is phase-shifted relative to a portion of the first waveform in the second process variable signal, while a portion of the second waveform in the first process variable signal is in phase with a portion of the second waveform in the second process variable signal. For example, the second process variable signal can include a portion of a delayed signal that is phase-shifted relative to another portion of the delayed signal included in the first process variable signal. The second process variable signal can also include a portion of a priority signal that is in phase with another portion of the priority signal included in the first process variable signal. The first process variable signal and the second process variable signal are pulsating as a result of the pulsations between the priority signal and the delayed signal, i.e., the pulsations in the first pulsating signal and the second pulsating signal, respectively.

[0199] The electronics 62 includes a process variable identifier 320 that receives the process variable signal. The process variable identifier 320 uses the process variable signal to generate a channel signal (f) carrying a channel that is received by the control unit 74 that includes the process variable identifier 320. CS ) and outputs an indicator signal that is indicative of, a function of, and / or usable to measure the frequency of the channel signal (f CS ) is an analog signal having one or more characteristics related to the frequency of the channel signal (f CS ) digital signal that quantifies the frequency of the channel signal (f CS ) frequency-related digital signal, or channel signal (f CS ) is a digital signal that can be used to quantify the frequency of channel λ. i The system output signal carrying i Since the frequency of the channel signal is a part of the transmitted channel LIDAR signal, the frequency of the channel signal is i can represent the value of the frequency of the system output signal that transmits

[0200] The electronics may include an optical control unit 322 that receives the instruction signal. In response to the instruction signal, the optical control unit 322 may control the laser light source 68 (FIG. 1B), which is the light source for the channel received by the control unit 74. For example, the laser light source 68 may be controlled by a control structure in which the frequency of the channel signal output by the laser light source 68 serves as the controlled process variable. When the controlled process variable is the frequency of the channel signal, the desired frequency of the system output signal serves as the reference variable. Because the frequency of the system output signal is modulated, the desired frequency of the system output signal changes as a function of time. For triangular modulation, FIG. 9C may represent an example of a desired waveform. FIG. 9C shows the desired frequency of the channel signal, and therefore the resulting system output signal, as a linear function of time. Thus, the control unit 74, the process variable identifier 320, and the channel λ iThe optical control unit 322 receives the channel λ i The control mechanism may be part of a control mechanism that controls the laser light source 68, which is the light source of the channel signal, so that the frequency of the channel signal output from the laser light source 68 substantially maintains a desired waveform. Suitable control mechanisms include, but are not limited to, control constructs that utilize feedback control and / or feedforward control. Thus, the control mechanism may be a feedback control loop and / or may include a control loop.

[0201] The optical controller 322 can control the characteristics of the channel signal and / or the system output signal in response to the value of the controlled process variable at a particular time and the value of an error signal measured from the value of the reference variable at the same time. For example, the optical controller 322 can control the characteristics of the channel signal to reduce the value of the error signal. As an example, the optical controller 322 can control the characteristics of the channel signal so that the value of the controlled process variable approaches the value of the reference variable. In some cases, the control mechanism is a control loop, such as a feedback control loop. When the control mechanism is a feedback control loop, the error signal of the control mechanism can be equal to the difference between the value of the controlled process variable and the value of the reference variable at a particular time.

[0202] If the process variable is the frequency of the channel signal, the optical controller 322 can send an optical control signal to adjust the frequency of the channel signal. For example, the optical controller 322 can adjust the frequency of the channel signal by sending an optical control signal that varies the level of current flowing through a laser light source that outputs the channel signal. Other optical control signals are possible. For example, if the laser light source is an electrostatic MEMS tunable laser, the optical controller 322 can adjust the frequency of the channel signal by sending an optical control signal that varies the voltage level that moves a MEMS facet of the MEMS tunable laser.

[0203] In some cases, the optical control unit 322 and / or the process variable identifier unit 320 may be configured to control the frequency (fCS ) of the channel signal, but this determination is not required. For example, CS ), the channel signal frequency (f CS The optical control signal can be derived directly from the instruction signal without actually quantifying the optical frequency. For example, the control signal can be a one-to-one function of the instruction signal and / or the conversion signal described below. As an example, the control signal can be a one-to-one function of the instantaneous frequency.

[0204] Figure 10C shows the amplitude of the in-phase and quadrature components of the optical process variable signal and / or process variable signal on the same time axis as the frequency of the system output signal. For example, Figure 10C can compare the frequency of the system output signal during the first two data periods shown in Figure 9C with the amplitude of the in-phase and quadrature components of the optical process variable signal and / or process variable signal. Although Figure 10C shows the optical process variable signal and / or process variable signal having only one period per data period, the optical process variable signal and / or process variable signal can also have multiple periods per data period.

[0205] Various process variable identifiers 320 can be used to measure the value of the process variable indicator. Figure 10D illustrates an example of a process variable identifier 320 applied when the process variable is the frequency of the channel signal and / or the system output signal. The illustrated process variable identifier 320 includes a local oscillator 324 that outputs local signals, including a first local signal and a second local signal. The first local signal and the second local signal each carry one of different components selected from the group consisting of an in-phase component of the local signal and a quadrature component of the local signal.

[0206] The process variable identifier 320 also includes a first multiplier 326 that receives the first process variable signal and the first local signal. The first multiplier 326 multiplies the first process variable signal by the first local signal. If the first process variable signal carries the in-phase component of the process variable signal, the first local signal carries the quadrature component of the local signal. If the first process variable signal carries the quadrature component of the process variable signal, the first local signal carries the in-phase component of the local signal. The first multiplier 326 outputs the first multiplied signal.

[0207] The process variable identifier 320 also includes a second multiplier 328 that receives the second process variable signal and the second local signal. The second multiplier 328 multiplies the second process variable signal by the second local signal. If the second process variable signal carries the in-phase component of the process variable signal, the second local signal carries the quadrature component of the local signal. If the second process variable signal carries the quadrature component of the process variable signal, the second local signal carries the in-phase component of the local signal. The second multiplier 326 outputs the second multiplied signal.

[0208] The process variable identification unit 320 includes an adder 330 that receives the first multiplied signal and the second multiplied signal, adds the first multiplied signal and the second multiplied signal, and outputs a control signal.

[0209] The control signal is received by the process variable estimator 334. The process variable estimator 334 uses the control signal to adjust the frequency (f CS ) of the channel signal. For example, the process variable estimator 334 may output an indicator signal having one or more characteristics related to the frequency (f CS ) ). In some cases, the time-to-digital converter (TDC) may be a time-to-digital converter (TDC) that outputs an indicator signal having a voltage related to the frequency (f) of the channel signal. CS ) which can be received by the light controller 322 to control the frequency of the laser light source.

[0210] Another example of a suitable process variable estimator 334 is a frequency counter that outputs an indicator signal indicating the time (dn) between baseline crossings of the control signal. CS ) is the formula 1:f TS = f LO is related to the time between baseline crossings (dn) by -1 / (2*dn), where f LO represents the frequency of the local oscillator. The process variable estimator 334 calculates the measured frequency (f CS ) can be output. The instruction signal can be received by the light controller 322 to control the frequency of the laser light source.

[0211] The local signal is selected so that the frequency of the control signal is higher than the frequency of the process variable signal. Increasing the frequency of the control signal increases the frequency at which the process variable can be accurately sampled. Increasing this sampling frequency allows the control mechanism to more accurately control the process variable. As a result, increasing the frequency of the control signal enhances the control mechanism's control of the process variable. Suitable sampling frequencies include, but are not limited to, sampling frequencies greater than 100 times the modulation frequency, where the modulation frequency is 1 / cycle duration. In some cases, all or part of the data period in each cycle has a sampling frequency greater than 30 or 100 times per data period duration. In some cases, the local signal is selected so that the frequency of the control signal is greater than 100 times but less than 10,000 times the frequency of the process variable signal.

[0212] 10E illustrates another example of the process variable identifier 320 when the process variable is the frequency of the channel signal and / or the system output signal. The process variable identifier 320 includes an analog-to-digital converter (ADC) 340 that receives the control signal from the summer 330. The analog-to-digital converter (ADC) 340 converts the first process variable signal from analog to digital form and outputs a digital data signal. The digital data signal is a digital representation of the control signal.

[0213] The process variable identifier 320 includes a transform unit 342 that receives the digital data signal. The transform unit 342 performs a mathematical transform on the digital data signal. The mathematical transform is selected such that the transform unit 342 outputs a transformed signal that is related to, includes, or is indicative of the frequency of the LIDAR output signal. A suitable first mathematical transform includes, but is not limited to, a Hilbert transform. The Hilbert transform outputs a transformed signal that is indicative of the instantaneous phase of the control signal and, therefore, the frequency of the control signal.

[0214] The converted signal is received by a frequency estimator 344. The frequency estimator may be configured to output an indicator signal related to, including, and / or indicative of the frequency of the LIDAR output signal. For example, the frequency estimator may be configured to output a signal such as f CS =(finst-f LO )*(T / τ') to calculate the instantaneous frequency of the channel signal (f CS ), where f LO is the frequency of the local oscillator, and f inst is the instantaneous frequency extracted from the Hilbert transform, T is the duration of a data period in the triangular modulation scheme, and τ' is the delay due to the difference in length between the delay waveguide 62 and the priority waveguide 66. Thus, the indicator signal is a frequency (f CS ) The instruction signal can be received by the light control unit 322 to control the frequency of the laser light source.

[0215] Although the indicator signal has been described as a signal carrying data related to the frequency of the channel signal, the indicator signal may also carry data indirectly related to the frequency of the channel signal. For example, the indicator signal may carry data that can be used to measure the frequency of the channel signal. As an example, the indicator signal may carry data that can be used to measure the frequency (f TS ) can be measured from the rate of phase change of the channel signal. Thus, the indicator signal can carry data indicative of the rate of phase change of the channel signal.

[0216] By combining information from the in-phase and quadrature components at any given time, the process variable identifier 320 increases the sensitivity of the indicator signal to the frequency of the channel signal, thereby reducing the amount of delay that needs to be generated by the delay waveguide 62. Previous systems attempted to achieve this sensitivity by increasing the length of the delay path. Because the process variable identifier 320 increases the sensitivity of the indicator signal, the length of the delay path can exceed the length of the preferred path by a smaller amount than was achievable in previous systems. For example, the time delay in the path to the control unit 74 can exceed the time delay in the preferred path to the control unit 74 by more than 50 ps and less than 100 ns. In one example, the length of the delay path exceeds the length of the preferred path by less than 1000 cm, less than 500 cm, or less than 100 cm, and more than 0.0 cm or 0.4 cm. In one example, the delay path and the priority path to the same control section 74 guide light through silicon, with the length of the delay path exceeding the length of the priority path by an amount less than 1000 cm and greater than 0.0 cm or 0.4 cm.

[0217] Figures 10A - 10E illustrate an example of a suitable control unit used as all or part of control unit 74 disclosed in relation to Figures 1A - 4. As described above, each control unit 74 receives a delay path signal and a priority path signal that transmit the same channel. In some cases, the laser light source 68 is constructed such that different channel signals each transmit one of different channels and the different channel signals are output from different laser light sources 68 respectively. For example, Figure 1B shows a construction of light source 10 where different channel signals are output from different laser light sources 68 respectively. In these cases, each of the different control units 74 can be used to control the light source of the channel signal that transmits the channel received by the control unit. For example, each of the different control units 74 can be included in a feedback control loop that operates the laser light source, thereby controlling the frequency of the channel signal that transmits the channel received by this control unit, and thus controlling the system output signal that transmits the same channel. The electronic devices can operate the feedback control loops independently, and thus can operate the laser light sources within those feedback control loops independently.

[0218] The above LIDAR system shows a single system output signal that transmits each channel. As a result, each control mechanism can control the frequency - time pattern of a different one of the single system output signals. However, the LIDAR system can be constructed such that a plurality of different system output signals transmit the same channel. For example, the LIDAR output signal can be split into a plurality of different signals that are each used as a source of the system output signal. In this case, each of one or more control mechanisms can control the frequency - time pattern of a plurality of different system output signals that transmit the same channel.

[0219] The controller disclosed in connection with Figures 10A-10E operates based on the in-phase and quadrature components of the process variable signal. However, the controller can also be configured to operate based on the in-phase component of the process variable signal and exclude the quadrature component of the process variable signal. As a result, the controller can exclude the second optical combiner 286. Thus, the controller can include one optical combiner, and the delay and priority paths to the controller can extend to only one optical combiner within the controller.

[0220] Although the LIDAR system is disclosed as including multiple control mechanisms, each including one of the controls 74, the LIDAR system may include only one control mechanism. For example, the laser light source 68 may be configured to adjust the frequency of one laser light source 68 at a rate α i , the other laser source 68 can be configured to be adjusted at the same rate, so that controlling one laser source 68, as disclosed above, provides the desired adjustment to each laser source, and therefore the desired frequency versus time pattern, in each system output signal.

[0221] As mentioned above, delay waveguides such as delay waveguide 62 and / or first delay waveguide 80 can include a delay section 70 that can be used to increase the length of the delay waveguide beyond the length of priority waveguide 66. Delay section 70 can represent a helical arrangement of delay waveguide 62. This helical arrangement is selected to reduce the amount of space taken up by a longer waveguide such as delay waveguide 62 and / or first delay waveguide 80. FIG. 11 shows a portion of delay waveguide 62 or first delay waveguide 80 with a helical arrangement that functions as delay section 70. Near the center of the helical arrangement, the waveguide is folded back. The helical configuration is defined by the portion of the helical arrangement where the radius of curvature of the waveguide is smallest (R in FIG. 11 ). minThe helical arrangement may have other shapes, such as ellipses, rectangles, or triangles. As a result, the helical arrangement may include straight and / or substantially straight waveguide segments.

[0222] Suitable platforms for LIDAR and scanning chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. Figure 12A shows a cross-sectional view of a portion of a chip constructed from a silicon-on-insulator wafer. Silicon-on-insulator (SOI) wafers include a buried layer 310 between a substrate 312 and an optically transmissive medium 314. In silicon-on-insulator wafers, the buried layer 310 is silica, while the substrate 312 and optically transmissive medium 314 are silicon. The substrate 312 of an optical platform such as an SOI wafer can serve as the base for the entire LIDAR chip. For example, the optical components shown on the LIDAR chips in Figures 1A-4 can be located on the top and / or side surfaces of the substrate 312.

[0223] 12A is a cross-sectional view of a portion of a LIDAR chip including a waveguide structure applied to a LIDAR chip constructed from a silicon-on-insulator wafer. A ridge 316 of optical transmission medium extends away from a slab region 318 of optical transmission medium. The optical signal is confined between the top of the ridge 316 and the buried layer 310.

[0224] The dimensions of the ridge waveguide are shown in FIG. 12A. For example, the width of the ridge is designated w and the height is designated h. The thickness of the slab region is designated T. These dimensions may be more important than others in LIDAR applications because they require the use of higher levels of optical power than other applications. The ridge width (designated w) is greater than 1 μm and less than 4 μm, the ridge height (designated h) is greater than 1 μm and less than 4 μm, and the thickness of the slab region is greater than 0.5 μm and less than 3 μm. These dimensions may apply to straight or substantially straight sections of the waveguide, curved sections of the waveguide, and tapered sections of the waveguide. Thus, these sections of the waveguide are single-mode. However, in some cases, these dimensions may apply to straight or substantially straight sections of the waveguide. Additionally or alternatively, the slab thickness of the curved sections of the waveguide may be reduced to reduce optical loss in the curved sections of the waveguide. For example, the curved portion of the waveguide can have a ridge extending away from the slab region, and the ridge can have a thickness of 0.0 μm or more and less than 0.5 μm. While the above dimensions generally result in a single-mode structure in the straight or substantially straight portions of the waveguide, multimode tapered and / or curved portions may also result. Coupling between multimode and single-mode shapes can be achieved using tapered portions that do not substantially excite higher-order modes. Thus, the waveguide can be constructed such that signals transmitted through the waveguide are transmitted in single mode, even when transmitted through a waveguide section having multimode dimensions. The waveguide construction disclosed in connection with FIG. 12A is suitable for all or a portion of the waveguides on LIDAR chips constructed according to FIGS. 1A-4.

[0225] 12B-12D show an example of a feedback device 82 constructed on a silicon-on-insulator platform and suitable for use on a LIDAR chip constructed according to FIGS. 2 and 4. FIG. 12B is a top view of a portion of a LIDAR chip including feedback device 82. FIG. 12C is a cross-sectional view of feedback device 82 taken along the line labeled C in FIG. 12B. FIG. 12D is a cross-sectional view of feedback device 82 taken along the line labeled C in FIG. 12B.

[0226] The illustrated feedback device 82 includes a recess 360 that extends partially or completely through the optical transmission medium 314. The illustrated recess 360 does not extend into the buried layer 310, but it could extend into or through the buried layer 310. A surface of the recess 360 functions as a return surface 362. The return surface 362 is configured so that at least a portion of an optical signal incident on the return surface 362 from the optical transmission medium 314 is returned to the optical transmission medium 314. The mechanism by which this feedback occurs can be reflection at or by the return surface 362. For example, a recess medium 366 can be disposed within the recess 360 and in contact with the return surface 362. The recess medium 366 can be a material layer that fills the recess 360 or that is in contact with the return surface 362. The recess medium 366 can be a fluid or a solid. As shown in FIG. 12C , the recess medium 366 can be a solid that also functions as a cladding 368. In some cases, recess medium 366 has a lower refractive index than light transmission medium 314 to cause reflection at return surface 362. Suitable recess media having a lower refractive index than light transmission medium 314 include, but are not limited to, air, epoxy resin, silicon dioxide, and silicon nitride. Suitable recess media having a lower refractive index than light transmission medium 314 that can also function as cladding include, but are not limited to, silicon dioxide and silicon nitride.

[0227] In some cases, the recessed medium 366 is a medium that reflects the outgoing LIDAR signal or the input signal off the return surface 362. For example, the recessed medium 366 can be a reflective material 370 that contacts the return surface 362. FIG. 12D shows a layer of reflective material 370 that contacts the return surface 362. While FIG. 12D shows a cladding disposed over the recessed medium 366 and extending into the recess 360, the cladding is optional. Suitable reflective materials 370 include, but are not limited to, multilayer dielectric films including silicon dioxide, hafnium oxide, and aluminum oxide, and metals such as aluminum, nickel, and gold. Suitable cladding includes, but is not limited to, silicon dioxide, silicon nitride, and aluminum oxide.

[0228] As mentioned above, the splitter 120 can be a wavelength-dependent splitter. Suitable wavelength-dependent splitters include, but are not limited to, arrayed waveguide gratings and echelle gratings. Figures 13A-13D show an example of an echelle grating constructed on a silicon-on-insulator platform and suitable for use as the splitter 120 and / or wavelength-dependent splitter in a LIDAR system. For ease of explanation, the echelle grating is shown in the context of a splitter 120 on a scanning chip, but the illustrated echelle grating construction can also be used for splitters on a LIDAR chip or a scanning chip.

[0229] The scanning chip includes one or more first divider waveguides 400, second divider waveguides 402, and signal redirection portions 404 arranged around a free space region 406. When an echelle grating functions as the divider 120, each of the first divider waveguides can be one of the alternative waveguides 119, and each of the second divider waveguides 402 can be one of the channel output waveguides 121.

[0230] Each of the first splitter waveguides 400 can direct a switch signal into a free space region 406. The switch signal travels through the free space region 406 to the signal redirection section 404, which directs light from the switch signal into the second splitter waveguide 402. As a result, light from the switch signal travels from the signal redirection section 404 through the free space region 406 to the second splitter waveguide 402.

[0231] The signal redirection portion 404 is constructed such that the different wavelengths carried in the second signal separate into channel output signals as they travel away from the free space region 406. For example, FIG. 13A shows how the channel output signals carrying channels labeled λ1 and λ2 separate as they travel away from the signal redirection portion 404. The second splitter waveguide 402 terminates at a location where portions of the second splitter waveguide 402 each receive one of the channel output signals. The portions of the second splitter waveguide 402 that each receive one of the channel output signals change as the first splitter waveguide 400 carrying the switch signal changes.

[0232] The echelle grating of Figure 13A can be operated in the reverse direction as a multiplexer. A The channel output signal, denoted as A represents the channel feedback signal carrying B The channel output signal, denoted as B The channel return signal may represent a channel return signal carrying a signal. The channel return signal may travel from the second divider waveguide 402 through a spatial region 406 to a signal redirector 404. The signal redirector 404 may direct light from the channel return signals to the first divider waveguide 400. The signal redirector 404 is configured such that light from the channel return signals combine to form an assembly return signal. The assembly return signal is received by the first divider waveguide 400, which outputs a switch signal.

[0233] Although the echelle grating in Figure 13A is shown as being constructed on a silicon-on-insulator platform, other platforms can be used. The first divider waveguide 400 and / or the second divider waveguide 402 can be constructed as disclosed in the context of Figure 12A. For example, Figure 12A can represent a cross section of Figure 13A taken along any of the lines labeled B in Figure 13A.

[0234] FIG. 13B is a cross-sectional view of the echelle grating taken through the signal redirection portion 404, as shown by the line labeled E in FIG. 13A. The illustrated signal redirection portion 404 includes a recess 410 that extends partially or completely through the optical transmission medium 314. The illustrated recess 410 does not extend into the buried layer 310, but it could extend into or through the buried layer 310. The surface of the recess 410 functions as a return surface 362. The return surface 362 is configured so that at least a portion of the switch signal or channel return signal incident on the return surface 362 from the optical transmission medium 314 is returned to the optical transmission medium 314. The mechanism by which this feedback occurs can be reflection at or by the return surface 362. For example, a recess medium 366 can be disposed within the recess 410 and in contact with the return surface 362. The recess medium 366 can be a layer of material that fills the recess 410 or contacts the return surface 362. The recessed medium 366 can be a fluid or a solid. As shown in FIG. 13B, the recessed medium 366 can be a solid that also functions as a cladding 416 for all or a portion of the LIDAR chip. In some cases, the recessed medium 366 has a lower refractive index than the optically transmitting medium 314, causing reflection at the return surface 362. Suitable recessed media having a lower refractive index than the optically transmitting medium 314 include, but are not limited to, air, epoxy resin, silicon dioxide, and silicon nitride. Suitable recessed media having a lower refractive index than the optically transmitting medium 314 that can also function as a cladding include, but are not limited to, silicon dioxide and silicon nitride.

[0235] In some cases, recessed medium 366 is a medium that reflects the outgoing LIDAR signal or the input signal off return surface 362. For example, recessed medium 366 can be a reflective material 370 in contact with return surface 362. FIG. 13C shows a layer of reflective material 370 in contact with return surface 362. Suitable reflective materials 370 include, but are not limited to, multilayer dielectric films including silicon dioxide, hafnium oxide, and aluminum oxide, and metals such as aluminum, nickel, and gold. Suitable cladding includes, but is not limited to, silicon dioxide, silicon nitride, and aluminum oxide.

[0236] 13D is an enlarged top view of a portion of the return surface 362, excluding the recess medium 366 or reflective material 370 disposed within the recess 410. The return surface 362 is configured to function as an optical grating. For example, the return surface 362 includes a plurality of grooves 422 arranged such that the signal redirection portion 404 functions as an echelle grating. Suitable groove 422 configurations include, but are not limited to, steps. The bandwidth of an optical filter including or consisting of an echelle grating can be adjusted by changing the focal length and / or changing the dimensions of the grating.

[0237] The free space region 406 can confine the optical signal in one direction. For example, the free space region 406 in FIGS. 13A-13D can confine the optical signal in the vertical direction. In these cases, the optical signal can diverge or converge laterally. As a result, all or part of the free space region 406 can be a slab waveguide.

[0238] Various optical switches suitable for LIDAR systems can be constructed on planar optical platforms, such as silicon-on-insulator platforms. Examples of optical switches suitable for integration into silicon-on-insulator platforms include, but are not limited to, Mach-Zehnder interferometers. Figure 14 shows a schematic diagram of a Mach-Zehnder interferometer. The switch includes a first switch waveguide 500 connecting a common waveguide 117 to a first of a plurality of alternate waveguides 119A. A second of the plurality of alternate waveguides 119B is connected to a second switch waveguide 502. The first switch waveguide 500 and the second switch waveguide 502 are included in a first optical coupler 504 and a second optical coupler 506. A phase shifter 508 is disposed along the first switch waveguide 500 or the second switch waveguide 502 between the first optical coupler 504 and the second optical coupler 506. Suitable phase shifters include, but are not limited to, PIN diodes, PN junctions operating in carrier depletion mode, and thermal heaters.

[0239] The electronics can operate the phase shifter to switch the switch between a pass mode and a switch mode. In the pass mode, the switch signal transmitted on the common waveguide 117 passes through the first alternate waveguide 119A. In the switch mode, the switch signal transmitted on the common waveguide 117 is directed to the second alternate waveguide 119B.

[0240] While the optical switch shown in Figure 14 is suitable for a LIDAR system that directs a switch signal to one of two alternative waveguides 119A, a LIDAR system may also direct a switch signal to more than two alternative waveguides 119A. In these cases, switches such as the optical switch of Figure 14 may be cascaded so that the electronics can direct the switch signal to more than two alternative waveguides 119A.

[0241] The LIDAR chip may include a control assembly other than those disclosed above. Suitable examples of control assemblies are disclosed in U.S. Patent Application No. 17 / 244,869, filed April 29, 2021, entitled "Size Reduction of LIDAR System Control Assemblies," which is incorporated herein in its entirety.

[0242] FIG. 15A shows the control assembly of FIG. 4 modified so that the control section 74 simultaneously receives a series of different channels. As described in the context of FIG. 4, each splitter 50 moves a portion of a channel signal from the light source waveguide 69 to a control waveguide 52. The portion of the channel signal received by the control waveguide 52 can function as a drop signal. Each channel signal carries one of the different channels, so that each light in the drop signal carries one of the different channels.

[0243] Each control waveguide 52 carries one of the branch signals to a signal mixer 522 that outputs the branch signals onto a common channel waveguide 524. The signal mixer may be a wavelength-dependent mixer such as a multiplexer. Alternatively, the signal mixer may be a wavelength-independent mixer such as a Y-junction, cascaded Y-junctions, a multimode interferometer (MMI), or a star coupler.

[0244] An attenuator 526 is disposed along each control waveguide 52. The attenuator can be operated by electronics 62. The electronics 62 operates the attenuator 526 so that one of the branch signals is received by the signal mixer 522 and output to the common channel waveguide 524, where it acts as a selected signal. The attenuator 526 is operated so that one or more branch signals that are not the selected signal are sufficiently attenuated and effectively blocked from reception by the signal mixer 522. As a result, one or more branch signals that are not the selected signal are not output to the common channel waveguide 524. Thus, the electronics 62 can operate the attenuator 526 to select which of the branch signals to output to the common channel waveguide 524. The combination of the attenuator 526 and the signal mixer can operate as an optical switch. As a result, the illustrated attenuator 526 and signal mixer 522 can be replaced with an optical switch.

[0245] The dropped signal output onto common channel waveguide 524 can function as a selected signal. Common channel waveguide 524 transmits the selected signal to splitter 78, which splits the selected signal into a priority signal and a first delay signal. As described in connection with FIG. 4, the priority signal is received on priority waveguide 66, and the first delay signal is received at first delay waveguide 80. Thus, light from the selected signal travels on a delay path from splitter 78 to controller 74, and light from the dropped signal also travels on a priority path from splitter 78 to controller 74. As previously described, the controller simultaneously receives a delay path signal carrying one of the channels from the delay path and a priority path signal carrying the same channel from the priority path.

[0246] The electronics 62 operates the attenuator 526 so that a series of different drop signals carrying different channels are received at the signal mixer 522. For example, the electronics 62 can operate the attenuator 526 so that drop signals from each of the different channels are sequentially received at the signal mixer 522. As a result, the selected signal carries a series of different channels. Thus, the channels carried by the delayed path signal and the preferred path signal received by the control unit 74 change continuously. The control unit 74 can be operated as disclosed above. For example, the optical control unit 322 (FIGS. 10D and 10E) can control the laser light source 68 (FIG. 15A), which is the light source for the channel received by the control unit 74, in response to an instruction signal resulting from the control unit 74 receiving that channel. As a result, the control unit 74 and / or the optical control unit 322 can sequentially control the different laser light sources 68.

[0247] 15A, each splitter 50 can be configured to transfer a portion of the reference signal from one of the reference waveguides 40 onto the control waveguide 52, as shown in FIG. 15B. The portion of the channel signal received in the reference waveguide 40 can be used as the split signal. Such a configuration may be desirable when the channel signal output from the laser source 68 carries multiple wavelength channels.

[0248] In some cases, the LIDAR adapter may be removed from the LIDAR system. In these cases, components from the scanning chip may optionally be integrated into the LIDAR chip. The optical switch 118 may receive the outgoing LIDAR signal from the utility waveguide 12. Thus, the portion of the outgoing LIDAR signal received at the switch may function as the switch signal. Also, the input waveguide 16 receives the incoming LIDAR signal from the splitter 36, rather than from the adapter, to receive the LIDAR signal.

[0249] For example, FIG. 16 shows the LIDAR system of FIG. 15B modified to exclude the LIDAR adapter. If an object is present in the sample area illuminated by the system output signal, the object may reflect light from the system output signal. The reflected light returns to the LIDAR system as a system return signal. Each system return signal may carry one of the different channels. The system return signals may be received by an optical grating 123. The optical grating 123 may be configured to output at least a portion of each system output signal. The portion of each system output signal output from the optical grating 123 may serve as a channel return signal. The optical grating 123 may be configured to receive at least a portion of each system output signal from the optical grating 123 ... i ) is transmitted through wavelength channel i(λ i ) in the opposite direction. The channel feedback signal carrying wavelength channel i passes through signal redirection unit 122 and travels along the same or substantially the same path as the channel output signal carrying wavelength channel i (λ i ) travels in the opposite direction along the same or substantially the same path as the channel output signal carrying the

[0250] The scanning chip can receive a channel return signal that includes or is composed of light from a different one of the system return signals. For example, the scanning chip can receive the channel return signal from the signal redirector 122. As an example, the channel output waveguide 121 receives a channel return signal that carries the same wavelength channel as the channel output signal output from the channel output waveguide 121. For example, during illumination of the sample area, the channel (λ i ) is transmitted through the channel (λ) during illumination of the sample area. i ) are fed back to channel output waveguides 121 that output channel output signals carrying the sample area illumination. Some of the channel output waveguides 121 do not output channel output signals during illumination of the sample area, so some of the channel output waveguides 121 do not receive channel return signals during illumination of the sample area, but may receive channel return signals during illumination of a different sample area.

[0251] The channel output waveguides 121 transmit the received channel return signals to the splitter 120. The splitter 120 combines the channel return signals with the assembly return signals received on one of the alternative waveguides 119. Thus, the splitter 120 can operate as a demultiplexer / multiplexer. The alternative waveguide 119, which receives the assembly return signal, transmits the assembly return signal to the optical switch 118. The optical switch 118 directs the assembly return signal to the utility waveguide 12. The utility waveguide 12 transmits the assembly return signal to the splitter 36. The splitter 36 transfers at least a portion of the assembly return signal from the utility waveguide 12 onto the input waveguide 16. The portion of the assembly return signal that enters the input waveguide 16 functions as the incident LIDAR signal. As described above, the input waveguide 16 transmits the incident LIDAR signal to the comparison demultiplexer 30.

[0252] The optical sensor that interfaces with the waveguide on the LIDAR chip can be separate from the chip and attached to the chip. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, InGaAs PIN photodiodes or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu Corporation, Hamamatsu, Japan. These optical sensors can be located in the center of the LIDAR chip. Alternatively, all or part of the waveguide terminating in the optical sensor can terminate in a facet at the edge of the chip, and the optical sensor can be attached to the edge of the chip on the facet. This allows the optical sensor to receive light passing through the facet. The use of an optical sensor that is separate from the chip is suitable for all or part of the optical sensors selected from the group consisting of the first auxiliary optical sensor 218, the second auxiliary optical sensor 220, the first optical sensor 223, and the second optical sensor 224.

[0253] As an alternative to a separate optical sensor, all or part of the optical sensor can be integrated on the chip. For example, examples of optical sensors interfaced with ridge waveguides on chips constructed from silicon-on-insulator wafers are described in Optics Express Vol. 15, No. 21, pp. 13965-13971 (2007), U.S. Patent No. 8,093,080 issued January 10, 2012, U.S. Patent No. 8,242,432 issued August 14, 2012, and U.S. Patent No. 6,108,8472 issued August 22, 2000, all of which are incorporated herein in their entirety. The use of an optical sensor integrated on the chip is suitable for all or part of the optical sensors selected from the group consisting of auxiliary optical sensor 218, second auxiliary optical sensor 220, first optical sensor 223, and second optical sensor 224.

[0254] A suitable laser source 68 can be a laser chip that is separate from the LIDAR chip and then attached to the LIDAR chip. For example, the laser source 68 can be a laser chip that is attached to the chip using a flip-chip structure. The use of a flip-chip structure is suitable for interfacing the laser source 68 with a ridge waveguide on a chip constructed from a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 can include an optical grating (not shown), such as a Bragg grating, that functions as a reflector for an external cavity laser. In these cases, the laser source 68 can include a gain element that is separate from the LIDAR chip and then attached to the LIDAR chip using a flip-chip structure. Examples of suitable interfaces between flip-chip gain elements and ridge waveguides on chips constructed from silicon-on-insulator wafers are described in U.S. Patent No. 9,705,278, issued July 11, 2017, and U.S. Patent No. 5,991,484, issued November 23, 1999, both of which are incorporated herein in their entireties. If the laser source 68 is a gain element or laser chip, the electronics 62 can vary the frequency of the channel signal by varying the current level applied to the gain element or laser cavity.

[0255] Suitable electronics 62 include, but are not limited to, electronic controllers that include or consist of analog electrical circuitry, digital electrical circuitry, processors, microprocessors, digital signal processors (DSPs), field programmable gate arrays (FPGAs), computers, microcomputers, or any combination suitable for performing the above-described operation, control, and control functions. In some cases, the electronic controller has access to a memory containing instructions executed by the electronic controller in performing the operation, control, and control functions. Although the electronics is shown as a single component in a single location, the electronics may include multiple different components that are separate from one another and / or located in different locations. Also, as noted above, all or a portion of the disclosed electronics may be included on a chip, including integrated electronics on the chip.

[0256] The LIDAR system described above includes multiple optical components, such as a LIDAR chip, a LIDAR adapter, a light source, a light sensor, a waveguide, and an amplifier. In some cases, the LIDAR system includes one or more passive optical components in addition to or in place of the optical components shown. Passive optical components can be solid-state components that do not include moving parts. Suitable passive optical components include, but are not limited to, lenses, mirrors, optical gratings, reflective surfaces, splitters, demultiplexers, multiplexers, polarizers, polarization splitters, and polarization rotators. In some cases, the LIDAR system includes one or more active optical components in addition to or in place of the optical components shown. Suitable active optical components include, but are not limited to, optical switches, phase tuners, attenuators, steerable mirrors, steerable lenses, tunable demultiplexers, tunable multiplexers, etc.

[0257] Other embodiments, combinations, and modifications of the present invention will occur to those skilled in the art in light of these teachings. Accordingly, the present invention is limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.

Claims

1. 1. A LIDAR system comprising a switch and an optical grating, the switch is configured to receive a switch signal from the switch and direct the switch signal to one of a plurality of different alternative waveguides, such that the alternative waveguide to which the switch directs the switch signal carries a plurality of different channels; the optical grating is configured to receive a plurality of different channel output signals, each different channel output signal including light from the switch signal and carrying one of the different channels; the optical grating is configured to output each channel output signal such that the direction in which that channel output signal travels away from the optical grating changes in response to a change in the alternate waveguide through which the switch directs the switch signal; LIDAR system.

2. The system of claim 1 , wherein the optical grating is selected from the group consisting of a diffraction grating, a holographic diffraction grating, and a digital planar holographic diffraction grating.

3. 10. The system of claim 1, wherein the LIDAR system is configured to output a plurality of system output signals, each carrying one of the different channels, and wherein the direction in which each of the system output signals travels away from the LIDAR system varies in response to a change in the alternate waveguide to which a switch directs a switch signal.

4. 2. The system of claim 1, wherein the optical grating receives different channel output signals from a lens configured such that the direction in which each of the channel output signals travels away from the lens changes in response to a change in the alternate waveguide through which the switch directs a switch signal.

5. 10. The system of claim 1, further comprising a splitter configured to receive a switch signal from an alternate waveguide along which the switch directs the switch signal, The system, wherein the divider is configured to divide the switch signal into the plurality of different channel output signals.

6. The system of claim 5 , wherein the divider is a demultiplexer.

7. The system of claim 5 , wherein the optical path along which each of the channel output signals travels from the splitter to the optical grating passes through a lens.

8. The system of claim 7 , wherein each of the channel output signals is incident on a different region of the lens.

9. the splitter includes a plurality of first splitter waveguides and a plurality of second splitter waveguides; the divider is configured to receive the switch signal on one of the first divider waveguides; the splitter is configured to output the channel output signals on a portion of the second splitter waveguide. The system of claim 5.

10. 10. The system of claim 9, wherein the splitter comprises at least four first splitter waveguides and at least sixteen second splitter waveguides.

11. 11. The system of claim 10, wherein the system is configured to output system output signals each including light from a different one of the channel output signals, and wherein a viewing angle of the system output signals is greater than 20° and less than 60°.

12. 10. The system of claim 9, wherein each of the second splitter waveguides terminates in a facet, and the center-to-center spacing between the facets is between 5 μm and 100 μm.

13. 10. The system of claim 9, wherein the portion of the second divider waveguide from which the channel output signal is output varies in response to a change in the first divider waveguide receiving the switch signal.

14. 10. The system of claim 9, wherein the portion of the second divider waveguide through which the channel output signal is output varies in response to a change in the alternate waveguide receiving the switch signal.

15. The system of claim 9 , wherein each of the alternative waveguides functions as one of the first splitter waveguides.

16. 10. The system of claim 9, wherein the divider is a demultiplexer.

17. The system of claim 1 , wherein each of the channel output signals has a different angle of incidence with respect to the optical grating.

18. The system of claim 1 , wherein the dispersion of the optical grating is in the range of 0.05 degrees / nm to 0.2 degrees / nm.

19. 1. A method of operating a LIDAR system, comprising: directing a switch signal to one of a plurality of different alternative waveguides such that the alternative waveguide to which the switch signal is directed receives the switch signal from a switch, the switch signal carrying a plurality of different channels; receiving a plurality of different channel output signals at an optical grating, each of the different channel output signals including light from the switch signal and carrying a different one of the channels; and changing an alternate waveguide through which the switch directs a switch signal, the direction in which each of the channel output signals travels away from the optical grating changing in response to the change in the alternate waveguide through which the switch directs the switch signal; A method comprising:

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