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 alternative waveguides, the switch signal carrying a plurality of different channels. The system also includes one or more redirecting elements that receive a plurality of different channel output signals, each channel output signal carrying a different one of the channels. The one or more redirecting elements are configured to redirect the channel output signals such that a direction in which each channel output signal travels away from the one or more redirecting elements changes in response to a change in the alternative waveguide that receives the switch signal.

Description

Related Applications

[0001] This application is a continuation of U.S. Patent Application No. 17 / 351,170, entitled "SCANNING MULTIPLE LIDAR SYSTEM OUTPUT SIGNALS," filed June 17, 2021, and is incorporated in its entirety.

[0002] The present invention relates to optical devices, and in particular to LIDAR systems.

[0003] There is an increasing commercial demand for LIDAR systems that can be used in applications such as ADAS (Advanced Driver Assistance Systems) and AR (Augmented Reality). However, LIDAR systems typically use moving mirrors to scan the system output signal from one location to another within a field of view. Stopping and starting the movement of these mirrors takes time due to inertia. Most LIDAR applications require rapid scanning of the field of view by the system output signal, so it is desirable to avoid the time delay associated with the mirror movement. As a result, the system output signal is typically scanned continuously within the field of view. The continuous movement of the system output signal while generating LIDAR data (line of sight velocity and / or distance between the LIDAR system and objects external to the LIDAR system) can introduce errors and complications into the LIDAR system. Therefore, an improved LIDAR system is needed. Overview

[0004] The LIDAR system includes a switch configured to direct a switch signal to one of a plurality of different alternative waveguides, the switch signal carrying a plurality of different channels. The system also includes one or more redirecting elements that receive a plurality of different channel output signals, each channel output signal carrying a different one of the channels. The one or more redirecting elements are configured to redirect the channel output signals such that a direction in which each channel output signal travels away from the one or more redirecting elements changes in response to a change in the alternative waveguide that receives the switch signal.

[0005] Another embodiment of the LIDAR system includes a scanning chip configured to direct the movement of system output signals away from the LIDAR system to a plurality of different sample areas in a field of view. Each system output signal carries a different channel. The system also includes a LIDAR chip configured to generate composite signals, separate from the scanning chip, each pulsating at a pulsating frequency. Generating each composite signal includes combining a comparison signal and a reference signal carrying the same channel. Each of the comparison signals includes light from one of a plurality of different system return signals carrying a different channel. Each system return signal includes light from one of the system output signals after it has been reflected by an object in the field of view. Each reference signal includes light that has not been reflected by the object. The system also includes an adapter configured to separate an output signal from the return signal. The output signal includes light that has not been reflected by an object in the field of view. The return signal includes light from the output signal and light from each system return signal. Each system output signal includes light from the output signal. The system also includes electronics configured to use the beating frequency to generate LIDAR data indicative of one or more items selected from the group consisting of: a line-of-sight velocity between the LIDAR system and an object, and a distance between the LIDAR system and the object. [Brief description of the drawings]

[0006] FIG. 1A is a top view of the LIDAR chip.

[0007] FIG. 1B shows a light source that includes multiple laser sources.

[0008] FIG. 2 is a top view of the LIDAR chip.

[0009] FIG. 3 is a top view of the LIDAR chip.

[0010] FIG. 4 is a top view of the LIDAR chip.

[0011] FIG. 5 is a top view of a LIDAR assembly including a LIDAR adapter in optical communication with the LIDAR chip.

[0012] FIG. 6 is a top view of a scanning tip being used with an adapter constructed according to FIG.

[0013] FIG. 7A is a top view of a LIDAR system including a LIDAR chip as disclosed in the context of FIG. 1A, a LIDAR adapter as disclosed in the context of FIG. 5, and a scanning chip and redirecting element as disclosed in the context of FIG.

[0014] FIG. 7B is a top view of another embodiment of a LIDAR system including the LIDAR system of FIG. 7A in combination with multiple steering elements.

[0015] FIG. 8A shows an example of a processing element applied to a LIDAR system.

[0016] FIG. 8B shows a schematic diagram of the electronics applied to a processing element constructed according to FIG. 7A.

[0017] FIG. 8C is a graph of frequency versus time of the system output signal having triangular frequency tuning.

[0018] FIG. 8D illustrates another example of a processing element applied to a LIDAR system.

[0019] FIG. 8E shows a schematic diagram of the electronics applied to a processing element constructed according to FIG. 7D.

[0020] Figures 9A and 9B show an example of a control element that applies to all or part of the control elements disclosed in the context of Figures 1A to 4. Figure 9A shows an interface between optical components and a light sensor that may be located on a LIDAR chip.

[0021] FIG. 9B is a schematic diagram of the relationship between electronics and light sensors that may be included in a LIDAR chip.

[0022] FIG. 9C 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.

[0023] FIG. 9D shows an example of a process variable discrimination element applied to the electronics of a LIDAR system.

[0024] FIG. 9E illustrates another example of a process variable identification element applied to the electronics of a LIDAR system.

[0025] FIG. 10 is a top view of a portion of a waveguide that includes a helical waveguide.

[0026] Figure 11A is a cross-sectional view of a portion of a LIDAR chip containing a waveguide on a silicon-on-insulator platform.

[0027] Figures 11B to 11D show an example of a feedback device built on a silicon-on-insulator platform and applied to a LIDAR chip constructed according to Figures 2 and 4. Figure 11B shows a top view of a portion of a LIDAR chip equipped with the feedback device.

[0028] FIG. 11C is a cross-sectional view of the feedback device taken along the line labeled C in FIG. 11B.

[0029] FIG. 11D is a cross-sectional view of the feedback device taken along the line labeled C in FIG. 11B.

[0030] FIG. 12A is a top view of a portion of a LIDAR chip including an echelle grating.

[0031] Figure 12B is a cross-sectional view of an echelle grating made through a redirecting element contained on the LIDAR chip of Figure 12 A. The cross-section was made along the line labeled E in Figure 12A.

[0032] FIG. 12C is a cross-sectional view of another embodiment of an echelle grating.

[0033] FIG. 12D is an enlarged top view of a portion of the return surface.

[0034] FIG. 13 is a top view of an example of an optical switch.

[0035] The LIDAR system is configured to simultaneously output multiple system output signals. In some cases, the system output signals each carry a different one of the channels. The LIDAR system includes a scanning chip that exchanges optical signals with the LIDAR assembly. The LIDAR system can include electronics that operate the scanning chip to scan the direction in which the different system output signals move away from the LIDAR system. The different system output signals are thereby scanned to different sample areas in the field of view, respectively. The electronics can use light returning from the system output signals to the LIDAR system to generate LIDAR data indicative of line-of-sight velocity and / or distance between the LIDAR system and an object located in the field of view. The scanning chip can be a solid-state chip that includes integrated optical circuitry. The ability to scan multiple system output signals using solid-state devices increases the reliability of the LIDAR data and the speed at which the LIDAR data is generated.

[0036] FIG. 1A is a top view of a LIDAR chip configured to generate a composite signal pulsating at a pulsating frequency that electronics can use to generate LIDAR data. The LIDAR chip includes an optical integrated circuit. The optical 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 increase in wavelength 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. Suitable light sources 10 for generating multiple channels having periodically spaced wavelengths include, but are not limited to, a comb laser, one or more single wavelength lasers, and / or one or more multi-wavelength lasers having outputs multiplexed into the outgoing LIDAR signal.

[0037] 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 carries the outgoing LIDAR signal to the facet 14. The facet 14 can be positioned such that the outgoing LIDAR signal passing through the facet 14 exits the chip to serve 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 passing through the facet 14 exits the chip to serve as the LIDAR output signal.

[0038] 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 is fed back to an input waveguide 16 on the LIDAR chip as a LIDAR input signal. The input waveguide 16 includes facets 18 through which the LIDAR input signal can enter the input waveguide 16. The portion of the LIDAR input signal that enters the input waveguide 16 can be considered the incident LIDAR signal. The input waveguide 16 carries the incident LIDAR signal to a comparison splitter 30. If the incident LIDAR signal includes multiple channels, the comparison splitter 30 splits the incident LIDAR signal into different comparison signals, each carrying a different channel. The comparison splitter 30 outputs the comparison signals on different comparison waveguides 32. Each of the comparison waveguides 32 carries one of the comparison signals to a different processing element 34.

[0039] The LIDAR chip includes a splitter 36 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto a reference waveguide 37 as a reference signal. Suitable splitters 36 include, but are not limited to, optical couplers, y-junctions, and MMIs.

[0040] The reference waveguide 37 carries the reference optical signal to a reference splitter 38. If the reference optical signal includes multiple channels, the reference splitter 38 splits the reference optical signal into different reference signals, each having a different wavelength. The reference splitter 38 outputs the reference signals on different reference waveguides 40. Each of the reference waveguides 40 carries one of the reference signals to a different one of the processing elements 34.

[0041] The comparison waveguide 32 and the reference waveguide 40 are configured such that a comparison signal and a corresponding reference signal are received at the same processing element 34. For example, the comparison waveguide 32 and the reference waveguide 40 are configured such that a comparison signal and a reference signal that are at the same wavelength and / or carry the same channel are received at the same processing element 34.

[0042] As described in more detail below, each processing element 34 combines the comparison signal with a corresponding reference signal to form a composite signal carrying LIDAR data for the sample area on the field of view. The composite signal can then be processed to extract LIDAR data for the sample area (such as radial velocity and / or distance between the LIDAR system and objects external to the LIDAR system).

[0043] The LIDAR chip may 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 serves as the tap signal. The splitter 50 may be a wavelength independent splitter such as a directional coupler, an optical coupler, a y-junction, a tapered coupler, and a multimode interference (MMI) device.

[0044] The control waveguide 52 carries the tap signal to a differential delay mechanism 54 that may provide a first indication of the delay between the delay path signal and the expedited path signal. The delay mechanism 54 includes a splitter 60 that receives the tap signal and splits the tap signal into a delay signal and an expedited signal. The splitter 60 may be a wavelength independent splitter. For example, the second splitter 60 may be configured such that the delay signal and the expedited signal carry the same or substantially the same wavelength selection. Thus, the delay signal and the expedited signal may each carry multiple channels. In some cases, the delay signal and the expedited signal carry respective channels. Suitable second splitters 68 include, but are not limited to, directional couplers, optical couplers, y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0045] The delay waveguide 62 carries the delayed signal to a first divider 64. The forward waveguide 66 carries the forward signal to a second divider 68. The delay waveguide 62 may include a delay section 70 that may be used to increase the length of the delay waveguide beyond the length of the forward waveguide 66. For example, the delay section 70 shown in FIG. 1A may represent a helical arrangement of the delay waveguide 62. The longer length of the delay waveguide 62 creates a delay between the delayed signal and the forward signal.

[0046] The first splitter 64 splits the delayed signal into delayed channel signals, each of which is carried on a different delay channel waveguide 72. The first splitter 64 may be a wavelength-dependent splitter. For example, the first splitter 64 may be configured such that each of the delayed channel signals carries a different wavelength selection. As an example, the first splitter 64 may be configured such that each of the delayed channel signals carries one different channel. Each of the delay channel waveguides 72 carries one of the delayed channel signals to a different control element 74. As a result, each of the control elements 74 receives a delayed channel signal carrying a different channel. Thus, each of the control elements 74 may be associated with a different channel. Suitable first splitters 64 include, but are not limited to, splitters such as arrayed waveguide gratings, echelle gratings, and ring resonator-based devices.

[0047] The second splitter 68 splits the prompt signal into prompt sub-signals each carried on a different prompt sub-waveguide 76. The second splitter 68 can be a wavelength-dependent splitter. For example, the second splitter 68 can be configured such that each of the prompt sub-signals carries the same or substantially the same wavelength selection. Thus, each of the prompt sub-signals can carry multiple channels. In some cases, each of the prompt sub-signals carries each channel. Each of the prompt sub-waveguides 76 carries one of the prompt sub-signals to a different one of the control elements 74. As a result, each of the control elements 74 can receive a prompt sub-signal that carries the channel associated with that control element 74 and also carries one or more other channels. Thus, each of the control elements 74 can receive a prompt sub-signal and a delayed channel signal carrying the same channel. Suitable second splitters 68 include, but are not limited to, directional couplers, optical couplers, y-junctions, tapered couplers, and multi-mode interference (MMI) devices.

[0048] In some examples, the second splitter 68 is a wavelength-dependent splitter. The wavelength-dependent splitter functioning as the second splitter 68 may be configured such that the prompt sub-signals each carry a different channel. Additionally, the prompt sub-waveguides 76 may be configured such that the prompt sub-signals received by each control element 74 carry the channel associated with that control element 74. As a result, each control element 74 may receive a prompt sub-signal carrying the same channel as the delayed channel signal received by the control element 74.

[0049] As is evident from the above description, light from the tap signal passes through one of several different delay paths from the splitter 60 to one of the couplers in the control element 74. Each of the delay paths is defined primarily by the delay waveguide 62, the first splitter 64, and one of the delay channel waveguides 72. A delay path signal passes through each delay path, which is a combination of the delay signal and one of the delay channel signals. Light from the tap signal also passes through one of several different facilitate paths from the splitter 60 to the control element 74. Each of the facilitate paths is defined primarily by one of the facilitate sub-waveguides 76, the second splitter 68, and one of the facilitate sub-waveguides 76. A facilitate path signal passes through each facilitate path, which is a combination of the facilitate signal and one of the facilitate sub-signals.

[0050] Each delay path has a common portion and an isolated portion. The common portion of each delay path is shared by multiple delay paths. In contrast, the isolated portions of a delay path are not shared with other delay paths. Optical signals passing through the common portion may carry multiple different channels. Optical signals passing through the isolated portions may each carry a different channel. For example, delay waveguide 62 is common to each delay path and functions as a common portion. In contrast, delay channel waveguide 72 is each isolated from the other delay channel waveguides 72 and functions as an isolated portion.

[0051] Each facilitate path has a common portion and a separation portion. The common portion of each facilitate path is shared by multiple facilitate paths. In contrast, the separation portions of the facilitate path are not shared with other facilitate paths. Optical signals passing through the common portion may carry multiple different channels. Optical signals passing through the separation portions may each carry a different channel. For example, facilitate waveguide 66 is common to each delay path and functions as a common portion. In contrast, each facilitate sub-waveguide 76 may be separated from the other facilitate sub-waveguides 76 and function as a separation portion.

[0052] The expedited and delayed paths are configured such that each control element 74 receives delay and expedited path signals that carry the same channel (common channel). The expedited and delayed paths may be configured such that each different control element 74 receives delay and expedited path signals that carry different common channels. The delay and expedited paths may also be configured such that the delay and / or expedited path signals received at each control element 74 carry only one of the channels or essentially only one of the channels.

[0053] The components defining the delay path and the expedited path are configured such that, for an expedited path signal and a delayed path signal arriving at the same control element 74, the delayed path signal arrives at the control element 74 later than the expedited path signal.

[0054] Since the delay path signal and the expedited path signal contain different portions of the tap signal, each control element 74 receives a delayed portion of the tap signal and also receives an expedited portion of the tap signal, but the delayed portion is delayed relative to the tap portion. The components defining the delay path and the expedited path can be configured to provide a delay between the tap portion and the expedited portion arriving at the control element 74. For example, the waveguides defining the delay path and the waveguides defining the expedited path can be configured such that the delay path is longer than the expedited path by a length that provides the desired delay at each control element 84. The length of the delay section 70 can be a primary indicator of the length difference between the delay path and the expedited path leading to the same control element 74. As is evident from FIG. 1A, delayed signals carrying different channels pass through the same delay section 70. As a result, the same delay section 70 is common to each delay path and each channel.

[0055] Further details regarding the configuration and operation of the control assembly are described in U.S. patent application Ser. No. 17 / 244,869, entitled "Signal Reduction of LIDAR System Control Assembly," filed April 29, 2021, and incorporated herein in its entirety.

[0056] Although the light source 10 is shown as being located on the LIDAR chip, all or a portion of the light source 10 may be located remotely from the LIDAR chip. FIG. 1B shows an example of a light source 10 including multiple laser sources 68. The light sources in FIG. 1B may be located remotely from the LIDAR chip, located on the LIDAR chip, or integrated on the LIDAR chip. In some cases, each of the laser sources 68 outputs a channel signal on a light source waveguide 70. Each channel signal can carry one or more channels. For example, FIG. 1B shows one possible arrangement, in which a light source waveguide 70 guiding a channel signal carrying channel i is located at λ. i where i represents a channel index, and the channels are associated with channel indices i=1 to i=N, respectively.

[0057] Each of the optical source waveguides 70 carries a channel signal to a laser combiner 72 that combines the channel signals to form an optical signal that is received on the channel or utility waveguide 12. Suitable laser combiners 72 include, but are not limited to, arrayed waveguide grating (AWG) combiners, echelle grating combiners, and star combiners. The electronics can operate the laser sources 68 such that the laser sources 68 output each channel simultaneously. The electronics can operate the laser sources 68 such that the laser sources 68 output each channel simultaneously.

[0058] In some cases, each of the laser sources 68 outputs one of the channels on the light source waveguide 70. The total number of laser sources 68 included in the light source 10 can be greater than or equal to the number of LIDAR output signals simultaneously directed to the sample region. In some cases, the total number of laser sources 68 included in the 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 LIDAR output signal simultaneously directed to the sample region.

[0059] The electronics 62 can independently operate the laser sources 68. For example, the electronics can operate the laser sources 68 to provide a particular LIDAR output signal having a particular frequency versus time waveform. Because the electronics can independently operate the laser sources 68 and each laser source 68 can be a source of a different LIDAR output signal, the electronics can operate the laser sources 68 such that the different LIDAR output signals have different frequency versus time waveforms.

[0060] 2 shows the LIDAR chip of FIGS. 1A and 1B modified to reduce the length of the delay section 70. A splitter 60 receives the tap signal from the control waveguide 52 and splits the tap signal into a prompt signal and a first delayed signal. The prompt signal is received on a prompt waveguide 66 as disclosed in the context of FIG. 1. Suitable splitters 60 include, but are not limited to, a multi-mode interference (MMI) coupler and a directional coupler.

[0061] The first delay waveguide 80 receives the first delayed signal from the splitter 60. The first delay waveguide 80 conveys 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 passes from the feedback device 82 through the first delay waveguide 80 back to the splitter 60. As a result, the first delayed signal passes through the first delay waveguide 80 twice. For example, the first delayed signal passes through the first delay waveguide 80 once in each direction as shown by the arrows labeled A in FIG. 2. Suitable feedback devices 82 include, but are not limited to, mirrors and reflective surfaces.

[0062] The splitter 60 receives a first delayed signal from the first delay waveguide 80 and outputs the first delayed signal to the delay waveguide 62. The portion of the first delayed signal received on the delay waveguide 62 functions as a second delayed signal carried on the delay waveguide 62. The delay waveguide 62 carries the second delayed signal to the first splitter 64. Thus, light from the tap signal passes from the splitter 60 through the first delay waveguide 80 twice and through the delay waveguide 62 once before being received at the first splitter 64. As a result, both the first delayed signal and the second delayed signal effectively function as the delayed signals disclosed in the context of FIG. 1A.

[0063] The first delay waveguide 80 includes a delay section 70. Passing the light twice through the first delay waveguide 80 increases the effective path length that the delayed signal travels between the splitter 60 and the first splitter 64. This increase in effective path length allows the length of the delay section 70 to be shortened to provide the desired delay between the delayed signal and the forward signal.

[0064] As is evident from the above description of FIG. 2, light from the tap signal passes through one of several different delay paths from the splitter 60 to one of the control elements 74. Each of the delay paths is defined primarily by one of the first delay waveguide 80, the splitter 60, the delay waveguide 62, the first splitter 64, and the delay channel waveguide 72. Each of the delay paths is passed by a delay path signal that is a combination of the first delay signal, the second delay signal, and one of the delay channel signals. Light from the tap signal also passes through one of several different facilitate paths from the splitter 60 to the control element 74. Each of the facilitate paths is defined primarily by one of the facilitate waveguide 66, the second splitter 68, and the facilitate sub-waveguide 76.

[0065] Each delay path has a common portion and an isolated portion. The common portion of each delay path is shared by multiple delay paths. In contrast, the isolated portions of a delay path are not shared with other delay paths. Optical signals passing through the common portion may carry multiple different channels. Optical signals passing through the isolated portions may 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. In contrast, the delay channel waveguide 72 is isolated from the other delay channel waveguides 72 and functions as an isolated portion.

[0066] Each of the facilitate paths has a common portion and a separation portion. The common portion of each facilitate path is shared by the facilitate paths. In contrast, the separation portions of the facilitate paths are not shared with other facilitate paths. Optical signals passing through the common portion may carry multiple different channels. Optical signals passing through the separation portions may each carry a different channel. For example, facilitate waveguide 66 is common to each of the delay paths and functions as a common portion. In contrast, each facilitate sub-waveguide 76 may be separated from the other facilitate sub-waveguides 76 and function as a separation portion.

[0067] Each expedited path has an expedited path signal passing therethrough that is a combination of the expedited signal and one of the expedited sub-signals. The expedited and delay paths are configured such that each control element 74 receives delay path and expedited path signals that carry the same channel (common channel). The expedited and delay paths can be configured such that each different control element 74 receives delay path and expedited path signals that carry different common channels. Also, the delay and expedited paths can be configured such that the delay path and / or expedited path signals received at each control element 74 carry only one of the channels or essentially only one of the channels.

[0068] The components defining the delay path and the expedited path are configured such that, for an expedited path signal and a delayed path signal arriving at the same control element 74, the delayed path signal arrives at the control element 74 later than the expedited path signal.

[0069] Since the delay path signal and the expedited path signal represent different portions of the tap signal, each control element 74 receives a delayed portion of the tap signal and also receives an expedited portion of the tap signal, but the delayed portion is delayed relative to the tap portion. The components defining the delay path and the expedited path can be configured to provide a delay between the tap portion and the expedited portion arriving at the control element 74. For example, the waveguides defining the delay path and the waveguides defining the expedited path can be configured such that the delay path is longer than the expedited path by a length that provides the desired delay at each control element 84. The length of the delay section 70 can be a primary indicator of the difference in length between the delay path and the expedited path leading to the same control element 74. As is evident from FIG. 2, first delayed signals carrying different channels pass through the same delay section 70. As a result, the same delay section 70 is common to each delay path.

[0070] As mentioned above, in some cases, the second splitter 68 can be a wavelength-dependent splitter configured so that the facilitating sub-signals each carry a different channel. Although FIGS. 1A and 2 show these facilitating sub-signals separated from a common signal (the facilitating signal), the facilitating sub-signals, each carrying a different channel, can be tapped from the light source waveguides 70. For example, FIG. 3 shows the LIDAR system of FIG. 1A modified to include a light source 10 constructed according to FIG. 1B. Each of the light source waveguides 70 includes a splitter 60 configured to move a portion of the channel signal from the light source waveguide 70 to one of the facilitating sub-waveguides 76. The portion of the channel signal received by the facilitating sub-waveguide 76 serves as one of the facilitating sub-signals. Each of the facilitating sub-signals carries a different one of the channels. As mentioned above, each of the facilitating sub-waveguides 76 carries one of the facilitating sub-signals to one of the control elements 74. Because the forward sub-signal is not separated from the tap signal, the delay waveguide 62 may receive a delayed signal from the splitter 50, as shown in Figure 3. For example, the delay waveguide 62 may 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 may 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 multimode interference (MMI) devices.

[0071] The forward sub-signals and delayed channel signals received by the same control element 74 each contain light from the same light source waveguide 70, and thus the same channel signal. The light from each channel signal passes through one of several different delay paths from the splitter 60 on the light source waveguide 70 to one of the control elements 74. Each of the delay paths is primarily defined by the portion of the light source waveguide 70 after the splitter 60, the laser combiner 72, the portion of the utility waveguide 12 between the laser combiner 72 and the splitter 50, the splitter 50, the delay waveguide 62, the first splitter 64, and one of the delay channel waveguides 72.

[0072] Each delay path has a common portion and multiple separate portions. The common portion of each delay path is shared by multiple delay paths. In contrast, the separate portions of a delay path are not shared with other delay paths. Optical signals passing through the common portion may carry multiple different channels. Optical signals passing through the separate portions may each carry a different channel. For example, the portion of the utility waveguide 12 between the laser multiplexer 72 and the splitter 50 and the delay waveguide 62 are common to each delay path and function as the common portion. In contrast, the portion of the light source waveguide 70 after the splitter 60 and the delay channel waveguide 72 are separate from the other delay channel waveguides 72 and function as the separate portions.

[0073] In the LIDAR system of Figure 3, each delay path has a delay path signal that is a combination of one of the channel signals, the outgoing LIDAR signal, the delay signal, and the delayed channel signal. Also, light from each channel signal passes through a different facilitate path from the splitter 60 on the light source waveguide 70 to one of the control elements 74. The facilitate paths have no common portions. Each of the facilitate paths is primarily defined by the facilitate sub-waveguide 76. Each of the facilitate sub-signals functions as a facilitate path signal that passes through one of the facilitate paths.

[0074] The expedited and delayed paths are configured such that each control element 74 receives delay and expedited path signals that carry the same channel (common channel). The expedited and delayed paths may be configured such that each different control element 74 receives delay and expedited path signals that carry different common channels. The delay and expedited paths may also be configured such that the delay and / or expedited path signals received at each control element 74 carry only one of the channels or essentially only one of the channels.

[0075] The components defining the delay path and the expedited path are configured such that, for an expedited path signal and a delayed path signal arriving at the same control element 74, the delayed path signal arrives at the control element 74 later than the expedited path signal.

[0076] Since the delay path signal and the expedited path signal contain different portions of the common signal (channel signal), each control element 74 receives a delayed portion of the common signal and also receives an expedited portion of the tap signal, but the delayed portion is delayed compared to the tap portion. The components defining the delay path and the expedited path can be configured to provide a delay between the tap portion and the expedited portion arriving at the control element 74. For example, the waveguides defining the delay path and the waveguides defining the expedited path can be configured such that the delay path is longer than the expedited path by a length that provides the desired delay at each control element 84. The length of the delay section 70 can be a primary indicator of the length difference between the delay path and the expedited path leading to the same control element 74. As is evident from FIG. 3, the delayed signals carrying different channels pass through the same delay section 70. As a result, the same delay section 70 is common to each delay path and each channel.

[0077] FIG. 3 illustrates a LIDAR system in which the light in the forward signal is not separated from the common signal carrying multiple channels, but the light in the delayed signal is separated from the common signal. However, the LIDAR system can be configured such that the light in the forward 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 such that the light in the forward and delayed signals is not separated from the common signal. Each of the light source waveguides 70 includes a splitter 50 and a differential delay mechanism 54 as disclosed in the context of FIG. 2. As a result, each splitter 50 is configured to move a portion of the channel signal from the light source waveguide 70 to the control waveguide 52. The portion of the channel signal received by the control waveguide 52 can function as a tap signal. Since each channel signal carries one different channel, the light in each tap signal carries one of the different channels.

[0078] The tap signals are received at different splitters 60. Each splitter 60 splits the tap signal into a forward signal and a first delayed signal. Each forward signal is received on a forward waveguide 66. Suitable splitters 60 include, but are not limited to, multi-mode interference couplers (MMI) and directional couplers.

[0079] Each of the first delay waveguides 80 receives a first delayed signal from the splitter 60. The first delay waveguides 80 convey 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 travels from the feedback device 82 through the first delay waveguide 80 and back to the splitter 60. As a result, the first delayed signal passes through the first delay waveguide 80 twice. Each of the splitters 60 receives the first delayed signal from the first delay waveguide 80 and outputs the first delayed signal on the delay waveguide 62. The portion of the first delayed signal received on the delay waveguide 62 functions as a second delayed signal conveyed on the delay waveguide 62. The first delayed signal and the associated second delayed signal can effectively function together as a delayed signal.

[0080] When the channel signals each carry a single channel, the resulting first and second delayed signals also carry a single channel. As a result, the second delayed signal is not a common signal and the first divider 64 disclosed in the context of Figures 1A-3 is not required. Furthermore, because the second delayed signals carry a single channel, each can effectively function as one of the delayed channel signals disclosed in the context of Figures 1A-3. As a result, each of the delay waveguides 62 can function as the delayed channel waveguide 72 of Figures 1A-3 by carrying the second delayed signal, which functions as a delayed channel signal, to one of the control elements 74.

[0081] If the channel signals each carry a single channel, the resulting facilitate signal also carries a single channel. As a result, each of the resulting facilitate signals is not a common signal, and the second splitter 68 disclosed in the context of Figures 1A-3 is not required. Moreover, because each of the facilitate signals carries a single channel, each can effectively function as one of the facilitate sub-signals disclosed in the context of Figures 1A-3. As a result, each of the facilitate waveguides 66 can function as a facilitate sub-waveguide 76 by carrying a facilitate signal that functions as a facilitate sub-signal to one of the control elements 74.

[0082] The forward sub-signals and delayed channel signals received by the same control element 74 each contain light from the same light source waveguide 70, and therefore from the same channel signal. Light from each channel signal passes through one of several different delay paths from the splitter 50 on the light source waveguide 70 to one of the control elements 74. Each delay path is primarily defined by the control waveguide 52, the splitter 60, the first delay waveguide 80, and the delay waveguide 62. Each forward path and each delay path is disjoint.

[0083] In the LIDAR system of FIG. 4, each of the delay paths is passed by a delay path signal that is a combination of the control signal, the first delay signal, and the second delay signal. Additionally, light from each channel signal passes through a different expedited path from the splitter 50 on the light source waveguide 70 to one of the control elements 74. Each expedited path is primarily defined by the control waveguide 52, the splitter 60, and the expedited waveguide 66. Each of the expedited paths is passed by an expedited path signal that is a combination of the control signal, the splitter 60, and the expedited sub-signal. The expedited and delay paths are configured such that each control element 74 receives a delay path signal and an expedited path signal carrying the same channel. The components defining the delay and expedited paths are configured such that, for expedited and delayed path signals arriving at the same control element 74, the delayed path signal arrives at the control element 74 later than the expedited path signal.

[0084] Since the delay path signal and the expedited path signal contain different portions of the common signal (one of the channel signals), each control element 74 receives a delayed portion of the common signal and also receives an expedited portion of the tap signal, but the delayed portion is delayed compared to the tap portion. The components defining the delay path and the expedited path can be configured to provide a delay between the tap portion and the expedited portion arriving at the control element 74. For example, the waveguides defining the delay path and the waveguides defining the expedited path can be configured such that the delay path is longer than the expedited path by a length that provides the desired delay at each control element 84. The length of the delay section 70 can be a primary indicator of the length difference between the delay path and the expedited path leading to the same control element 74. As is clear from FIG. 4, first delayed signals carrying different channels pass through different delay sections 70.

[0085] 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 including light already exiting the LIDAR system and returning to the LIDAR system. In some cases, the LIDAR adapter can be physically and optically disposed 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 the 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 different optical paths between the LIDAR adapter and the LIDAR chip, but travel the same optical path between the LIDAR adapter and the reflective objects in the field of view.

[0086] An example of a LIDAR adapter applied to the LIDAR chip of FIGS. 1A to 4 is shown in FIG. 5. The LIDAR adapter includes multiple components disposed on a base. For example, the LIDAR adapter includes a circulator 100 disposed on a base 102. The illustrated optical circulator 100 includes three ports, configured such 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. The LIDAR output signal enters the first port 104 from the utility waveguide 12 of the LIDAR chip and exits from the second port 106.

[0087] The LIDAR adapter can be configured such that the output of the LIDAR output signal from the second port 106 can also serve as the output of the LIDAR output signal from the LIDAR adapter, and thus from the LIDAR system, such that the LIDAR output signal output from the LIDAR adapter can serve as the assembly output signal.

[0088] 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 or substantially the same as the LIDAR output signal received from the LIDAR chip. However, there may be differences between the output signal of the assembly and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal may experience light 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.

[0089] 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 a second port 106. Figure 5 shows how the assembly output signal travels away from the LIDAR assembly along the same path as the signal returning to the LIDAR assembly.

[0090] The system 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 function as a first LIDAR input signal, which includes or consists of light from the assembly return signal. Thus, the LIDAR output signal and the first LIDAR input signal pass along different optical paths between the LIDAR adapter and the LIDAR chip.

[0091] As is evident from Figure 5, the LIDAR adapter may include optical components in addition to the circulator 100. For example, the LIDAR adapter may 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 Figure 5 includes an optional amplifier 110 positioned to receive and amplify the LIDAR output signal before it is incident on the circulator 100. The amplifier 110 may be operated by the electronics 62, allowing the electronics 62 to control the power of the LIDAR output signal.

[0092] 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, the first lens 112 is configured to couple the LIDAR output signal to the first port 104 when the LIDAR adapter does not include an amplifier 110. As another example, the first lens 112 can be configured to couple the LIDAR output signal on the input port to the amplifier 110 when the LIDAR adapter includes an amplifier 110. The second lens 114 can be configured to couple the LIDAR output signal at 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 the facet 35 of the comparison waveguide 18.

[0093] The LIDAR adapter may also include one or more redirecting elements, such as mirrors. Figure 5 shows a LIDAR adapter including a mirror as a redirecting element 116 that redirects the assembly return signal from the circulator 100 to the facet 20 of the comparison waveguide 18.

[0094] The LIDAR chip includes one or more waveguides that restrict the optical path of one or more optical signals. Although the LIDAR adapter can include waveguides, the optical paths along which the assembly return signals and the 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 the LIDAR output signals can travel through the air in which the LIDAR chip, the LIDAR adapter, and / or the base 102 are disposed 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 elements can be utilized to control the characteristics of the optical paths along which the assembly return signals and the LIDAR output signals pass to and from the LIDAR adapter.

[0095] 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. The components may be individual components that are attached to a substrate. Suitable techniques for attaching individual parts to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamps. In one example, one or more components are integrated elements and the remaining components are individual elements. In another example, the LIDAR adapter includes one or more integrated amplifiers and the remaining components are individual elements.

[0096] The circulator 100 applied to the adapter includes, but is not limited to, the circulators disclosed in U.S. Patent Application No. 16 / 726,235, filed December 23, 2019, entitled "LIDAR System with Signal Separation by Polarization Angle," and U.S. Patent Application No. 17 / 221,770, filed April 2, 2021, entitled "Use of a Circulator in a LIDAR System," both of which are incorporated herein in their entirety.

[0097] The LIDAR assembly can be used in combination with a scanning chip where electronics can operate to control the direction in which the system output signal travels away from the LIDAR system to multiple different sample areas in the field of view. FIG. 6 is a top view of an example of a 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 signal from the adapter. The common waveguide 117 carries the assembly output signal to an optical switch 118. Although not shown in FIG. 6, other optical components such as amplifiers, lenses, or optical fibers can be placed 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 signal before it is received at the optical switch 118. A portion of the assembly output signal received at the optical switch 118 can function as a switch signal. The optical switch 118 directs the switch signal to a portion of multiple alternative waveguides 119. The optical switch 118 can be operated by the electronics 62. For example, the electronics can operate an 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 of the alternative waveguides 119 is associated with an alternative waveguide index m=1 to M.

[0098] The scanning chip includes a splitter 120 in optical communication with an alternative waveguide 119 and a number of channel output waveguides 121. The alternative waveguide 119 can function as a first splitter waveguide, and the channel output waveguides 121 can function as a first splitter waveguide. The alternative waveguide 119, which receives the switch signal, directs light from the switch signal to the splitter 120. The splitter 120 is configured to split the light from the switch signal into a number of different channel output signals that are respectively received on the channel output waveguides 121. Since the switch signal includes or consists 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 a different one channel. Suitable first dividers 120 include, but are not limited to, splitters such as arrayed waveguide gratings, echelle gratings, and ring resonator-based devices.

[0099] The splitter 120 is configured such that a portion of the channel output waveguides 121 each receive one of the channel output signals. The one or more output waveguides 121 that receive one of the channel output signals can change in response to a change in which of the alternative waveguides 119 receive the switch signal. For example, the channel output waveguides 121 in FIG. i,m where i represents the channel index and m represents the alternative waveguide index. When the alternative waveguide 119 of alternative waveguide index m receives the switch signal, C i,m Each of the channel output waveguides 121 labeled as C receives one of the channel output signals. As an example, when the alternate waveguide 119 with alternate waveguide index 2 receives a switch signal, C i,2 Each of the channel output waveguides 121, labeled C 1,2 , C 2,2 , and C N,2 Each of the channel output waveguides 121, labeled C 1,1 , C2,1 , C N,1 , C 1,2 , C 1,M , C 2,M , and C N,M 121 does not receive one of the channel output signals. In comparison, when the alternative waveguide 119 with alternative 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.

[0100] 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 waveguide 121 that receives one of the channel output signals changes depending on which of the alternative waveguides 119 receive the switch signal, so that the electronics can operate the optical switch 118 to control which of the channel output waveguides 121 receive one of the channel output signals.

[0101] The LIDAR system also includes a redirecting element configured to receive the channel output signals from any one of the channel output waveguides 121 and redirect the received channel output signals such that different channel output signals travel in different directions away from the redirecting element. Additionally, the redirecting element redirects the received channel output signals such that the direction in which each of the outgoing LIDAR signals travels away from the redirecting element is a function of the channel output waveguide 121 from which the redirecting element receives the outgoing LIDAR signal.

[0102] The channel output signals travel in different directions away from the redirecting element and, as a result, travel in different directions away from the LIDAR system.

[0103] The different directions of the channel output signals may be a function of the channel output waveguides 121 in that the direction in which each channel output signal travels away from the redirect element changes in response to changes in the channel output waveguides 121 at which the redirect element receives the channel output signal. In some cases, the redirect element is configured such that none of the different directions are parallel to one another. For example, the redirect element may be configured such that different channel output signals travel away from the redirect element at different transmit angles, such that the transmit angles change as the redirect element receives the channel output signals from different channel output waveguides 121. The transmit angles are measured relative to the redirect element.

[0104] In Figure 6, a lens functions as the redirecting element 122. The lens is positioned to receive the channel output signals from the channel output waveguides 121. The lens and the channel output waveguides 121 are positioned such that the channel output signals from different channel output waveguides 121 are incident on different regions of the input side of the lens and / or have different angles of incidence at the input side of the lens. As a result, the channel output signals from the different channel output waveguides 121 travel in different directions away from the lens. For example, Figure 6 shows an example in which the redirecting element 122 is C i,m The transmission angle of the channel output signal received from the channel output waveguide 121 is denoted as θ i,m Here, i represents the channel index and m represents the alternative waveguide index.

[0105] Figure 6 shows the C 1,M and C N,M The transmission angle label (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, denoted as 1,M C N,M The channel output signal output from the channel output waveguide 121, denoted as N,M The transmission angle θ 1、M is the transmission angle θN,M , the redirection element 122 can simultaneously output channel output signals carrying different channels and traveling in different directions away from the redirection element 122.

[0106] Figure 6 also shows that N,1 and C N,M The transmission angle label (θ i,m When the switch signal is directed to an alternative waveguide, denoted m=1, the channel output signal carrying channel N is transmitted through a transmission angle C N,1 If the alternative waveguide receiving the switch signal is changed to an alternative waveguide denoted m=M, the transmission angle of the channel output signal carrying channel N is θ N,M As is clear from Fig. 6, the transmission angle C N,1 is the transmission angle θ N,M As a result, the direction in which the channel output signal travels away from the redirection element 122 changes in response to a change in the alternate waveguide that receives the switch signal.

[0107] The transmission angle is measured relative to the redirecting element 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. 6, 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 the switches to direct the switch signals to the alternate waveguides 119 that provide the desired direction for the channel output signals. 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, the lens structure can be altered to increase or decrease the degree of change in direction between the alternate waveguides.

[0108] The LIDAR system is configured to output system output signals each including or consisting of light from one of the channel output signals output from the redirection element 122. As a result, each system output signal can carry a different channel. As described below, each of the channel output signals output from the redirection element 122 can function as one of the system output signals. Each system output signal illuminates a sample area in the field of view. If an object is present in the sample area illuminated by the system output signal, the object can reflect light from the system output signal. The reflected light returns to the LIDAR system as a system return signal. Each system return signal can carry a different channel.

[0109] As described below, the direction that each of the system output signals travels away from the LIDAR system changes in response to a change in the alternate waveguide 119 that receives the switch signal. As a result, the electronics can scan each of the system output signals through different sample areas in the field of view by changing the alternate waveguide 119 that receives the switch signal. The LIDAR system can be configured to generate LIDAR data for each sample area.

[0110] In some cases, the electronics delay switching of the alternate waveguide 119 receiving the switch signal for a sample area illumination period having a sample area duration, such that each system output signal illuminates a different sample area during the sample area duration. The sample area duration can be selected to provide at least enough time for the system output signal to travel from the LIDAR system to an object at a maximum operating distance and then return to the LIDAR system.

[0111] The scanning chip can receive channel return signals that each include or consist of light from a different one of the system return signals. As described below, in some cases, each of the system return signals serves as a different one of the channel return signals. The channel output waveguide 121 receives a channel return signal that carries the same channel as the channel output signal output from the channel output waveguide 121. For example, during sample area illumination, the channel λ i The channel feedback signal carrying i Some of the channel output waveguides 121 do not output a channel output signal during the sample area illumination period, so some of the channel output waveguides 121 do not receive a channel feedback signal during the sample area illumination period, but may receive a channel feedback signal during a different sample area illumination period.

[0112] The channel output waveguides 121 carry the received channel return signals to the splitter 120. The splitter 120 can combine the channel return signals with the assembly return signal received on the common waveguide 117. Thus, the splitter 120 can operate as a splitter / combiner. The common waveguide carries the assembly return signal to an exit port through which it exits the scanning chip and can be received by the LIDAR adapter as described above. In some examples, the exit port is a facet of the common waveguide 117.

[0113] In FIG. 6, R represents the radius of the channel output signal at the input side of the lens, R' represents the lens radius, and s represents the distance from the lens to the object. The value of R' can be chosen to increase the amount of divergent light captured by the lens. The R / s ratio can be used to approximate the required value for R' and can be a function of the divergence angle of the light from the waveguide facet. To increase the capture of divergent light, twice the divergence half angle Φ can be used. In that case, R / s is at least equal to tan(2Φ). For example, if the lateral dimension of the alternative waveguide facet is 10 μm, the lateral divergence half angle Φ is about 6°. In that case, R / s is at least equal to tan(12°)=1 / 5. R' represents the lens radius, which can be larger than the half-width of the LIDAR output signal (R) to accommodate the change in the 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).

[0114] The center-to-center distance between the facets of the channel output waveguides 121 is labeled d in FIG. 6. Angular resolution can be improved by reducing d. In some cases, the center-to-center distance is constant for each pair of adjacent facets. However, the center-to-center distance may vary from pair of facets. 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.

[0115] 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, the 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 greater than or equal to 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 of the alternative waveguides 119 can be determined by the following formula: N,M ) can be increased by increasing N or M. Thus, within the limits of the optical system, the resolution can be improved by decreasing d, and the scanning range can be improved by increasing N or M.

[0116] The lenses may be configured to collimate the LIDAR output signals from the different channel output waveguides 121. Additionally or alternatively, the lenses may be positioned such that one or more facets are located at the focal point of the lens.

[0117] Although FIG. 6 shows the redirection element 122 located remotely from the scanning tip, the redirection element 122 can be included on the scanning tip.

[0118] The LIDAR system includes electronics, a LIDAR chip, a LIDAR adapter, a scanning chip, and a redirecting element. For example, Figure 7A is a top view of a LIDAR system including a LIDAR chip disclosed in the context of Figure 1A, a LIDAR adapter disclosed in the context of Figure 5, and a scanning chip and redirecting element disclosed in the context of Figure 6. The LIDAR chip, LIDAR adapter, scanning chip, and redirecting element can be solid state to provide a solid state LIDAR system.

[0119] The channel output signals output from redirection element 122 travel away from the LIDAR system and therefore function as system output signals, each carrying a different channel, such that each system output signal includes or consists of light from a channel output signal.

[0120] As discussed above, the direction that each channel output signal travels away from the redirection element 122 changes in response to a change in the channel output waveguide 121 through which the redirection element receives the channel output signal. As a result, the direction that each of the system output signals travels away from the LIDAR system changes in response to a change in the alternate waveguide 119 through which the switch signal is received. As a result, the electronics can scan each of the system output signals through different sample areas within the field of view by changing the alternate waveguide 119 through which the switch signal is received.

[0121] Light from the system return signal may be reflected by an object illuminated by the system output signal. The reflected light may travel back 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 may function as a channel return signal. For example, each system return signal received by a channel output signal may be returned as one of the channel return signals.

[0122] In the LIDAR system of FIG. 7A, the channel output signals serve as system output signals, but the LIDAR system may include one or more other components that operate on the channel output signals output from the redirection element. Examples of components that may operate on the channel output signals output from the redirection element include steering elements. For example, FIG. 7B is a top view of a LIDAR system including a steering element 123 that receives the channel output signals output from the redirection element 122 of the LIDAR system of FIG. 7A. The steering element or elements may be operated by electronics to steer the channel output signals, and the steering element or elements may be fixed. The steering element or elements 123 shown in FIG. 7B are mirrors that receive and reflect the channel output signals. The channel output signals that move away from the steering element or elements 123 may move away from the LIDAR system and serve as system output signals. It is noted that other suitable steering elements include, but are not limited to, fixed and / or steerable optical gratings and solid-state steering devices.

[0123] In FIG. 7B, one of the steering elements 123 is fixed and one of the steering elements 123 is movable. The movable steering element can be manipulated 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 steering elements 123 to steer the system output signal within a field of view. The electronics can manipulate one or more steering elements 123 to steer the system output signal outside of a field of view provided solely by the operation of the optical switch. For example, the 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 steering elements 123 to steer the channel output signal outside of the substantially two-dimensional steering provided by the optical switch 118. As a result, the electronics can manipulate the optical switch 118 and one or more steering elements 123 to steer the system output signal to a sample area within a three-dimensional field of view.

[0124] The scan rate provided by the operation of the scan switches can be greater than the scan rate provided by the one or more steering elements 123. For example, the scan rate provided by the operation of the scan switches can be at least 5, 10, or 100 times greater than the scan rate provided by the one or more steering elements 123. The scan rate can be an angular rate of change of all or a portion of the system output signals. For example, the scan rate provided by the operation of the scan switches can be an average rate of change of the transmission angle of all or a portion of the system output signals resulting from the operation of the scan switches.

[0125] Light may be reflected by an object illuminated by the system output signal. This reflected light may travel back to the LIDAR system and thus function as a system return signal. Different system return signals each carry a different one of the channels. The system return signals received by the LIDAR system may function as a channel return signal. For example, each of the system return signals received by one or more steering elements 123 may function as one of the channel return signals.

[0126] 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 may be disposed remotely from the common support 126. Although Figure 7B shows the redirection element 122 and the one or more steering elements 123 disposed remotely from the common support 126, one or more components selected from the group consisting of the redirection element 122 and the one or more steering elements 123 may be disposed on the common support 126. Suitable approaches for attaching components such as the LIDAR chip, electronics, scanning chip, LIDAR adapter, redirection element, and the one or more steering elements to the common support include, but are not limited to, epoxy, solder, and mechanical clamps.

[0127] 7A and 7B show the LIDAR adapter components disposed on the base 102 and the base disposed on the common support 126, all or a portion of the LIDAR adapter components can be disposed on the common support 126. As a result, the base 102 can be selected arbitrarily.

[0128] 8A-8C show an example of a processing element that may be applied to all or part of the processing element 34. The processing element 34 receives a comparison signal from one of the comparison waveguides 32 and a reference signal from one of the reference waveguides 40. The processing element includes a second splitter 200 that splits the comparison signal carried on the comparison waveguide 32 into a first comparison waveguide 204 and a second comparison waveguide 206. The first comparison waveguide 204 carries a first portion of the comparison signal to an optical coupling element 211. The second comparison waveguide 208 carries a second portion of the comparison signal to a second optical coupling element 212.

[0129] The processing element includes a first splitter 202 that splits a reference signal carried on the reference waveguide 40 into a first reference waveguide 204 and a second reference waveguide 206. The first reference waveguide 204 carries a first portion of the reference signal to an optical combining element 211. The second reference waveguide 208 carries a second portion of the reference signal to a second optical combining element 212.

[0130] The second optical combining element 212 combines the second portion of the comparison signal and the second portion of the reference signal into a second composite signal, where the second composite signal pulsates between the second portion of the comparison signal and the second portion of the reference signal due to the difference in frequency between the second portion of the comparison signal and the second portion of the reference signal.

[0131] The second optical combining element 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 conveys 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 conveys 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).

[0132] In some cases, the second optical combining element 212 splits the second composite signal such that a portion of the comparison signal (i.e., a portion of the second portion of the comparison signal) included in the first portion of the second composite signal is phase shifted by 180 degrees relative to a portion of the comparison signal (i.e., a portion of the second portion of the comparison signal) in the second portion of the second composite signal, but a portion of the reference signal (i.e., a portion of the second portion of the reference signal) in the second portion of the second composite signal is not phase shifted relative to a portion of the reference signal (i.e., a portion of the second portion of the reference signal) in the first portion of the second composite signal. Alternatively, the second optical combining element 212 splits the second composite signal such that a portion of the reference signal (i.e., a portion of the second portion of the reference signal) in the first portion of the second composite signal is phase shifted by 180° with respect to a portion of the reference signal (i.e., a portion of the second portion of the reference signal) in the second portion of the second composite signal, but a portion of the comparison signal (i.e., a portion of the second portion of the comparison signal) in the first portion of the second composite signal is not phase shifted with respect to a portion of the comparison signal (i.e., a portion of the second portion of the comparison signal) in the second portion of the second composite signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0133] The first optical combining element 211 combines the first portion of the comparison signal and the first portion of the reference signal into a first composite signal. Due to the difference in frequency 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.

[0134] The first optical combining element 211 also splits the first composite signal into a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 carries a first portion of the first composite signal to a first optical sensor 223 that converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 carries a second portion of the second composite signal to a second optical sensor 224 that converts the second portion of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0135] In some cases, the optical combining element 211 splits the first composite signal such that a portion of the comparison signal (i.e., a portion of the first portion of the comparison signal) included in the first portion of the composite signal is phase shifted 180° with respect to a portion of the comparison signal (i.e., a portion of the first portion of the comparison signal) in the second portion of the composite signal, but a portion of the reference signal (i.e., a portion of the first portion of the reference signal) in the first portion of the composite signal is not phase shifted with respect to a portion of the reference signal (i.e., a portion of the first portion of the reference signal) in the second portion of the composite signal. Alternatively, the optical combining element 211 splits the composite signal such that a portion of the reference signal (i.e., a portion of the first portion of the reference signal) in the first portion of the composite signal is phase shifted 180° with respect to a portion of the reference signal (i.e., a portion of the first portion of the reference signal) in the second portion of the composite signal, but a portion of the comparison signal (i.e., a portion of the first portion of the comparison signal) in the first portion of the composite signal is not phase shifted with respect to a portion of the comparison signal (i.e., a portion of the first portion of the comparison signal) in the second portion of the composite signal.

[0136] When the second optical combining element 212 splits the second composite signal such that a portion of the comparison signal in the first portion of the second composite signal is phase shifted 180° relative to a portion of the comparison signal in the second portion of the second composite signal, the optical combining element 211 also splits the composite signal such that a portion of the comparison signal in the first portion of the composite signal is phase shifted 180° relative to a portion of the comparison signal in the second portion of the composite signal. When the second optical combining element 212 splits the second composite signal such that a portion of the reference signal in the first portion of the second composite signal is phase shifted 180° relative to a portion of the reference signal in the second portion of the second composite signal, the optical combining element 211 also splits the composite signal such that a portion of the reference signal in the first portion of the composite signal is phase shifted 180° relative to a portion of the reference signal in the second portion of the composite signal.

[0137] Suitable light combining elements 211 and second light combining elements 212 include, but are not limited to, multi-mode interference couplers and tapered couplers.

[0138] 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 reference signal 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. In one example, the first reference waveguide 210 and the second reference waveguide 208 are constructed such that the first reference signal portion is a cosine function and the second reference signal portion is a sine function. Thus, the portion of the reference signal in the second composite signal is phase shifted relative to the portion of the reference signal in the first composite signal, 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.

[0139] The first light sensor 223 and the second light sensor 224 can be connected as a balanced detector, and the first auxiliary light sensor 218 and the second auxiliary light sensor 220 can also be connected as a balanced detector. For example, FIG. 8B shows a schematic diagram of the relationship between the electronics, the first light sensor 223, the second light sensor 224, the first auxiliary light sensor 218, and the second auxiliary light sensor 220. Although a photodiode symbol is used to represent the first light sensor 223, the second light sensor 224, the first auxiliary light sensor 218, and the second auxiliary light sensor 220, one or more of these sensors can have other structures. In some cases, all of the components shown in the schematic diagram of FIG. 8B are included in the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 8B are distributed between the LIDAR chip and the electronics located outside the LIDAR chip.

[0140] The electronics 62 connects the first photosensor 223 and the second photosensor 224 as a first balanced detector 225, and connects the first auxiliary photosensor 218 and the second auxiliary photosensor 220 as a second balanced detector 226. In particular, the first photosensor 223 and the second photosensor 224 are connected in series. Also, the first auxiliary photosensor 218 and the second auxiliary photosensor 220 are connected in series. The series connection in the first balanced detector communicates with a first data line 228 that carries the output from the first balanced detector as a first data signal. The series connection in the second balanced detector communicates with a second data line 232 that carries the output from the second balanced detector as a second data signal. 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 composite of the first and second waveforms. 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 a 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.

[0141] The electronics 62 includes a transform mechanism 238 configured to perform a mathematical transformation on the first and second data signals. For example, the mathematical transformation can be a complex Fourier transform using the first and second data signals as inputs. The first data signal is an in-phase component and the second data signal is a quadrature component, such that the first and second data signals together function as a complex data signal, in which the first data signal is the real component of the input value and the second data signal is its imaginary component.

[0142] 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 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 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 composite signal, in which the first digital data signal functions as a real component of the composite signal and the second digital data signal functions as an imaginary component of the composite data signal.

[0143] The conversion mechanism 238 includes a conversion element 268 that receives the composite data signal. For example, the conversion element 268 receives as input a first digital data signal from a first analog-to-digital converter (ADC) 264 and also receives as input a second digital data signal from a second analog-to-digital converter (ADC) 266. The conversion element 268 can be configured to perform a mathematical transformation on the composite signal to convert it from the time domain to the frequency domain. The mathematical transformation can be a complex transformation, such as a complex Fast Fourier Transform (FFT). A complex transformation, 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 the reflecting object and the LIDAR chip. The electronics use one or more frequency peaks output from the conversion element 268 for further processing to generate LIDAR data (distance and / or line-of-sight velocity between the reflecting object and the LIDAR chip or LIDAR system). The conversion element 268 can use firmware, hardware, software, or a combination thereof to perform the attribution function.

[0144] FIG. 8C shows an example of the relationship between frequency, time, cycle, and data period of a system output signal. 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 (f0) of the system output signal may be the lowest frequency of the system output signal during a cycle.

[0145] The frequency vs. time pattern is a cycle j and cycle j+1 FIG. 8C shows a sequence of two cycles, labeled . In some cases, the frequency versus time pattern is repeated with each cycle, as shown in FIG. 8C.

[0146] Each cycle is associated with a period index k, and the DP k In the example of FIG. 8C, each cycle includes K data periods, denoted as DP k The cycle includes two data periods denoted as (k=1 and 2). In some cases, the frequency versus time pattern is the same for data periods that correspond to each other in different cycles, as shown in FIG. 8C. Corresponding data periods are data periods that have the same period index. As a result, each data period DP1 can be considered to be a corresponding data period, and the associated frequency versus time pattern is the same in FIG. 8C. At the end of the cycle, the electronics resets the frequency to the same frequency level as at the beginning of the previous cycle.

[0147] During the data periods DP1 and DP2, the electronic device adjusts the frequency of the system output signal to a linear rate α i (where i represents the channel index) i The direction of the frequency change in data period DP1 is opposite to the direction of the frequency change in data period DP2.

[0148] 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. 8C, the sample area SR k,i is the channel λ i The sample area SR is illuminated by the system output signal carrying 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 SR 11,1 The radiation can be irradiated before the irradiation.

[0149] The sample area illumination period, denoted SRP, may be the same as the time of each cycle. As a result, the duration of the sample area may be the same as 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 area illumination period. As a result, during each sample area illumination period, the system output signal does not move in response to a change to the alternate waveguide 119 that receives the switch signal.

[0150] In some cases, moving the system output signal to a different sample region includes changing the alternate waveguide 119 that receives the switch signal. The change of the alternate waveguide 119 that receives the switch signal can occur between cycles. In some cases, there may be a delay associated with changing the alternate waveguide 119 that receives the switch signal. Although that delay may exist, the delay is not shown in FIG. 8C.

[0151] When the electronics manipulate the one or more steering elements 123 to steer the system output signal within the field of view, the steering of the system output signal by the one or more steering elements 123 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.

[0152] LIDAR systems are typically configured to provide reliable LIDAR data when an object is within an operational range of the LIDAR system. The operational range can extend from a minimum operational distance to a maximum operational distance. The maximum round trip time can be the time required for a system emitted signal to leave the LIDAR system, travel the maximum operational distance to the object, and return to the LIDAR system. In FIG. 8C, this is represented as τ M It is written as follows.

[0153] 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 necessary for the composite signal to have a beating frequency, the electronics measure the beating frequency resulting from the system return signal returning to the LIDAR system during a data window in the data period. In FIG. 8C, 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 ), the data window can be longer than the maximum operating time delay (τ M ) to the end of the data period.

[0154] Although FIG. 8C shows frequency versus time patterns for two channels, the frequency versus time patterns disclosed in the context of FIG. 8C can be applied to each channel.

[0155] As is evident from the above discussion, each processing element 34 receives a comparison signal and a reference signal carrying the same channel. As a result, the frequency output from the complex Fourier transform associated with a processing element 34 represents the pulsating frequency of a composite signal including the comparison signal pulsating relative to the reference signal, where the comparison signal and the reference signal carry the same channel. The pulsating frequencies from the same processing element 34 and from two or more different data periods can be combined to generate LIDAR data for one of the sample regions. For example, the pulsating frequencies from the same processing element 34 and from two or more different data periods can be combined to generate LIDAR data for one of the sample regions. i The processing element 34 receives the comparison signal and the reference signal carrying the comparison signal, and combines the pulsation frequency generated from DP1 in cycle j with the pulsation frequency generated from DP2 in cycle j to obtain the sample area SR k,i As an example, the following equation is applied during a data period during which the electronics increases the frequency of the outgoing LIDAR signal, such as occurs during data period DP1 in FIG. 8C: ub =-f d +α i τ, where f ub is the frequency provided by the transducer 268, and f d is the Doppler shift (f d =2vf c / c), where f c is the base frequency (f o ), c represents the speed of light, v is the line of sight velocity between the reflecting object and the LIDAR system, assuming the positive direction is from the reflecting object toward the LIDAR system, c is the speed of light, and τ represents 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 a system return signal (round trip time). The following equation applies during data periods in which the electronics reduce the frequency of the outgoing LIDAR signal, such as occurs during data period DP2 in FIG. 8C: f db =-f d -α i *τ, where f db is the frequency provided by the transducer element 268. In these two equations, fd and τ are unknowns. The electronics solves the two equations for these two unknowns. i The radial velocity of the sample area illuminated by the system output signal carrying the Doppler shift (v=c*f d / (2f c )) and / or the separation distance of the sample regions can be determined from S=c*τ / 2. The resulting LIDAR data (S and / or v) can be divided into channels λ i The LIDAR data represents LIDAR data for a sample area illuminated by a system output signal carrying a channel. A number of different sample areas can be simultaneously illuminated by system output signals carrying different channels, such that LIDAR data can be generated for each different sample area simultaneously illuminated by one of the system output signals. Additionally, the different LIDAR data results can be generated in parallel using different processing elements 34. Alternatively, the different LIDAR data results can be generated in series using different processing elements 34, depending on the configuration of the electronics.

[0156] In some cases, there may be multiple objects in the sample volume. In some cases where there are multiple objects in the sample volume, the transform may output multiple frequencies, where each frequency is associated with a different object. Frequencies resulting from the same object in different data periods of the same cycle may be considered corresponding frequency pairs. LIDAR data may be generated for each corresponding frequency pair output by the transform. As a result, separate LIDAR data may be generated for each object in the sample volume.

[0157] 8A-8B show an optical combining element combining a portion of the reference signal and a portion of the comparison signal, the processing element may include a single optical combining element 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.

[0158] As an example of a processing element that combines a reference signal and a comparison signal to form a composite signal, Figures 8D-8E show the processing element of Figures 8A-8B modified to include a single optical combining element. The comparison waveguide 196 carries the comparison signal directly to the first optical combining element 211, and the reference waveguide 198 carries the reference signal directly to the first optical combining element 211.

[0159] The first optical combining element 211 combines the comparison signal and the reference signal into a composite signal. Due to the difference in frequency between the comparison signal and the reference signal, the first composite signal pulsates between the comparison signal and the reference signal. The first optical combining element 211 also splits the composite signal into a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 carries a first portion of the composite signal to a first optical sensor 223 that converts the first portion of the second composite signal into a first electrical signal. The second detector waveguide 222 carries a second portion of the composite signal to a second optical sensor 224 that converts the second portion of the second composite signal into a second electrical signal.

[0160] 8E shows a schematic diagram of the relationship between the electronics, the first light sensor 223, and the second light sensor 224. Although a photodiode symbol is used to represent the first light sensor 223 and the second light 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. 8E are included on the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 8E are distributed between the LIDAR chip and electronics located external to the LIDAR chip.

[0161] The electronics connect the first photosensor 223 and the second photosensor 224 as a first balanced detector 225. In particular, the first photosensor 223 and the second photosensor 224 are connected in series. The series connection in the first balanced detector communicates with a first data line 228 that carries the output from the first balanced detector as a first data signal. The first data signal is an electrical representation of the composite signal.

[0162] The electronics 62 includes a transform mechanism 238 configured to perform a mathematical transform on the first data signal. The mathematical transform may be a real Fourier transform with the first data signal as an input. The electronics can use the frequency output from the transform to extract the LIDAR data as described above.

[0163] Each of the balanced detectors disclosed in the context of Figures 8A through 8E can be replaced with a single photosensor, such that the processing element can include one or more photosensors each receiving at least a portion of the composite signal, where the portion of the composite signal received can be all or a portion of the composite signal.

[0164] As discussed in the context of Figure 8C, 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 produces frequency modulation via strong nonlinear carrier / photon coupling.

[0165] 9A and 9B show an example of a control element that may be implemented in whole or in part as the control elements 74 disclosed in the context of FIGS. 1A-4. As described above, each of the control elements 74 receives a delay path signal from a delay channel waveguide 72, a delay path signal from the delay channel waveguide 72, and an expedited path signal from an expedited sub-waveguide 76. The delay path signals and expedited path signals received at the control elements 74 are λ i , and carry the same channel denoted as .

[0166] The delay channel waveguide 72 carries the delayed path signal to a first splitter 274. The forward sub-waveguide 76 carries the forward path signal to a second splitter 278. Splitters suitable for use as the first splitter 274 and the second splitter 278 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.

[0167] The first splitter 274 splits the delay path signal into a first portion of the delayed signal and a second portion of the delayed signal. The first delay waveguide 280 conveys the first portion of the delayed signal to a first optical combining element 282. The second delay waveguide 284 conveys the second portion of the delayed signal to a second optical combining element 286.

[0168] The second splitter 278 splits the encouragement signal into a first portion of the encouragement signal and a second portion of the encouragement signal. The first encouragement waveguide 290 conveys the first portion of the encouragement signal to the first optical combining element 282. The second encouragement waveguide 292 conveys the second portion of the encouragement signal to the second optical combining element 286.

[0169] The first optical combining element 282 combines a first portion of the prompt signal and a first portion of the delayed signal into the first pulsatile signal, and the second optical combining element 286 combines a second portion of the prompt signal and a second portion of the delayed signal into the second pulsatile signal, such that each of the delay paths extends from the splitter to an optical combiner that combines light from one of the delayed path signals with light from one of the prompt path signals.

[0170] As discussed above, the length of the delay path exceeds the length of the forward path. As a result, the second portion of the delayed signal is delayed relative to the second portion of the forward 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 forward signal. Due to the difference in frequency between the second portion of the forward signal and the second portion of the delayed signal, the second pulsating signal pulsates between the second portion of the forward signal and the second portion of the delayed signal.

[0171] The second optical coupling element 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 conveys 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 conveys 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 germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0172] In some cases, the second optical coupling element 286 splits the second pulsating signal such that a portion of the promotion signal (i.e., a portion of the second portion of the promotion signal) included in the first portion of the second pulsating signal is phase shifted 180 degrees relative to a portion of the promotion signal (i.e., a portion of the second portion of the promotion signal) in the second portion of the second pulsating signal, but a portion of the delayed signal (i.e., a portion of the second portion of the delayed signal) in the second portion of the second pulsating signal is not phase shifted relative to a portion of the delayed signal (i.e., a portion of the second portion of the delayed signal) in the first portion of the second pulsating signal.

[0173] As described above, the length of the delay path exceeds the length of the promotion path. As a result, the first portion of the delayed signal is delayed relative to the first portion of the promotion signal. This delay causes the first portion of the delayed signal to have a different frequency than the first portion of the promotion signal. Due to the difference in frequency between the first portion of the promotion signal and the first portion of the delayed signal, the first pulsating signal pulsates between the second portion of the promotion signal and the second portion of the delayed signal.

[0174] The first optical coupling element 282 also splits the first pulsatile signal into a first detector waveguide 302 and a second detector waveguide 304. The first detector waveguide 302 conveys 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 conveys 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 germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0175] In some cases, the first optical coupling element 282 splits the first pulsating signal such that a portion of the promotion signal (i.e., a portion of the first portion of the promotion signal) included in the first portion of the pulsating signal is phase-shifted by 180 degrees relative to a portion of the promotion signal (i.e., a portion of the first portion of the promotion signal) in the second portion of the pulsating signal, but a portion of the delayed signal (i.e., a portion of the first portion of the delayed signal) in the first portion of the pulsating signal is not phase-shifted relative to a portion of the delayed signal (i.e., a portion of the first portion of the delayed signal) in the second portion of the pulsating signal.

[0176] When the second optical combining element 286 splits the second pulsating signal such that the portion of the promotion signal in the first portion of the second pulsating signal is phase shifted 180° relative to the portion of the promotion signal in the second portion of the second pulsating signal, the first optical combining element 282 also splits the pulsating signal such that the portion of the promotion signal in the first portion of the pulsating signal is phase shifted 180° relative to the portion of the promotion signal in the second portion of the pulsating signal.

[0177] The first delay waveguide 280, the second delay waveguide 284, the first facilitate waveguide 80, and the second facilitate waveguide 292 can be configured such that the first pulsating signal and the second pulsating signal together function as an in-phase component and a quadrature component 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. Or, 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 constructed to provide a phase shift between the first portion of the delayed signal and the second portion of the delayed signal, while the first facilitate waveguide 80 and the second facilitate waveguide 292 are constructed such that the first portion of the facilitate signal and the second portion of the facilitate 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 operated with the same arguments as the sine function. In one example, the first delay waveguide 280 and the second delay waveguide 284 are constructed such 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 portion of the delayed signal in the second pulsating signal is phase shifted relative to the portion of the delayed signal in the first pulsating signal, but the portion of the prompt signal in the first pulsating signal is not phase shifted relative to the portion of the prompt signal in the second pulsating signal.

[0178] In another example, the first and second delay waveguides 280 and 284 are constructed such that the first and second portions of the delayed signal are in phase, while the first and second facilitate waveguides 80 and 292 are constructed to provide a phase shift between the first and second portions of the facilitate signal. As an example, the first and second facilitate waveguides 80 and 292 can be constructed to provide a 90° phase shift between the first and second portions of the facilitate signal. Thus, one of the facilitate signal portions can be a sine function and the other facilitate signal portion can be a cosine function operated with the same arguments as the sine function. In one example, the first and second facilitate waveguides 80 and 292 are constructed such that the first and second portions of the facilitate signal are a cosine function and the second portion of the facilitate signal is a sine function operated with the same arguments as the cosine function. In this example, the portion of the promotion signal in the second pulsating signal is phase shifted relative to the portion of the promotion signal in the first pulsating signal, but the portion of the delayed signal in the first pulsating signal is not phase shifted relative to the portion of the delayed signal in the second pulsating signal.

[0179] The first light sensor 306 and the second light sensor 308 can be connected as a balanced detector, and the first auxiliary light sensor 298 and the second auxiliary light sensor 300 can also be connected as a balanced detector. For example, FIG. 9B shows a schematic diagram of the relationship between the electronics 62, the first light sensor 306, the second light sensor 308, the first auxiliary light sensor 298, and the second auxiliary light sensor 300. Although a photodiode symbol is used to represent the first light sensor 306, the second light sensor 308, the first auxiliary light sensor 298, and the second auxiliary light sensor 300, one or more of these sensors can have other configurations. In some cases, all of the components shown in the schematic diagram of FIG. 9B are included in the LIDAR chip. In some cases, the components shown in the schematic diagram of FIG. 9B are distributed between the LIDAR chip and electronics located outside the LIDAR chip.

[0180] The electronics 62 connects the first photosensor 306 and the second photosensor 308 as a first balanced detector 312 and connects the first auxiliary photosensor 298 and the second auxiliary photosensor 300 as a second balanced detector 314. In particular, the first photosensor 306 and the second photosensor 308 are connected in series. Also, the first auxiliary photosensor 298 and the second auxiliary photosensor 300 are connected in series. The series connection of the first balanced detector is in communication with a first data line 316 that carries the output from the first balanced detector as a first process variable signal. The series connection of the second balanced detector is in communication with a second data line 318 that carries the output from the second balanced detector as a second process variable signal.

[0181] 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 and the second process variable signal is pulsating. Also, the first process variable signal and the second process variable signal can each carry a different one of components 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 a different portion of the delayed signal included in the first process variable signal. Also, the second process variable signal can include a portion of an expedited signal that is in phase with a different portion of an expedited 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 prompt and delayed signals, i.e., the pulsations in the first pulsatile signal and the second pulsatile signal, respectively.

[0182] The electronics 62 includes a process variable identification element 320 that receives the process variable signal. The process variable identification element 320 uses the process variable signal to output an indicative signal. The indicative signal is a channel signal (f CS ) and can be used to measure its frequency. In some cases, the indicator signal is a function of and / or a function of 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 ) is a digital signal that quantifies the frequency of the channel signal (f CS ) related to the frequency of the channel signal (f CS ) can be used to quantify the frequency of the channel λ i The system output signal carrying the channel λ i Since the frequency of the channel signal is a part of the channel LIDAR signal carrying the outgoing LIDAR signal and / or the channel λ i can represent the value of the frequency of the system output signal carrying

[0183] The electronics may include an optical control element 322 that receives the instruction signal. The optical control element 322 may control the laser source 68 (FIG. 1B) that is the source of the channel received by the control element 74 in response to the instruction signal. For example, the laser source 68 may be controlled by a control construct in which the frequency of the channel signal output by the laser 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. Since the frequency of the system output signal is modulated, the desired frequency of the system output signal varies as a function of time. In the case of triangular modulation, FIG. 8C may represent an example of a desired waveform. FIG. 8C illustrates the desired frequency of the channel signal and the resulting system output signal accordingly as a linear function of time. Thus, the control element 74, the process variable identification element 320, and the channel λ iλ , the optical control element 322 that receives the laser source 68 controls the frequency of the channel signal λ , so that the frequency of the channel signal output from the laser source 68 substantially maintains the desired waveform. i The control mechanism may be part of a control mechanism that controls a laser source 68, which is a source of the light. 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.

[0184] The optical control element 322 may control characteristics of the channel signal and / or the system output signal in response to a value of an error signal measured from a value of the controlled process variable at a particular time and a value of a reference variable at the same time. For example, the optical control element 322 may control the characteristics of the channel signal to reduce the value of the error signal. As an example, the optical control element 322 may control the characteristics of the channel signal such 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. If the control mechanism is a feedback control loop, the error signal of the control mechanism may be equal to the difference between the value of the controlled process variable and the value of the reference variable at a particular time.

[0185] If the process variable is a frequency of the channel signal, the optical control element 322 can send an optical control signal to adjust the frequency of the channel signal. For example, the optical control element 322 can adjust the frequency of the channel signal by sending an optical control signal that changes a level of current through a laser source that outputs the channel signal. Other optical control signals are possible. For example, if the laser source is an electrostatic MEMS tunable laser, the optical control element 322 can adjust the frequency of the channel signal by sending an optical control signal that changes a voltage level that drives a MEMS facet of the MEMS tunable laser.

[0186] In some cases, the light control element 322 and / or the process variable identification element 320 may be configured to control the frequency (f CS) of the channel signal, but such quantification 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 instantaneous 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.

[0187] FIGURE 9C illustrates the amplitude of the in-phase and quadrature components of the process variable signal on the same time axis as the frequency of the optical process variable signal and / or system output signal. For example, FIGURE 9C can compare the frequency of the system output signal during the first two data periods shown in FIGURE 8C with the variations in the in-phase and quadrature components of the optical process variable signal and / or process variable signal. Although FIGURE 9C illustrates 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 have more than one period per data period.

[0188] Various process variable identification elements 320 can be used to measure the value of the process variable index. Figure 9D illustrates an example of a process variable identification element 320 applied when the process variable is the frequency of the channel signal and / or the system output signal. The illustrated process variable identification element 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 a different one of components selected from the group consisting of an in-phase component of the local signal and a quadrature component of the local signal.

[0189] The process variable identification element 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 with the first local signal. If the first process variable signal carries an in-phase component of the process variable signal, the first local signal carries a quadrature component of the local signal. If the first process variable signal carries a quadrature component of the process variable signal, the first local signal carries an in-phase component of the local signal. The first multiplier 326 outputs the first multiplied signal.

[0190] The process variable identification element 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 with the second local signal. If the second process variable signal carries an in-phase component of the process variable signal, the second local signal carries a quadrature component of the local signal. If the second process variable signal carries a quadrature component of the process variable signal, the second local signal carries an in-phase component of the local signal. The second multiplier 326 outputs the second multiplied signal.

[0191] The process variable identification element 320 includes a summer 330 that receives the first multiplied signal and the second multiplied signal and outputs a control signal by summing the first multiplied signal and the second multiplied signal.

[0192] The control signal is received by a 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 indicative signal having one or more characteristics related to the frequency (f CS ) of the channel signal. 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 CS ) which can be received by the light control element 322 for use in controlling the frequency of the laser source.

[0193] Another example of a suitable process variable estimator 334 is a frequency counter that outputs an indicator signal indicative of the time between baseline crossings (dn) of the control signal. CS ) can be related to the time between baseline crossings (dn) by Equation 1: TS =f LO - 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 received by the light control element 322 for use in controlling the frequency of the laser source.

[0194] The local signal is selected such 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 results in more accurate control of the process variable by the control mechanism. As a result, increasing the frequency of the control signal enhances the control of the process variable by the control mechanism. Suitable sampling frequencies include, but are not limited to, sampling frequencies greater than 100 times the modulation frequency, where the modulation frequency is 1 / (duration of the cycle). In some cases, all or a portion of the data period in each cycle has a sampling frequency greater than 30 or 100 times the duration of the data period. In some cases, the local signal is selected such that the frequency of the control signal is greater than 100 times and less than 10,000 times the frequency of the process variable signal.

[0195] 9E illustrates another example of a suitable process variable identification element 320 for use when the process variable is the frequency of the channel signal and / or the system output signal. The process variable identification element 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 form to digital form and outputs a digital data signal. The digital data signal is a digital representation of the control signal.

[0196] The process variable identification element 320 includes a conversion element 342 that receives the digital data signal. The conversion element 342 performs a mathematical transformation on the digital data signal. The mathematical transformation is selected such that the conversion element 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 transformation includes, but is not limited to, a Hilbert transform. The Hilbert transform outputs a transformed signal that is indicative of the instantaneous phase, i.e., frequency, of the control signal.

[0197] The transformed signal is received by a frequency estimator 344. The frequency estimator may be configured to output an indication signal related to, including, and / or indicative of the frequency of the LIDAR output signal. For example, the frequency estimator may convert the instantaneous frequency to the frequency of the channel signal (f CS ) can be converted to: CS =(finst-f LO )*(T / τ'), where f LO is the frequency of the local oscillator, finst 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 resulting from the difference in length between the delay waveguide 62 and the forward waveguide 66. Thus, the instruction signal is a frequency signal having a frequency (f CS ) The instruction signal can be received by the light control element 322 for use in controlling the frequency of the laser source.

[0198] Although the indicator signal has been described in the context of a signal carrying data regarding the frequency of a channel signal, the indicator signal may carry data that is 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, 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.

[0199] The process variable discriminating element 320, by combining information from the in-phase and quadrature components at any one time, reduces the amount of delay that needs to be generated by the delay waveguide 62 to increase the sensitivity of the indicator signal to the frequency of the channel signal. Prior systems have attempted to increase this sensitivity by increasing the length of the delay path. Because the process variable discriminating element 320 increases the sensitivity of the indicator signal, the length of the delay path can exceed the length of the facilitate path by an amount less than that achievable in prior systems. For example, the time delay in the path to the control element 74 can exceed the time delay in the facilitate path to the control element 74 by an amount greater than or equal to 50 ps and less than or equal to 100 ns. In one example, the length of the delay path exceeds the length of the facilitate path by an amount less than 1000 cm, less than 500 cm, or less than 100 cm, and greater than 0.0 cm or 0.4 cm. In one example, the delay path and the facilitate path to the same control element 74 guide light through silicon, and the length of the delay path exceeds the length of the facilitate path by an amount less than 1000 cm and greater than 0.0 cm or 0.4 cm.

[0200] 9A-9E show an example of a control element suitable for use as all or part of the control element 74 disclosed in the context of FIGS. 1A-4. As discussed above, each of the control elements 74 receives a delay path signal and an expedited path signal carrying the same channel. In some cases, the laser sources 68 are constructed such that the different channel signals each carry a different one of the channels and are output from different laser sources 68. For example, FIG. 1B shows a possible light source 10 structure, in which the different channel signals are output from different laser sources 68. In these examples, each of the different control elements 74 can be used to control the source of the channel signal carrying the channel received by the control element. For example, each of the different control elements 74 can be included in a feedback control loop that controls the frequency of the channel signal carrying the channel received by the control element and operates the laser source accordingly to control the system output signal carrying the same channel. The electronics can operate the feedback control loops independently and independently operate the laser sources in those feedback control loops accordingly.

[0201] The LIDAR system described above shows a single system output signal carrying each channel. As a result, each control mechanism can control the frequency versus time pattern of a different one of the single system output signals. However, the LIDAR system can be constructed such that multiple different system output signals carry the same channel. For example, the LIDAR output signal can be split into multiple different signals, each of which is used as a source of a system output signal. In this case, one or more control mechanisms can each control the frequency versus time pattern of multiple different system output signals carrying the same channel.

[0202] The control elements disclosed in the context of FIGS. 9A through 9E operate on the in-phase component of the process variable signal and the quadrature component of the process variable signal. However, the control elements can be configured to operate on the in-phase component of the process variable signal and can exclude the quadrature component of the process variable signal. As a result, the control elements can exclude the second optical coupling element 286. Thus, the control elements can include one optical coupler, and the delay path and the boost path to the control elements can extend only to one optical coupler within the control elements.

[0203] A LIDAR system is disclosed as having a plurality of control mechanisms each including one of the control elements 74, but the LIDAR system can include only one control mechanism. For example, when the frequency of one laser source 68 is adjusted at a rate α i the other laser source 68 can be configured to be adjusted at the same rate. In this case, by controlling one of the laser sources 68 as disclosed above, the desired adjustment is provided to each laser source, and in response, the desired frequency-versus-time pattern is provided to each system output signal.

[0204] As described 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 the boost waveguide 66. The delay section 70 can represent a spiral arrangement of the delay waveguide 62. The spiral arrangement is selected to reduce the amount of space occupied by a longer waveguide such as delay waveguide 62 and / or first delay waveguide 80. FIG. 10 shows a portion of a delay waveguide 62 or first delay waveguide 80 having a spiral arrangement that functions as the delay section 70. Near the center of the spiral arrangement, the waveguide turns back on itself. The spiral arrangement has a portion where the radius of curvature of the waveguide is smallest (R in FIG. 10) min) is selected to have a radius of curvature that exceeds a curvature threshold. Suitable curvature thresholds include, but are not limited to, 0.1 mm, 0.25 mm, and curvature thresholds of 0.5 mm or greater. Although the helical arrangement is shown with a geometric shape that approximates a circle, the helical arrangement may be other geometric shapes, such as a shape that approximates an ellipse, a rectangle, or a triangle. As a result, the helical arrangement may include straight and / or substantially straight waveguide sections.

[0205] Suitable platforms for LIDAR and scanning chips include, but are not limited to, silica, indium phosphide, and silicon-on-insulator wafers. FIG. 11A is a cross-sectional view of a portion of a chip constructed from a silicon-on-insulator wafer. A silicon-on-insulator (SOI) wafer includes a buried layer 310 between a substrate 312 and an optically transmissive medium 314. In a silicon-on-insulator wafer, the buried layer 310 is silica, and the substrate 312 and the optically transmissive medium 314 are silicon. The substrate 312 of an optical platform such as a SOI wafer can serve as the base for the entire LIDAR chip. For example, the optical components shown on the LIDAR chips of FIGS. 1A-4 can be located on top of the substrate 312 or on the top and / or sides.

[0206] 11A 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 optically transmissive medium extends away from a planar region 318 of optically transmissive medium. The optical signal is confined between the top of the ridge 316 and the buried layer 310.

[0207] The dimensions of the ridge waveguide are labeled in FIG. 11A. For example, the ridge has a width labeled w and a height labeled h. The thickness of the plate region is labeled T. For LIDAR applications, these dimensions may be more important than other dimensions because of the need to use higher levels of optical power than are used in other applications. The ridge width (labeled w) is greater than 1 μm and less than 4 μm, the ridge height (labeled h) is greater than 1 μm and less than 4 μm, and the thickness of the plate region is greater than 0.5 μm and less than 3 μm. These dimensions may apply to straight or substantially straight portions of the waveguide, curved portions of the waveguide, and tapered portions of the waveguide. These portions of the waveguide are thus single mode. However, in some cases, these dimensions apply to straight or substantially straight portions of the waveguide. Additionally or alternatively, the plate thickness of the curved portions of the waveguide may be reduced to reduce optical loss in the curved portions of the waveguide. For example, the curved portion of the waveguide may have a ridge extending away from the plate region having a thickness of 0.0 μm or more and less than 0.5 μm. The above dimensions generally provide a single mode structure for the straight or substantially straight portions of the waveguide, but the tapered and / or curved portions may result in multimode. Coupling between multimode and single mode geometries can be achieved using tapers that do not substantially excite higher order modes. Thus, the waveguide can be constructed such that the signal carried in the waveguide is carried in a single mode even when carried in a waveguide section having multimode dimensions. The waveguide construction disclosed in the context of FIG. 11A is suitable for all or part of the waveguide on a LIDAR chip constructed according to FIGS. 1A to 4.

[0208] 11B-11D show an example of a feedback device 82 built on a silicon-on-insulator platform and applied on a LIDAR chip built according to FIGS. 2 and 4. FIG. 11B is a top view of a portion of a LIDAR chip having a feedback device 82. FIG. 11C is a cross-sectional view of the feedback device 82 taken along the line labeled C in FIG. 11B. FIG. 11D is a cross-sectional view of the feedback device 82 taken along the line labeled C in FIG. 11B.

[0209] The illustrated feedback device 82 includes a recess 360 that extends partially or completely through the optical transmission medium 314. Although the illustrated recess 360 does not extend into the buried layer 310, the illustrated recess 360 can extend into or through the buried layer 310. A surface of the recess 360 serves as a return surface 362. The return surface 362 is configured such that at least a portion of the 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 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 fill the recess 360 or can be a layer of material in contact with the return surface 362. The recess medium 366 can be a fluid or a solid. 11C, recess medium 366 may be a solid that also functions as a cladding 368. In some cases, recess medium 366 has a lower index of refraction than light transmission medium 314, causing reflection at return surface 362. Suitable recess media having a lower index of refraction than light transmission medium 314 include, but are not limited to, air, epoxy, silicon dioxide, and silicon nitride. Suitable recess media having a lower index of refraction than light transmission medium 314 that also function as a cladding include, but are not limited to, silicon dioxide and silicon nitride.

[0210] In some cases, the recessed medium 366 is a medium that reflects the outgoing LIDAR signal or the incoming signal off the return surface 362. For example, the recessed medium 366 may be a reflective material 370 in contact with the return surface 362. FIG. 11D shows a layer of reflective material 370 in contact with the return surface 362. Although FIG. 11D shows the cladding positioned such that it is on the recessed medium 366 and extends into the recess 360, the cladding may be selected as desired. 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 claddings include, but are not limited to, silicon dioxide, silicon nitride, and aluminum oxide.

[0211] As discussed 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 12A-12D show an example of an echelle grating constructed on a silicon-on-insulator platform and suitable for use as a splitter 120 and / or wavelength-dependent splitter in a LIDAR system. For purposes of illustration, the echelle grating is shown in the context of a splitter 120 on a scanning chip, although the illustrated echelle grating structure can be utilized for splitters on a LIDAR chip or a scanning chip.

[0212] The scanning chip includes one or more first splitter waveguides 400, second splitter waveguides 402, and redirecting elements 404 arranged around a free space region 406. When an echelle grating functions as the splitter 120, each of the first splitter waveguides can be one of the alternative waveguides 119 and each of the second splitter waveguides 402 can be one of the channel output waveguides 121.

[0213] 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 redirection element 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 redirection element 404 through the free space region 406 towards the second splitter waveguide 402.

[0214] The redirection element 404 is constructed such that the different wavelengths carried in the second signal are separated into channel output signals as they move away from the free space region 406. For example, FIG. 12A shows that the channel output signals carrying channels labeled λ1 and λ2 separate as they move away from the redirection element 404. The second splitter waveguide 402 terminates at a location where a portion of the second splitter waveguide 402 each receives one of the channel output signals. The portion of the second splitter waveguide 402 that each receives one of the channel output signals changes as the first splitter waveguide 400 carrying the switch signal changes.

[0215] The echelle grating of FIG. 12A can be operated in the reverse direction as a combiner. For example, λ 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 switch signal. The channel return signal may travel from the second splitter waveguide 402 through a spatial region 406 to the redirect element 404. The redirect element 404 may direct light from the channel return signal to the first splitter waveguide 400. The redirect element 404 is configured such that the light from the channel return signals combine to form an assembly return signal. The assembly return signal is received by the first splitter waveguide 400 which outputs a switch signal.

[0216] The echelle grating in Figure 12A is shown as constructed on a silicon-on-insulator platform, although other platforms may be used. The first splitter waveguide 400 and / or the second splitter waveguide 402 may be constructed as disclosed in the context of Figure 11A. For example, Figure 11A may represent a cross-sectional view of Figure 12A taken at any of the lines labeled B in Figure 12A.

[0217] FIG. 12B is a cross-sectional view of an echelle grating made through a redirect element 404, as shown by the line labeled E in FIG. 12A. The illustrated redirect element 404 includes a recess 410 that extends partially or completely through the optically transmissive medium 314. Although the illustrated recess 410 does not extend into the buried layer 310, the illustrated recess 410 can extend into or through the buried layer 310. A surface of the recess 410 serves as a return surface 362. The return surface 362 is configured such that at least a portion of the switch signal or channel return signal incident on the return surface 362 from the optically transmissive medium 314 is returned to the optically transmissive medium 314. The mechanism by which the 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 may fill the recess 410 or may be a layer of material that contacts the return surface 362. The recess medium 366 may be a fluid or a solid. As shown in FIG. 12B, the recess medium 366 may be a solid that also serves as a cladding 416 for all or a portion of the LIDAR chip. In some cases, the recess medium 366 has a lower refractive index than the optically transmitting medium 314, causing reflections at the return surface 362. Suitable recess media with a lower refractive index than the optically transmitting medium 314 include, but are not limited to, air, epoxy, silicon dioxide, and silicon nitride. Suitable recess media with a lower refractive index than the optically transmitting medium 314 that also serve as a cladding include, but are not limited to, silicon dioxide and silicon nitride.

[0218] In some cases, the recessed medium 366 is a medium that reflects the outgoing LIDAR signal or the incoming signal off the return surface 362. For example, the recessed medium 366 may be a reflective material 370 in contact with the return surface 362. FIG. 12C shows a layer of reflective material 370 in contact with the 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 claddings include, but are not limited to, silicon dioxide, silicon nitride, and aluminum oxide.

[0219] 12D is an enlarged top view of a portion of the return surface 362 without the recess medium 366 or reflective material 370 disposed within the recess 410. The return surface 362 is configured to function as an optical diffraction grating. For example, the return surface 362 includes a plurality of grooves 422 arranged such that the redirecting element 404 functions as an echelle grating. Suitable groove 422 structures include, but are not limited to, steps. The bandwidth of an optical filter that includes or consists of an echelle grating can be adjusted by changing the focal length and / or dimensions of the grating.

[0220] The free space region 406 may confine the optical signal in one direction. For example, the free space region 406 in Figures 12A-12D may confine the optical signal vertically. In these cases, the optical signal may spread laterally and / or become more concentrated laterally. As a result, all or part of the free space region 406 may be a planar waveguide.

[0221] Various optical switches for LIDAR systems can be built on planar device 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. FIG. 13 is a schematic diagram of a Mach-Zehnder interferometer. The switch includes a first switch waveguide 500 that connects the common waveguide 117 and a first of the alternative waveguides 119A. A second of the alternative 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.

[0222] The electronics can operate the phase shifter to change the switch between a pass mode and a switch mode. In the pass mode, the switch signal carried on the common waveguide 117 passes through the first alternative waveguide 119A. In the switch mode, the switch signal carried on the common waveguide 117 is directed to the second alternative waveguide 119B.

[0223] 13 is suitable for a LIDAR system that directs a switch signal to one of two alternative waveguides 119A, but LIDAR systems may direct a switch signal to more than one alternative waveguide 119A. In these examples, switches such as the optical switch of FIG. 13 may be cascaded so that the electronics can direct the switch signal to more than one alternative waveguide 119A.

[0224] The light sensor interfering with the waveguide on the LIDAR chip may be a component separate from the chip and subsequently attached to the chip. For example, the light sensor may be a photodiode or an avalanche photodiode. Examples of suitable light sensor elements include, but are not limited to, InGAs PIN photodiodes manufactured by Hamamatsu Corporation, Hamamatsu, Japan, or InGAs APD (Avalanche Photodiode) manufactured by Hamamatsu Corporation, Hamamatsu, Japan. These light sensors may be centrally located on the LIDAR chip. Alternatively, all or a portion of the waveguide terminating in the light sensor may terminate in a facet located at the edge of the chip, and the light sensor may be attached to the edge of the chip on the facet to receive light passing through the facet. The use of a light sensor that is a separate component from the chip is suitable for all or a portion of the light sensors selected from the group consisting of the first auxiliary light sensor 218, the second auxiliary light sensor 220, the first light sensor 223, and the second light sensor 224.

[0225] As an alternative to a light sensor that is a separate component, all or a portion of the light sensor can be integrated with the chip. For example, examples of light sensors interfacing with ridge waveguides on chips constructed from silicon-on-insulator wafers can be found in Optics Express Vol. 15, No. 21, pp. 13965-13971 (2007); U.S. Patent No. 8,093,080 issued Jan. 10, 2012; U.S. Patent No. 8,242,432 issued Aug. 14, 2012; and U.S. Patent No. 6,108,8472 issued Aug. 22, 2000, each of which is incorporated herein in its entirety. The use of a light sensor integrated with the chip is suitable for all or a portion of the light sensors selected from the group consisting of the auxiliary light sensor 218, the second auxiliary light sensor 220, the first light sensor 223, and the second light sensor 224.

[0226] A suitable laser source 68 may be a laser chip that is separate from the LIDAR chip and then attached to the LIDAR chip. For example, the laser source 68 may be a laser chip that is attached to the chip using a flip-chip arrangement. Use of a flip-chip arrangement is suitable when the laser source 68 is interfaced with a ridge waveguide on a chip constructed from a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 may include an optical grating (not shown), such as a Bragg grating, that serves as a reflector for an external cavity laser. In these examples, the laser source 68 may include a gain element that is separate from the LIDAR chip and then attached to the LIDAR chip in a flip-chip arrangement. Examples of suitable interfaces between flip-chip gain elements and ridge waveguides on chips constructed from silicon-on-insulator wafers may be found in U.S. Pat. No. 9,705,278, issued July 11, 2017, and U.S. Pat. No. 5,991,484, issued November 23, 1999. If the laser source 68 is a gain element or laser chip, the electronics 62 can change the frequency of the channel signal by changing the level of current applied through the gain element or laser cavity.

[0227] Suitable electronics 62 may include, but are not limited to, electronic controllers that include or consist of analog electrical circuits, digital electrical circuits, processors, microprocessors, digital signal processors (DSPs), field programmable gate arrays (FPGAs), computers, microcomputers, or combinations thereof suitable for performing the operation, monitoring, and control functions described above. In some cases, the electronic controller accesses a memory that contains instructions that are executed by the electronic controller during the performance of the operation, control, and monitoring 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 electronics integrated with the chip.

[0228] The LIDAR system 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 as an alternative to the optical components shown. The passive optical components may be solid components excluding moving parts. Suitable passive optical components include, but are not limited to, lenses, mirrors, optical gratings, reflective surfaces, splitters, splitters, combiners, polarizers, polarization splitters, and polarization rotators. In some cases, the LIDAR system includes one or more active optical components in addition to or as an alternative to the optical components shown. Suitable active optical components include, but are not limited to, optical switches, phase tuners, attenuators, steerable mirrors, steerable lenses, tunable splitters, and tunable combiners.

[0229] Other embodiments, combinations, and modifications of this invention will occur to those of ordinary skill in the art in light of these teachings. Accordingly, this invention is to be limited only by the following claims, which include all such embodiments and modifications, when viewed in conjunction with the above specification and accompanying drawings.

Claims

1. a scanning chip configured to steer a system output signal moving away from the LIDAR system to a plurality of different sample areas within a field of view, each system output signal carrying a different one of the channels; a LIDAR chip separate from the scanning chip and configured to generate composite signals, each pulsating at a pulsating frequency, wherein generating each composite signal includes combining a comparison signal and a reference signal carrying the same channel; each comparison signal includes light from one of a plurality of different system return signals, each carrying a different channel; each system return signal includes light from one of the system output signals after reflection of the system output signal by an object within the field of view; a LIDAR chip, each reference signal including light not reflected by objects in the field of view; an adapter configured to separate an output signal from a feedback signal, the output signal includes light not reflected by objects within a field of view; the return signal includes light from the output signal and each system return signal; and an adapter, each system output signal including light from said output signal; and and an electronic device configured to use the pulsating frequency to generate LIDAR data indicative of one or more items selected from the group consisting of a line-of-sight velocity between the LIDAR system and an object and a distance between the LIDAR system and an object.

1. A LIDAR system comprising:

2. 10. The system of claim 1, wherein the LIDAR chip and the scanning chip each include a waveguide, and the adapter excludes a waveguide.

3. 3. The system of claim 2, wherein the LIDAR chip and the scanning chip each include an optical integrated circuit and the adapter includes discrete components.

4. The system of claim 1 , wherein the output signal and the return signal travel the same optical path between the adapter and the scanning tip.

5. The system of claim 4 , wherein the output signals carry each of the channels and the return signals carry each of the channels.

6. The system of claim 4 , wherein the optical path includes free space such that the output signal and the return signal pass through free space as they travel on the optical path.

7. 5. The system of claim 4, wherein the LIDAR chip is solid-state, the scanning chip is solid-state, and the adapter is solid-state.

8. 5. The system of claim 4, wherein the LIDAR chip includes a utility waveguide configured to guide an outgoing LIDAR signal carrying each of the channels, and wherein each of the reference signals and each of the comparison signals include light from the outgoing LIDAR signal.

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