Control of signal chirp in LIDAR systems

Abstract

The LIDAR system includes a light source that outputs an outgoing LIDAR signal. The LIDAR system also includes a plurality of phase difference generators, each phase difference generator combining the first optical signal with the second optical signal to generate a beat vibration control signal. Each first optical signal and each second optical signal include light from an outgoing LIDAR signal. Further, the phase difference generator generates each beat vibration control signal having a phase difference between the contribution of the first optical signal to the beat vibration control signal and the contribution of the second optical signal to the beat vibration control signal.

Description

Technical Field

[0001] The present invention relates to optical devices. In particular, the present invention relates to LIDAR systems. Background Art

[0002] There is an increasing commercial demand for LIDAR systems deployable in applications such as ADAS (Advanced Driver Assistance Systems) and AR (Augmented Reality). A LIDAR (Light Detection and Ranging) system typically outputs a system output signal that is reflected by an object located outside the LIDAR system. At least a portion of the reflected light signal returns to the LIDAR system. The LIDAR system directs the received light signal to an optical sensor that converts the light signal into an electrical signal. Electronic devices may use the output of the optical sensor to quantify LIDAR data that indicates the radial velocity and / or distance between the object and the LIDAR system.

[0003] Many LIDAR systems chirp the frequency of the system output signal linearly or in other well-defined waveforms with respect to time relationships to achieve accurate measurement of LIDAR data. In these cases, the LIDAR system may monitor the frequency of the system output signal and adjust the frequency in response to the monitored frequency to achieve a desired waveform shape. Systems for monitoring the frequency of the system output signal may require one or more delay waveguides that are used to create a time delay between the optical signal carried in the delay waveguide and the optical signal carried in another waveguide. To achieve the desired results, these delay waveguides typically need to be inappropriately long. Increasing the length of the delay waveguide generally improves the quality of monitoring and adjusting the system output signal. The length of these delay waveguides typically means that the delay waveguides occupy an undesirably large proportion of the available space in the LIDAR system. In addition, the length of these delay waveguides may result in a high level of signal loss. High levels of loss in the arm waveguide degrade the signal quality. Therefore, the length of the waveguide is typically shortened to the extent that the chirp quality of the system output signal degrades. Accordingly, there is a need for an improved system for controlling the frequency chirp of a LIDAR system output signal. Summary of the Invention

[0004] A LIDAR system includes a light source that outputs an outgoing LIDAR signal. The LIDAR system also includes a plurality of phase difference generators, each of which combines a first optical signal and a second optical signal to generate a beat control signal. Each first optical signal and each second optical signal includes light from the outgoing LIDAR signal. Additionally, the phase difference generators generate each beat control signal having a phase difference between the contribution of the first optical signal to the beat control signal and the contribution of the second optical signal to the beat control signal. For the beat control signals from different phase difference generators, the phase differences are different. Electronics applies a light source control signal to the light source to chirp the frequency of the outgoing LIDAR signal. The electronics is configured to modify the light source control signal in response to a change in the frequency of the baseline crossing of the beat control signal.

[0005] A method of operating a LIDAR includes outputting an outgoing LIDAR signal from a light source. The method also includes generating a plurality of different beat control signals, each of which includes a contribution from a first optical signal and a contribution from a second optical signal. Each first optical signal and each second optical signal includes light from the outgoing LIDAR signal. Each beat control signal is generated with a phase difference between the contribution of the first optical signal to the beat control signal and the contribution of the second optical signal to the beat control signal. For the beat control signals from different phase difference generators, the phase differences are different. The method also includes applying a light source control signal to the light source to chirp the frequency of the outgoing LIDAR signal. Modify the light source control signal in response to a change in the frequency of the baseline crossing of the beat control signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A A top view of a schematic diagram of a LIDAR system that includes or consists of a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal on a common waveguide.

[0007] Figure 1B A top view of a schematic diagram of a LIDAR system that includes or consists of a LIDAR chip that outputs a LIDAR output signal and receives a LIDAR input signal on different waveguides.

[0008] Figure 1C A top view of a schematic diagram of another embodiment of a LIDAR system that includes or consists of a LIDAR chip that outputs a LIDAR output signal and receives a plurality of LIDAR input signals on different waveguides.

[0009] Figure 2 Top view of an example of a LIDAR adapter adapted to be used with a Figure 1B LIDAR chip.

[0010] Figure 3 Top view of an example of a LIDAR adapter adapted to be used with a Figure 1C LIDAR chip.

[0011] Figure 4 Top view of an example of a LIDAR system including a Figure 1A LIDAR chip and a Figure 2 LIDAR adapter on a common support.

[0012] Figure 5A Shows an example of an optical signal processor adapted to be used with a LIDAR system.

[0013] Figure 5B Provides a schematic diagram of an electronic device adapted to be used with an optical signal processor constructed according to Figure 5A ...

[0014] Figure 5C Frequency versus time graph of a system output signal with triangular frequency tuning.

[0015] Figure 5D Shows another example of an optical signal processor adapted to be used with a LIDAR system.

[0016] Figure 5E Provides a schematic diagram of an electronic device adapted to be used with an optical signal processor constructed according to Figure 5D ...

[0017] Figure 6A And Figure 6B Shows an example of a suitable control signal processor for use as all or part of a control signal processor disclosed in the context of Figures 1A to 1C ... Figure 6A Shows an interface that can be positioned between optical components and a photosensor on a LIDAR chip.

[0018] Figure 6B Is a schematic diagram of an example of the relationship between an electronic device and a photosensor that can be included on a LIDAR chip.

[0019] Figure 6C Is a graph showing the relationship of the baseline crossing points of an electrical beat control signal versus time.

[0020] Figure 6D Is a schematic diagram of another example of the relationship between an electronic device and a photosensor that can be included on a LIDAR chip.

[0021] Figure 6E is a graph of multiple different error signals over a frequency chirp duration. Figure 6E is also a graph of a composite error signal over a frequency chirp duration, where the composite error signal is generated from the shown error signals.

[0022] Figure 6F is a graph of the composite error signal.

[0023] Figure 6G shows examples of waveforms of a light source control signal and a modified light source control signal over a chirp duration during multiple data cycles, where the multiple data cycles are all associated with the same cycle index.

[0024] Figure 7A is a schematic diagram of an example of the relationship between an electronic device that can be included on a LIDAR chip and an optical sensor.

[0025] Figure 7B is a graph of an error signal over a frequency chirp duration.

[0026] Figure 7C is a graph of the composite error signal.

[0027] Figure 7D shows examples of waveforms of a light source control signal and a modified light source control signal over a chirp duration during multiple data cycles, where the multiple data cycles are all associated with the same cycle index.

[0028] Figure 8 is an operation such as Figure 6D or Figure 7A is a flowchart of a method of operating an electronic device constructed as shown.

[0029] Figure 9 is a graph of voltage versus time showing examples of voltage levels of a light source control signal and a modified light source control signal.

[0030] Figure 10 is a cross-sectional view of a portion of a LIDAR chip including a waveguide on a silicon-on-insulator platform.

[0031] Figure 11 is a top view of a portion of a waveguide including a spiral waveguide. Detailed Description

[0032] The LIDAR system outputs a system output signal. At least a portion of the system output signal returns to the LIDAR system after being reflected by an object located outside the LIDAR system. The LIDAR system can then use the reflected light to generate LIDAR data of the object. The LIDAR data indicates the radial velocity and / or distance between the object and the LIDAR system.

[0033] The LIDAR system includes a light source that outputs an outgoing LIDAR signal. The system output signal includes light from the outgoing LIDAR signal or consists of light from the outgoing LIDAR signal. The LIDAR system includes electronics that apply a light source control signal to the light source to chirp the frequency of the outgoing LIDAR signal.

[0034] In addition, the LIDAR system includes a plurality of phase differential generators. Each phase differential generator combines a first optical signal with a second optical signal to generate a beating signal. The first optical signals from different phase differential generators include light from the outgoing LIDAR signal. In addition, the second optical signals from different phase differential generators include light from the outgoing LIDAR signal. Each phase differential generator is configured such that there is a phase difference between the contribution of the first optical signal to the beating signal and the contribution of the second optical signal to the beating signal. The phase differences of the beating signals from different phase differential generators are different.

[0035] Each beating signal includes a series of baseline crossing points, such as zero-crossings. The baseline crossing points of the plurality of beating signals occur at a certain frequency. The electronics modifies the light source control signal in response to a change in the frequency of the collective baseline crossing points. For example, the electronics can modify the light source control signal in response to a change in the time gap between the baseline crossing points of the beating signal, where the time gap between two baseline crossing points can be measured between the baseline crossing points of two different beating signals.

[0036] The presence of a plurality of different beating signals increases the number and frequency of the baseline crossing points. Increasing the frequency of the baseline crossing points increases the resolution of the feedback that the electronics uses to modify the light source control signal. Therefore, increasing the number of baseline crossing points can provide a more reliable chirping of the outgoing LIDAR signal and the resulting system output signal. This increase in reliability is achieved without the need for a plurality of delay waveguides that would inappropriately occupy a large amount of space on a semiconductor chip.

[0037] Figure 1AA top view of a schematic diagram of a LIDAR chip, which can act as a LIDAR system or can be included in a LIDAR system that includes other components in addition to the LIDAR chip. The LIDAR chip can include a Photonic Integrated Circuit (PIC) and can be a Photonic Integrated Circuit chip. The LIDAR chip includes a light source 4 that outputs a preliminary outgoing LIDAR signal. Suitable light sources 4 include, but are not limited to, semiconductor lasers such as External Cavity Lasers (ECL), Distributed Feedback Lasers (DFB), Discrete Mode (DM) lasers, and Distributed Bragg Reflector lasers (DBR).

[0038] The LIDAR chip includes a utility waveguide 12 that receives the outgoing LIDAR signal from the light source 4. 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 traveling through the facet 14 leaves the LIDAR chip and acts as a LIDAR output signal. For example, the facet 14 can be located at the edge of the chip such that the outgoing LIDAR signal traveling through the facet 14 leaves the chip and acts as a LIDAR output signal. In some cases, a portion of the LIDAR output signal leaving the LIDAR chip can also be considered a system output signal. For example, when the departure of the LIDAR output signal from the LIDAR chip is also the departure of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0039] The LIDAR output signal travels away from the LIDAR system through free space in the atmosphere and / or the environment in which the LIDAR system is located. The LIDAR output signal may be reflected by one or more objects in the path of the LIDAR output signal. When the LIDAR output signal is reflected, at least a portion of the reflected light travels back towards the LIDAR chip as a LIDAR input signal. In some cases, the LIDAR input signal can also be considered a system return signal. For example, when the departure of the LIDAR output signal from the LIDAR chip is also the departure of the LIDAR output signal from the LIDAR system, the LIDAR input signal can also be considered a system return signal.

[0040] The LIDAR input signal can enter the utility waveguide 12 through the facet 14. A portion of the LIDAR input signal entering the utility waveguide 12 acts as an incoming LIDAR signal. The utility waveguide 12 carries the incoming LIDAR signal to a splitter 16 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto a comparison waveguide 18 as a comparison signal. The comparison waveguide 18 carries the comparison signal to an optical signal processor 22 for further processing. AlthoughFigure 1A The directional coupler is shown operating as splitter 16, but other tapping components can also be used as splitter 16. Suitable splitters 16 include, but are not limited to, directional couplers, star couplers, optical couplers, Y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0041] The utility waveguide 12 also carries the outgoing LIDAR signal to the splitter 16. The splitter 16 moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto the reference waveguide 20 as a reference signal. The reference waveguide 20 carries the reference signal to the optical signal processor 22 for further processing.

[0042] The percentage of the light transmitted by the splitter 16 from the utility waveguide 12 can be fixed or substantially fixed. For example, the splitter 16 can be configured such that the power of the reference signal transmitted to the reference waveguide 20 is an outgoing percentage of the power of the outgoing LIDAR signal, or such that the power of the comparison signal transmitted to the comparison waveguide 18 is an incoming percentage of the power of the incoming LIDAR signal. In many splitters 16, such as directional couplers and multimode interferometers (MMIs), the outgoing percentage is equal to or substantially equal to the incoming percentage. In some cases, the outgoing percentage is greater than 30%, 40%, or 49%, and / or less than 51%, 60%, or 70%, and / or the incoming percentage is greater than 30%, 40%, or 49%, and / or less than 51%, 60%, or 70%. Splitters 16 such as multimode interferometers (MMIs) typically provide an outgoing percentage and an incoming percentage of 50% or approximately 50%. However, it is easier to fabricate multimode interferometers (MMIs) in platforms such as silicon-on-insulator platforms compared to some alternatives. In one example, the splitter 16 is a multimode interferometer (MMI), and the outgoing percentage and the incoming percentage are 50% or approximately 50%. As will be described in more detail below, the optical signal processor 22 combines the comparison signal and the reference signal to form a composite signal that carries LIDAR data for a sample region in the field of view. Thus, the composite signal can be processed to extract the LIDAR data (radial velocity and / or distance between the LIDAR system and an object external to the LIDAR system) for the sample region.

[0043] The LIDAR chip can include a control branch for controlling the operation of the light source 4. The control branch includes a splitter 26 that moves a portion of the outgoing LIDAR signal from the utility waveguide 12 onto the control waveguide 28. The coupled portion of the outgoing LIDAR signal acts as a tapped signal. While Figure 1Ashows a directional coupler operating as splitter 26, but other signal tapping components can also be used as splitter 26. Suitable splitters 26 include, but are not limited to, directional couplers, optical couplers, star couplers, Y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0044] Control waveguide 28 carries the tapped signal to a plurality of phase difference generators 29. Each phase difference generator 29 is associated with a phase difference generator index n, where n = 1 to N. Each phase difference generator 29 includes a control splitter 30 that moves a portion of the tapped signal from control waveguide 28 onto a first waveguide 31. The coupled portion of the tapped signal serves as a first control signal. First waveguide 31 carries the first control signal to control signal processor 36. Although Figure 1A shows a directional coupler operating as splitter 30, but other signal tapping components can also be used as control splitter 30. Suitable control splitters 30 include, but are not limited to, directional couplers, star couplers, optical couplers, Y-junctions, tapered couplers, and multimode interference (MMI) devices. A suitable number (N) of phase difference generators 29 includes, but is not limited to, the number of phase difference generators 29 being greater than or equal to 2, 3, or 5 and less than 6, 8, or 10.

[0045] In addition, utility waveguide 12 carries the outgoing LIDAR signal to phase difference generators 29. Each phase difference generator 29 includes a utility splitter 33 that moves a portion of the outgoing LIDAR signal from utility waveguide 12 onto a second waveguide 34. The coupled portion of the outgoing LIDAR signal serves as a second control signal. Second waveguide 34 carries the second control signal to control signal processor 36. Control signal processor 36 can be in electrical communication with electronics 32, and / or all or a portion of control signal processor 36 can be included in electronics 32.

[0046] Although Figure 1A shows a directional coupler operating as utility splitter 33, but other signal tapping components can also be used as utility splitter 33. Suitable utility splitters 33 include, but are not limited to, directional couplers, optical couplers, star couplers, Y-junctions, tapered couplers, and multimode interference (MMI) devices.

[0047] Control waveguide 28 can optionally terminate at a signal dump 35 that is configured to prevent and / or reduce reflected tapped signal back into control waveguide 28.

[0048] The LIDAR system can be modified such that the incoming LIDAR signal and the outgoing LIDAR signal can be carried on different waveguides. For example, Figure 1B is Figure 1ATop view of a LIDAR chip, which is modified such that incoming LIDAR signals and outgoing LIDAR signals are carried on different waveguides. The outgoing LIDAR signal exits the LIDAR chip through end face 14 and serves as the LIDAR output signal. When light from the LIDAR output signal is reflected by an object outside the LIDAR system, at least a portion of the reflected light returns to the LIDAR chip as a first LIDAR input signal. The first LIDAR input signal enters the comparison waveguide 18 through end face 35 and serves as a comparison signal. The comparison waveguide 18 carries the comparison signal to the optical signal processor 22 for further processing. As described in the context of Figure 1A described below, the reference waveguide 20 carries a reference signal to the optical signal processor 22 for further processing. As will be described in more detail below, the optical signal processor 22 combines the comparison signal with the reference signal to form a composite signal that carries LIDAR data for a sample region in the field of view.

[0049] The LIDAR chip can be modified to receive multiple LIDAR input signals. For example, Figure 1C shows a Figure 1B LIDAR chip modified to receive two LIDAR input signals. The splitter 40 is configured to place a portion of the reference signal carried on the reference waveguide 20 onto the first reference waveguide 42 and another portion of the reference signal onto the second reference waveguide 44. Thus, the first reference waveguide 42 carries a first reference signal and the second reference waveguide 44 carries a second reference signal. The first reference waveguide 42 carries the first reference signal to the first optical signal processor 46 and the second reference waveguide 44 carries the second reference signal to the second optical signal processor 48. Examples of suitable splitters 40 include, but are not limited to, Y-junctions, optical couplers, and multimode interference couplers (MMIs).

[0050] The outgoing LIDAR signal exits the LIDAR chip through end face 14 and serves as the LIDAR output signal. When light from the LIDAR output signal is reflected by one or more objects located outside the LIDAR system, at least a portion of the reflected light returns to the LIDAR chip as a first LIDAR input signal. The first LIDAR input signal enters the comparison waveguide 18 through end face 35 and serves as a first comparison signal. The comparison waveguide 18 carries the first comparison signal to the first optical signal processor 46 for further processing.

[0051] In addition, when the light from the LIDAR output signal is reflected by one or more objects located outside the LIDAR system, at least a portion of the reflected signal returns to the LIDAR chip as a second LIDAR input signal. The second LIDAR input signal enters the second comparison waveguide 50 through the end face 52 and serves as the second comparison signal carried by the second comparison waveguide 50. The second comparison waveguide 50 carries the second comparison signal to the second optical signal processor 48 for further processing.

[0052] Although the light source 4 is shown as being located on the LIDAR chip, the light source 4 can also be located outside the LIDAR chip. For example, the utility waveguide 12 can terminate at a second end face, and the outgoing LIDAR signal from the light source 4 located outside the LIDAR chip can enter the utility waveguide 12 through the second end face.

[0053] In some cases, the LIDAR chip constructed according to Figure 1B or Figure 1C is used in combination with a LIDAR adapter. In some cases, the LIDAR adapter can be physically and optically positioned between the LIDAR chip and one or more reflective objects and / or the field of view such that the optical path of the (one or more) first LIDAR input signals and / or the LIDAR output signal from the LIDAR chip to the field of view passes through the LIDAR adapter. In addition, the LIDAR adapter can be configured to operate on the first LIDAR input signal and the LIDAR output signal such that the first LIDAR input signal and the LIDAR output signal travel on different optical paths between the LIDAR adapter and the LIDAR chip, but on the same optical path between the LIDAR adapter and the reflective objects within the field of view.

[0054] Figure 2 An example of a LIDAR adapter suitable for use with Figure 1B the LIDAR chip is shown. The LIDAR adapter includes a plurality of components located on a base. For example, the LIDAR adapter includes a circulator 100 located on the base 102. The illustrated optical circulator 100 includes three ports and is configured such that light entering one port exits from the next port. For example, the illustrated 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.

[0055] 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. Accordingly, the LIDAR output signal can be output from the LIDAR adapter such that the LIDAR output signal travels towards the sample area in the field of view. Thus, in some cases, a portion of the LIDAR output signal leaving the LIDAR adapter can also be considered a system output signal. For example, when the departure of the LIDAR output signal from the LIDAR adapter is also the departure of the LIDAR output signal from the LIDAR system, the LIDAR output signal can also be considered a system output signal.

[0056] The LIDAR output signal output from the LIDAR adapter includes light from the LIDAR output signal received from the LIDAR chip and consists of or is mainly composed of light from the LIDAR output signal received from the LIDAR chip. Accordingly, the LIDAR output signal output from the LIDAR adapter can be the same as or substantially the same as the LIDAR output signal received from the LIDAR chip. However, there may be differences between the LIDAR output signal output from the LIDAR adapter and the LIDAR output signal received from the LIDAR chip. For example, the LIDAR output signal may experience optical losses as it travels through the LIDAR adapter, and / or the LIDAR adapter may optionally include an amplifier configured to amplify the LIDAR output signal as the LIDAR output signal travels through the LIDAR adapter.

[0057] When one or more objects in the sample area reflect the LIDAR output signal, at least a portion of the reflected light travels back to the circulator 100 as a system return signal. The system return signal enters the circulator 100 through the second port 106. Figure 2 It is shown that the LIDAR output signal and the system return signal travel between the LIDAR adapter and the sample area along the same optical path.

[0058] The system return signal exits the circulator 100 through the third port 108 and is directed to the comparison waveguide 18 on the LIDAR chip. Accordingly, all or a portion of the system return signal can serve as a first LIDAR input signal, and the first LIDAR input signal includes light from the system return signal or consists of light from the system return signal. Thus, the LIDAR output signal and the first LIDAR input signal travel between the LIDAR adapter and the LIDAR chip along different optical paths.

[0059] From Figure 2It can be clearly seen that, in addition to the circulator 100, the LIDAR adapter may also include optical components. For example, the LIDAR adapter may include components for guiding and controlling the optical paths of the LIDAR output signal and the system return signal. For example, Figure 2 the adapter of Figure 2 includes an optional amplifier 110, which is positioned to receive and amplify the LIDAR output signal before the LIDAR output signal enters the circulator 100. The amplifier 110 may be operated by the electronics 32, which allows the electronics 32 to control the power of the LIDAR output signal.

[0060] Figure 2 The LIDAR adapter is also shown to include an optional first lens 112 and an optional second lens 114. The first lens 112 may be configured to couple the LIDAR output signal to a desired location. In some cases, the first lens 112 is configured to focus or collimate the LIDAR output signal at the desired location. In one example, when the LIDAR adapter does not include the amplifier 110, the first lens 112 is configured to couple the LIDAR output signal to the first port 104. As another example, when the LIDAR adapter includes the amplifier 110, the first lens 112 may be configured to couple the LIDAR output signal to the input port of the amplifier 110. The second lens 114 may 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 at the desired location. For example, the second lens 114 may be configured to couple the LIDAR output signal to the end face 35 of the comparison waveguide 18.

[0061] The LIDAR adapter may also include one or more direction-changing components, such as mirrors. Figure 2 The LIDAR adapter is shown to include a mirror as the direction-changing component 116, which redirects the system return signal from the circulator 100 to the end face 20 of the comparison waveguide 18.

[0062] The LIDAR chip includes one or more waveguides that confine the optical paths of one or more optical signals. Although the LIDAR adapter may include waveguides, the optical paths traveled by the system return signal and the LIDAR output signal between components on the LIDAR adapter and / or between the LIDAR chip and components on the LIDAR adapter can be free space. For example, when the system return signal and / or the LIDAR output signal travel between different components on the LIDAR adapter and / or between a component on the LIDAR adapter and the LIDAR chip, they can travel through the atmosphere in which the LIDAR chip, the LIDAR adapter, and / or the base 102 are located. Thus, optical components such as lenses and direction-changing components can be used to control the characteristics of the optical paths traveled by the system return signal and the LIDAR output signal on, to, and from the LIDAR adapter.

[0063] Suitable bases 102 for the LIDAR adapter include, but are not limited to, substrates, platforms, and plates. Suitable substrates include, but are not limited to, glass, silicon, and ceramics. These components can be discrete components attached to the substrate. Suitable techniques for attaching the discrete components to the base 102 include, but are not limited to, epoxy, solder, and mechanical clamping. In one example, one or more of the components are integrated components while the remaining components are discrete components. In another example, the LIDAR adapter includes one or more integrated amplifiers while the remaining components are discrete components.

[0064] The LIDAR system can be configured to compensate for polarization. Light from a laser source is typically linearly polarized, and thus the LIDAR output signal is typically also linearly polarized. Reflection from an object may change the polarization angle of the returned light. Thus, the system return signal can include light of different linear polarization states. For example, a first portion of the system return signal can include light of a first linear polarization state while a second portion of the system return signal can include light of a second linear polarization state. The intensity of the resulting composite signal is proportional to the square of the cosine of the angle between the comparison signal polarization field and the reference signal polarization field. If this angle is 90 degrees, the LIDAR data in the resulting composite signal may be lost. However, the LIDAR system can be modified to compensate for changes in the polarization state of the LIDAR output signal.

[0065] Figure 3 is shown Figure 3 The LIDAR system of Figure 1Cfor use with a LIDAR chip. The LIDAR adapter includes a beam splitter 120 that receives the system return signal from the circulator 100. The beam splitter 120 splits the system return signal into a first portion of the system return signal and a second portion of the system return signal. Suitable beam splitters include, but are not limited to, Wollaston prisms and MEMS-based beam splitters.

[0066] The first portion of the system return signal is directed to a comparison waveguide 18 on the LIDAR chip and serves as Figure 1C the first LIDAR input signal as described in the context of. The second portion of the system return signal is directed to a polarization rotator 122. The polarization rotator 122 outputs a second LIDAR input signal that is directed to a second input waveguide 76 on the LIDAR chip and serves as the second LIDAR input signal.

[0067] The beam splitter 120 can be a polarization beam splitter. An example of a polarization beam splitter is configured such that the first portion of the system return signal has a first polarization state but has no or substantially no second polarization state, and the second portion of the system return signal has a second polarization state but has no or substantially no first polarization state. The first polarization state and the second polarization state can be linear polarization states, and the second polarization state is different from the first polarization state. For example, the first polarization state can be TE, and the second polarization state can be TM, or the first polarization state can be TM, and the second polarization state can be TE. In some cases, the laser source can be linearly polarized such that the LIDAR output signal has a first polarization state. Suitable beam splitters include, but are not limited to, Wollaston prisms and microelectromechanical system-based polarization beam splitters.

[0068] The polarization rotator can be configured to change the polarization state of the first portion of the system return signal and / or the second portion of the system return signal. For example, Figure 3 the illustrated polarization rotator 122 can be configured to change the polarization state of the second portion of the system return signal from the second polarization state to the first polarization state. Thus, the second LIDAR input signal has a first polarization state but has no or substantially no second polarization state. Thus, both the first LIDAR input signal and the second LIDAR input signal have the same polarization state (in this example, the first polarization state). Although the light carries the same polarization state, due to the use of a polarization beam splitter, the first LIDAR input signal and the second LIDAR input signal are associated with different polarization states. For example, the first LIDAR input signal carries light reflected in the first polarization state, while the second LIDAR input signal carries light reflected in the second polarization state. Thus, the first LIDAR input signal is associated with the first polarization state, and the second LIDAR input signal is associated with the second polarization state.

[0069] Since the first LIDAR input signal and the second LIDAR transmit light of the same polarization state, the comparison signal generated from the first LIDAR input signal has the same polarization angle as the comparison signal generated from the second LIDAR input signal.

[0070] Suitable polarization rotators include, but are not limited to, polarization-maintaining fiber rotators, Faraday rotators, half-wave plates, MEM-based polarization rotators, and integrated optical polarization rotators using asymmetric y-branches, Mach-Zehnder interferometers, and multimode interference couplers.

[0071] Since the outgoing LIDAR signal is linearly polarized, the first reference signal can have the same linear polarization state as the second reference signal. Additionally, components on the LIDAR adapter can be selected such that the first reference signal, the second reference signal, the comparison signal, and the second comparison signal all have the same polarization state. In Figure 3 the examples described in the context of, the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal can all have light of the first polarization state.

[0072] Due to the above configuration, the first composite signal generated by the first optical signal processor 46 and the second composite signal generated by the second optical signal processor 48 are both produced by combining reference signals and comparison signals of the same polarization state, and will thus provide a desired beat between the reference signal and the comparison signal. For example, the composite signal is produced by combining the first reference signal and the first comparison signal of the first polarization state and does not include or substantially does not include light of the second polarization state; or, the composite signal is produced by combining the first reference signal and the first comparison signal of the second polarization state and does not include or substantially does not include light of the first polarization state. Similarly, the second composite signal includes the second reference signal and the second comparison signal of the same polarization state and will thus provide a desired beat between the reference signal and the comparison signal. For example, the second composite signal is produced by combining the second reference signal and the second comparison signal of the first polarization state and does not include or substantially does not include light of the second polarization state; or, the second composite signal is produced by combining the second reference signal and the second comparison signal of the second polarization state and does not include or substantially does not include light of the first polarization state.

[0073] The above configuration enables the LIDAR data of a single sample region in the field of view to be generated from multiple different composite signals (i.e., the first composite signal and the second composite signal) from that sample region. In some cases, determining the LIDAR data of the sample region includes the electronic device combining the LIDAR data from different composite signals (i.e., the composite signal and the second composite signal). Combining the LIDAR data can include taking the mean, median, or mode of the LIDAR data generated by different composite signals. For example, the electronic device can average the distance between the LIDAR system and the reflective object determined according to the composite signal and the distance determined according to the second composite signal, and / or the electronic device can average the radial velocity between the LIDAR system and the reflective object determined according to the composite signal and the radial velocity determined according to the second composite signal.

[0074] In some cases, determining the LIDAR data of the sample region includes the electronic device identifying one or more composite signals (i.e., the composite signal and / or the second composite signal) as the source of the LIDAR data that best represents reality (representative LIDAR data). Then, the electronic device can use the LIDAR data from the identified composite signal as the representative LIDAR data for additional processing. For example, the electronic device can identify the signal with a larger amplitude (the composite signal or the second composite signal) as having representative LIDAR data and can use the LIDAR data from the identified signal for further processing by the LIDAR system. In some cases, the electronic device combines identifying the composite signal with representative LIDAR data with combining the LIDAR data from different LIDAR signals. For example, the electronic device can identify each composite signal with an amplitude higher than the amplitude threshold as having representative LIDAR data; and when more than two composite signals are identified as having representative LIDAR data, the electronic device can combine the LIDAR data from each identified composite signal. When one composite signal is identified as having representative LIDAR data, the electronic device can use the LIDAR data from that composite signal as the representative LIDAR data. When no composite signal is identified as having representative LIDAR data, the electronic device can discard the LIDAR data of the sample region associated with these composite signals.

[0075] Although Figure 3 is described in the context where the components are arranged such that the first comparison signal, the second comparison signal, the first reference signal, and the second reference signal all have the first polarization state, but Figure 3Other configurations of the middle component can also be arranged such that a composite signal is generated by combining a reference signal and a comparison signal with the same linear polarization state, and a second composite signal is generated by combining a reference signal and a comparison signal with the same linear polarization state. For example, the beam splitter 120 can be configured such that the second part of the system return signal has a first polarization state, while the first part of the system return signal has a second polarization state; the polarization rotator receives the first part of the system return signal, and the outgoing LIDAR signal can have a second polarization state. In this example, both the first LIDAR input signal and the second LIDAR input signal have the second polarization state.

[0076] The above system configuration causes the first part and the second part of the system return signal to be directed into different composite signals. Therefore, since the first part and the second part of the system return signal are each associated with a different polarization state, but the electronic device can process each composite signal, the LIDAR system compensates for the change in the polarization state of the LIDAR output signal in response to the reflection of the LIDAR output signal.

[0077] Figure 3 The LIDAR adapter can include additional optical components, including passive optical components. For example, the LIDAR adapter can include an optional third lens 126. The third lens 126 can be configured to couple the second LIDAR output signal at a desired position. In some cases, the third lens 126 focuses or collimates the second LIDAR output signal at a desired position. For example, the third lens 126 can be configured to focus or collimate the second LIDAR output signal on the end face 52 of the second comparison waveguide 50. The LIDAR adapter also includes one or more direction-changing components 124, such as mirrors and prisms. Figure 3 It is shown that the LIDAR adapter includes a mirror as the direction-changing component 124, which redirects the second part of the system return signal from the circulator 100 to the end face 52 of the second comparison waveguide 50 and / or the third lens 126.

[0078] When the LIDAR system includes a LIDAR chip and a LIDAR adapter, the LIDAR chip, the electronic device, and the LIDAR adapter can be located on a common mount. Suitable common mounts include, but are not limited to, glass plates, metal plates, silicon plates, and ceramic plates. For example, Figure 4 is included on the common support 140 Figure 1A the LIDAR chip and the electronic device 32 Figure 2Top view of a LIDAR system with a LIDAR adapter. Although the electronics 32 are shown as being located on a common support, all or a portion of the electronics may be located outside the common support. When the light source 4 is located outside the LIDAR chip, the light source may be located on the common support 140 or outside the common support 140. Suitable methods for mounting the LIDAR chip, electronics, and / or LIDAR adapter on the common support include, but are not limited to, epoxy, solder, and mechanical clamping.

[0079] The LIDAR system may include components that include additional passive and / or active optical components. For example, the LIDAR system may include one or more components that receive a LIDAR output signal from the LIDAR chip or the LIDAR adapter. A portion of the LIDAR output signal that exits from the one or more components may serve as the system output signal. For example, the LIDAR system may include one or more beam steering components that receive the LIDAR output signal from the LIDAR chip or the LIDAR adapter and output all or a portion of the LIDAR output signal as the system output signal. For example, Figure 4 A beam steering component 142 is shown that receives the LIDAR output signal from the LIDAR adapter. Although Figure 4 the beam steering component is shown as being located on the common support 140, the beam steering component may be located on the LIDAR chip, on the LIDAR adapter, outside the LIDAR chip, or outside the common support 140. Suitable beam steering components include, but are not limited to, movable mirrors, MEMS mirrors, optical phased arrays (OPAs), and actuators for moving the LIDAR chip, the LIDAR adapter, and / or the common support.

[0080] The electronics may operate one or more beam steering components 142 to steer the system output signal to different sample regions 144. The sample regions may extend away from the LIDAR system to a maximum distance for which the LIDAR system is configured to provide reliable LIDAR data. The sample regions may be stitched together to define a field of view. For example, the field of view of the LIDAR system includes the space occupied by the combination of the sample regions or consists of the space occupied by the combination of the sample regions.

[0081] Figures 5A to 5C An example of a suitable optical signal processor is shown that serves as all or a portion of the optical signal processors selected from the group consisting of optical signal processor 22, first optical signal processor 46, and second optical signal processor 48. The optical signal processor receives a comparison signal from the comparison waveguide 196 and a reference signal from the reference waveguide 198. Figure 1A and Figure 1BThe comparison waveguide 18 and the reference waveguide 20 shown can serve as the comparison waveguide 196 and the reference waveguide 198, Figure 1C The comparison waveguide 18 and the first reference waveguide 42 shown can serve as the comparison waveguide 196 and the reference waveguide 198, or Figure 1C The second comparison waveguide 50 and the second reference waveguide 44 shown can serve as the comparison waveguide 196 and the reference waveguide 198.

[0082] The optical signal processor includes a second splitter 200 that splits the comparison signal carried on the comparison waveguide 196 onto 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 signal combiner 211. The second comparison waveguide 208 carries a second portion of the comparison signal to an optical signal combiner 212.

[0083] The optical signal processor includes a first splitter 202 that splits the reference signal carried on the reference waveguide 198 onto 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 signal combiner 211. The second reference waveguide 208 carries a second portion of the reference signal to an optical signal combiner 212.

[0084] The optical signal combiner 212 combines the second portion of the comparison signal and the second portion of the reference signal into a second composite signal. Due to the frequency difference between the second portion of the comparison signal and the second portion of the reference signal, the second composite signal beats between the second portion of the comparison signal and the second portion of the reference signal.

[0085] The optical signal combiner 212 also splits the resulting second composite signal onto a first detector waveguide 214 and a second detector waveguide 216. The first detector waveguide 214 carries a first portion of the second composite signal to a first optical sensor 218 that converts the first portion of the second composite signal into a first auxiliary electrical signal. The second detector waveguide 216 carries a second portion of the second composite signal to a second optical sensor 220 that converts the second portion of the second composite signal into a second auxiliary electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0086] In some cases, the optical signal combiner 212 splits the second composite signal such that the portion of the comparison signal included in the first part of the second composite signal (i.e., the portion of the second part of the comparison signal) is phase-shifted by 180° relative to the portion of the comparison signal in the second part of the second composite signal (i.e., the portion of the second part of the comparison signal), but the portion of the reference signal in the second part of the second composite signal (i.e., the portion of the second part of the reference signal) is not phase-shifted relative to the portion of the reference signal in the first part of the second composite signal (i.e., the portion of the second part of the reference signal). Alternatively, the optical signal combiner 212 splits the second composite signal such that the portion of the reference signal in the first part of the second composite signal (i.e., the portion of the second part of the reference signal) is phase-shifted by 180° relative to the portion of the reference signal in the second part of the second composite signal (i.e., the portion of the second part of the reference signal), but the portion of the comparison signal in the first part of the second composite signal (i.e., the portion of the second part of the comparison signal) is not phase-shifted relative to the portion of the comparison signal in the second part of the second composite signal (i.e., the portion of the second part of the comparison signal). Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0087] The first optical signal combiner 211 combines the first part of the comparison signal and the first part of the reference signal into a first composite signal. Due to the frequency difference between the first part of the comparison signal and the first part of the reference signal, the first composite signal beats between the first part of the comparison signal and the first part of the reference signal.

[0088] The first optical signal combiner 211 also separates the first composite signal onto a first detector waveguide 221 and a second detector waveguide 222. The first detector waveguide 221 carries the first part of the first composite signal to a first optical sensor 223, which converts the first part of the second composite signal into a first electrical signal. The second detector waveguide 222 carries the second part of the second composite signal to a second optical sensor 224, which converts the second part of the second composite signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0089] In some cases, the optical signal combiner 211 splits the first composite signal such that the portion of the comparison signal included in the first part of the composite signal (i.e., the portion of the first part of the comparison signal) is phase-shifted by 180° with respect to the portion of the comparison signal in the second part of the composite signal (i.e., the portion of the first part of the comparison signal), but the portion of the reference signal in the first part of the composite signal (i.e., the portion of the first part of the reference signal) is not phase-shifted with respect to the portion of the reference signal in the second part of the composite signal (i.e., the portion of the first part of the reference signal). Alternatively, the optical signal combiner 211 splits the composite signal such that the portion of the reference signal in the first part of the composite signal (i.e., the portion of the first part of the reference signal) is phase-shifted by 180° with respect to the portion of the reference signal in the second part of the composite signal (i.e., the portion of the first part of the reference signal), but the portion of the comparison signal in the first part of the composite signal (i.e., the portion of the first part of the comparison signal) is not phase-shifted with respect to the portion of the comparison signal in the second part of the composite signal (i.e., the portion of the first part of the comparison signal).

[0090] When the optical signal combiner 212 splits the second composite signal such that the portion of the comparison signal in the first part of the second composite signal is phase-shifted by 180° with respect to the portion of the comparison signal in the second part of the second composite signal, the optical signal combiner 211 also splits the composite signal such that the portion of the comparison signal in the first part of the composite signal is phase-shifted by 180° with respect to the portion of the comparison signal in the second part of the composite signal. When the optical signal combiner 212 splits the second composite signal such that the portion of the reference signal in the first part of the second composite signal is phase-shifted by 180° with respect to the portion of the reference signal in the second part of the second composite signal, the optical signal combiner 211 also splits the composite signal such that the portion of the reference signal in the first part of the composite signal is phase-shifted by 180° with respect to the portion of the reference signal in the second part of the composite signal.

[0091] The first reference waveguide 210 and the second reference waveguide 208 are configured to provide a phase shift between a first portion of the reference signal and a second portion of the reference signal. For example, the first reference waveguide 210 and the second reference waveguide 208 can be configured to provide a 90-degree phase shift between a first portion of the reference signal and a second portion of the reference signal. For example, one reference signal portion can be the in-phase component, while the other reference signal portion can be the quadrature component. Thus, one of the reference signal portions can be a sine function, while 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 configured 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. However, 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.

[0092] The first optical sensor 223 and the second optical sensor 224 can be connected as a balanced detector, and the first optical sensor 218 and the second optical sensor 220 can also be connected as a balanced detector. For example, Figure 5B A schematic diagram of the relationship between the electronic device, the first optical sensor 223, the second optical sensor 224, the first optical sensor 218, and the auxiliary optical sensor 220 is provided. The symbol of a photodiode is used to represent the first optical sensor 223, the second optical sensor 224, the first optical sensor 218, and the second optical sensor 220, but one or more of these sensors can have other configurations. In some cases, Figure 5B all of the components shown in the schematic diagram of are included on the LIDAR chip. In some cases, Figure 5B the components shown in the schematic diagram of are distributed between the LIDAR chip and an electronic device located outside the LIDAR chip.

[0093] The electronic device connects the first optical sensor 223 and the second optical sensor 224 as a first balanced detector 225, and connects the first optical sensor 218 and the second optical sensor 220 as a second balanced detector 226. In particular, the first optical sensor 223 and the second optical sensor 224 are connected in series. In addition, the first optical sensor 218 and the second optical sensor 220 are connected in series. The series connection in the first balanced detector communicates with the first data line 228, which carries the output from the first balanced detector as a first data signal. The series connection in the second balanced detector communicates with the second data line 232, which carries the output from the second balanced detector as a second data signal. The first data signal is an electrical representation of a first composite signal, and the second data signal is an electrical representation of a second composite signal. Thus, the first data signal includes contributions from a first waveform and a second waveform, and the second data signal is a composite of the first waveform and the second waveform. The portion of the first waveform in the first data signal is phase-shifted relative to the portion of the first waveform in the first data signal, but the portion of the second waveform in the first data signal is in-phase relative to the 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. In addition, the second data signal includes a portion of a comparison signal that is in-phase relative to a different portion of the comparison signal included in the first data signal. The first data signal and the second data signal beat due to the beat between the comparison signal and the reference signal, i.e., the beat in the first composite signal and the second composite signal.

[0094] The electronic device 32 includes a mathematical transformer 238 that is configured to perform a mathematical transformation on the first data signal and the second data signal. For example, the mathematical transformation can be a complex Fourier transform, taking the first data signal and the second data signal as inputs. Since the first data signal is the in-phase component and the second data signal is its quadrature component, the first data signal and the second data signal together act as a complex data signal, where the first data signal is the real part of the input and the second data signal is the imaginary part of the input.

[0095] The mathematical transducer 238 includes a first analog-to-digital converter (ADC) 264 that receives a first data signal from the first data line 228. The first analog-to-digital converter (ADC) 264 converts the first data signal from an analog form to a digital form and outputs a first digital data signal. The mathematical transducer 238 includes a second analog-to-digital converter (ADC) 266 that receives a second data signal from the second data line 232. The second analog-to-digital converter (ADC) 266 converts the second data signal from an analog form to a digital form 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 act as a complex signal, where the first digital data signal acts as the real part of the complex signal and the second digital data signal acts as the imaginary part of the complex data signal.

[0096] The mathematical transducer 238 includes a transformation component 268 that receives a complex data signal. For example, the transformation component 268 receives the first digital data signal from the first analog-to-digital converter (ADC) 264 as an input and also receives the second digital data signal from the second analog-to-digital converter (ADC) 266 as an input. The transformation component 268 can be configured to perform a mathematical transformation on the complex signal to convert 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) can provide an explicit solution for the frequency shift of the LIDAR input signal relative to the LIDAR output signal caused by the radial velocity between the reflecting object and the LIDAR chip. The electronic device uses one or more frequency peaks output from the transformation component 268 for further processing to generate LIDAR data (the distance and / or radial velocity between the reflecting object and the LIDAR chip or LIDAR system). The transformation component 268 can perform attributed functions using firmware, hardware, software, or a combination thereof.

[0097] Figure 5C An example of the relationship between the frequency, time, cycle, and data period of the system output signal is shown. The fundamental frequency (f o ) of the system output signal can be the frequency of the system output signal at the start of the cycle.

[0098] Figure 5C The frequency-versus-time relationship for two cycle sequences labeled cycle j and cycle j+1 is shown. In some cases, the frequency-versus-time pattern repeats in each cycle, as Figure 5CAs shown. The cycle shown does not include a repositioning period and / or the repositioning period is not located between cycles. Thus, Figure 5C shows the result of continuous scanning.

[0099] Each cycle includes K data periods, each data period is associated with a cycle index k and is labeled as DP k . In Figure 5C 's example, each cycle includes two data periods, labeled as DP k , where k = 1 and 2. In some cases, as Figure 5C shown, the frequency vs. time pattern is the same for corresponding data periods in different cycles. Corresponding data periods are data periods with the same cycle index. Thus, each data period DP1 can be considered a corresponding data period, and the associated frequency vs. time pattern is the same in Figure 5C . At the end of a cycle, the electronic device restores the frequency to the same frequency level at which it started the previous cycle.

[0100] During data period DP1 and data period DP2, the electronic device operates the light source such that the frequency of the system output signal varies as a linear function of time. The direction of frequency change during data period DP1 is opposite to the direction of frequency change during data period DP2. In some cases, the target rate of frequency change during data period DP1 is a constant, denoted as α, while the target rate of frequency change during data period DP2 is a constant, denoted as -α.

[0101] The frequency output from the complex Fourier transform represents the beat frequency of the composite signal, and each composite signal includes a comparison signal that beats relative to a reference signal. The beat frequencies (f LDP ) from two or more different data periods can be combined to generate LIDAR data. For example, the beat frequency determined from DP1 in Figure 5C can be combined with the beat frequency determined from DP2 in Figure 5C to determine LIDAR data. For example, the following equation applies during such a data period, where the electronic device increases the frequency of the outgoing LIDAR signal during this data period, such as what happens in data period DP1 of Figure 5C : f ub = -f d + ατ, where f ub is the frequency provided by the transform component 268 (f determined from DP1 in this example LDP ), f d represents the Doppler shift (f d = 2νf c / c), where f c represents the optical frequency (f o), where c represents the speed of light, ν is the radial velocity between the reflecting object and the LIDAR system, with the direction from the reflecting object towards the LIDAR system assumed to be the positive direction, and c is the speed of light. The following equations apply during such data periods where the electronics reduces the frequency of the outgoing LIDAR signal, such as what occurs in Figure 5C data period DP2: f db =-f d -ατ, where f db is the frequency provided by the transformation component 268 (in this example, f i,LDP ) determined from DP2. In these two equations, f d and τ are unknowns. The electronics solves these two equations to obtain these two unknowns. Then, the radial velocity of the sample region can be quantified based on the Doppler shift (ν = c * f d / (2f c )) and / or the gap distance of the sample region can be quantified based on c * f d / 2.

[0102] In some cases, there is more than one object in the sample region. In some cases, when there is more than one object in the sample region, the transducer may output more than one frequency, where each frequency is associated with a different object. Frequencies generated by the same object within different data periods of the same cycle can be considered corresponding frequency pairs. LIDAR data can be generated for each corresponding frequency pair output by the transformation. Thus, separate LIDAR data can be generated for each object in the sample region.

[0103] Although Figures 5A to 5B shows an optical signal combiner that combines a portion of the reference signal with a portion of the comparison signal, the optical signal processor can include a single optical signal combiner that combines the reference signal with the comparison signal to form a composite signal. Thus, at least a portion of the reference signal and at least a portion of the comparison signal can be combined to form a composite signal. The combined portion of the reference signal can be the entire reference signal or a portion of the reference signal, and the combined portion of the comparison signal can be the entire comparison signal or a portion of the comparison signal.

[0104] As an example of an optical signal processor that combines a reference signal and a comparison signal to form a composite signal, Figures 5D to 5E shows that Figures 5A to 5B the optical signal processor is modified to include a single optical signal combiner. The comparison waveguide 196 directly carries the comparison signal to the first optical signal combiner 211, and the reference waveguide 198 directly carries the reference signal to the first optical signal combiner 211.

[0105] The first optical signal combiner 211 combines the comparison signal and the reference signal into a composite signal. Due to the frequency difference between the comparison signal and the reference signal, the first composite signal beats between the comparison signal and the reference signal. The first optical signal combiner 211 also splits the composite signal onto the first detector waveguide 221 and the second detector waveguide 222. The first detector waveguide 221 carries a first portion of the composite signal to the first optical sensor 223, which 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 the second optical sensor 224, which converts the second portion of the second composite signal into a second electrical signal.

[0106] Figure 5E A schematic diagram of the relationship between the electronic device, the first optical sensor 223, and the second optical sensor 224 is provided. The symbol of a photodiode is used to represent the first optical sensor 223 and the second optical sensor 224, but one or more of these sensors may have other configurations. In some cases, Figure 5E all the components shown in the schematic diagram are included on the LIDAR chip. In some cases, Figure 5E the components shown in the schematic diagram are distributed between the LIDAR chip and electronic devices located outside the LIDAR chip.

[0107] The electronic device connects the first optical sensor 223 and the second optical sensor 224 into a first balanced detector 225. In particular, the first optical sensor 223 and the second optical sensor 224 are connected in series. The series connection in the first balanced detector communicates with the first data line 228, which 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.

[0108] The electronic device 32 includes a mathematical transformer 238 that is configured to perform a mathematical transform on the first data signal. The mathematical transform can be a real Fourier transform with the first data signal as the input. The electronic device can use the frequency output from the transform as described above to extract LIDAR data.

[0109] Figures 5A to 5E Each balanced detector disclosed in the context of

[0110] as in Figure 5CAs discussed in the context of, the electronic device 32 adjusts the frequency of the system output signal. When the light source 4 is a gain element or a laser chip, the electronic device 32 can modulate the voltage applied to the light source, thereby regulating the current passing through the light source. The voltage applied over time can serve as a light source control signal, which is selected to achieve a desired frequency-versus-time relationship pattern in the optical signal including the light from the outgoing LIDAR signal. Additionally or alternatively, the light source 4 can also include a modulator (not shown), which is configured to modulate the frequency of the outgoing LIDAR signal. When the light source 4 includes a modulator, the light source controller can apply the light source control signal to the modulator to achieve a desired frequency-versus-time relationship pattern in the optical signal including the light from the outgoing LIDAR signal. Suitable modulators include, but are not limited to, phase modulators. When the light source is a laser cavity or includes a laser cavity, the modulator can be located outside the laser cavity along the utility waveguide 12. Alternatively, when the light source is a laser cavity or includes a laser cavity such as an external cavity laser (ECL), the modulator can be located outside the cavity.

[0111] Figure 6A is shown as being used as Figures 1A to 1C and Figure 4 a configuration of a portion of a suitable phase difference generator that is all or a part of the phase difference generator 29 disclosed in the context of. As described above, the first waveguide 31 carries the first control signal to the control signal processor 36, and the second waveguide 34 carries the second control signal to the control signal processor 36. The control signal processor 36 includes an optical signal combiner 286. The optical signal combiner 286 combines the first control signal and the second control signal into a beat control signal. For different phase difference generators 29, the phase difference between the contribution of the first control signal to the beat control signal and the contribution of the second control signal to the beat control signal is different. For example, the contribution of the first control signal to the beat control signal and the contribution of the second control signal to the beat control signal can have a phase difference represented by φ n where φ n = π(n - 1) / N, where φ n represents the phase difference of the phase difference generator 29 associated with the phase difference generator index n, and N represents the number of phase difference generators 29 associated with the phase difference generator index. Thus, the phase difference (φ n ) can be between 0 and π, and there is a constant phase change (π / N) between adjacent phase differences (φ n ).

[0112] The length of the first optical path that the light included in the first control signal travels from the optical splitter 26 to the optical signal combiner 286 can be different from the length of the second optical path that the light included in the second control signal travels from the optical splitter 26 to the optical signal combiner 286. Therefore, the first optical path, the second optical path, the optical splitter 26, and the optical signal combiner 286 in each phase difference generator 29 can be used as a Mach-Zehnder interferometer.

[0113] The lengths of the first optical path and the second optical path can be selected to provide the desired phase difference (φ n ) for each phase difference generator 2. For example, the phase difference (φ n ) of the phase difference generator 29 is a function of the length of the first optical control path of the phase difference generator 29 from the optical splitter 26 to the utility splitter 33, the length of the second optical control path of the phase difference generator 29 from the optical splitter 26 to the control splitter 30, the length of the first waveguide 31, and the length of the second waveguide 34. Therefore, the lengths of the optical control paths and / or the waveguides are selected to provide the desired phase difference (φ n ) for each phase difference generator 29. The control waveguide 28 can include a delay section 37, which can be used to increase the length of the control waveguide 28. For example, Figure 1A the shown delay section 37 can represent a spiral arrangement of the control waveguide 28 to reduce the amount of space occupied by the delay section 37 on the LIDAR chip.

[0114] Since the electronic device can adjust the frequency of the outgoing LIDAR signal that is the source of the light included in the first control signal and the second control signal, the delay that is the source of the phase difference causes the second control signal to have a different frequency from the first control signal. Due to the frequency difference between the second control signal and the first control signal, a beat control signal beats between the first control signal and the second control signal.

[0115] The optical signal combiner 286 also separates the beat control signal onto the first detector waveguide 294 and the second detector waveguide 296. The first detector waveguide 294 carries the first part of the beat control signal to the first optical sensor 298, which converts the first part of the beat control signal into a first electrical signal. The second detector waveguide 296 carries the second part of the beat control signal to the second optical sensor 300, which converts the second part of the beat control signal into a second electrical signal. Examples of suitable optical sensors include germanium photodiodes (PDs) and avalanche photodiodes (APDs).

[0116] In some cases, the optical signal combiner 286 separates the beat control signal such that the part of the first signal included in the first part of the beat control signal is phase-shifted by 180° with respect to the part of the first signal included in the second part of the beat control signal.

[0117] An example of a suitable optical signal combiner 286 is a multimode interference (MMI) device, such as a 2x2 MMI device. Other suitable optical signal combiners 286 include, but are not limited to, adiabatic splitters and directional couplers. In some cases, the functionality of the illustrated optical signal combiner 286 is performed by more than one optical component or a combination of optical components.

[0118] Figure 6B is a schematic diagram showing the relationship between an electronic device and a different phase difference generator 29. The symbols of photodiodes are used to represent the first optical sensor 298 and the second optical sensor 300, but one or more of these sensors may have other configurations. In some cases, Figure 6B all the components shown in the schematic diagram are included on the LIDAR chip. In some cases, Figure 6B the components shown in the schematic diagram are distributed between the LIDAR chip and an electronic device located outside the LIDAR chip.

[0119] The first optical sensor 298 and the second optical sensor 300 can be connected as a balanced detector. For example, in Figure 6B the electronic device connects the first optical sensor 298 and the second optical sensor 300 into a balanced detector 314. In particular, the first optical sensor 298 and the second optical sensor 300 are connected in series. The series connection in the balanced detector communicates with a data line 318, which carries the output from the balanced detector as an electrical beat control signal.

[0120] The electrical beat control signal is an electrical representation of the beat control signal. Therefore, the electrical beat control signal beats at the beat frequency of the beat control signal.

[0121] The waveform converter 320 receives the electrical beat control signal, and the waveform converter outputs a converted signal. The waveform converter 320 is configured to convert the waveform of the electrical beat control signal from a sinusoidal current to a square wave voltage or a substantially square wave voltage. Therefore, the waveform converter 320 outputs a converted signal. In one example, the waveform converter includes an amplifier 322 connected in series with a comparator 324, such that the amplifier 322 receives the electrical beat control signal, and the comparator outputs the converted signal. Suitable waveform converters 320 include, but are not limited to: a linear transimpedance amplifier (TIA) followed by a voltage comparator, a non-linear limiting TIA followed by a comparator, and a current mode comparator.

[0122] Each phase difference generator 29 outputs a different converted signal. The electronic device 32 includes a digital logic gate 329, which receives the converted signal from the phase difference generator 29. Suitable digital logic gates 329 include, but are not limited to, edge combiners based on combinational logic such as XOR gates or XOR gates) and edge combiners based on sequential logic. Therefore, the digital logic gate outputs a falling edge or a rising edge in response to the converted signal having a baseline crossing point. Otherwise, the digital logic gate output does not undergo a transition. In some cases, the baseline crossing point of the converted signal is the zero crossing point of the converted signal.

[0123] Figure 6C A graphical representation of the logic signal amplitude over time of N=4 phase difference generators 29 is provided, which are based on φ n =π(n-1) / N provides a phase difference (φ n ), where the phase difference (φ n ) represents the phase difference between the first signal and the second signal in the beat control signal of different phase difference generators 29. Figure 6C The transition points of the voltage values ​​indicated by the arrows in the figure appear at the time of the baseline crossing point of one of the converted signals, and thus appear at the time of the baseline crossing point of the electric beat vibration control signal. Figure 6C A timing diagram of the baseline crossing point of the converted signal can be represented. Since the converted signal is a conversion of the electric beat vibration control signal, the baseline crossing point of the converted signal can represent the baseline crossing point of the electric beat vibration control signal. For example, Figure 6C A graph of the zero crossings of the converted signal over time and / or the zero crossings of the electrical beat control signal over time may be represented. Each falling or rising edge is represented by an arrow, labeled with the phase difference generator index (n), being the source of the baseline crossing point that results in a high voltage value.

[0124] Each of the first signal and each of the second signals includes, consists of, or consists essentially of light from the outgoing LIDAR signal. Therefore, when the frequency of the outgoing LIDAR signal has a linear chirp, the phase difference (φ) of different phase difference generators 29 is n ) are spaced by a gap constant π / N (π / 4 in this case). Therefore, when the frequency chirp of the outgoing LIDAR signal is linear, the time gap between adjacent edges in the logic signal ( Figure 6C The time interval between baseline crossing points is constant during the chirp duration. Therefore, when the frequency chirp of the outgoing LIDAR signal is linear, the time interval between baseline crossing points is constant during the chirp duration. However, since the actual chirp rate (α a ) deviates from the target chirp rate (α), so the time gap between adjacent edges in the logic signal ( Figure 6CThe one marked as g) in [ ] changes over time. Therefore, the change in the time gap between adjacent edges indicates non - linear chirping and variable chirp rate. Thus, the time gap between adjacent edges in the logic signal and the time gap between the baseline crossing points in the beat signal are functions of the actual chirp rate (α) of the outgoing LIDAR signal. For example, increasing the actual chirp rate (α a ) decreases the time gap between adjacent edges in the logic signal and between the baseline crossing points ( Figure 6C ) marked as g) in [ ]. Decreasing the actual chirp rate (α) increases the time gap between adjacent edges in the logic signal and between the baseline crossing points ( Figure 6C ) marked as g) in [ ].

[0125] This time gap is related to the frequency of the baseline crossing points of the beat signal. For example, this frequency can be approximated as 1 / g. When the frequency chirp of the outgoing LIDAR signal is linear, the frequency of the baseline crossing points remains constant during the chirp duration. When the frequency chirp of the outgoing LIDAR signal is linear, the time gap between the baseline crossing points remains constant during the chirp duration. However, since the actual chirp rate (α a ) deviates from the target chirp rate (α), the frequency changes over time. Therefore, the change in the frequency of the baseline crossing points indicates non - linear chirping and variable chirp rate. Thus, the frequency of the baseline crossing points in the beat signal is a function of the actual chirp rate (α) of the outgoing LIDAR signal. For example, increasing the actual chirp rate (α a ) increases the frequency of the crossing points in the beat signal, while decreasing the actual chirp rate (α) increases the frequency of the crossing points.

[0126] The chirp rate (α) represents the target chirp rate of the outgoing LIDAR signal during the data period. Since the actual time gap (g a ) between adjacent edges is a function of the actual chirp rate (α a ), the target chirp rate is associated with the target time gap (g t ). Since the time gap between adjacent edges also represents the time gap between the baseline crossing points, the actual time gap (g a ) can represent the actual time gap between the baseline crossing points of the beat signal, and the target time gap (g t ) can represent the target time gap between the beat signals. The actual time gap (g a ) can be a function of multiple actual time gaps. For example, the actual time gap (g a ) can each represent the time gap value obtained by averaging multiple different time gaps. Similarly, the actual frequency (f a ) can be a function of multiple baseline crossing points. For example, the actual frequency (f a) can each represent a frequency obtained by averaging multiple baseline crossing points.

[0127] The target frequency (f t ) can each be associated with a specific data period. For example, data periods with the same period index k can be associated with a target chirp rate and an associated target frequency (f t ). The target chirp rate and the associated target frequency (f t ) associated with data periods having different period indices (k) can be different or can be the same. The system can maintain the outgoing LIDAR signal at the desired chirp rate for the data period with period index k by keeping or substantially keeping the baseline crossing point frequency at the target frequency (f t ) associated with the data period having period index k.

[0128] The target chirp rate and the associated target time gap can each be associated with a specific data period. For example, data periods with the same period index k can be associated with a target chirp rate and an associated target time gap. The target chirp rate and the associated target time gap associated with data periods having different period indices (k) can be different or can be the same. As described above, the system can maintain the outgoing LIDAR signal at the desired chirp frequency for the data period with period index k by keeping or substantially keeping the frequency of the baseline crossing points at the target frequency (f t ) associated with the data period having period index k. In one example, by operating the system to keep or substantially keep the actual time gap (g a ) between adjacent edges or the actual time gap (g a ) between adjacent baseline crossing points at the target frequency (f t ) associated with the data period having period index k, the system keeps or substantially keeps the frequency of the baseline crossing points at the target frequency (f t ) associated with the data period having period index k.

[0129] The system can operate the system by using a feedback loop such as a phase-locked loop (PLL) to keep or substantially keep the actual time gap (g a ) at the target time gap (g t ). An example phase-locked loop can lock the phase of a logic signal to the phase of a local oscillator. The error signal generator outputs an error signal having one or more characteristics that indicate the degree and direction of the mismatch between the actual time gap (g a ) and the target time gap (g t ). Thus, one or more characteristics of the error signal indicate the degree and direction of the mismatch between the chirp rate (α a ) and the target chirp rate (α).

[0130] For example, Figure 6B FIG. shows a schematic diagram of an example of an electronic device 32 including an error signal generator 330, which may be an analog error signal generator. The error signal generator 330 includes a phase detector 332 that receives a logic signal and outputs an example of an error signal. The phase detector 332 may be an analog phase detector. Thus, the error signal may be an analog signal.

[0131] The error signal generator 330 includes a local oscillator 334 that outputs a local signal, which is also received at the phase detector 332. The local signal may be a continuous wave with a fixed frequency and phase. The frequency of the local signal is selected such that the local signal has a baseline crossing point separated by a target time gap (g t ). For example, the frequency of the local signal may be selected such that the local signal has a zero crossing point separated by a target time gap (g t ). In one example, the frequency of the local signal is selected to be equal to Figure 6C the frequency of the logic signal shown. Thus, when the phase of the logic signal matches the phase of the local signal, the edge of the logic signal aligns with the baseline crossing point of the local signal. Thus, when the phase of the local signal matches the phase of the logic signal, the sign and magnitude of the error signal do not indicate an error in the logic signal. However, as the actual chirp rate (α a ) of the outgoing LIDAR signal moves away from the target chirp rate (α), the magnitude and sign of the error signal indicate the magnitude and direction of the error between the actual chirp rate (α a ) and the target chirp rate (α). Thus, the local oscillator 334 serves as a reference for the target time gap (g t ). Suitable local oscillators include, but are not limited to, MEMS oscillators, crystal oscillators, or electronic phase-locked loops locked to MEMS or crystal oscillators.

[0132] The error signal generator 330 may optionally include a filter 338, such as a low-pass filter, that receives the error signal and outputs a filtered version of the error signal.

[0133] Suitable phase detectors include, but are not limited to, analog hybrid-based phase detectors, digital phase detectors, or phase-frequency detectors using flip-flops. Suitable local oscillators include, but are not limited to, MEMS oscillators, crystal oscillators, or electronic phase-locked loops locked to MEMS or crystal oscillators. Suitable filters 338 include, but are not limited to, analog RC filters and digital filters.

[0134] The error signal is received at the control signal generator 340, which uses the error signal to modify the light source control signal. The light source control signal is the signal that the light source controller 342 applies to the light source 4 to cause the light source to output light included in the outgoing LIDAR signal. For example, the light source control signal may indicate the voltage level applied to the light source 4 during a frequency chirp duration, or may indicate the voltage level applied to a modulator included in the light source.

[0135] The control signal generator 340 can modify the light source control signal to correct the magnitude and direction of the error indicated by the error signal. For example, if the error signal indicates that the actual time gap (g a ) is 10% smaller than the target time gap (g t ), the control signal generator 340 can modify the light source control signal to reduce the difference between the actual time gap (g a ) and the target time gap (g t ). For example, the control signal generator 340 can modify the light source control signal such that applying the modified light source control signal to the light source will cause the actual time gap (g a ) to increase by approximately 10%. In some cases, the actual time gap (g a ) can be increased by approximately 10% by modifying the light source control signal such that the voltage applied to the light source is reduced by approximately 10%.

[0136] The modified light source control signal is received by the light source controller 342. The light source controller 342 applies the modified light source control signal to the light source 4 as the light source control signal, which can later be modified by the control signal generator 340. Thus, the light source control signal can be modified multiple times during a data cycle. Thus, the modification of the light source control signal can be performed in real time and / or "on-the-fly".

[0137] As described above, modifying the light source control signal such that the light source control signal is applied to the light source reduces the difference between the actual time gap (g a ) and the target time gap (g t ). Reducing this difference locks the phase of the logic signal to the phase of the local signal. Since the phase of the local signal is constant, the phase of the logic signal also remains constant. Since a linear chirp will generate a logic signal with a constant phase, the constant phase of the logic signal indicates the presence of a linear chirp. Thus, the light source control signal is controlled by a feedback loop, where the phase of the logic signal is locked to the phase of the local signal.

[0138] The control signal generator 340 and the light source controller 342 can be the same component or can be different components. In some cases, the control signal generator 340 and the light source controller 342 are integrated into the same component. Examples of suitable control signal generators 340 include, but are not limited to, DSP chips, FPGAs, and microprocessors. Examples of suitable control signal generators 340 can perform the attributing function using firmware, hardware, software, or a combination thereof. Examples of suitable light source controllers 342 include, but are not limited to, a current mode DAC or a voltage DAC followed by a transconductance amplifier.

[0139] Figure 6D shows the relationship between the electronic device and the phase difference generator 29 that has been modified for use with the digital error signal generator 330. The error signal generator 330 can include a digital phase detector 332 and a filter 338. The error signal output from the phase detector 332 can be a digital signal that is received at the storage device 344. When the filter 338 receives the error signal, the filtered error signal from the filter 338 can be a digital signal that is received at the storage device 344. The storage device stores error signals from a plurality of different data cycles of the frequency chirp duration in the data cycle. For example, Figure 6B The solid lines in show an example of error signals stored for four different data cycles, each data cycle associated with k = 1 (DP1). The y-axis represents the error direction and magnitude indicated by the error signal. For example, the error shown on the y-axis can represent one or more characteristics that indicate the actual time gap (g Figure 6E ) between adjacent edges in the logic signal and the target time gap (g a ) and the degree and direction of inconsistency. In one example, the error shown on the y-axis represents the percentage difference between the actual time gap (g t ) between adjacent edges in the logic signal and the target time gap (g a ) between adjacent edges in the logic signal. Suitable storage devices 344 include random access memory (RAM). t ) between adjacent edges in the logic signal. Suitable storage devices 344 include random access memory (RAM).

[0140] The control signal generator 340 can access the signals stored in the storage device 344. In response to a threshold number of error signals, each from data cycles having the same cycle index k, stored in the storage device 344, the control signal generator 340 can generate one or more composite error signals from all or part of the stored error signals. For example, the control signal generator 340 can average the error signals from different data cycles all having the same cycle index k to generate a composite error signal that is the average of the error signals over time. For example, Figure 6EThe dashed line in can represent the average of the error signals stored from data cycles associated with the same cycle index (k = 1). This dashed line can represent the composite error signal within the frequency chirp duration during the data cycle.

[0141] Since Figure 6E the solid line in is associated with the cycle index k = 1 (DP1), the resulting composite error signal is also associated with the cycle index k = 1 (DP1). Therefore, Figure 6E the dashed lines shown in are associated with data cycles all associated with k = 1 (DP1). However, the control signal generator 340 can generate composite error signals for all or some of the different cycle indices (k). In some cases, the control signal generator 340 stores the composite error signals over time for one or more different cycle indices (k) in the storage device 344.

[0142] Figure 6E The signals in are shown as analog signals, but these signals can also be digital signals. Therefore, the time axis can be divided into multiple time periods, each with a constant duration. For ease of illustration, Figure 6E the time periods in the signals of are short enough such that the digital signals appear continuous over time. For ease of illustration, Figure 6F will Figure 6E the composite error signal in be shown as a digital signal divided into multiple time periods. Figure 6F The time periods shown in are longer than those in Figure 6E so that the digital nature of the composite error signal is more apparent in the image.

[0143] In some cases, the control signal generator 340 determines whether to generate a modified light source control signal. The control signal generator 340 can calculate the composite error level of the composite error signal. For example, the control signal generator 340 can calculate the deviation or root mean square of the composite error signal during the chirp duration. The control signal generator 340 can compare the composite error level with one or more error criteria to determine whether to generate a modified light source control signal. For example, the control signal generator 340 can compare the composite error level with an error threshold. The control signal generator 340 can generate a modified light source control signal in response to the composite error level exceeding the error threshold. The control signal generator 340 can refrain from generating a modified light source control signal in response to the composite error level being less than or equal to the error threshold.

[0144] The control signal generator 340 can modify the waveform of the light source control signal to correct the magnitude and direction of the error indicated by the composite error signal. Figure 6GShows an example of the waveform of the light source control signal during the chirp duration in different data cycles, where the different data cycles are all associated with the same cycle index (k). The shown voltage levels each show the voltage applied to the light source 4 during the associated time period. The voltage level labeled V0 represents the waveform of the light source control signal. Thus, during the chirp duration, a series of digital signals or bits representing the series of voltage levels labeled V0 can serve as the digital representation of the light source control signal.

[0145] The control signal generator 340 can modify the waveform of the light source control signal (V0) to have a waveform represented by the voltage level labeled (V m ). Thus, the voltage level labeled V m represents the waveform of the modified light source control signal. Thus, during the chirp duration, a series of digital signals or bits representing the series of voltage levels labeled V m can serve as the digital representation of the modified light source control signal.

[0146] The modification of the light source control signal can be by the magnitude and direction of the error indicated by the corrected composite error signal. For example, the control signal generator 340 can modify the light source control signal to generate a modified light source control signal that can reduce the magnitude of the error level indicated by the composite error signal. For example, Figure 6F can represent the composite error signal generated by applying the light source control signal in Figure 6G to the light source during a data cycle having the same cycle index associated with the composite error signal. Figure 6F The error on the y-axis in a can represent the percentage difference, where the percentage difference represents the actual time gap (g t ) between adjacent edges in the logic signal and the target time gap (g a ) between adjacent edges in the logic signal (er). The light source control signal can be modified such that the voltage applied during each time period changes the percentage of the percentage difference for that time period, but in the opposite direction. For example, when the percentage difference for a time period indicates that the actual time gap (g t ) of that time period is 10% smaller than the target time gap (g m ), the voltage of the light source control signal for that time period can be increased by 10%. Thus, the V m value for each time period can be generated by V m = V0*(1 - (er / 100)), where er represents the percentage difference value, and the values of V o and er are associated with the same time period. The error value labeled V m can represent the modified waveform of the light source control signal. Thus, representing the labeled Vm The digital signal of the error value sequence can serve as a modified light source control signal.

[0147] The light source control signals are each associated with different data periods and thus also with different cycle indices. Accordingly, the control signal generator 340 can generate different modified light source control signals associated with different cycle indices.

[0148] The above example of modifying the light source control signal changes the light source control signal in proportion to the error level indicated by the composite error signal. However, other relationships or more complex filtering and signal shaping can also be used. For example, the association between the change in the light source control signal and different error values can be stored in the storage device 344. For a given composite error, the control signal generator 340 can modify the light source control signal indicated by the change in the light source control signal associated with the given composite error. The association between the composite error and the change in the light source control signal can be represented by a data structure, such as a lookup table, a mathematical formula, a filter, and / or an adaptive filter.

[0149] The modified light source control signal is received by the light source controller 342. The light source controller 342 can include a digital-to-analog converter that receives the modified light source control signal and converts the modified light source control signal into an analog signal. The digital-to-analog converter outputs an analog version of the modified light source control signal, and the light source controller 342 applies the analog version of the modified light source control signal to the light source 4. Since different light source control signals are associated with different data periods and thus also with different cycle indices, the light source controller 342 applies the modified light source control signal such that the data period and the light source control signal applied to the light source are associated with the same cycle index. Accordingly, different light source control signals can be applied to the light source during different data periods in a cycle. In addition, the same light source control signal can be applied to data periods in multiple different cycles. Accordingly, there is no need to dynamically apply the light source control signal.

[0150] The digital version of the modified light source control signal can be stored in a storage device and can serve as a light source control signal that can be later modified by the control signal generator 340.

[0151] After generating the composite error signal associated with the data cycle index, the control signal generator 340 can clear the storage device to store another set of error signals associated with the data cycle index. The control signal generator 340 and the light source controller 342 can repeat the process of generating and applying the modified light source control signal in response to the number of error signals in the set exceeding a threshold number.

[0152] Figure 7AIt is a schematic diagram showing another example of the relationship between an electronic device and different phase difference generators 29. Each phase generator includes a counter 346 that receives the converted signal from the waveform converter 320. Each counter also receives an event signal from a clock 348 such as a time-to-digital converter. The event signal can indicate the occurrence of an event, such as the arrival of an incoming electrical pulse. Each counter 346 can count the number of times the baseline crosses a point during a time interval. For example, each counter 346 can count the number of zero-crossing points of the converted signal during a time interval. Suitable counters include, but are not limited to, synchronous counters.

[0153] Each counter outputs a counter data signal that indicates the number of times the baseline crosses a point during different times. The counter data signals output from different phase difference generators 29 are received by the error signal generator 330. The error signal generator 330 can be a digital component, such as a digital controller, a processor, or a microprocessor. Thus, the error signal generator 330 can include a control signal generator 340 and / or can perform Figure 6D the functions of the control signal generator 340 disclosed in the context of Figure 7A Alternatively,

[0154] In addition to receiving the counter data signal, the error signal generator 330 can also receive the duration of each time interval from the clock. The error signal generator 330 can divide the number of times the baseline crosses a point during the time interval by the duration of the time interval to determine the period between the points where the baseline crosses for each different converted signal. In addition, the error signal generator 330 can identify the leading edge of each converted signal by accumulating time intervals and accordingly identify the time at which the leading edge of each beat control signal occurs. The leading edge time of each converted signal combined with the period between the points where the baseline crosses the converted signal indicates the time at which each point where the baseline crosses occurs. The timing of the points where the baseline crosses the converted signals from different conversions plotted on the same time line provides a graph, such as Figure 2 the graph in C. Thus, the error signal generator 330 combines the timings of the points where the baseline crosses the converted signals from different conversions to calculate the actual time gap (g a ) between the points where the baseline crosses.

[0155] The error signal generator 330 can calculate the error between the actual time gap (g a ) between the points where the baseline crosses and the target time gap (g t ). For example, the error can be calculated as the actual time gap (g a ) between the points where the baseline crosses and the target time gap (g t) the difference between, or the percentage change from the target time interval (g t ) to the actual time interval (g a ). A series of error values calculated during the chirp duration can serve as an error signal as disclosed in the context of Figure 6E and as shown in Figure 7B . As described above, the target time interval (g t ) is associated with a period index. Thus, a series of error values calculated during the chirp duration and that can serve as an error signal is associated with one of the period indices. The error signal generator 330 can access the memory 344 and store the error values and the resulting error signal in the memory 344.

[0156] In response to a threshold number of error signals, all of which are from data periods having the same period index k, being stored in the device 344, the error signal generator 330 can generate a composite error value based on all or a portion of the stored error values. Thus, the error signal generator 330 can generate one or more composite error signals based on all or a portion of the stored error signals. For example, the error signal generator 330 can average the error signals from multiple data periods all having the same period index k to generate a composite error value that is the average of how the error signal changes over time. For example, Figure 7C the error value in can represent the average of the stored error values from data periods associated with the same period index (i.e., k = 1), where the average error value for a certain time period is the average of the error values during that time period. A digital signal carrying the composite error value during the frequency chirp duration can serve as a composite error signal.

[0157] Since the composite error value and the resulting error signal are associated with the period index, i.e., k = 1 (DP1), the error value and the resulting composite error signal are also associated with the period index k = 1 (DP1). Thus, the error signal generator 330 can generate composite error values and / or composite error signals for all or a portion of different period indices (k). In some cases, the error signal generator 330 stores the composite error values and / or composite error signals for one or more different period indices (k) during the frequency chirp duration in the storage device 344.

[0158] In some cases, the error signal generator 330 determines whether to generate a modified light source control signal. The error signal generator 330 can calculate the composite error level of the composite error signal. For example, the error signal generator 330 can calculate the deviation or root mean square of the composite error signal during the chirp duration. The error signal generator 330 can compare the composite error level with one or more error criteria to determine whether to generate a modified light source control signal. For example, the error signal generator 330 can compare the composite error level with an error threshold. The error signal generator 330 can generate a modified light source control signal in response to the composite error level exceeding the error threshold. The error signal generator 330 can refrain from generating a modified light source control signal in response to the composite error level being less than or equal to the error threshold.

[0159] The error signal generator 330 can modify the waveform of the light source control signal to correct the magnitude and direction of the error indicated by the composite error signal. Figure 7D An example of the waveform of the light source control signal during the chirp duration in different data periods is shown, and the different data periods are all associated with the same period index (k). The shown voltage levels each show the voltage applied to the light source 4 during the associated time period. The voltage level labeled V0 represents the waveform of the light source control signal. The error signal generator 330 can modify the waveform of the light source control signal (V0) to have a waveform represented by the voltage level labeled (V m )). Therefore, the voltage level labeled V m represents the waveform of the modified light source control signal.

[0160] The light source control signal can be modified to correct the magnitude and direction of the error indicated by the composite error signal. For example, the error signal generator 330 can modify the light source control signal to generate a modified light source control signal that reduces the magnitude of the error level indicated by the composite error signal. For example, Figure 7D can represent the composite error signal generated by applying the Figure 7C light source control signal to the light source during a data period having the same period index associated with the composite error signal. Figure 7C The y-axis in can represent the percentage difference, where the percentage difference represents the actual time gap (g a ) between adjacent high voltage values in the logic signal and the target time gap (g t ) between adjacent high voltage values in the logic signal. The light source control signal can be modified such that the voltage applied during each time period changes the percentage of the percentage difference of that time period, but in the opposite direction. For example, when the percentage difference of a certain time period indicates that the actual time gap (g a ) of that time period is longer than the target time gap (gt ) When it is less than 10%, the voltage of the light source control signal for this time period can be increased by 10%. Therefore, the V value for each time period can be generated by V m = V0*(1 - (er / 100)), where er represents the percentage difference, and the values of V m , V m , and er are associated with the same time period. o

[0161] The light source control signals are each associated with different data cycles and thus also with different cycle indices. Therefore, the error signal generator 330 can generate different modified light source control signals associated with different cycle indices.

[0162] The above example of modifying the light source control signal changes the light source control signal in proportion to the error level indicated by the composite error signal. However, other relationships can also be used. For example, the association between the change in the light source control signal and different error values can be stored in the storage device 344. For a given composite error, the error signal generator 330 can modify the light source control signal indicated by the change in the light source control signal associated with the given composite error. The association between the composite error and the change in the light source control signal can be represented by a data structure, such as a look-up table, a mathematical formula, one or more filters, and / or one or more adaptive filters.

[0163] The modified light source control signal is received by the light source controller 342. The light source controller 342 can include a digital-to-analog converter that receives the modified light source control signal and converts the modified light source control signal into an analog signal. The digital-to-analog converter outputs an analog version of the modified light source control signal, and the light source controller 342 applies the analog version of the modified light source control signal to the light source 4. Since different light source control signals are associated with different data cycles and thus also with different cycle indices, the light source controller 342 applies the modified light source control signal such that the data cycle and the light source control signal applied to the light source are associated with the same cycle index. Therefore, different light source control signals can be applied to the light source during different data cycles in a loop. In addition, the same set of light source control signals can be applied to the data cycles in multiple different loops. Therefore, there is no need to dynamically apply the light source control signal.

[0164] The digital version of the modified light source control signal can be stored in the storage device and can serve as the light source control signal that can be modified by the error signal generator 330 later.

[0165] ​After generating the composite error signal associated with the data cycle index, the error signal generator 330 may clear the storage device to store another set of error signals associated with the data cycle index. The error signal generator 330 may repeat the process of generating and applying the modified light source control signal in response to the number of error signals in the set exceeding a threshold number.

[0166] Figure 8 is in accordance with Figure 7A or Figure 6D A process flow method for operating an electronic device. At process block 360, the error signal generator 330 may generate an error signal and store the error signal in the storage device 344. The error signal may be generated for one or more different cycle indices, where each error signal is associated with one of the cycle indices. At determination block 362, the error signal generator 330 may determine whether a threshold number of error signals associated with the same cycle index has been stored. This determination may be made for all or part of the cycle indices. In response to a negative determination for all cycle indices, the error signal generator 330 may return to process block 360. When the determination is affirmative for one or more cycle indices, each cycle index for which the determination is affirmative may serve as a target cycle index. When the determination is affirmative, the error signal generator 330 may proceed to process block 364, where the storage device may be cleared to store an additional set of error signals for each target cycle index. The threshold number for different cycle indices may be the same or different. Examples of suitable threshold numbers include, but are not limited to, a threshold number greater than or equal to 1 or 2.

[0167] The error signal generator 330 can proceed from process block 364 to process block 366. At process block 366, the error signal generator 330 can generate a composite error signal for each target cycle index. The error signal generator 330 can optionally store the composite error signal for each target cycle index in a storage device. The error signal generator 330 can proceed from process block 366 to determination block 368. At determination block 368, for each target cycle index, the error signal generator 330 and / or the control signal generator 340 can determine whether the error level indicated by the composite error signal generated at process block 336 is sufficient to generate a modified light source control signal for that target cycle index. For example, for each target cycle index, the error signal generator 330 and / or the control signal generator 340 can determine whether the error level indicated by the composite error signal generated at process block 336 is higher than an error threshold. As another example, for each target cycle index, the error signal generator 330 can determine whether the root mean square of the composite error signal generated at process block 336 is higher than the error threshold. In response to a negative determination for all cycle indices, the error signal generator 330 and / or the control signal generator 340 can return to process block 360. When the determination is affirmative for one or more target cycle indices, each target cycle index for which the determination is affirmative can serve as an erroneous target cycle index. When the determination is affirmative for one or more target cycle indices, the error signal generator 330 and / or the control signal generator 340 can proceed to process block 370, where the error signal generator 330 and / or the control signal generator 340 can generate a modified light source control signal for each erroneous target cycle index.

[0168] The process flow can proceed from process block 370 to process block 372. At process block 373, during the data cycle having each erroneous target cycle index, the light source controller 342 can apply an analog version of the modified light source control signal generated at process block 370 for that data cycle index to the light source. The analog version of the modified light source control signal for the erroneous target cycle index can be applied in place of the light source control signal previously associated with that erroneous target cycle index. Any light source control signal previously applied to the light source to generate an error signal at process block 360 for cycle indices that did not become target cycle indices can continue to be applied to the light source during the data cycles having those cycle indices.

[0169] As described above, Figures 1A to 1CThe control waveguide 28 shown may include a delay section 37, which can be used to increase the length of the control waveguide 28. Increasing the length of the control waveguide 28 increases the difference between the length of the first optical path and the length of the second optical path. Increasing the length difference between these optical paths increases the beat frequency of the beat control signal. The increased beat frequency increases the number of baseline crossing points providing the above time gaps. Thus, increasing the length difference between these optical paths can reduce the size of these time gaps, and accordingly can improve the resolution of the modification of the light source control signal.

[0170] As an alternative to the delay section 37 in the control waveguide 28, or in addition to the delay section 37 in the control waveguide 28, the first waveguide 31 or the second waveguide 34 in all or part of the phase difference generator 29 may include a delay section 37. However, the delay section 37 would occupy an inappropriately large amount of space on a semiconductor chip such as a LIDAR chip. Thus, the ability to have a single delay section 37 as Figures 1A to 1C shown can provide a more efficient use of the available space on the LIDAR chip.

[0171] Although the digital versions of the light source control signal and the modified light source control signal are disclosed above as having voltage levels over a constant time period, the light source control signal and the modified light source control signal can have voltage levels separated by a constant voltage increment over a variable time period. For example, Figure 9 is a graph of voltage versus time showing an example of the voltage levels of the light source control signal and the modified light source control signal. The constant voltage increment is labeled v i . The graph includes voltage levels labeled V m and V0, which have varying durations indicated by the time axis. The duration of the voltage level labeled V m and overlapping the voltage level labeled V0 is represented by parentheses rather than a line.

[0172] The voltage level labeled V0 represents the waveform of the light source control signal. Thus, a series of digital signals or bits representing the durations of the voltage levels labeled V0 over the chirp duration can serve as a digital representation of the light source control signal. The control signal generator 340 and / or the error signal generator 330 can use the above composite error signal to modify the waveform of the light source control signal (V0) to have a waveform represented by the voltage level labeled (V m ). Thus, the voltage level labeled V m represents the waveform of the modified light source control signal. A series of digital signals or bits representing the durations of the voltage levels labeled V m over the chirp duration can serve as a digital representation of the modified light source control signal.

[0173] Figure 9 including a real curve that may represent an example of an analog version of a modified light source control signal generated by a digital-to-analog converter based on a voltage level labeled V m Thus, the light source controller 342 may apply the analog version of the modified light source control signal as an analog light source control signal to the light source 4.

[0174] Figures 6A to 8 In addition to the illustrated components, the electronic device 32 disclosed in the context of Figure 6D 、 Figure 6E and Figure 7A may further include a mathematical converter 238.

[0175] A suitable electronic device 32 may include an electronic controller that includes or consists of: analog circuits, digital circuits, application-specific integrated circuits (ASICs), processors, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), computers, microcomputers, or combinations thereof, which are suitable for performing the above-described operations, monitoring, and control functions. In some cases, the electronic device 32 includes one or more storage devices that store instructions to be executed by the electronic controller during the execution of the operations, control, and monitoring functions. Although the electronic device is shown as a single component located in a single location, the electronic device may include multiple different components that are independent of each other and / or located in different locations. In addition, as described above, all or part of the disclosed electronic device may be included on a chip that includes the electronic device integrated with the chip.

[0176] In Figure 6B the context of Figure 6D the phase detector 332 disclosed may be or include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or a microprocessor. The analog phase detector 332 may perform the attributing function using discrete or analog integrated circuits. For example, in

[0177] For example, in Figure 6B the context of Figure 6DThe digital control signal generator 340 disclosed in the context of

[0178] For example, in Figure 6B the context of, the light source controller 342 may be or include an application-specific integrated circuit (ASIC) or discrete electronic devices. In some cases, the analog light source controller 342 uses a digital-to-analog converter, a transconductance amplifier, a current-mode digital-to-analog converter, and combinations thereof to perform the attribution function.

[0179] For example, in Figure 7A the context of, the error signal generator 330 may be or include a controller, a processor or a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP). In some cases, the digital error signal generator 330 uses a time-to-digital converter or other implementations using digital gates to perform the attribution function.

[0180] Suitable platforms for LIDAR chips include, but are not limited to, silicon dioxide, indium phosphide, and silicon-on-insulator wafers. Figure 10 is a cross-section of a part of a chip constructed from a silicon-on-insulator wafer. The silicon-on-insulator (SOI) wafer includes a buried layer 410 located between a substrate 412 and an optical transmission medium 414. In the silicon-on-insulator wafer, the buried layer 410 is silicon dioxide, while the substrate 412 and the optical transmission medium 414 are silicon. The substrate 412 of an optical platform such as an SOI wafer can serve as the base of the entire LIDAR chip. For example, Figures 1A to 1C the optical components on the LIDAR chip of

[0181] Figure 10 A part of the LIDAR chip in

[0182] Figure 10The dimensions of the ridge waveguide are marked. For example, the width of the ridge is marked as w, and the height is marked as h. The thickness of the flat region is marked as T. For LIDAR applications, these dimensions may be more important than other dimensions because higher levels of optical power than those used in other applications are required. The ridge width (marked as w) is greater than 1 mm and less than 4 mm, the ridge height (marked as h) is greater than 1 mm and less than 4 mm, and the flat region thickness is greater than 0.5 mm and less than 3 mm. These dimensions may apply to straight or substantially straight portions of the waveguide, curved portions of the waveguide, and tapered portions of the (one or more) waveguides. Thus, these portions of the waveguide will be single-mode. However, in some cases, these dimensions apply to straight or substantially straight portions of the waveguide. Additionally or alternatively, the curved portions of the waveguide may have a reduced plate thickness to reduce optical losses in the curved portions of the waveguide. For example, the curved portions of the waveguide may have a ridge extending away from a flat region having a thickness greater than or equal to 0.0 mm and less than 0.5 mm. While the above dimensions will generally provide straight or substantially straight portions of the waveguide having a single-mode structure, they may result in multimode (one or more) tapered portions and / or (one or more) curved portions. A taper that substantially does not excite higher-order modes can be used to achieve coupling between the multimode geometry and the single-mode geometry. Thus, the waveguide can be configured such that even when the signal carried in the waveguide is carried in a portion of the waveguide having multimode dimensions, the signal carried in the waveguide is carried in single-mode. In Figure 10 the context of the waveguide structures disclosed is applicable to all or a portion of the waveguide on a LIDAR chip constructed in accordance with Figures 1A to 1C the

[0183] As described above, controlling waveguide 28 can include a delay section 37, which can be used to increase the length of control waveguide 28. Delay section 37 can represent a helical arrangement of control waveguide 28. The helical arrangement is selected to reduce the amount of space occupied by the longer waveguide. Figure 11 A portion of control waveguide 28 having a helical arrangement is shown. Near the center of the helical arrangement, the waveguide turns back on itself. While the geometry of the helical arrangement approximates a circle, the helical arrangement can also be other geometries, such as approximately elliptical, rectangular, or triangular. Thus, the helical arrangement can include straight waveguide sections and / or substantially straight waveguide sections.

[0184] The optical sensor that docks with the waveguide on the LIDAR chip can be a component that is separate from the chip and then attached to the chip. For example, the optical sensor can be a photodiode or an avalanche photodiode. Examples of suitable optical sensor components include, but are not limited to, InGaAs PIN photodiodes manufactured by Hamamatsu located in Hamamatsu, Japan, or InGaAs APDs (avalanche photodiodes) manufactured by Hamamatsu located in Hamamatsu, Japan. These optical sensors can be located at the center of the LIDAR chip. Alternatively, all or part of the waveguide that terminates at the optical sensor can terminate at a facet located at the edge of the chip, and the optical sensor can be attached to the chip edge above the facet such that the optical sensor receives the light passing through the facet. Using an optical sensor as a component separate from the chip is applicable to all or part of the optical sensors selected from the group consisting of the first optical sensor 218, the second optical sensor 220, the first optical sensor 223, the second optical sensor 224, the first optical sensor 298, and the second optical sensor 300.

[0185] As an alternative to the optical sensor being a separate component, all or part of the optical sensors can be integrated with the chip. For example, examples of optical sensors that dock with ridge waveguides on chips composed of silicon-on-insulator wafers can be found in: Optics Express Vol.15, No.21, 13965 - 13971 (2007); U.S. Patent No. 8,093,080 issued on January 10, 2012; U.S. Patent No. 8,242,432 issued on August 14, 2012; and U.S. Patent No. 6,108,847 issued on August 22, 2000, each of which is incorporated herein by reference in its entirety. Using an optical sensor integrated with the chip is applicable to all or part of the optical sensors selected from the group consisting of the auxiliary optical sensor 218, the second optical sensor 220, the first optical sensor 223, the second optical sensor 224, the second optical sensor 224, the first optical sensor 298, and the second optical sensor 300.

[0186] The light source 4 that interfaces with the utility waveguide 12 can be a laser chip that is separated from the LIDAR chip and then attached to the LIDAR chip. For example, the light source 4 can be a laser chip attached to the chip using a flip-chip arrangement. A flip-chip arrangement is suitable when the light source 4 is to interface with a ridge waveguide on a chip constructed from a silicon-on-insulator wafer. Alternatively, the utility waveguide 12 can include a grating (not shown), such as a Bragg grating, that acts as a reflector for an external cavity laser. In these cases, the light source 4 can include a gain element that is separated from the LIDAR chip and then attached to the LIDAR chip in a flip-chip arrangement. Suitable examples of interfacing between a flip-chip gain element and a ridge waveguide on a chip constructed from a silicon-on-insulator wafer can be found in U.S. Patent No. 9,705,278, issued July 11, 2017, and U.S. Patent No. 5,991,484, issued November 23, 1999; each of which is incorporated herein by reference in its entirety. When the light source 4 is a gain element or a laser chip, the electronics 32 can change the frequency of the outgoing LIDAR signal by changing the current level applied to the gain element or the laser cavity.

[0187] The LIDAR system described above includes a plurality of optical components, such as a LIDAR chip, a LIDAR adapter, a light source, a light sensor, waveguides, and amplifiers. In some cases, the LIDAR system includes one or more passive optical components in addition to or in place of the illustrated optical components. Passive optical components can be solid-state components that do not contain moving parts. Suitable passive optical components include, but are not limited to, lenses, mirrors, gratings, reflective surfaces, splitters, demultiplexers, multiplexers, polarizers, polarization splitters, and polarization rotators. In some cases, the LIDAR system includes one or more active optical components in addition to or in place of the illustrated optical components. Suitable active optical components include, but are not limited to, optical switches, phase tuners, attenuators, steerable mirrors, steerable lenses, tunable demultiplexers, and tunable multiplexers.

[0188] In view of these teachings, other embodiments, combinations, and modifications of the present invention will be readily apparent to those of ordinary skill in the art. Accordingly, the present invention is limited only by the appended claims, which, when viewed in conjunction with the above specification and drawings, include all such embodiments and modifications.

Claims

1. A LIDAR system, comprising: a light source that outputs an outgoing LIDAR signal; a plurality of phase difference generators, each phase difference generator combining a first optical signal and a second optical signal to generate a beat control signal, each of the first optical signals includes light from the outgoing LIDAR signal, and each of the second optical signals includes light from the outgoing LIDAR signal, each of the beat control signals is generated with a phase difference between the contribution of the first optical signal to the beat control signal and the contribution of the second optical signal to the beat control signal, for the beat control signals from different phase difference generators, the phase differences are different, each of the beat signals has a plurality of baseline crossing points, and the baseline crossing points of the beat signal occur at a frequency; and an electronic device that applies a light source control signal to the light source to chirp the frequency of the outgoing LIDAR signal, the electronic device is configured to modify the light source control signal in response to a change in the frequency of the baseline crossing points of the beat control signal.

2. The LIDAR system according to claim 1, wherein, There are more than three phase difference generators.

3. The LIDAR system according to claim 2, wherein, The phase difference generators are configured such that the difference between each pair of numerically adjacent phase differences is a constant.

4. The LIDAR system according to claim 3, wherein, The phase difference generators are configured such that the difference between each pair of numerically adjacent phase differences is π / N, where N represents the number of phase difference generators.

5. The LIDAR system according to claim 4, wherein, Each of the phase difference generators can be associated with a phase difference generator index n, where n is an integer with a value from 1 to N, and the phase difference can be represented by φ n = π(n - 1) / N, where φ n represents the phase difference of the phase difference generator associated with the phase difference generator index n.

6. The LIDAR system according to claim 1, wherein, The light in the first optical signal and the second optical signal does not leave the LIDAR system.

7. The LIDAR system according to claim 6, wherein, The LIDAR chip includes a photonic integrated circuit having a functional waveguide that carries the outgoing LIDAR signal, and the light in the first optical signal and the second optical signal does not leave the LIDAR chip.

8. The LIDAR system according to claim 1, wherein, The LIDAR system is configured to output a system output signal that includes light from the outgoing LIDAR signal.

9. The LIDAR system according to claim 1, wherein, The LIDAR system is configured to output a system output signal that includes light from the outgoing LIDAR signal.

10. The LIDAR system according to claim 9, further comprising: an optical signal combiner configured to combine a comparison optical signal and a reference optical signal to generate a beat signal, the comparison optical signal includes light from the system output signal that has been reflected by an object located outside the LIDAR system and returned to the LIDAR system, and the reference optical signal includes light from the outgoing LIDAR signal that does not leave the LIDAR system.

11. The LIDAR system according to claim 10, wherein, The electronic device is configured to calculate LIDAR data based on the beat frequency of the beat signal, the LIDAR data indicating the radial velocity and / or distance between the object and the LIDAR system.

12. The LIDAR system according to claim 1, wherein, Each of the phase difference generators includes an optical signal combiner that receives the first optical signal from a first waveguide and the second optical signal from a second waveguide, and each of the first waveguides receives the first optical signal from a control waveguide.

13. The LIDAR system according to claim 12, wherein, The control waveguide includes a spiral waveguide.

14. The LIDAR system according to claim 12, wherein, Each of the first waveguides receives the first optical signal from a utility waveguide that carries the outgoing LIDAR signal.

15. The LIDAR system according to claim 14, wherein, The control waveguide receives a portion of the outgoing LIDAR signal from the utility waveguide.

16. The LIDAR system according to claim 1, wherein, The electronic device is configured to modify the light source control signal such that the chirp of the frequency of the outgoing LIDAR signal is a linear chirp.

17. The LIDAR system according to claim 1, wherein, The electronic device is configured to modify the light source control signal such that the time gap is constant.

18. The LIDAR system according to claim 1, wherein, The electronic device configured to modify the light source control signal in response to a change in the frequency of the baseline crossing point of the beat control signal includes: the electronic device configured to modify the light source control signal in response to a change in the time gap between the baseline crossing points of the beat signal.

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