Dual path light detection and ranging system
A dual path configuration Integrated LiDAR architecture can contain a focal plane transmitter and a focal plane coherent receiver. The integrated LiDAR transmitter can contain an optical frequency chirp generator and a focal plane optical beam scanner with integrated driving electronics. The integrated LiDAR receiver architecture can be implemented with per-pixel coherent detection and amplification.
1. A method comprising:
generating a light beam using an integrated light source in an optical transmitter photonic integrated circuit (PIC);
splitting the light beam into multiple outgoing beams to a target object, the light beam split into the multiple outgoing beams by an optical switch tree in the transmitter PIC, the optical switch tree comprising one or more optical switches controlled by an electronic switch control circuit integrated in the transmitter PIC, the electronic switch control circuit comprising an electrical multiplexer to generate a feedback signal for control of the one or more optical switches using a demultiplexer in the electronic switch control circuit to compensate for changes in optical loss, each of the one or more optical switches comprising photodetectors to generate a current from the multiple outgoing beams, the current being input into the electrical multiplexer to generate the feedback signal, each one of the one or more optical switches comprising two phase shifters driven by outputs of the demultiplexer, the demultiplexer receiving a selection setting that is set using the feedback signal;
transmitting the multiple outgoing beams to a target using a plurality of couplers in the transmitter PIC;
receiving reflected light beams from the target using an optical receiver array; and
generating, using one or more processors of a machine, ranging information from the reflected light beams.
2. The method of claim 1 , wherein a change in temperature of the transmitter PIC causes a change in the optical loss and wherein the electronic switch control circuit compensates by changing the selection setting of the demultiplexer to change phase shifts of one or more of the two phase shifters.
3. The method of claim 1 , wherein the demultiplexer has an input selectively fed to one of the outputs as a function of the selection setting, and wherein the electronic switch control circuit includes a digital to analog converter (DAC) adapted to feed a signal to the input of the demultiplexer based on the feedback signal.
4. The method of claim 3 , wherein the DAC sets the selection setting based on preconfigured values stored in the electronic switch control circuit.
5. The method of claim 1 , wherein the phase shifters are heaters that change a phase of light propagating through waveguides of the one or more optical switches.
6. The method of claim 1 , wherein the optical receiver array is a coherent optical receiver.
7. The method of claim 6 , wherein the coherent optical receiver is integrated in the transmitter PIC.
8. The method of claim 1 , wherein the ranging information is a point cloud comprising a plurality of points that correspond to portions of the reflected light beams.
9. The method of claim 8 , wherein each of the plurality of points includes a distance value to the target.
10. The method of claim 9 , wherein each of the plurality of points includes a velocity value indicating a velocity for the target.
11. The method of claim 1 , wherein the integrated light source is an optical frequency chirp generator.
12. The method of claim 1 , wherein the plurality of couplers is a plurality of optical gratings that transmit the multiple outgoing beams.
13. The method of claim 12 , wherein the plurality of optical gratings receives the reflected light beams.
14. A light ranging system comprising:
a transmitter photonic integrated circuit (PIC) comprising an integrated light source to generate a light beam, the transmitter PIC comprising an optical switch tree that splits the light beam into multiple outgoing beams to be transmitted towards a target, the optical switch tree comprising one or more optical switches controlled by an electronic switch control circuit integrated in the transmitter PIC, the electronic switch control circuit comprising an electrical multiplexer to generate a feedback signal for control of the one or more optical switches using a demultiplexer in the electronic switch control circuit to compensate for changes in optical loss, each of the one or more optical switches comprising photodetectors to generate a current from the multiple outgoing beams, the current being input into the electrical multiplexer to generate the feedback signal, each one of the one or more optical switches comprising two phase shifters driven by outputs of the demultiplexer, the demultiplexer receiving a selection setting that is set using the feedback signal;
an optical receiver array to receive reflected light beams from the target; and
a processor of a machine and memory storing instructions that when executed by the processor cause the machine to perform operations comprising determining ranging information from the reflected light beams.
15. A method comprising:
generating a light beam using an integrated light source in an optical transmitter photonic integrated circuit, wherein the optical transmitter photonic integrated circuit comprises:
an optical switch tree with optical switches, wherein each optical switch comprises two thermal phase shifters between two couplers, and wherein the optical switch tree further comprises photodetectors, and
an electronic switch control circuit with an electrical multiplexer connected to the photodetectors and an electronic demultiplexer connected to the thermal phase shifters;
the method further comprising:
splitting the light beam into multiple outgoing beams to a target object by the optical switch tree;
generating, by means of the photodetectors, currents from the multiple outgoing beams and generating a feedback signal from the electrical multiplexer;
controlling the optical switch tree using the feedback signal to generate a selection setting of the electronic demultiplexer;
transmitting the multiple outgoing beams to a target using a plurality of further couplers in the optical transmitter photonic integrated circuit;
receiving reflected light beams from the target using an optical receiver array; and
generating, using one or more processors of a machine, ranging information from the reflected light beams.
16. The method of claim 15 , wherein the electronic demultiplexer has an input selectively fed to an output of the electronic demultiplexer as a function of the selection setting, and wherein the electronic switch control circuit includes a digital to analog converter feeding a signal to the input of the electronic demultiplexer based on the feedback signal.