Lidar with switchable local oscillator signals

Abstract

A light detection and ranging (LIDAR) sensor system includes a plurality of LIDAR pixels and a local oscillator module. The local oscillator module is coupled to the plurality of LIDAR pixels. The local oscillator module includes a first local oscillator input configured to receive a first local oscillator signal and a second local oscillator input configured to receive a second local oscillator signal. The local oscillator module is configured to provide the first local oscillator signal or the second local oscillator signal to a first LIDAR pixel of the plurality of LIDAR pixels.

1 . A light detection and ranging (LIDAR) sensor system comprising:
 a laser source configured to emit a laser beam,   a splitter configured to split the laser beam into a transmit beam and a local oscillator signal;   a polarizing module configured to receive the local oscillator signal and generate a first local oscillator signal and a second local oscillator signal that is different from the first local oscillator signal;   a plurality of LIDAR pixels;   a transmit beam module coupled to the plurality of LIDAR pixels;   a local oscillator module coupled to the plurality of LIDAR pixels, the local oscillator module comprising a first local oscillator input configured to receive the first local oscillator signal, a second local oscillator input configured to receive the second local oscillator signal, a first plurality of output ports corresponding to the first local oscillator signal, and a second plurality of output ports corresponding to the second local oscillator signal;   one or more processors configured to: simultaneously drive the transmit beam, the first local oscillator signal, and the second local oscillator signal to a particular LIDAR pixel of the plurality of LIDAR pixels one at a time to sequentially scan through the plurality of LIDAR pixels; and   a power monitor coupled to the particular LIDAR pixel, the power monitor configured to detect a quantity of power in the transmit beam provided to the particular LIDAR pixel.   
     
     
         2 - 4 . (canceled) 
     
     
         5 . The LIDAR sensor system of  claim 1 , wherein the one or more processors are configured to drive the transmit beam module to provide the transmit beam to the particular LIDAR pixel while the one or more processors drive the local oscillator module to provide the first local oscillator signal and the second local oscillator signal to the particular LIDAR pixel. 
     
     
         6 . The LIDAR sensor system of  claim 1 , wherein the particular LIDAR pixel includes:
 a first optical antenna configured to emit the transmit beam;   a second optical antenna configured to detect a return beam;   a first receiver configured to receive (i) a first polarization orientation of the return beam; and (ii) the first local oscillator signal from the local oscillator module; and   a second receiver configured to receive (i) a second polarization orientation of the return beam; and (ii) the second local oscillator signal from the local oscillator module.   
     
     
         7 . The LIDAR sensor system of  claim 6 , wherein the second optical antenna includes a dual-polarization receive grating configured to (i) direct the first polarization orientation of the return beam to the first receiver; and (ii) direct the second polarization orientation of the return beam to the second receiver. 
     
     
         8 . The LIDAR sensor system of  claim 6 , wherein the second optical antenna includes:
 a first polarization receive grating configured to direct the first polarization orientation of the return beam to the first receiver; and   a second polarization receive grating configured to direct the second polarization orientation of the return beam to the second receiver, wherein the first polarization receive grating is spaced apart from the second polarization receive grating.   
     
     
         9 . The LIDAR sensor system of  claim 6 , wherein the first receiver includes a first optical mixer, and wherein the second receiver includes a second optical mixer. 
     
     
         10 . The LIDAR sensor system of  claim 1 , wherein the one or more processors are configured to drive the transmit beam module to provide the transmit beam to the particular LIDAR pixel while the one or more processors drive the local oscillator module to provide the first local oscillator signal and the second local oscillator signal to the particular LIDAR pixel. 
     
     
         11 . (canceled) 
     
     
         12 . The LIDAR sensor system of  claim 1 , wherein the local oscillator module includes a plurality of optical switches arranged in a multi-tiered configuration. 
     
     
         13 . The LIDAR sensor system of  claim 1 , wherein the first local oscillator signal has a first polarization orientation, and wherein the second local oscillator signal has a second polarization orientation that is different from the first polarization orientation. 
     
     
         14 . The LIDAR sensor system of  claim 13 , wherein the first polarization orientation is orthogonal to the second polarization orientation. 
     
     
         15 . An autonomous vehicle control system for an autonomous vehicle, the autonomous vehicle control system comprising:
 a light detection and ranging (LIDAR) system including:
 a laser source configured to emit a laser beam; 
 a splitter configured to split the laser beam into a transmit beam and a local oscillator signal; 
 a polarizing module configured to receive the local oscillator signal and generate a first local oscillator signal and a second local oscillator signal that is different from the first local oscillator signal; 
 a plurality of LIDAR pixels; 
 a transmit beam module coupled to the plurality of LIDAR pixels; 
 a local oscillator module coupled to the plurality of LIDAR pixels, the local oscillator module comprising a first local oscillator input configured to receive the first local oscillator signal, a second local oscillator input configured to receive the second local oscillator signal, a first plurality of output ports corresponding to the first local oscillator signal, and a second plurality of output ports corresponding to the second local oscillator signal; 
 one or more processors configured to: simultaneously drive the transmit beam, the first local oscillator signal, and the second local oscillator signal to a particular LIDAR pixel of the plurality of LIDAR pixels one at a time to sequentially scan through the plurality of LIDAR pixels; and 
 a power monitor coupled to the particular LIDAR pixel, the power monitor configured to detect a quantity of power in the transmit beam provided to the particular LIDAR pixel. 
   
     
     
         16 - 18 . (canceled) 
     
     
         19 . The autonomous vehicle control system of  claim 15 , wherein the one or more processors are configured to drive the transmit beam module to provide the transmit beam to the particular LIDAR pixel while the one or more processors drive the local oscillator module to provide the first local oscillator signal and the second local oscillator signal to the particular LIDAR pixel. 
     
     
         20 . An autonomous vehicle comprising:
 a light detection and ranging (LIDAR) system including:
 a laser source configured to emit a laser beam; 
 a splitter configured to split the laser beam into a transmit beam and a local oscillator signal; 
 a polarizing module configured to receive the local oscillator signal and generate a first local oscillator signal and a second local oscillator signal that is different from the first local oscillator signal; 
 a plurality of LIDAR pixels; 
 a transmit beam module coupled to the plurality of LIDAR pixels; 
 a local oscillator module coupled to the plurality of LIDAR pixels, the local oscillator module comprising a first local oscillator input configured to receive the first local oscillator signal, a second local oscillator input configured to receive the second local oscillator signal, a first plurality of output ports corresponding to the first local oscillator signal, and a second plurality of output ports corresponding to the second local oscillator signal; 
 one or more processors configured to: simultaneously drive the transmit beam, the first local oscillator signal, and the second local oscillator signal to a particular LIDAR pixel of the plurality of LIDAR pixels one at a time to sequentially scan through the plurality of LIDAR pixels; and 
 a power monitor coupled to the particular LIDAR pixel, the power monitor configured to detect a quantity of power in the transmit beam provided to the particular LIDAR pixel. 
   
     
     
         21 . The LIDAR sensor system of  claim 1 , wherein the power monitor comprises a detector. 
     
     
         22 . The LIDAR sensor system of  claim 21 , wherein the detector comprises a photodiode. 
     
     
         23 . The LIDAR sensor system of  claim 1 , wherein at least one of the local oscillator module or the transmit beam module comprises a plurality of optical switches in a multi-tiered configuration. 
     
     
         24 . The LIDAR sensor system of  claim 23 , wherein:
 the local oscillator module comprises a first plurality of optical switches arranged in a first multi-tiered configuration; and   the transmit beam module comprises a second plurality of optical switches arranged in a second multi-tiered configuration that is different from the first multi-tiered configuration.   
     
     
         25 . The LIDAR sensor system of  claim 24 , wherein the first multi-tiered configuration includes more switches than the second multi-tiered configuration. 
     
     
         26 . The LIDAR sensor system of  claim 1 , further comprising:
 a first waveguide coupled between the polarizing module and the first local oscillator input of the local oscillator module; and   a second waveguide coupled between the polarizing module and the second local oscillator input of the local oscillator module.   
     
     
         27 . The LIDAR sensor system of  claim 21 , wherein the power monitor further comprises a first waveguide through which the transmit beam passes and a second waveguide configured to receive a portion of the transmit beam from the first waveguide, and wherein the detector is configured to convert the portion of the transmit beam into an electrical signal to support power monitoring.