TECHNICAL FIELD

This disclosure relates generally to imaging and in particular to a LIDAR (Light Detection and Ranging).

BACKGROUND INFORMATION

Frequency Modulated Continuous Wave (FMCW) LIDAR directly measures range and velocity of an object by directing a frequency modulated, collimated light beam at a target. Both range and velocity information of the target can be derived from FMCW LIDAR signals. Designs and techniques to increase the accuracy of LIDAR signals are desirable.

The automobile industry is currently developing autonomous features for controlling vehicles under certain circumstances. According to SAE International standard J3016, there are 6 levels of autonomy ranging from Level 0 (no autonomy) up to Level 5 (vehicle capable of operation without operator input in all conditions). A vehicle with autonomous features utilizes sensors to sense the environment that the vehicle navigates through. Acquiring and processing data from the sensors allows the vehicle to navigate through its environment. Autonomous vehicles may include one or more FMCW LIDAR devices for sensing its environment.

BRIEF SUMMARY OF THE INVENTION

Implementations of the disclosure include a light detection and ranging (LIDAR) system including a laser, a splitter, a polarization controller, and a dual-polarization grating coupler. The laser is configured to generate light. The splitter is configured to split the light into a plurality of lights. The polarization controller is configured to receive a first split light of the plurality of split lights. The polarization controller includes a first arm and a second arm. The first arm includes a first phase shifter and a second phase shifter that are configured to be controlled to set a phase of the first arm relative to the second arm. The grating coupler includes a first port to receive light from the first arm and a second port configured to receive light from the second arm. The dual-polarization grating coupler is configured to couple the light from the first port into a first beam having a first polarization orientation. The dual-polarization grating coupler is configured to couple the light from the second arm into a second beam with a second polarization orientation.

In an implementation, the LIDAR system further includes an optical mixer configured to receive second light of the plurality of split lights. The dual-polarization grating coupler is configured to couple reflected light having the first polarization orientation into the first arm and configured to couple the reflected light having the second polarization orientation into the second arm. The optical mixer may be configured to output an output signal in response to the reflected light and the second light.

In an implementation, the LIDAR system further includes a splitter configured to provide the first portion of the split light to the polarization controller. The splitter is also configured to provide the second light to the optical mixer.

In an implementation, the LIDAR system further includes a first stage and a second stage. The first stage including a first 2×2 splitter and the first phase shifter. The first 2×2 splitter connects to an interconnect that feeds into the optical mixer. The second stage including a second 2×2 splitter and the second phase shifter.

In an implementation, the first port of the dual-polarization grating coupler is optically coupled to the second phase shifter.

In an implementation, the second beam with the second polarization orientation is orthogonal to the first polarization orientation.

An implementation of the disclosure includes a system for an autonomous vehicle including an active polarization controlled coherent pixel array coupled to a LIDAR processing engine. Pixels in the active polarization controlled coherent pixel array include a polarization controller and a dual-polarization grating coupler. The polarization controller includes a first arm and a second arm. The first arm includes a first phase shifter and a second phase shifter that can be controlled to set a phase of the first arm relative to the second arm. The dual-polarization grating coupler includes a first port to receive light from the first arm and a second port configured to receive light from the second arm. The dual-polarization grating coupler is configured to couple the light from the first port into a first beam having a first polarization orientation. The dual-polarization grating coupler is configured to couple the light from the second arm into a second beam with a second polarization orientation.

In an implementation, the pixels in the active polarization controlled coherent pixel array include an optical mixer configured to receive second light. The dual-polarization grating coupler is configured to couple reflected light having the first polarization orientation into the first arm and configured to couple the reflected light having the second polarization orientation into the second arm. The optical mixer is configured to output an output signal in response to the reflected light and the remaining portion of the split light.

In an implementation, the pixels in the active polarization controlled coherent pixel array include a splitter configured to provide a first portion of the split light to the polarization controller. The splitter is also configured to provide the remaining portion of the split light to the optical mixer.

In an implementation, the first port of the dual-polarization grating coupler is optically coupled to the second phase shifter.

An implementation of the disclosure includes an autonomous vehicle system for an autonomous vehicle including a LIDAR pixel and one or more processors. The LIDAR pixel includes a polarization controller, a grating coupler, and an optical mixer. The polarization controller is configured to receive a first portion of split light. The polarization controller includes a first arm and a second arm. A phase shifter of the polarization controller sets a phase of first-light propagating in the first arm relative to second-light propagating in the second arm. The grating coupler is configured to output an output beam in response to receiving the first-light and the second-light. The grating coupler is configured to receive a reflected beam of the output beam. The optical mixer is configured to output a beat signal in response to receiving a remaining portion of the split light and the reflected beam. The one or more processors are configured to control the phase shifter in response to receiving the beat signal from the pixel.

In an implementation, the grating coupler is a dual-polarization grating coupler configured to couple the first-light from the first arm into a first beam having a first polarization orientation. The dual-polarization grating coupler is configured to couple the second-light from the second arm into a second beam with a second polarization orientation orthogonal to the first polarization orientation.

In an implementation, the one or more processors control the phase shifter to increase a signal level of the beat signal.

In an implementation, the one or more processors control the phase shifter to maximize a signal level of the beat signal.

In an implementation, the system for the autonomous vehicle includes a control system configured to control a powertrain of the autonomous vehicle in response to the beat signal.

In an implementation, the output beam is an infrared output beam.

In an implementation, the system for the autonomous vehicle includes a splitter configured to provide the first portion of the split light to the polarization controller. The splitter is also configured to provide the remaining portion of the split light to the optical mixer.

In an implementation, the polarization controller includes a second phase shifter.

In an implementation, the polarization controller includes a first stage and a second stage. The first stage includes a first 2×2 splitter and the phase shifter. The first 2×2 splitter connects to an interconnect that feeds into the optical mixer. The second stage includes a second 2×2 splitter and the second phase shifter.

In an implementation, a first port of the grating coupler is optically coupled to the second phase shifter.

