Systems and methods for isolating excitation and signal paths for chip-scale LIDAR

Patent metadata

Field	Value
Publication number	US-10908372-B2
Application number	US-201815912196-A
Country	US
Kind code	B2
Filing date	Mar 5, 2018
Priority date	Mar 5, 2018
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

Embodiments described herein improve the performance of active sensing systems, such as LiDAR systems, and enable detection of objects closer to the system's sensor. Illustrative embodiments enable spatial separation of the excitation and return signal on a photonic integrated chip (“PIC”) such that separate waveguides can be used for the excitation and return signals, enabling isolation of the system's detectors from the excitation source without the use of a splitter or circulator. For example, preferred embodiments avoid loss due to the use of splitters and the need for gating the detector, and are desirably compatible with chip-scale systems. Moreover, illustrative embodiments enable keeping the excitation and detection paths on the same PIC (e.g. in an interleaved configuration), which helps keep the system more compact and avoid issues introduced by parallax.

First claim

What is claimed is:

1. An integrated chip for transmitting a Light Detection and Ranging (LiDAR) signal into free space and receiving a reflection of the transmitted LiDAR signal from free space as a return signal, comprising:
a substrate defining a surface, and a space vector normal to the surface, the substrate having:
an output waveguide configured to carry an excitation light signal from a light source for a given pixel;
a return waveguide, distinct and isolated from the output waveguide, configured to carry the return signal for the given pixel to a detector; and
an optical coupler movable between a first position and a second position, wherein:
in the first position, the optical coupler is disposed to couple the excitation light signal from the output waveguide to the free space as the transmitted LiDAR signal, and to couple the return signal from the free space to the return waveguide; and
in the second position, the optical coupler is optically decoupled from the output waveguide and the return waveguide.

2. The integrated chip of claim 1 , wherein the return waveguide forms a waveguide crossing with the output waveguide.

3. The integrated chip of claim 1 , wherein the optical coupler comprises an output grating coupler and an input grating coupler.

4. The integrated chip of claim 1 , wherein the return waveguide does not form a waveguide crossing with the output waveguide.

5. The integrated chip of claim 4 , wherein the output waveguide runs parallel to the return waveguide.

6. The integrated chip of claim 1 , wherein:
the optical coupler comprises a pillar grating, the pillar grating configured to couple the excitation signal from the output waveguide to the free space and to couple the return signal from the free space to the return waveguide; and
the integrated chip further comprises an actuator configured to selectively move the optical coupler between the first position and the second position.

7. The integrated chip of claim 1 , wherein:
the optical coupler comprises an output grating coupler and an input grating coupler; and
the integrated chip further comprises an actuator configured to selectively move the optical coupler between the first position and the second position.

8. The integrated chip of claim 7 , wherein the actuator further comprises a bridge waveguide in optical communication with the input grating coupler and the return waveguide to couple the return signal from the input grating coupler to the return waveguide.

9. The integrated chip of claim 1 , wherein:
the return waveguide is a first return waveguide and is configured to carry a TM component of the return signal to a TM detector; and
the integrated chip further comprises a second return waveguide configured to carry a TE component of the return signal to a TE detector, wherein:
in the first position, the optical coupler is disposed to couple the TM component to the first return waveguide, and to couple the TE component to the second return waveguide.

10. An integrated chip for transmitting a Light Detection and Ranging (LiDAR) signal into free space and receiving a reflection of the transmitted LiDAR signal from free space as a return signal, comprising:
a substrate defining a surface, and a space vector normal to the surface, the substrate having:
an output waveguide configured to carry an excitation light signal from a light source;
a return waveguide, distinct and isolated from the output waveguide, configured to carry the return signal to a detector; and
an optical coupler movable between a first position and a second position, wherein:
in the first position, the optical coupler is disposed to couple the excitation light signal from the output waveguide to the free space as the transmitted LiDAR signal, and to couple the return signal from the free space to the return waveguide; and
in the second position, the optical coupler is optically decoupled from the output waveguide and the return waveguide,
wherein more than a terminal portion of the output waveguide and more than a terminal portion of the return waveguide are disposed in or on the substrate.

11. The integrated chip of claim 10 , wherein all portions of the output waveguide and all portions of the return waveguide are disposed in or on the substrate.

12. An integrated chip for transmitting a Light Detection and Ranging (LiDAR) signal into free space and receiving a reflection of the transmitted LiDAR signal from free space as a return signal, comprising:
a substrate defining a surface, and a space vector normal to the surface, the substrate having:
an output waveguide configured to carry an excitation light signal from a light source;
a return waveguide, distinct and isolated from the output waveguide, configured to carry the return signal to a detector; and
an optical coupler movable between a first position and a second position, wherein:
in the first position, the optical coupler is disposed to couple the excitation light signal from the output waveguide to the free space as the transmitted LiDAR signal, and to couple the return signal from the free space to the return waveguide; and
in the second position, the optical coupler is optically decoupled from the output waveguide and the return waveguide,
wherein the output waveguide is configured to carry the excitation light signal transmitted into free space and not the return signal received from free space, and the return waveguide is configured to carry the return signal received from free space and not the excitation light signal transmitted into free space.

Assignees

• Charles Stark Draper Laboratory Inc

Inventors

• Moebius Michael G
• Spector Steven J

Classifications

• G02B2006/12107

  Grating · CPC title

• G01S7/4818

  using optical fibres · CPC title

• G02B6/43 Primary

  Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections · CPC title

• G02B27/0087

  Phased arrays · CPC title

• G02B26/0875

  by means of one or more refracting elements · CPC title