Multi-mode interference coupler-based flat compressive and transform imager

Patent metadata

Field	Value
Publication number	US-11218655-B2
Application number	US-201816173854-A
Country	US
Kind code	B2
Filing date	Oct 29, 2018
Priority date	Oct 27, 2017
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

A compressive/transform imager comprising a lens array positioned above input ports for collecting light into the input ports, waveguides routing the light from the input port to waveguide mixing regions (e.g. multi-mode interference couplers), and detectors for receiving outputs of the waveguide mixing regions.

First claim

What is claimed is:

1. A transform imager comprising:
a chip;
a plurality of input ports formed in the chip for coupling light to a waveguide array;
a waveguide mixing region configured to receive light from the waveguide array; and
a plurality of detectors for receiving outputs from the waveguide mixing region, the waveguide mixing region having some outputs that are terminated, such that the plurality of input ports has a number greater than the plurality of detectors, wherein the waveguide array is a multi-mode H-tree array configured to maintain substantially equal path lengths between the plurality of input ports and the plurality of detectors.

2. The transform imager of claim 1 , further comprising: a micro-lens array formed on the chip for collecting light into the plurality of input ports.

3. The transform imager of claim 1 , further comprising: a randomly spaced, sparsely spaced, or non-uniformly spaced input array for collecting light into the plurality of input ports.

4. The transform imager of claim 1 , wherein the plurality of input ports includes a grid of N×M regularly spaced input ports.

5. The transform imager of claim 1 , wherein the waveguide array and waveguide mixing region are made of a material selected from the group consisting of a silicon, silicon nitride, sapphire, titanium dioxide, diamond, silicon carbide, chalcogenide glass, and plasmonic structures.

6. The transform imager of claim 1 , wherein each of the plurality of input ports is an aperture or a grating coupler.

7. The transform imager of claim 1 , wherein the waveguide array and a plurality of initial waveguide mixing regions are formed in a plurality of layers.

8. The transform imager of claim 7 , wherein the terminated outputs of the initial waveguide mixing region are randomly or irregularly spaced.

9. The transform imager of claim 7 , further comprising a final waveguide mixing region configured to receive non-terminated outputs from the plurality of initial waveguide mixing regions and scramble information from the non-terminated outputs before coupling them to the plurality of detectors.

10. The transform imager of claim 9 , wherein the final waveguide mixing region is a compressive imager wherein at least some of the outputs of the final waveguide mixing region are terminated prior to detection by second plurality of detectors.

11. The transform imager of claim 1 , wherein the waveguide mixing region is a multi-mode Rotman lens configured to focus light received from the first plurality of input ports.

12. A method of making a compressive transform imager of claim 1 having n number of input ports suitable for detecting a number of expected features k in a scene, comprising:
forming a chip having n input ports formed on the chip for coupling light to a waveguide array;
forming a waveguide mixing region configured to receive light from the waveguide array;
coupling a plurality of detectors to the waveguide mixing region for receiving outputs from the waveguide mixing region; and
terminating some of the outputs from the waveguide mixing region, wherein a number of terminated outputs is proportional to k*log(n/k).

13. The transform imager of claim 1 , wherein the first plurality of input ports includes n number of input ports for detecting a number of expected features k in a scene, and a number of terminated outputs is proportional to k*log(n/k).

14. A transform imager comprising:
a chip;
a plurality of input ports formed in the chip for coupling light to a waveguide array;
a waveguide mixing region configured to receive light from the waveguide array; and
a plurality of detectors for receiving outputs from the waveguide mixing region, the waveguide mixing region having some outputs that are terminated, such that the plurality of input ports has a number greater than the plurality of detectors;
wherein the first plurality of input ports includes n number of input ports for detecting a number of expected features k in a scene, and a number of terminated outputs is proportional to k*log(n/k).

15. The transform imager of claim 14 , further comprising: a micro-lens array formed on the chip for collecting light into the plurality of input ports.

16. The transform imager of claim 14 , further comprising: a randomly spaced, sparsely spaced, or non-uniformly spaced input array for collecting light into the plurality of input ports.

17. A transform imager comprising:
a chip;
a plurality of input ports formed in the chip for coupling light to a waveguide array;
a waveguide mixing region configured to receive light from the waveguide array; and
a plurality of detectors for receiving outputs from the waveguide mixing region, the waveguide mixing region having some outputs that are terminated, such that the plurality of input ports has a number greater than the plurality of detectors;
wherein the waveguide mixing region is a multi-mode Rotman lens configured to focus light received from the first plurality of input ports.

18. The transform imager of claim 17 , further comprising: a micro-lens array formed on the chip for collecting light into the plurality of input ports.

19. The transform imager of claim 17 , further comprising: a randomly spaced, sparsely spaced, or non-uniformly spaced input array for collecting light into the plurality of input ports.

Assignees

• Charles Stark Draper Laboratory Inc

Inventors

• Moebius Michael
• Brown Julian
• Spector Steven
• Lane Benjamin
• Zhou Alan
• Clevenson Hannah Anne
• Benney Lucas David

Classifications

• H04N25/70 Primary

  SSIS architectures; Circuits associated therewith · CPC title

• G02B27/0087 Primary

  Phased arrays · CPC title

• G02B6/29344

  operating by modal interference or beating, i.e. of transverse modes, e.g. zero-gap directional coupler, MMI · CPC title

• G02B6/2813

  based on multimode interference effect, i.e. self-imaging · CPC title

• G02B2005/1804

  Transmission gratings · CPC title