LiDAR with microlens array and integrated photonic switch array
The present disclosure is directed to imaging LiDARs with optical antennas fed by optical waveguides. The optical antennas can be activated through an optical switch network that connects the optical antennas to a laser source to a receiver. A microlens array is positioned between a lens of the LiDAR system and the optical antennas, the microlens array being positioned so as to transform an emission angle from a corresponding optical antenna to match a chief ray angle of the lens. Methods of use and fabrication are also provided.
1. An imaging LiDAR system, comprising:
a lens having an aperture center;
at least one light emitter;
at least one light detector;
an antenna array comprising a plurality of optical antennas;
a programmable optical switch network configured to provide an optical path from the at least one light emitter to a selected transmit optical antenna and from a selected receiving optical antenna to the at least one light detector;
a microlens array comprising a plurality of microlenses corresponding to the plurality of optical antennas of the antenna array, the microlens array being disposed between and spaced from each of the plurality of optical antennas and the lens, wherein the microlens array is positioned approximately at a focal plane of the lens and the antenna array is positioned approximately at a focal plane of the microlens array;
wherein centers of at least some of the microlenses of the microlens array are offset relative to corresponding ones of the optical antennas so as to redirect light from the corresponding ones of the optical antennas toward the aperture center of the lens.
2. The system of claim 1 , wherein the microlens array selected from the group consisting of silicon, glass, silicon nitride, polymers, photoresists, plastic, ceramic, dielectric, and other semiconductor materials.
3. The system of claim 1 , wherein each microlens is selected from the group consisting of Fresnel lens, meta lens, metasurface lens, an any other artificially synthesized lens.
4. The system of claim 1 , wherein the microlens array further comprises an anti-reflection coatings on one or more surf aces.
5. The system of claim 1 , wherein the lens is selected from the group consisting of a single lens, a compound lens, a multiple-element lens, a smartphone lens, and a telephoto lens.
6. The system of claim 1 , further comprising:
a spacer disposed along at least one edge of the antenna array, the spacer being configured to maintain an optimal spacing in which the microlens array is positioned approximately at the focal plane of the lens and the antenna array is positioned approximately at the focal plane of the microlens array.
7. The system of claim 6 , wherein the spacer and the microlens array form a sealed cavity.
8. The system of claim 7 , wherein the sealed cavity is hermetic.
9. The system of claim 1 , wherein the plurality of optical antennas comprise separate transmit and receiving optical antennas and separate optical paths connecting to these separate transmit and receiving optical antennas.
10. The system of claim 1 , wherein the microlens array comprises a single-sided design.
11. The system of claim 1 , wherein the microlens array comprises a double-sided design.
12. The system of claim 1 , wherein the microlens array is periodic.
13. The system of claim 1 , wherein the antenna array is periodic.
14. The system of claim 12 , wherein the antenna array is periodic.
15. The system of claim 12 , wherein the antenna array is not periodic.
16. The system of claim 13 , wherein the microlens array is not periodic.
17. The system of claim 1 , wherein the microlens array and the antenna array both have fiducial markers configured to allow for alignment and permanent attachment.
18. The system of claim 1 , wherein the plurality of optical antennas have an emission angle of 8° and a beam divergence angle of 30°.
19. The system of claim 18 , wherein the microlens array is configured to convert the beam divergence angle to 22° and an angle between an emission chief ray and a normal to a focal plane of the lens, to a value ranging between 0°-37°.
20. A programmable integrated circuit (PIC) for an imaging LiDAR system, comprising:
an antenna array comprising a plurality of optical antennas;
a programmable optical switch network configured to provide an optical path to a selected transmit optical antenna and from a selected receiving antenna; and
a microlens array comprising a plurality of microlenses corresponding to the plurality of optical antennas of the antenna array, wherein the antenna array is positioned approximately at a focal plane of the microlens array;
wherein centers of at least some of microlenses of the microlens array are offset relative to corresponding ones of optical antennas so as to redirect light from the corresponding ones of the optical antennas toward an aperture center of a lens of the imaging LiDAR system.
21. The system of claim 1 , wherein the microlens array is configured to convert an angle between a chief ray and the normal to a focal plane of the lens, to a value ranging between 0°-37°.
22. The system of claim 1 , wherein the plurality of optical antennas comprise the selected transmit optical antenna and the selected receiving optical antenna and the programmable optical switch network is configured to provide a first optical path from the at least one light emitter to the selected transmit optical antenna and a second optical path from the selected receiving optical antenna to the at least one light detector, wherein at least a portion of the first optical path is shared with the second optical path.
23. The system of claim 1 , wherein the selected transmit optical antenna and the selected receiving optical antenna are optically connected to the at least one light emitter and the at least one light detector via a single coupler.
24. The system of claim 1 , wherein the plurality of optical antennas comprises transmit optical antennas and receiving optical antennas, and wherein the transmit and receiving optical antennas transmit and receive light to and from a target via the lens and the microlens array.
25. The system of claim 1 , wherein the selected transmit optical antenna comprises the selected receiving optical antenna.
26. The system of claim 9 , wherein the selected transmit optical antenna and the selected receiving optical antenna transmit and receive light via a single microlens of the microlens array.