Waveguide-based projector

Patent metadata

Field	Value
Publication number	US-11604352-B2
Application number	US-202016950109-A
Country	US
Kind code	B2
Filing date	Nov 17, 2020
Priority date	Jul 29, 2020
Publication date	Mar 14, 2023
Grant date	Mar 14, 2023

Abstract

A projector includes an illumination waveguide layer, a collimation waveguide layer, and a spatial modulator. The illumination waveguide layer expands a light beam which is coupled to the spatial modulator. The spatial modulator modulates the expanded light beam to provide a line of light points of controllable brightness. The collimation waveguide collimates light of the light points to obtain a fan of collimated light beams. Each collimated light beam of the fan has an angle corresponding to a coordinate of the corresponding light point of the line. A tiltable reflector may be placed at the exit pupil to scan the fan of light beams in a plane non-parallel to the plane of the fan, thus providing a 2D image in angular domain. An array of Mach-Zehnder interferometers may be used in place of the illumination waveguide layer and the spatial modulator to provide the line of light points.

First claim

What is claimed is:

1. A projector comprising:
an illumination waveguide layer comprising a first input port for receiving a first light beam, a slab waveguide portion optically coupled to the first input port for expanding the first light beam, and an output surface for outputting the first light beam expanded in the slab waveguide portion;
a spatial modulator optically coupled to the output surface of the illumination waveguide layer for spatially modulating the expanded first light beam to provide a line of light points; and
a collimation waveguide layer optically coupled to the spatial modulator for receiving and collimating light of the light points to obtain a fan of collimated light beams at an exit pupil of the collimation waveguide layer, each collimated light beam of the fan having an angle corresponding to a coordinate of the corresponding light point of the line.

2. The projector of claim 1 , wherein the slab waveguide portion of the illumination waveguide layer comprises a curved reflector for collimating the first light beam in a plane of the slab waveguide portion.

3. The projector of claim 1 , wherein the illumination waveguide layer comprises:
a first linear waveguide optically coupling the first input port to the slab waveguide portion;
second and third input ports for receiving second and third light beams respectively; and
second and third linear waveguides optically coupling the second and third input ports, respectively, to the slab waveguide portion, wherein the slab waveguide portion is configured for expanding the second and third light beams received at the second and third input ports, respectively, and wherein the first, second, and third linear waveguides are disposed closer together proximate the slab waveguide portion than proximate the first, second, and third input ports.

4. The projector of claim 3 , further comprising:
first, second, and third semiconductor light sources for emitting the first, second, and third light beams, respectively; and
first, second, and third couplers for coupling the first, second, and third semiconductor light sources to the first, second, and third input ports of the illumination waveguide layer.

5. The projector of claim 1 , wherein the spatial modulator comprises an array of reflective pixels of variable reflectivity, and wherein the projector further comprises a coupling element for coupling the expanded first light beam outputted from the illumination waveguide layer to the array of reflective pixels, and for coupling the expanded first light beam reflected from the array of reflective pixels into the collimation waveguide layer.

6. The projector of claim 5 , wherein the coupling element comprises a holographic optical element configured to direct different wavelength components of the expanded first light beam onto different reflective pixels of the array of reflective pixels.

7. The projector of claim 5 , wherein the coupling element comprises a cylindrical optical element for collimating the expanded first light beam in a plane perpendicular to a plane of the slab waveguide portion.

8. The projector of claim 1 , wherein the collimation waveguide layer comprises a slab waveguide portion comprising two coaxial curved reflectors.

9. The projector of claim 8 , wherein the slab waveguide portion of the collimation waveguide layer comprises a few-mode waveguide.

10. The projector of claim 8 , wherein the slab waveguide portion of the collimation waveguide layer comprises an evanescent out-coupler for out-coupling the fan of collimated light beams from the collimation waveguide layer.

11. The projector of claim 1 , wherein the illumination and collimation waveguide layers are parts of a same waveguide structure.

12. The projector of claim 1 , further comprising a tiltable reflector at the exit pupil of the collimation waveguide, wherein the tiltable reflector is configured to receive and redirect the fan of collimated light beams in a plane non-parallel to a plane of the fan of collimated light beams.

13. The projector of claim 12 , wherein the spatial modulator comprises an array of tiltable micromirrors, and wherein the projector further comprises a coupling element for coupling the expanded first light beam outputted from the illumination waveguide layer to the array of tiltable micromirrors, and for coupling the expanded first light beam reflected from the array of tiltable micromirrors into the collimation waveguide layer, wherein the array of tiltable micromirrors is operable to selectively tilt micromirrors of the array to provide spatial modulation of amplitude of the expanded first light beam.

14. The projector of claim 1 , wherein the illumination waveguide layer and the collimation waveguide layer comprise a same waveguide layer.

15. A waveguide projector comprising:
an input port for receiving a first light beam;
an array of Mach-Zehnder interferometers (MZIs) coupled to the input port and configured for redistributing optical power of the first light beam between light points of a line of light points in response to control signals applied to MZIs of the array; and
a slab waveguide portion coupled to the array of MZIs and configured for receiving and collimating light of the light points to obtain a fan of collimated light beams at an exit pupil, each collimated light beam of the fan having an angle corresponding to a coordinate of the corresponding light point of the line of light points.

16. The waveguide projector of claim 15 , wherein the slab waveguide portion comprises at least one of: a pair of coaxial curved reflectors; or a few-mode waveguide.

17. The waveguide projector of claim 15 , wherein the slab waveguide portion comprises an evanescent out-coupler for out-coupling the fan of collimated light beams from the slab waveguide portion.

18. The waveguide projector of claim 15 , further comprising a tiltable reflector at the exit pupil, wherein the tiltable reflector is configured to receive and redirect the fan of light beams in a plane non-parallel to a plane of the fan of collimated light beams.

19. A method for projecting a light beam, the method comprising:
receiving the light beam at an input port of an illumination waveguide layer;
expanding the light beam in a slab waveguide portion of the illumination waveguide layer;
spatially modulating the expanded light beam to provide a line of light points; and
collimating light of the light points to obtain a fan of collimated light beams at an exit pupil, each collimated light beam of the fan having an angle corresponding to a coordinate of the corresponding light point of the line.

20. The method of claim 19 , further comprising redirecting the fan of collimated light beams in a plane non-parallel to a plane of the fan, using a tiltable reflector at the exit pupil.

Assignees

• Facebook Tech Llc
• Meta Platforms Tech Llc

Inventors

• Koshelev Alexander
• Calafiore Giuseppe

Classifications

• G02B27/0983

  being curved · CPC title

• G02B27/30

  Collimators · CPC title

• G03B21/208

  Homogenising, shaping of the illumination light · CPC title

• G02B6/0011

  the light guides being planar or of plate-like form · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title