Non-Telecentric Emissive Micro-Pixel Array Light Modulators and Methods of Fabrication Thereof

• US 20170184776A1
• Filed: 12/27/2016
• Published: 06/29/2017
• Est. Priority Date: 12/28/2015
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Ostendo Technologies Inc.
• Inventors: Chuang, Chih-Li, Pitchumani, Mahesh, Alpaslan, Zahir Y., McNeill, Dale A., El-Ghoroury, Hussein S.
• Granted Patent: US 10,578,882 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 27/0075 with means for altering, e.g. increasing, the depth of field or depth of focus
• CPC Class Codes: G02B 30/10 using integral imaging methods
• CPC Class Codes: G02B 30/50 the image being built up from image elements distributed over a 3D volume, e.g. voxels
• CPC Class Codes: H04N 13/30 Image reproducers optical systems for producing stereoscopic or other three-dimensional effects G02B30/00
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

Emissive micro-pixel spatial light modulators with non-telecentric emission are introduced. The individual light emission from each multi-color micro-scale emissive pixel is directionally modulated in a unique direction to enable application-specific non-telecentric emission pattern from the micro-pixel array of the emissive spatial light modulator. Design methods for directionally modulating the light emission of the individual micro-pixels using micro-pixel level optics are described. Monolithic wafer level optics methods for fabricating the micro-pixel level optics are also described. An emissive multi-color micro-pixel spatial light modulator with non-telecentric emission is used to exemplify the methods and possible applications of the present invention: ultra-compact image projector, minimal cross-talk 3D light field display, multi-view 2D display, and directionally modulated waveguide optics for see-through near-eye displays.

Claims

1. A non-telecentric emissive micro-pixel array light modulator comprising:

a control layer;

pixelated, multiple color emission III/V semiconductor layers stacked above the control layer and controllable from the control layer to emit at least partially collimated, pixelated light that is modulated chromatically and temporally; and

a directional modulation layer of optical elements above the pixelated multiple color emission III/V semiconductor layers, each optical element to directionally modulate light coupled onto it from a corresponding pixel to a respective direction relative to an axis perpendicular to the pixelated, multiple color emission III/V semiconductor layers.

2. The non-telecentric emissive micro-pixel array light modulator of claim 1 further comprising a cover glass layer over the directional modulation layer.

3. The non-telecentric emissive micro-pixel array light modulator of claim 2 wherein the cover glass layer is spaced apart from the directional modulation layer to provide an air gap between the directional modulation layer and the cover glass layer.

4. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer comprises refractive micro optical elements.

5. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer comprises diffractive micro optical elements.

6. The non-telecentric emissive micro-pixel array light modulator of claim 5 wherein the diffractive micro optical elements comprise blazed gratings or rail gratings.

7. The non-telecentric emissive micro-pixel array light modulator of claim 6 wherein the directional modulation of the directional modulation layer is determined by the slant angle and pitch of the blazed grating.

8. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer comprises semiconductor dielectric materials.

9. The non-telecentric emissive micro-pixel array light modulator of claim 8 wherein the directional modulation layer comprises multiple dielectric layers of silicon oxide or silicon nitride.

10. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer comprises a UV curable polymer.

11. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the pixelated, multiple color emission III/V semiconductor layers are divided into groups, each comprising a plurality of pixels.

12. The non-telecentric emissive micro-pixel array light modulator of claim 11 wherein each group of pixels is organized into a square, rectangle or hexagonal pattern.

13. The non-telecentric emissive micro-pixel array light modulator of claim 11 wherein the directional modulation layer comprises patterns, each directional modulation layer pattern corresponding to a respective pixel pattern, each directional modulation layer having the same directional modulation pattern.

14. The non-telecentric emissive micro-pixel array light modulator of claim 11 wherein the directional modulation layer comprises patterns, each directional modulation layer pattern corresponding to a respective pixel pattern, each directional modulation layer having a unique directional modulation pattern.

15. The non-telecentric emissive micro-pixel array light modulator of claim 11 wherein each directional modulation layer pattern directionally modulates light coupled onto it to a respective converging pattern.

16. The non-telecentric emissive micro-pixel array light modulator of claim 11 wherein each directional modulation layer pattern directionally modulates light coupled onto it to a respective diverging pattern.

17. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer comprises diffractive micro optical elements, and wherein the diffractive directional modulation layer comprises successive layers of either metal rails or dielectric material with different indexes of refraction.

18. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer directionally modulates light coupled onto it to a respective diverging pattern.

19. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer directionally modulates light coupled onto it to a respective converging pattern.

20. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer is comprised of pixel level refractive micro optical elements in the form of de-centered micro lenses of successive layers of dielectric materials with different indexes of refraction.

21. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer is comprised of pixel level refractive micro optical elements in the form of tilted micro lenses of successive layers of dielectric materials with different indexes of refraction.

22. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein:

the pixilated light emitted by the pixelated, multiple color emission III/V semiconductor layers is at least partially collimated by a waveguide for each pixel emitting the light from each of the stacked layers of the pixelated, multiple color emission III/V semiconductor layers;

each optical element of the directional modulation layer is a Fourier lens;

centers of each optical element of the directional modulation layer are aligned with a respective pixel of the pixelated, multiple color emission III/V semiconductor layers; and

the position of the waveguides, each with respect to a respective optical element, is spatially modulated to provide a desired directional modulation pattern.

23. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer is a diffractive directional modulation layer comprised of micro gratings formed by successive layers of either metal rails or dielectric materials with different indexes of refraction.

24. The non-telecentric emissive micro-pixel array light modulator of claim 23 wherein the micro gratings are wideband transmission gratings or multilevel gratings.

25. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer is a diffractive directional modulation layer comprised of micro gratings formed by multiple layers of silicon oxide and silicon nitride.

26. The non-telecentric emissive micro-pixel array light modulator of claim 1 wherein the directional modulation layer directionally modulates light coupled onto it from a corresponding pixel to a respective converging direction, and further comprising projection optics positioned to receive converging light from the non-telecentric emissive micro-pixel array light modulator and project the converging light, thereby forming a multicolor projector.

27. The non-telecentric emissive micro-pixel array light modulator of claim 1, together with a waveguide, the non-telecentric emissive micro-pixel array light modulator being coupled to an input aperture of the waveguide, the waveguide also having an output aperture, the non-telecentric emissive micro-pixel array light modulator being positioned on the waveguide and the directional modulation layer being selected to direct an image from the pixelated multiple color emission III/V semiconductor layers into the input aperture, to be reflected by total internal reflection before exiting the waveguide through the output aperture of the waveguide.

28. The non-telecentric emissive micro-pixel array light modulator of claim 1, together with a tapered waveguide, the non-telecentric emissive micro-pixel array light modulator being coupled to an input aperture of the tapered waveguide in a region of the tapered waveguide of a first thickness, the tapered waveguide also having an output aperture in a region of the tapered waveguide of a second thickness, the second thickness being less than the first thickness, the non-telecentric emissive micro-pixel array light modulator being positioned on the tapered waveguide and the directional modulation layer being selected to direct an image from the pixelated multiple color emission III/V semiconductor layers to be reflected by at least a first internal surface of the tapered waveguide by total internal reflection before exiting the tapered waveguide through the output aperture of the tapered waveguide as a result of the breaking of the total internal reflection caused by the taper of the tapered waveguide.

29. A method of making anon-telecentric emissive micro-pixel array light modulator having a control layer, pixelated, multiple color emission III/V semiconductor layers stacked above the control layer and controllable from the control layer to emit at least partially collimated, pixelated light that is modulated chromatically and temporally, a directional modulation layer of optical elements above the pixelated multiple color emission III/V semiconductor layers, each optical element to directionally modulate light coupled onto it from a corresponding pixel to a respective direction relative to an axis perpendicular to the pixelated, multiple color emission III/V semiconductor layers, and a cover glass layer over the directional modulation layer comprising:

fabricating the directional modulation layer on the cover glass layer using the cover glass layer as a substrate;

bonding the pixelated, multiple color emission III/V semiconductor layer stack to the directional modulation layer on the cover glass layer; and

,

bonding the pixelated, multiple color emission III/V semiconductor layer stack to a CMOS control layer;

or

fabricating the directional modulation layer on the cover glass layer using the cover glass layer as a substrate; and

bonding the directional modulation layer to the pixelated, multiple color emission III/V semiconductor layer stack as already bonded to the CMOS control layer, or

bonding the pixelated, multiple color emission III/V semiconductor layer stack to a CMOS control layer;

fabricating the directional modulation layer on the pixelated, multiple color emission III/V semiconductor layer stack; and

bonding the cover glass layer to the directional modulation layer.

30. A method of fabricating an ultra compact display projector comprising:

providing a control layer;

providing a pixelated, multiple color emission III/V semiconductor layers stacked above the control layer and controllable from the control layer to emit at least partially collimated, pixelated light across an emissive optical aperture that is modulated chromatically and temporally;

providing a directional modulation layer of optical elements above the pixelated multiple color emission III/V semiconductor layers and extending across the entire emissive optical aperture, each optical element to directionally modulate light coupled onto it from a corresponding pixel to a respective converging direction relative to an axis perpendicular to the directional modulation layer;

providing projection optics, including a first optical element for receiving the converging light from the directional modulation layer, a second optical element for receiving light from the first optical element, and one or more additional optical elements for receiving light from the second optical element to magnify a projected image, the optical elements directionally modulating the light emitted to achieve maximum fill factor of the optical aperture of the first optical element, the first optical element redirecting the light rays toward an optical aperture the second optical element while maintaining the fill factor at a maximum, the second optical element redirecting the light to the one or more additional optical elements for receiving light from the second optical element to magnify the projected image.

31. A method of fabricating a minimum cross-talk light field modulator comprising:

providing a control layer;

providing a pixelated, multiple color emission III/V semiconductor layers stacked above the control layer and controllable from the control layer to emit at least partially collimated, pixelated light that is modulated chromatically and temporally;

providing a directional modulation layer of optical elements above the pixelated multiple color emission III/V semiconductor layers, the optical elements being organized in groups, each group of optical elements representing a hogel of the light field, each optical element within a group of optical elements to directionally modulate light coupled onto it from a corresponding pixel to a respective converging direction toward a center of the respective group of optical elements relative to an axis perpendicular to the directional modulation layer, causing the pixelated light emitted from the respective group of optical elements to directionally converge systematically toward the axis perpendicular to the directional modulation layer such that the light from the optical elements remains substantially confined within optical apertures of associated hogel lens apertures, thus minimizing the light leakage or cross-talk between adjacent the hogel lenses.

32. A method for guiding an image comprising of a plurality of pixel outputs in a total internal reflection waveguide comprising the steps of:

directionally modulating a plurality of imager pixel outputs using a plurality of respective micro optical elements wherein the micro optical elements are configured to directionally modulate the respective imager pixel outputs in a total internal reflection waveguide in a unique direction within a tangential or lateral, and a vectorial or elevation plane, to define a waveguiding angle of the imager pixel outputs and a lateral divergence from a respective pixel'"'"'s (x, y) coordinates;

whereby the tangential or lateral plane determines a total expansion or magnification of an image being modulated as the imager pixel outputs propagate through the waveguide.

33. The method of claim 32 wherein the directional modulation of the imager pixel outputs in the tangential or lateral plane defines an x-axis magnification factor of an image being modulated and the directional modulation of the imager pixel outputs in a vectorial or elevation plane defines an angle at which the imager pixel outputs propagate through the waveguide.

34. A method for minimizing optical cross-talk in a light field display comprising the steps of:

directionally modulating a plurality of light field imager pixel outputs in a sub array of micro pixels associated with a hogel lens using a plurality of respective micro optical elements;

whereby the respective micro optical elements confine the respective light field imager pixel outputs within the optical aperture of the hogel lens.