Reflective coherent spatial light modulator

• US 20020149584A1
• Filed: 04/13/2001
• Published: 10/17/2002
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Simpson, John T., Simpson, Marcus L., Hutchinson, Donald P., Richards, Roger K.
• Granted Patent: US 6,552,842 B2
• Time in Patent Office: Days
• US Class Current: 345/423
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2202/107 Zn×S or Zn×Se and alloys
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

A reflective coherent spatial light modulator (RCSLM) includes a subwavelength resonant grating structure (SWS), the SWS including at least one subwavelength resonant grating layer (SWL) have a plurality of areas defining a plurality of pixels. Each pixel represents an area capable of individual control of its reflective response. A structure for modulating the resonant reflective response of at least one pixel is provided. The structure for modulating can include at least one electro-optic layer in optical contact with the SWS. The RCSLM is scalable in both pixel size and wavelength. A method for forming a RCSLM includes the steps of selecting a waveguide material and forming a SWS in the waveguide material, the SWS formed from at least one SWL, the SWL having a plurality of areas defining a plurality of pixels.

Claims

1. A reflective coherent spatial light modulator (RCSLM), comprising:

a subwavelength resonant grating structure (SWS), said SWS formed from at least one subwavelength resonant grating layer (SWL), said SWLs having a plurality of areas defining a plurality of pixels, said plurality of pixels adapted to produce a resonant reflective response characterized by reflecting a band of incident light while transmitting light outside said band, and

structure for modulating a resonant reflective response of at least one pixel from said plurality of pixels.

2. The RCSLM of claim 1, wherein said structure for modulating includes at least one electro-optic layer, said at least one electro-optic layer disposed in optical contact with at least one of said SWLs.

3. The RCSLM of claim 2, further comprising a structure for modulating the refractive index of said at least one electro-optic layer.

4. The RCSLM of claim 3, further comprising a first electrically conductive layer and a second electrically conductive layer, said at least one electro-optic layer positioned substantially between said electrically conductive layers.

5. The RCSLM of claim 4, wherein at least one of said electrically conductive layers comprises a plurality of electrically conductive plates, said plurality of plates substantially electrically isolated from one another and adapted to control said resonant reflective response of individual ones of said plurality of pixels.

6. The RCSLM of claim 1, wherein said RCSLM is formed on a die.

7. The RCSLM of claim 5, wherein said RCSLM is formed on a die, said die having electronic components including control electronics a high speed voltage driver circuit, wherein said plurality of pixels are separately switchable by application by said control electronics of a voltage signal from said high speed voltage driver circuit to said plurality of plates.

8. The RCSLM of claim 7, wherein said plurality of plates are adapted for connection to said electronic components through back plane via connections.

9. The RCSLM of claim 1, further comprising an anti-reflective coating layer disposed on a surface of said RCSLM.

10. The RCSLM of claim 4, further comprising an anti-reflective coating layer disposed on a surface of said RCSLM and a buffer layer disposed between said anti-reflective coating layer and said second conductive layer.

11. The RCSLM of claim 10, wherein said buffer layer is at least one selected from the group consisting of air, SiO₂, TiO₂, and WO.

12. The RCSLM of claim 1, wherein said at least one SWL comprises a plurality of features, at least a portion of said features having asymmetric exposed surfaces.

13. The RCSLM of claim 12, further comprising an electronically controllable quarter wave plate.

14. RCSLM of claim 7, wherein said electronic components include an amplitude controller for controlling amplitude of light reflected from said plurality of pixels.

15. The RCSLM of claim 14, wherein said amplitude controller includes a feedback and control system.

16. The RCSLM of claim 15, wherein said feedback and control system is adapted to separately control amplitudes of light reflected by said plurality of pixels.

18. The method for forming a RCSLM of claim 17, wherein said at least one SWL comprise a plurality of features formed from at least one material having a second refractive index greater than said first refractive index.

19. The method for forming a RCSLM of claim 17, further comprising the step of providing at least one electro-optic layer, said at least one electro-optic layer disposed in optical contact with at least one of said SWL.

20. The method for forming a RCSLM of claim 19, further comprising a first electrically conductive layer and a second electrically conductive layer, said at least one electro-optic layer positioned substantially between said electrically conductive layers.

21. The method for forming a RCSLM of claim 20, wherein at least one of said electrically conductive layers comprises a plurality of electrically conductive plates, said plurality of plates substantially electrically isolated from one another and adapted to control said resonant reflective response of individual ones of said plurality of pixels.

22. The method for forming a RCSLM of claim 17, further comprising the step of providing a bulk substrate material having a plurality of die, wherein a plurality of said RCSLMs are formed on said plurality of die.

23. The method for forming a RCSLM of claim 21, further comprising the step of forming electronic components including control electronics and a high speed voltage driver circuit on said die, wherein said plurality of pixels are separately switchable by application by said control electronics of a voltage signal from said high speed voltage driver circuit to said plurality of plates.

24. The method for forming a RCSLM of claim 23, further comprises the step of forming a plurality of back plane via connections, wherein said plurality of plates are provided electrical connection to said electronic components.

25. The method for forming a RCSLM of claim 17, wherein at least one of said SWLs comprises a plurality of features, at least a portion of said plurality of features having asymmetrical exposed surfaces.

28. The method of claim 27, wherein said modulating is electronic modulating.

29. The method of claim 28, wherein said electronic modulating is electro-optic modulating.

30. The method of claim 29, wherein a voltage is applied across at least one electro-optic layer, said at least one electro-optic layer disposed in optical contact with the at least one pixel.

31. The method of claim 30, wherein said voltage is capable of variation, said voltage variation modulating said reflective response of the at least one pixel.

32. The method of claim 27, wherein said plurality of pixels are separately controllable and adapted to produce a plurality of distinct resonant reflective responses, further comprising the step of separately modulating said reflective responses of said plurality of pixels.

33. The method of claim 32, wherein said modulating is electro-optic modulating.

34. A method for processing an electromagnetic signal which comprising the step of utilizing the RCSLM of claim 1, wherein said utilizing includes at least one selected from the group consisting of image projecting systems, 3-D holographic projecting and communications transceiving.

17. A method for forming a reflective coherent spatial light modulator (RCSLM), comprising the steps of:

selecting a waveguide material having a first refractive index, and

forming a subwavelength resonant grating structure (SWS), said SWS formed from at least one subwavelength resonant grating layer (SWL) in said waveguide material, said SWLs having a plurality of areas defining a plurality of pixels, said plurality of pixels adapted to produce a resonant reflective response characterized by reflecting a band of incident light while transmitting light outside said band.

26. A high frame rate projection image system, comprising:

at least three RCSLMs, each of said RCSLMs adapted to reflect a different wavelength band, each of said RCSLMs comprising;

a subwavelength resonant grating structure (SWS), said SWS formed from at least one subwavelength resonant grating layer (SWL), said SWLs having a plurality of areas defining a plurality of pixels, said plurality of pixels adapted to produce a resonant reflective response characterized by reflecting a band of incident light while transmitting light outside said band;

structure for modulating a resonant reflective response of at least one pixel from said plurality of pixels;

structure for providing a light beam to each of said RCSLMs, said light beams provided having wavelengths within said RCSLM wavelength bands, and

a viewing screen for receiving reflected light from said RCSLMs.

27. A method for modulating light, comprising:

providing a reflective coherent spatial light modulator (RCSLM) comprising a subwavelength resonant grating structure (SWS), said SWS formed from at least one subwavelength resonant grating layer (SWL), said SWLs having a plurality of areas defining a plurality of pixels, at least one from said plurality of pixels adapted to produce a resonant reflective response characterized by substantially reflecting a band of incident light, and structure for modulating the resonant reflective response of the at least one pixel from said plurality of pixels, and

modulating said reflective response of the at least one pixel, whereby said band of light is substantially transmitted by the at least one pixel.

35. A coherent spatial light reflector adapted for fixed frequency operation, comprising:

a subwavelength resonant grating structure (SWS), said SWS formed from at least one subwavelength resonant grating layer (SWL), said SWLs having a plurality of areas defining a plurality of pixels, said plurality of pixels each adapted to produce a resonant reflective response characterized by reflecting a band of incident light while transmitting light outside said respective band.