Modulating the intensity of light from an interferometric reflector

• US 8,115,987 B2
• Filed: 07/11/2007
• Issued: 02/14/2012
• Est. Priority Date: 02/01/2007
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Bita, Ion, Kogut, Lior, Tung, Ming Hau
• Primary Examiner(s): Sugarman, Scott J
• Assistant Examiner(s): Patel, Vipin
• Application Number:
  US11/776,490
• Publication Number:
  US 20080186581A1
• Time in Patent Office: 1,679 Days
• Field of Search: 359290-297
• US Class Current: 359/291
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/005 based on electrowetting

Abstract

An optical device for modulating the intensity of light from an interferometric reflector. In one embodiment, the optical device can include an optical stack having a reflective layer and a partially reflective, partially transmissive layer for reflecting light. The optical device can also include a fluid cell comprising an absorptive fluid and a transmissive fluid. The optical device can also include a mechanism for controlling the portion of the reflector which is shadowed by the absorptive fluid.

Claims

1. An optical device comprising:

an at least partially optically transmissive first surface;

an optical stack spaced from the first surface, the optical stack comprising

a reflective first layer,

a partially reflective, partially transmissive second layer, wherein the reflective first layer has a greater thickness than the partially reflective, partially transmissive second layer, and

a dielectric third layer that separates and supports the first and second layers in a fixed relationship with respect to one another to create an optically resonant cavity between the first and second layers, the optical stack adapted to reflect light having a set of wavelengths determined by interference of light reflected from the first layer and from the second layer;

a first fluid between the first surface and the optical stack; and

a second surface between the first surface and the optical stack, the first fluid covering a first portion of the second surface when a first voltage is applied to the device, and the first fluid covering a second portion of the second surface when a second voltage is applied to the device.

2. The device of claim 1, wherein the second surface is positioned between the first surface and the first fluid.

3. The device of claim 1, wherein the second surface is positioned between the optical stack and the first fluid.

4. The device of claim 1, wherein the second layer comprises chromium and the first layer comprises aluminum.

5. The device of claim 1, wherein the dielectric layer comprises silicon dioxide.

6. The device of claim 1, wherein the first fluid comprises a liquid having a relatively low affinity for the second surface.

7. The device of claim 6, wherein the liquid comprises a substantially optically transmissive, water-based electrolyte.

8. The device of claim 1, wherein the first fluid comprises an optically absorptive liquid.

9. The device of claim 8, wherein the optically absorptive liquid comprises a hydrophobic liquid.

10. The device of claim 9, wherein the hydrophobic liquid comprises oil and one or more colored dyes.

11. The device of claim 8, wherein the optically absorptive liquid absorbs light having a predetermined range of visible wavelengths.

12. The device of claim 1, further comprising a second fluid between the first surface and the optical stack, wherein the first and second fluids are substantially non-soluble in one another, one of the first and second fluids being substantially non-absorptive to visible light, the other being substantially absorptive to visible light.

13. The device of claim 12, wherein the first fluid has a substantially lower affinity for the second surface than does the second fluid.

14. The device of claim 12, wherein the first fluid is electrically conductive and the second fluid is substantially non-conductive.

15. The device of claim 1, wherein the second surface comprises an optically transmissive layer of electrically insulating, hydrophobic material.

16. The device of claim 15, wherein the hydrophobic material comprises a fluoropolymer.

17. The device of claim 1, wherein the second surface is selectively configurable as hydrophobic when the first voltage is applied to the device and hydrophilic when the second voltage is applied to the device.

18. The device of claim 17, wherein the second surface comprises a plurality of molecular chains having hydrophilic end portions and hydrophobic body portions.

19. The device of claim 1, wherein the device further comprises a first electrode and a second electrode, the first and second voltages applied across the first and second electrodes.

20. The device of claim 19, wherein the first and second electrodes are located on opposing sides of the second surface.

21. The device of claim 19, wherein one of the first and second electrodes is in electrical communication with the fluid.

22. The device of claim 19, wherein one of the first and second electrodes comprises at least a portion of the optical stack.

23. The device of claim 19, wherein the first surface comprises one of the first and second electrodes.

24. The device of claim 1, wherein the reflective first layer and the partially reflective, partially transmissive second layer are electrically connected.

25. The device of claim 24, further comprising at least one via electrically connecting the first layer and the second layer.

26. The device of claim 1, further comprising a moisture barrier layer between the optical stack and the first fluid.

27. The device of claim 26, wherein the moisture barrier comprises the second surface.

28. A display including the optical device of claim 1, comprising:

a processor that is configured to communicate with said display, said processor being configured to process image data; and

a memory device that is configured to communicate with said processor.

29. The display of claim 28, further comprising a driver circuit configured to send at least one signal to said display.

30. The display of claim 28, further comprising an image source module configured to send said image data to said processor.

31. The display of claim 30, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

32. The display of claim 28, further comprising an input device configured to receive input data and to communicate said input data to said processor.

33. The display of claim 29, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

34. A method of modulating light, comprising:

providing an optical device comprising

an at least partially optically transmissive first surface;

an optical stack spaced from the first surface, the optical stack comprising

a reflective first layer,

a partially reflective, partially transmissive second layer, wherein the reflective first layer has a greater thickness than the partially reflective, partially transmissive second layer, and

a dielectric third layer that separates and supports the first and second layers in a fixed relationship with respect to one another to create an optically resonant cavity between the first and second layers, the optical stack adapted to reflect light having a set of visible wavelengths determined by interference of light reflected from the first layer and from the second layer;

a first fluid between the first surface and the optical stack; and

a second surface between the first surface and the optical stack;

applying a first voltage to the device to cause the first fluid to cover a first portion of the second surface; and

applying a second voltage to the device to cause the first fluid to cover a second portion of the second surface.

35. The method of claim 34, wherein the second portion has a larger area of the second surface than does the first portion.

36. The method of claim 35, wherein the second portion comprises the first portion.

37. A method of forming an optical device, comprising:

forming an optically transmissive first surface;

forming an optical stack, the optical stack comprising

a reflective first layer,

a partially reflective, partially transmissive second layer, wherein the reflective first layer has a greater thickness than the partially reflective, partially transmissive second layer, and

a dielectric third layer that separates and supports the first and second layers in a fixed relationship with respect to one another to create an optically resonant cavity between the first and second layers;

forming a perimeter wall of a cavity between the first surface and the optical stack; and

placing fluid in the cavity.

38. The method of claim 37, wherein the optically transmissive first surface is formed on an optically transmissive substrate.

39. The method of claim 37, wherein the optical stack is formed on a substrate.

40. The method of claim 37, wherein forming the perimeter wall of the cavity comprises depositing a sacrificial material and then removing the sacrificial material.

41. The method of claim 37, further comprising forming an optically transmissive, electrically insulating, hydrophobic second surface between the first surface and the optical stack.

42. An optical device comprising:

means for at least partially transmitting incident light;

means for reflecting light having a set of visible wavelengths determined by interferometry, wherein the means for reflecting light comprises

reflective first means, partially reflective,

partially transmissive second means, wherein the reflective first means has a greater thickness than the partially transmissive second means, and

third means for creating an optically resonant cavity between the first and second means; and

means for selectively varying an optical transmissivity of a region between the at least partially transmitting means and the reflecting means upon application of a voltage to the device.

43. The optical device of claim 42, wherein the means for at least partially transmitting incident light comprises an at least partially optically transmissive first surface.

44. The optical device of claim 42, wherein the means for reflecting light comprises an optical stack spaced from the at least partially transmitting means, and wherein the reflective first means comprises a reflective first layer, the partially reflective, partially transmissive second means comprises a partially reflective, partially transmissive second layer, and the third means comprises a dielectric layer that separates and supports the first and second layers in a fixed relationship with respect to one another, the optical stack adapted to reflect light having a set of visible wavelengths determined by interference of light reflected from the first layer and from the second layer.

45. The optical device of claim 42, wherein the means for selectively varying an optical transmissivity comprises an absorptive fluid in the region between the at least partially transmitting means and the reflecting means, the absorptive fluid covering a first portion of a surface when a first voltage is applied to the device, and the absorptive fluid covering a second portion of the surface when a second voltage is applied to the device.