Interferometric Optical Modulator With Broadband Reflection Characteristics

• US 20090059346A1
• Filed: 08/29/2007
• Published: 03/05/2009
• Est. Priority Date: 08/29/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Gang
• Granted Patent: US 8,072,402 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B81B 5/00 Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• 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 5/0858 the reflecting layers comprising a single metallic layer with one or more dielectric layers
• CPC Class Codes: G06T 1/20 Processor architectures; Processor configuration, e.g. pipelining

Abstract

An optical device suitable for forming a pixel in a video display. The optical device includes a first layer having a first refractive index; a second layer over the first layer, the second layer having a second refractive index less than the first refractive index; and a third layer over the second layer, the third layer having a third refractive index larger than the second refractive index; and a fourth layer that is at least partially optically absorptive, wherein the optical stack and the fourth layer are a first distance from one another when the device is in a first state and are a second distance from one another when the device is in a second state, the first distance different from the second distance.

Claims

1. An optical device comprising:

an optical stack comprising;

a first layer having a first refractive index;

a second layer over the first layer, the second layer having a second refractive index less than the first refractive index; and

a third layer over the second layer, the third layer having a third refractive index larger than the second refractive index; and

a fourth layer that is at least partially optically absorptive,

wherein the optical stack and the fourth layer are a first distance from one another when the device is in a first state and are a second distance from one another when the device is in a second state, the first distance different from the second distance.

2. The optical device of claim 1, wherein at least one of the first layer and the third layer comprises two or more sub-layers.

3. The optical device of claim 2, wherein one of the sub-layers has a fourth refractive index greater than the second refractive index.

4. The optical device of claim 2, wherein one of the sub-layers is electrically conductive.

5. The optical device of claim 1, wherein a region between the optical stack and the at least partially optically absorptive layer has a fifth refractive index that is less than the third refractive index.

6. The optical device of claim 1, wherein at least one of the first layer and the third layer is electrically conductive.

7. The optical device of claim 1, wherein the first refractive index and the third refractive index are both greater than about 1.7.

8. The optical device of claim 1, wherein the second refractive index is less than about 1.5.

9. The optical device of claim 1, wherein the first layer or third layer comprises indium tin oxide, silicon nitride, titanium oxide, zirconium oxide, yttrium oxide, antimony oxide, or zinc selenide.

10. The optical device of claim 1, wherein the second layer comprises cryolite, magnesium fluoride, or fluorinated SiO_x.

11. The optical device of claim 1, wherein the fourth layer comprises molybdenum, nickel, silicon, TiN_xW_y, titanium nitride, germanium, carbon, iron, chromium, tungsten, Si_xGe_1-x, or tin nitride.

12. The optical device of claim 1, wherein the first layer has a thickness in a range between about 700 angstroms and about 1350 angstroms.

13. The optical device of claim 1, wherein the second layer has a thickness in a range between about 900 angstroms and about 1400 angstroms.

14. The optical device of claim 1, wherein the third layer has a thickness in a range between about 100 angstroms and about 550 angstroms.

15. The optical device of claim 1, wherein the fourth layer has a thickness in a range between about 30 angstroms and about 3000 angstroms.

16. The optical device of claim 1, wherein the first distance is in a range between about 1300 Å

and about 2300 Å

or between about 3000 Å and

4500 Å

.

17. The optical device of claim 1, wherein the second distance is approximately zero.

18. The optical device of claim 1, wherein the optical device in the first state has a first reflectance and the optical device in the second state has a second reflectance, the ratio of the first reflectance to the second reflectance of the optical device being greater than about ten.

19. The optical device of claim 18, wherein the ratio is greater than about one hundred.

20. The optical device of claim 1, wherein the optical device in the first state has a reflected spectral power distribution of visible light which substantially corresponds to the standard white point D65.

21. The optical device of claim 1, wherein the fourth layer is mounted on a mechanical support layer.

22. The optical device of claim 21, wherein the mechanical support layer comprises nickel.

23. The optical device of claim 1, wherein the optical stack is mounted on an at least partially optically transmissive substrate.

24. The optical device of claim 23, wherein the at least partially optically transmissive substrate comprises glass.

25. The optical device of claim 1, further comprising

a display;

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.

26. The optical device of claim 25, further comprising a driver circuit configured to send at least one signal to said display.

27. The optical device of claim 26, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

28. The optical device of claim 25, further comprising an image source module configured to send said image data to said processor.

29. The optical device of claim 28, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

30. The optical device of claim 25, further comprising an input device configured to receive input data and to communicate said input data to said processor.

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

forming a first layer, the first layer having a first refractive index;

forming a second layer over the first layer, the second layer having a second refractive index less than the first refractive index;

forming a third layer over the second layer, the third layer having a third refractive index larger than the second refractive index;

forming a sacrificial layer over the third layer;

forming a fourth layer that is at least partially optically absorptive over the sacrificial layer; and

removing the sacrificial layer.

32. The method of claim 31, wherein the first layer is formed on an optically transmissive substrate.

33. A method of modulating light, comprising:

providing an optical device comprising;

an optical stack comprising;

a first layer having a first refractive index;

a second layer over the first layer, the second layer having a second refractive index less than the first refractive index; and

a third layer over the second layer, the third layer having a third refractive index larger than the second refractive index; and

a fourth layer that is at least partially optically absorptive,

wherein the optical stack and the fourth layer are a first distance from one another when the device is in a first state and are a second distance from one another when the device is in a second state, the first distance different from the second distance;

applying a first voltage to the device to place the device in the first state; and

applying a second voltage to the device to place the device in the second state.

34. The method of claim 33, wherein the optical stack comprises a first electrode and the fourth layer comprises a second electrode.

35. The method of claim 34 further comprising applying the first and second voltages across the first and second electrodes.

36. An optical device comprising:

first means for reflecting and transmitting light, the first means having a first refractive index;

second means for reflecting and transmitting light, the second means over the first means, the second means having a second refractive index less than the first refractive index; and

third means for reflecting and transmitting light, the third means over the second means, the third means having a third refractive index larger than the second refractive index; and

fourth means for reflecting and absorbing light, wherein the third means and the fourth means are a first distance from one another when the device is in a first state and are a second distance from one another when the device is in a second state, the first distance different from the second distance.

37. The optical device of claim 36, wherein the first means comprises layer of material having the first refractive index, the second means comprises a layer of material having the second refractive index, and third means comprises a layer of material having the third refractive index.

38. The optical device of claim 36, wherein the fourth means comprises a layer of at least partially optically absorptive material.