Device for use with a micro-electro-mechanical system (MEMS) optical device and a method of manufacture therefor

• US 6,618,184 B2
• Filed: 04/03/2001
• Issued: 09/09/2003
• Est. Priority Date: 04/03/2001
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.), Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Jin, Sungho, Ryf, Roland, Mavoori, Hareesh
• Primary Examiner(s): Schwartz, Jordan M.
• Assistant Examiner(s): STULTZ, JESSICA T
• Application Number:
  US09/825,016
• Publication Number:
  US 20020141036A1
• Time in Patent Office: 889 Days
• Field of Search: 359/291, 359/838, 359/850, 359/862, 359/290, 359/214, 359/224, 359/230, 359/222, 257/418, 257/420, 735/040.9, 735/141.7
• US Class Current: 359/291
• CPC Class Codes: B81B 3/0035 Constitution or structural means for controlling the movement of the flexible or deformable elements
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02B 6/352 the reflective optical element having a shaped reflective surface, e.g. a reflective element comprising several reflective surfaces or facets that function together
• CPC Class Codes: G02B 6/3546 NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/358 Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
• CPC Class Codes: G02B 6/3582 Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Abstract

A device for use in a micro-electro-mechanical system (MEMS) optical system. The device includes a substrate having opposing first and second sides, wherein the first side has a light reflective optical layer located thereover, and the second side is an irregular surface.

Claims

1. For use with a micro-electro-mechanical system (MEMS) optical device, a movable element comprising:

a substrate having opposing first and second sides, wherein the first side has a light reflective optical layer located thereover and the second side is an irregular surface, wherein the irregular surface reduces interferrometric loss associated with the movable element.

2. The device as recited in claim 1 further including a stress balancing layer located over the second side.

3. The device as recited in claim 1 wherein the irregular surface includes a random pattern of topographical irregularities.

4. The device as recited in claim 3 wherein a depth of the topographical irregularities is approximate to an optical beam wavelength to be projected against the first side divided by 4 times a refractive index of the substrate.

5. The device as recited in claim 4 wherein the depth ranges from about 20 nm to about 1000 nm.

6. The device as recited in claim 4 wherein the depth ranges from about 50 nm to about 200 nm.

7. The device as recited in claim 3 wherein the random pattern has a roughness scale in terms of planar dimension that is approximate to an optical beam wavelength to be projected against the first side divided by a refractive index of the substrate.

8. The device as recited in claim 7 wherein the roughness ranges from about 50 nm to about 5000 nm.

9. The device as recited in claim 7 wherein the roughness ranges from about 100 nm to about 2000 nm.

10. The device as recited in claim 1 wherein the irregular surface includes a periodic pattern of macro-scale topographical irregularities.

11. The device as recited in claim 10 wherein the periodic pattern of macro-scale topographical irregularities has a roughness scale in terms of planar dimension that is approximate to about five times an optical beam wavelength to be projected against the first side.

12. The device as recited in claim 10 wherein the periodic pattern of macro-scale topographical irregularities has a roughness scale in terms of planar dimension that is approximate to about twenty times an optical beam wavelength to be projected against the first side.

13. The device as recited in claim 10 wherein the periodic pattern includes a number of multiple surfaces, wherein each surface is not parallel with the first side.

14. The device as recited in claim 13 wherein the number of multiple surfaces is at least about 4.

15. The device as recited in claim 13 wherein each surface is at least about 0.2 degrees off parallel from the first side.

16. The device as recited in claim 13 wherein each surface is at least about 5 degrees off parallel from the first side.

17. The device as recited in claim 10 wherein the periodic pattern includes surfaces selected from the group consisting of planar surfaces and curved surfaces.

18. A method of manufacturing a movable element for use in a micro-electro-mechanical system (MEMS) optical system, comprising:

forming a substrate having opposing first and second sides, wherein the second side has an irregular surface that reduces interferrometric loss associated with the movable element; and

forming a light reflective optical layer over the first side.

19. The method as recited in claim 18 further including forming a stress balancing layer over the second side.

20. The method as recited in claim 18 wherein forming a second side having an irregular surface includes forming a second side having a random pattern of topographical irregularities.

21. The method as recited in claim 20 wherein forming a second side having a random pattern of topographical irregularities includes forming a second side having a random pattern of topographical irregularities with a depth that is approximate to an optical beam wavelength to be projected against the first side divided by 4 times a refractive index of the substrate.

22. The method as recited in claim 21 wherein forming a second side having a random pattern of topographical irregularities with a depth includes forming a second side having a random pattern of topographical irregularities with a depth ranging from about 20 nm to about 1000 nm.

23. The method as recited in claim 21 wherein forming a second side having a random pattern of topographical irregularities with a depth includes forming a second side having a random pattern of topographical irregularities with a depth ranging from about 50 nm to about 200 nm.

24. The method as recited in claim 20 wherein forming a second side having a random pattern includes forming a second side having a roughness scale in terms of planar dimension that is approximate to an optical beam wavelength to be projected against the first side divided by a refractive index of the substrate.

25. The method as recited in claim 24 wherein forming a second side having a roughness includes forming a second side having a roughness that ranges from about 50 nm to about 5000 nm.

26. The method as recited in claim 24 wherein forming a second side having a roughness includes forming a second side having a roughness that ranges from about 100 nm to about 2000 nm.

27. The method as recited in claim 18 wherein forming a second side having an irregular surface includes forming a second side having a periodic pattern of macro-scale topographical irregularities.

28. The method as recited in claim 27 wherein forming a second side having a periodic pattern of macro-scale topographical irregularities includes forming a second side having a periodic pattern of macro-scale topographical irregularities having a roughness scale in terms of planar dimension that is approximate to about five times an optical beam wavelength to be projected against the first side.

29. The method as recited in claim 27 wherein forming a second side having a periodic pattern of macro-scale topographical irregularities includes forming a second side having a periodic pattern of macro-scale topographical irregularities having a roughness scale in terms of planar dimension that is approximate to about twenty times an optical beam wavelength to be projected against the first side.

30. The method as recited in claim 27 wherein forming a second side having a periodic pattern of topographical irregularities includes forming a second side having a number of multiple surfaces, wherein each surface is not parallel with the first side.

31. The method as recited in claim 30 wherein forming a second side having a number of multiple surfaces includes forming a second side having at least about 4 surfaces.

32. The method as recited in claim 30 wherein forming a second side having a number of multiple surfaces includes forming a second side having a number of multiple surfaces wherein each surface is at least about 0.2 degrees off parallel from the first side.

33. The method as recited in claim 30 wherein forming a second side having a number of multiple surfaces includes forming a second side having a number of multiple surfaces wherein each surface is at least about 5 degrees off parallel from the first side.

34. The method as recited in claim 27 wherein forming a second side having a periodic pattern includes forming a second side having surfaces selected from the group consisting of planar surfaces and curved surfaces.

35. The method as recited in claim 18 wherein forming a second side having an irregular surface includes forming a second side having an irregular surface by a subtractive process or an additive process.

36. The method as recited in claim 35 wherein the subtractive process may be selected from the group consisting of an etching process, a mechanical process and a thermal process.

37. The method as recited in claim 35 wherein the additive process may be selected from the group consisting of patterned epitaxial growth and chemical vapor deposition.

38. An optical communications system, comprising:

input/output fiber bundles;

a micro-electro-mechanical structure, comprising;

a mirror including a substrate having opposing first and second sides, wherein the first side has a light reflective optical layer located thereover and the second side is an irregular surface that reduces interferrometric loss associated with the movable element; and

a mounting substrate on which the mirror is movably mounted;

imaging lenses interposed between the input/output fiber bundles and the micro-electro-mechanical structure; and

a reflector.

39. The optical communications system as recited in claim 38 further including a stress balancing layer located over the second side.

40. The optical communications system as recited in claim 38 wherein the irregular surface includes a random pattern of topographical irregularities.

41. The optical communications system as recited in claim 40 wherein a depth of the topographical irregularities is approximate to an optical beam wavelength to be projected against the first side divided by 4 times a refractive index of the substrate.

42. The optical communications system as recited in claim 41 wherein the depth ranges from about 20 nm to about 1000 nm.

43. The optical communications system as recited in claim 41 wherein the depth ranges from about 50 nm to about 200 nm.

44. The optical communications system as recited in claim 40 wherein the random pattern has a roughness scale in terms of planar dimension that is approximate to an optical beam wavelength to be projected against the first side divided by a refractive index of the substrate.

45. The optical communications system as recited in claim 44 wherein the roughness ranges from about 50 rim to about 5000 nm.

46. The optical communications system as recited in claim 44 wherein the roughness ranges from about 100 nm to about 2000 nm.

47. The optical communications system as recited in claim 38 wherein the irregular surface includes a periodic pattern of macro-scale topographical irregularities.

48. The optical communications system as recited in claim 47 wherein the periodic pattern of macro-scale topographical irregularities has a roughness scale in terms of planar dimension that is approximate to about five times an optical beam wavelength to be projected against the first side.

49. The optical communications system as recited in claim 47 wherein the periodic pattern of macro-scale topographical irregularities has a roughness scale in terms of planar dimension that is approximate to about twenty times an optical beam wavelength to be projected against the first side.

50. The optical communications system as recited in claim 47 wherein the periodic pattern includes a number of multiple surfaces, wherein each surface is not parallel with the first side.

51. The optical communications system as recited in claim 48 wherein the number of multiple surfaces is at least about 4.

52. The optical communications system as recited in claim 51 wherein each surface is at least about 0.2 degrees off parallel from the first side.

53. The optical communications system as recited in claim 51 wherein each surface is at least about 5 degrees off parallel from the first side.

54. The optical communications system as recited in claim 47 wherein the periodic pattern includes surfaces selected from the group consisting of planar surfaces and curved surfaces.

55. The optical communications system recited in claim 38 that comprises one or more devices selected from the group consisting of:

a micro-electro-mechanical system (MEMS) optical cross connect system;

an optical power gain equalizer system;

a wavelength division multiplexing telecommunications system;

a light signal switch in an optical communications system; and

a variable optical attenuator in an optical communications system.