Low voltage micro-mirror array light beam switch

• US 6,681,063 B1
• Filed: 11/16/2000
• Issued: 01/20/2004
• Est. Priority Date: 11/16/2000
• Status: Expired due to Fees

• Current Assignee: Computer Optics, Inc. (Clear Align North)
• Original Assignee: Computer Optics, Inc. (Clear Align North)
• Inventors: Kane, Jonathan S., Hughes, Gareth A.
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): Doan, Jennifer
• Application Number:
  US09/714,253
• Time in Patent Office: 1,160 Days
• Field of Search: 385/17, 385/18, 359/872, 359/876, 359/877, 359/223, 359/224
• US Class Current: 385/18
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3578 Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A micro-optical light beam switch comprises a MEMS (Micro-Electromechanical Systems) mirror array with packaged CMOS driving circuitry. Each movable mirror is coupled to orthogonal pairs of thin unimorph PZT capacitor actuators about peripheral mirror portions for precise positional accuracy in two dimensions by the application of mirror tilt control voltages of 5 volts or less to the actuators. Each cantilevered actuator is individually controllable, allowing multi-axial movement of each mirror via simple flexible stress reducing hinging tab elements for the precise redirection of an incoming light beam to the appropriate targeted location, such as the direction of optical traffic throughout a fiber optic network.

Claims

1. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable and flexible support member for supporting a thin reflective mirror surface thereon and for supporting at least one pair of thin film cantilevered piezoelectric support member actuators mechanically coupled between a fixed substrate and movable portions of said thin movable support member, said actuators comprising a piezoelectric capacitor, the piezoelectric layer within said capacitor having a thickness of between 0.5 and 20 microns;

(b) piezoelectric actuator control means for applying control voltages of about five volts or less to said cantilevered piezoelectric actuators for inducing selected motion of portions of said thin movable support member; and

(c) wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein a first pair of thin film piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin piezoelectric actuators are coupled to third and fourth opposite edge portions of said movable support member perpendicular with respect to said first and second opposite edge portions; and

(e) wherein said first pair of thin film piezoelectric actuators are positioned along a first axis and said second pair of thin piezoelectric actuators are positioned along a second axis perpendicular with respect to said first axis; and

(f) wherein said thin movable support member is sufficiently thin and flexible in portions thereof adjacent movable terminal portions of said actuators so as to act as stress relieving hinge flexing areas, relieving stress from the actuators.

2. The optical switch of claim 1 wherein a layer of low stress silicon nitride is positioned beneath each piezoelectric actuator.

3. The optical switch of claim 2 wherein said layer of low stress silicon nitride has a thickness between one and three microns.

4. The optical switch of claim 3 wherein said piezoelectric material is PZT.

5. The optical switch of claim 1 wherein said piezoelectric material is PZT.

6. The optical switch of claim 1 wherein piezoelectric material within said capacitor has a thickness of between 0.5 and 1 micron.

7. The optical switch of claim 6 wherein said piezoelectric material is PZT.

8. The optical switch of claim 7 wherein said piezoelectric material is PZT.

9. The optical switch of claim 1 wherein said actuators include stacks of piezoelectric capacitors.

10. The optical switch of claim 1 wherein said actuators are positioned in parallel with respect to mirror support member edge portions, to provide a compact design.

11. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and coupled to at least one pair of thin film cantilevered piezoelectric support member actuators that are mechanically coupled between a substrate and opposite movable portions of said thin movable support member, said cantilevered piezoelectric support member actuators each comprising a piezoelectric capacitor, and having a piezoelectric layer within said piezoelectric capacitor having a thickness of between 0.5 and 20 microns; and

(b) wherein said thin movable support member, said thin reflective mirror surface and said thin film cantilevered piezoelectric support member actuators are substantially co-planar; and

(c) thin film cantilevered piezoelectric support member actuator control means for applying control voltages to said thin film cantilevered piezoelectric support member actuators for inducing non-torsional upward and downward motion of said thin film cantilevered piezoelectric support member actuators.

12. The micro-optical light beam switch of claim 11 wherein terminal portions of a first pair of thin film cantilevered piezoelectric support member actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member along a first axis of mirror rotation;

and

wherein terminal portions of a second pair of thin film cantilevered piezoelectric support member actuators are mechanically coupled to third and fourth opposite edge portions of said thin movable support member along a second axis of mirror rotation transverse to said first axis of mirror rotation.

13. The light beam switch of claim 12 wherein said thin movable support member bearing said thin reflective mirror surface, is flexibly coupled, via stress relieving flexing portions of the thin movable support member, between terminal portions of said thin film cantilevered piezoelectric support member actuators.

14. The optical switch of claim 13 wherein said first axis of mirror rotation and said second axes of mirror rotation are oriented at right angles with respect to each other.

15. The optical switch of claim 13 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

16. The optical switch of claim 15 wherein said piezoelectric material is PZT.

17. The optical switch of claim 12 wherein said first axis of mirror rotation and said second axes of mirror rotation are oriented at right angles with respect to each other.

18. The optical switch of claim 17 wherein a first axis of mirror rotation is positioned between said first pair of thin film cantilevered piezoelectric support member actuators and which passes through a center point of said mirror surface, and wherein a second axis of mirror rotation is positioned between said second pair of thin film cantilevered piezoelectric support member actuators and which passes through said center point of said mirror surface.

19. The optical switch of claim 17 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

20. The optical switch of claim 12 wherein a first axis of mirror rotation is positioned between said first pair of thin film cantilevered piezoelectric support member actuators and which passes through a center point of said mirror surface, and wherein a second axis of mirror rotation is positioned between said second pair of thin film cantilevered piezoelectric support member actuators and which passes through said center point of said mirror surface.

21. The optical switch of claim 12 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

22. The optical switch of claim 21 wherein said piezoelectric material is PZT.

23. The light beam switch of claim 11 wherein said thin movable support member bearing said thin reflective mirror surface is flexibly coupled, via stress relieving flexing portions of the thin movable support member, between terminal portions of said thin film cantilevered piezoelectric support member actuators.

24. The optical switch of claim 23 wherein said first axis of mirror rotation and said second axes of mirror rotation are oriented at right angles with respect to each other.

25. The optical switch of claim 24 wherein a first axis of mirror rotation is positioned between said first pair of thin film cantilevered piezoelectric support member actuators and which passes through a center point of said mirror surface, and wherein a second axis of mirror rotation is positioned between said second pair of thin film cantilevered piezoelectric support member actuators and which passes through said center point of said mirror surface.

26. The optical switch of claim 23 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

27. The optical switch of claim 11 wherein said thin film cantilevered piezoelectric support member actuators are aligned with a center point of said mirror surface.

28. The optical switch of claim 11 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

29. The optical switch of claim 28 wherein said piezoelectric material is PZT.

30. The optical switch of claim 11 wherein said piezoelectric material is PZT.

31. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon, and coupled to at least one pair of thin film cantilevered piezoelectric support member actuators that are mechanically coupled between a substrate and opposite movable portions of said thin movable support member, said thin film cantilevered piezoelectric support member actuators each comprising a piezoelectric capacitor, and

(b) wherein said thin movable support member, said thin reflective mirror surface and said thin film cantilevered piezoelectric support member actuators are substantially co-planar due to their thinness; and

(c) thin film cantilevered piezoelectric support member actuator control means for applying control voltages of opposite polarity to said pair of thin film cantilevered piezoelectric support member actuators for causing a terminal portion of one actuator to move upwardly while causing a terminal portion of the other actuator to move downwardly for inducing non-torsional tilting of said micro-mirror.

32. The micro-optical light beam switch of claim 31 wherein terminal portions of a first pair of thin film cantilevered piezoelectric support member actuators are coupled to first and second opposite edge portions of said thin movable support member along a first axis of mirror rotation;

and

wherein terminal portions of a second pair of thin film cantilevered piezoelectric support member actuators are coupled to third and fourth opposite edge portions of said thin movable support member along a second axis of mirror rotation transverse to said first axis of mirror rotation.

33. The light beam switch of claim 32 wherein said thin movable support member bearing said thin reflective mirror surface, is flexibly coupled, via stress relieving flexing portions of the thin movable support member, between said terminal portions of said thin film cantilevered piezoelectric support member actuators.

34. The optical switch of claim 32 wherein said first axis of mirror rotation and said second axes of mirror rotation are oriented at right angles with respect to each other.

35. The optical switch of claim 32 wherein a first axis of mirror rotation is positioned between said first pair of thin film cantilevered piezoelectric support member actuators and which passes through a center point of said mirror surface, and wherein a second axis of mirror rotation is positioned between said second pair of thin film cantilevered piezoelectric support member actuators and which passes through said center point of said mirror surface.

36. The light beam switch of claim 31 wherein said thin movable support member bearing said thin reflective mirror surface, is flexibly coupled, via stress relieving flexing portions of the thin movable support member, between said terminal portions of said thin film cantilevered piezoelectric support member actuators.

37. The optical switch of claim 31 wherein said thin film cantilevered piezoelectric support member actuators are aligned with a center point of said mirror surface.

38. The optical switch of claim 31 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 20 microns.

39. The optical switch of claim 38 wherein the piezoelectric layer within said capacitor has a thickness of between 0.5 and 1.0 microns.

40. The optical switch of claim 39 wherein the piezoelectric layer within said capacitor is PZT.

41. The optical switch of claim 38 wherein the piezoelectric layer within said capacitor is PZT.

42. The optical switch of claim 31 wherein said control voltages are less than five volts.

43. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled via coupling means between a fixed substrate and movable portions of said thin movable support member;

(b) piezoelectric actuator control means for applying control voltages to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member;

(c) and wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar;

(d) and wherein a first pair of thin film piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin piezoelectric actuators are coupled to third and fourth opposite edge portions of said movable support member; and

(e) wherein said thin movable support member is configured as a gimbal ring with a first pair of inner actuators coupled to opposite side portions of a central mirror portion of said support member and a second pair of outer actuators coupled to opposite outer side portions of said thin movable support member.

44. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled via coupling means between a fixed substrate and movable portions of said thin movable support member;

(b) piezoelectric actuator control means for applying control voltages to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member;

(c) and wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar;

(d) and wherein said first and second axis are oriented at right angles with respect to each other; and

(e) wherein said thin movable support member is configured as a gimbal ring with a first pair of inner actuators coupled to opposite side portions of a central mirror portion of said support member and a second pair of outer actuators coupled to opposite outer side portions of said thin movable support member.

45. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirro having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled via coupling means between a fixed substrate and movable portions of said thin movable support member;

(b) piezoelectric actuator control means for applying control voltages to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member;

(c) and wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein each of said coupling means includes a flexing layer of low stress silicon nitride or silicon dioxide integral with said thin movable support member and having a thickness of between 1-3 microns.

46. The optical switch of claim 45 wherein said flexing layer has a narrow tab-like configuration for enhancing flexure thereof.

47. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled between a fixed substrate and movable portions of said thin movable support member, said actuators comprising a piezoelectric capacitor;

(b) piezoelectric actuator control means for applying control voltages of about five volts or less to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member; and

(c) wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein a first pair of thin film piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin piezoelectric actuators are coupled to third and fourth opposite edge portions of said movable support member; and

(e) wherein said first pair of thin film piezoelectric actuators are positioned along a first axis and said second pair of thin piezoelectric actuators are positioned along a second axis perpendicular with respect to said first axis; and

(f) wherein each of said coupling means includes a flexing layer of low stress silicon nitride or silicon dioxide integral with said support member and having a thickness of between 1-3 microns.

48. The optical switch of claim 47 wherein said flexing layer has a narrow tab-like configuration for enhancing flexure thereof.

49. The optical switch of claim 47 wherein said thin movable support member has a square shape.

50. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled via coupling means between a fixed substrate and movable portions of said thin movable support member;

(b) piezoelectric actuator control means for applying control voltages to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member;

(c) and wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein said thin movable support member is sufficiently thin and flexible in portions thereof adjacent movable terminal portions of said actuators so as to act as stress relieving hinge flexing areas, relieving stress from the actuators.

51. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled between a fixed substrate and movable portions of said thin movable support member, said actuators comprising a unimorph piezoelectric capacitor;

(b) piezoelectric actuator control means for applying control voltages of about five volts or less to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member; and

(c) wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein a first pair of thin film piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin piezoelectric actuators are coupled to third and fourth opposite edge portions of said movable support member; and

(e) wherein said first pair of thin film piezoelectric actuators are positioned along a first axis and said second pair of thin piezoelectric actuators are positioned along a second axis perpendicular with respect to said first axis; and

(f) wherein said thin movable support member is sufficiently thin and flexible in portions thereof adjacent movable terminal portions of said actuators so as to act as stress relieving hinge flexing areas, relieving stress from the actuators.

52. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and for supporting a plurality of thin film piezoelectric support member actuators mechanically coupled between a fixed substrate and movable portions of said thin movable support member, said actuators comprising a piezoelectric capacitor;

(b) piezoelectric actuator control means for applying control voltages of about five volts or less to said piezoelectric actuators for inducing selected motion of portions of said thin movable support member; and

(c) wherein said thin movable support member, said thin reflective mirror surface and said thin film piezoelectric support member actuators are substantially co-planar; and

(d) wherein a first pair of thin film piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin piezoelectric actuators are coupled to third and fourth opposite edge portions of said movable support member; and

(e) wherein said first pair of thin film piezoelectric actuators are positioned along a first axis and said second pair of thin piezoelectric actuators are positioned along a second axis perpendicular with respect to said first axis; and

(f) wherein said thin movable support member is configured as a gimbal ring with a first pair of inner actuators coupled to opposite side portions of a central mirror portion of said support member and a second pair of outer actuators coupled to opposite outer side portions of said movable support member.

53. A micro-optical light beam switch array utilizing a thin film piezoelectric material for low voltage micro-mirror actuation with highly accurate positioning comprising:

(a) an array of individually controllable micro-mirrors, each micro-mirror having a thin movable support member for supporting a thin reflective mirror surface thereon and coupled to a plurality of thin film cantilevered piezoelectric support member actuators;

(b) piezoelectric actuator control means for applying control voltages to said, cantilevered piezoelectric support member actuators for inducing selected non-torsional motion of portions of said thin movable support member;

(c) and wherein said thin movable support member, said thin reflective mirror surface and said thin film cantilevered piezoelectric support member actuators are substantially co-planar;

(d) and wherein at least one pair of said thin film cantilevered piezoelectric support member actuators are mechanically coupled to widely separated edge portions of said thin movable support member, enabling one edge portion to be raised while a second edge portion is lowered.

54. The optical switch of claim 53 wherein a first pair of thin film cantilevered piezoelectric actuators are mechanically coupled to first and second opposite edge portions of said thin movable support member and wherein a second pair of thin film cantilevered piezoelectric actuators are mechanically coupled to third and fourth opposite edge portions of said movable support member.

55. The optical switch of claim 54 wherein said first pair of thin film cantilevered piezoelectric actuators are aligned along a first axis and said second pair of thin film cantilevered piezoelectric actuators are aligned along a second axis transverse with respect to said first axis.

56. The optical switch of claim 55 wherein said first and second axes are oriented at right angles with respect to each other.