Micro-electro-mechanical-system two dimensional mirror with articulated suspension structures for high fill factor arrays

• US 7,443,569 B2
• Filed: 08/17/2006
• Issued: 10/28/2008
• Est. Priority Date: 04/24/2003
• Status: Expired due to Fees

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: JDS Uniphase Corporation (Lumentum Holdings Inc.)
• Inventors: Ducellier, Thomas, Hnatiw, Alan, Mala, Mohiuddin
• Primary Examiner(s): Choi; William C
• Application Number:
  US11/505,378
• Publication Number:
  US 20070058238A1
• Time in Patent Office: 803 Days
• Field of Search: 359/198, 359/224, 359/225, 359/290, 359/295, 359/298
• US Class Current: 359/290
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic 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 6/3546 NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• 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

Abstract

The invention provides a micro-electro-mechanical-system (MEMS) mirror device, comprising: a mirror having a 2-dimensional rotational T-shaped hinge at a first end, and having a flexible connection at a second end opposite the first end. The invention also provides a MEMS mirror device, comprising: a mirror having a 2-dimensional rotational T-shaped hinge at a first end; and a vertical actuator connected to the 2-dimensional T-shaped hinge through a rigid connection. The invention also provides a MEMS mirror device, comprising: a mirror connected to a first end of a rotational actuator through bending springs at a first end, and having a torsional spring at a second end opposite the first end; a movable cantilever connected to the mirror through the torsional spring; and a support structure connected to the first end and a second end of the rotational actuator through torsional springs and connected to the movable cantilever.

Claims

1. A micro-electro-mechanical-system (MEMS) mirror device, comprising:

a mirror having a 2-dimensional rotational T-shaped hinge at a first end;

a support structure connected to the mirror through the 2-dimensional rotational T-shaped hinge;

whereby the mirror is rotatable about a first axis of rotation and a second torsional axis of rotation perpendicular to the first axis of rotation; and

wherein the 2-dimensional rotational T-shaped hinge comprises;

a first torsional spring having a first mounting point at a first end connected to the support structure and having a second end;

a second torsional spring having a second mounting point at a first end connected to the support structure and having a second end, the second end of the first torsional spring being connected to the second end of the second torsional spring;

a third torsional spring having a first end connected to the second ends of the first and second torsional springs and having a second end connected to the first end of the mirror;

whereby the first torsional spring and the second torsional spring define the first axis of rotation between the first and second mounting points, and the third torsional spring defines the second torsional axis of rotation perpendicular to the first axis of rotation.

2. A device according to claim 1 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio.

3. A device according to claim 1 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio, the beam being formed of a material or materials selected from a group consisting of Silicon, Polysilicon, Silicon Nitride, Silicon dioxide, and metallic depositable materials.

4. A device according to claim 2 wherein the beams are formed of a unitary construction.

5. A device according to claim 2 wherein the beams and the mirror are formed of a unitary construction.

6. A device according to claim 2 wherein the beams comprise articulated beams.

7. A device according to claim 1 in which the mirror has an angular range of motion at least 0.3 degrees in each axis.

8. A device according to claim 1 further comprising electrodes for applying electrostatic force to the mirror so as to move the mirror in at least one of the first and second axes of rotation.

9. A device according to claim 8 wherein the electrodes comprise two electrodes each for applying a respective electrostatic force to the mirror so as to move the mirror in a respective direction in the second axis of rotation, and at least one electrode for applying electrostatic force to the mirror so as to move the mirror in the first rotational axis.

10. A device according to claim 9 wherein the at least one electrode comprises at least one electrode mounted on the support structure proximal at least one of the first end of the mirror and a second end of the mirror opposite the first end of the mirror for applying a respective electrostatic force to the mirror so as to move the mirror in the first rotational axis.

11. A device according to claim 1 further comprising a vertical actuator connected to the 2-dimensional rotational T-shaped hinge through a rigid connection;

whereby movement of the vertical actuator causes rotation of the mirror in the first axis of rotation.

12. A device according to claim 11 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio.

13. A device according to claim 12 wherein the beams are formed of a unitary construction.

14. A device according to claim 12 wherein the beams, the vertical actuator and the mirror are formed of a unitary construction.

15. A device according to claim 12 wherein the beams comprise articulated beams.

16. A device according to claim 11 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio, the beam being formed of a material or materials selected from a group consisting of Silicon, Polysilicon, Silicon Nitride, Silicon dioxide, and metallic depositable materials.

17. A device according to claim 11 in which the mirror has an angular range of motion at least 0.3 degrees in each axis.

18. A device according to claim 11 further comprising electrodes for applying electrostatic force to the mirror so as to move the mirror in at least one of the first and second axes of rotation.

19. A device according to claim 18 wherein the electrodes comprise two electrodes each for applying a respective electrostatic force to the mirror so as to move the mirror in a respective direction in the second axis of rotation, and at least one electrode for applying electrostatic force to the mirror so as to move the mirror in the first rotational axis.

20. A device according to claim 19 further comprising at least one electrode mounted on the support structure beneath the vertical actuator for applying a respective electrostatic force to the vertical actuator so as to move the mirror in the first rotational axis.

21. A device according to claim 1 further comprising a flexible connection that is connected to the support structure and to a second end of the mirror that is opposite the first end of the mirror.

22. A device according to claim 21 wherein the flexible connection comprises a torsional spring and at least one bending spring.

23. A device according to claim 22 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio.

24. A device according to claim 23 wherein the beams are formed of a unitary construction.

25. A device according to claim 23 wherein the beams, the bending spring and the mirror are formed of a unitary construction.

26. A device according to claim 23 wherein the beams comprise articulated beams.

27. A device according to claim 22 wherein each torsional spring comprises a respective beam having a large thickness to width aspect ratio, the beam being formed of a material or materials selected from a group consisting of Silicon, Polysilicon, Silicon Nitride, Silicon dioxide, and metallic depositable materials.

28. A device according to claim 22 wherein the at least one bending spring comprises a rectangular spiral spring.

29. A device according to claim 22 wherein the at least one bending spring comprises a connected concentric spiral beam spring comprising connected concentric beams, wherein adjacent concentric beams are connected together at only one point.

30. A device according to claim 29 wherein the connected concentric spiral beam spring is circular.

31. A device according to claim 30 wherein a center of the connected concentric spiral beam spring is offset from the second torsional axis of rotation.

32. A device according to claim 29 wherein the connected concentric spiral beam spring is rectangular.

33. A device according to claim 22 wherein the at least one bending spring comprises a first connected concentric spiral beam spring and a second connected concentric spiral beam spring each comprising connected concentric beams, wherein adjacent concentric beams are connected together at only one point, and wherein respective centers of the first and the second connected concentric spiral beam springs are located on opposite sides of the second torsional axis of rotation and are equidistant to any point on the second torsional axis of rotation.

34. A device according to claim 33 wherein the first and the second connected concentric spiral beam springs are circular.

35. A device according to claim 33 wherein the at least one bending spring comprises a pair of articulated beam springs each comprising a plurality of partial sections of concentric circles defining a sector of a circle wherein adjacent sections are alternatingly connected at only one end to an adjacent section.

36. A device according to claim 22 wherein the at least one bending spring comprises a pair of S-shaped bending springs.

37. A device according to claim 22 wherein the at least one bending spring comprises a pair of articulated beam springs each with a medial point and connected at the medial point.

38. A device according to claim 21 in which the mirror has an angular range of motion at least 0.3 degrees in each axis.

39. A device according to claim 21 further comprising electrodes for applying electrostatic force to the mirror so as to move the mirror in at least one of the first and second axes of rotation.

40. A device according to claim 39 wherein the electrodes comprise two electrodes each for applying a respective electrostatic force to the mirror so as to move the mirror in a respective direction in the second axis of rotation, and at least one electrode for applying electrostatic force to the mirror so as to move the mirror in the first rotational axis.

41. A device according to claim 21 further comprising at least one restraining support for limiting movement of the mirror.

42. A device according to claim 21 wherein the flexible connection comprises a T-shaped hinge comprising one torsional spring and two bending springs.

43. A device according to claim 21 wherein the flexible connection comprises a torsional spring and a bending spring comprising a series of connected rectangles of diminishing size.

44. A device according to claim 1 in which the mirror is made of silicon plated with a metal.

45. A device according to claim 44 wherein the metal comprises Au, Al or Cu layers.

46. A plurality N of devices according to claim 1 arranged side by side to form a l×

N MEMs array, where N≧

2.

47. A plurality N×

M of devices according to claim 1 arranged in N rows of M devices thereby forming an N×

M MEMs array, where N≧

2 and M≧

2.

48. A device according to claim 1 wherein the mirror is used for optical switching.

49. An optical switch, comprising:

a plurality of optical ports;

a plurality of devices according to claim 1 each adapted to switch light between a respective pair of the optical ports.

50. A device according to claim 1, further comprising a movable cantilever connected to a second end of the mirror that is opposite the first end of the mirror through a fourth torsional spring and to the support structure;

whereby movement of the movable cantilever causes rotation of the mirror in the first axis of rotation; and

wherein the movable cantilever is used for capacitive, magnetic or optical sensing of mirror position.