Micromachined optomechanical switches

• US 6,498,870 B1
• Filed: 04/20/1998
• Issued: 12/24/2002
• Est. Priority Date: 04/20/1998
• Status: Expired due to Fees

• Current Assignee: Crossfiber Inc.
• Original Assignee: Omx Incorporated (The ODP Corporation)
• Inventors: Wu, Ming, Fan, Li, Husain, Anis
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/063,644
• Time in Patent Office: 1,709 Days
• Field of Search: 385/18, 385/15, 385/23.25, 385/88, 385/94, 385/83
• US Class Current: 385/18
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G02B 6/3514 the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
• 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 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• 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 6/3584 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

A micromachined plate 11, called a torsion plate, selectively pivots upon a substrate responsively to electrical force so as to move an attached micromirror 12 in a same plane; thereby to accurately selectively intercept, and to reflect, a light beam 2 that is moving parallel to the substrate; forming thus an optomechanical switch 1. The electrical force may be electromagnetic 3 in nature or, preferably, electrostatic. In various embodiments the pivoting torsion plate 11 with the micromirror 12 affixed may be (i) biased off the substrate by a three-dimensional structure 14 and/or by a “reshaped” torsion beam 11c, (ii) bent as plate 11d, and operated push OR pull, push AND pull, or push AND push, in a rocking operation, (iii) elevated above the substrate upon a self-assembling “micro-elevator structure” 16, and/or (iv) moved greatly in angular position by action of a “micro-flap” 11f. A new design spring-loaded landing electrode 18, and a torsion microhinge 131-134, further enhance performance. The micromachined, or Micro Electro Mechanical Systems (MEMS), optomechanical switch 1 so formed is both fast and accurate to switch light over large angles up to 180° while being highly resistant to sticking, or “stiction”.

Claims

1. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

a micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

2. The micromachined optomechanical switch according to claim 1 further comprising:

microhinges for hinging the micromachined plate to the substrate.

3. The micromachined optomechanical switch according to claim 2

wherein the microhinges are surface micromachined upon the substrate.

4. The micromachined optomechanical switch of claim 1 wherein said micromachined plate includes a first end and a second end opposite said first end, said pivot axis being proximate said first end of said micromachined plate.

5. The micromachined optomechanical switch of claim 4 wherein said micromirror is mounted to said micromachined plate proximate said second end.

6. The micromachined optomechanical switch according to claim 1 wherein the electrical force means comprises:

an electrostatic force means for selectively developing an electrostatic force between the micromachined plate and the substrate.

7. The micromachined optomechanical switch according to claim 1

wherein the micromirror is mounted to the micromachined plate orthogonally to the pivot axis, thus making that the micromirror moves in the same plane during angular positional pivoting movement of the micromachined plate.

8. The micromachined optomechanical switch according to claim 1 further comprising;

an electrical insulator between (i) the substrate and the (ii) micromachined plate that is hinged to and pivoting upon the substrate;

wherein an electrical charge can be selectively developed between, as a first electrode, (i) the substrate, and, as a second electrode, the (ii) micromachined plate, which electrical charge produces an electrostatic force that will serve to pivot the micromachined plate and the micromirror mounted thereon relative to the substrate.

9. An array of micromachined optomechanical switches according to claim 1 suitable to selectively switch a plurality of radiation beams.

10. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate;

a three-dimensional surface-micromachined mechanical structure physically supporting the same micromachined plate that is angled about the pivot axis in a position off the substrate regardless that any repulsive electrical force between the micromachined plate and the substrate, which repulsive electrical force would repel the micromachined plate and cause it to pivot away from the substrate, should be absent;

wherein micromachined plate is physically mechanically biased in position off the substrate, diminishing the possibility of stiction of the micromachined plate to the substrate and;

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

11. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an electrically conductive micromachined plate;

that is mechanically hinged and pivoting to

a substrate;

an electrical insulator located between (i) the substrate and the (ii) micromachined plate; and

electrical means for developing an electrical force between the micromachined plate and the substrate so that the micromachined plate, and the micromirror mounted thereto, is caused to pivot and to move in position, and wherein the electrical means comprises;

electrical voltage means for selectively developing an electrical voltage between, as a first electrode, (i) the substrate, and, as a second electrode, the (ii) micromachined plate, which voltage will produce an electrostatic force that will serve to pivot the micromachined plate and the micromirror mounted thereon relative to the substrate

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in position by action of the electrical force selectively developed in the substrate by the electrical means, making thus an optomechanical switch.

12. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate;

an electromagnet in one of (i) the substrate, and the (ii) micromachined plate; and

a permanent magnet in the other one of (i) the substrate and the (ii) micromachined plate; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate;

wherein selective electrical energization of the electromagnet by the electrical force means produces an electromagnetic force that serves to pivot the micromachined plate, and the micromirror mounted thereon, relative to the substrate, and wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

13. The micromachined optomechanical switch according to claim 12 further comprising;

wherein the electromagnet is in the substrate; and

wherein permanent magnet is in the micromachined plate.

14. The micromachined optomechanical switch according to claim 13 wherein the permanent magnet comprises:

a magnetic material integrated within the micromachined plate.

15. The micromachined optomechanical switch according to claim 13 further comprising;

wherein the permanent magnet in the micromachined plate force biases the micromachined plate to a pivoted position off the substrate regardless that the electromagnetic force which repels the micromachined plate and causes it to pivot away from the substrate should be absent;

wherein micromachined plate so biased in position off the substrate has a diminished possibility of stiction to the substrate.

16. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to a substrate wherein at least one of the micromachined plate and the substrate is electrically conducting; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate; and

wherein-the electrostatic force means comprises;

electrical charging means for selectively electrically charging at least the conductive one of the micromachined plate and the substrate so as to selectively develop an electrostatic force between the micromachined plate and the substrate, wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate making thus an optomechanical switch.

17. The micromachined optomechanical switch according to claim 16

wherein the electrical charging means is selectively developing an attractive electrostatic force between the micromachined plate and the substrate.

18. The micromachined optomechanical switch according to claim 16

wherein the electrical charging means is selectively developing a repulsive electrostatic force between the micromachined plate and the substrate.

19. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate;

wherein the micromachined plate is bent about an axis, and pivots about the substrate along this axis so that, as a consequence of the bend, only a portion of the micromachined plate that is upon a one side of the axis may be against the substrate at any one time, a remaining portion of the micromachined plate that is upon the other side of the axis being angled away from the substrate, and wherein the micromirror is mounted to one portion of the micromachined plate; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

20. The micromachined optomechanical switch according to claim 19

wherein the electrical force means is physically separately developing an electrical force between the substrate and, in sequence, each portion of the micromachined plate;

wherein the electrical forces developed between the substrate and each portion of the bent micromachined plate are temporally sequenced so as to positively force the micromachined plate to pivot in position.

21. The micromachined optomechanical switch according to claim 20

wherein the electrical forces separately developed between the substrate and each portion of the bent micromachined plate are temporally sequenced so as to push-the-first-portion of the bent micromachined plate, followed by a push-the-second-portion of the bent micromachined plate, or a push-push operation.

22. The micromachined optomechanical switch according to claim 20

wherein the electrical forces separately developed between the substrate and each portion of the bent micromachined plate are temporally sequenced so as to push-the-first-portion of the bent micromachined plate, followed by a pull-the-second-portion of the bent micromachined plate, or a push-pull operation.

23. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate;

a micromachined structure elevating the micromachined plate above the substrate about a pivot axis that is intermediary in position within the micromachined plate between a first portion and a second portion thereof, the micromirror being mounted to one portion of the micromachined plate; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate; and

wherein the electrical force means comprises;

electromagnetic force means for selectively developing an electromagnetic force between the substrate and one portion of the micromachined plate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate about the elevated pivot axis;

wherein, in accordance with the principle of a lever, and further in accordance with the fact that the micromachined plate may be greatly pivoted in angle in its position elevated above the substrate, the micromirror may be greatly moved in position;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

24. The micromachined optomechanical switch according to claim 23

wherein the micromirror is so greatly moved in position that no part of the mirror occupies the same space at one pivot extension of the micromachined plate that is otherwise occupied by any part of the mirror at an opposite pivot extension of the micromachined plate.

25. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an micromachined plate;

that is mechanically hinged about a pivot axis to

a substrate; and

an electrical force means for selectively developing an electrical force between the micromachined plate and the substrate, causing the micromachined plate and the micromirror mounted thereto to pivot in angular position relative to the substrate;

wherein the electrical force means comprises;

an electromagnetic force means for selectively developing an electromagnetic force between the micromachined, plate and the substrate;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is or is not, moved in angular position by action of the electrical force is selectively developed between the micromachined plate and the substrate, making thus an optomechanical switch.

26. The micromachined optomechanical switch according to claim 25

wherein at least one of the micromachined plate and the substrate develops a magnetic field directionally towards the other upon conducting electrical current; and wherein the electromagnetic force means comprises;

a current source for selectively passing an electrical current in the at least one of the micromachined plate and the substrate that develops a magnetic field in response to the current so as to selectively develop an electromagnetic force between the micromachined plate and the substrate.

27. The micromachined optomechanical switch according to claim 26

wherein the current source means is selectively developing an attractive electromagnetic force between the micromachined plate and the substrate.

28. The micromachined optomechanical switch according to claim 26

wherein the current source means is selectively developing a repulsive electromagnetic force between the micromachined plate and the substrate.

29. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an electrically conductive micromachined plate;

that is mechanically hinged and pivoting to

a substrate; and

electrical means for developing an electrical force between the micromachined plate and the substrate so that the micromachined plate, and the micromirror mounted thereto, is caused to pivot and to move in position;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in position by action of the electrical force selectively developed in the substrate by the electrical means, making thus an optomechanical switch.

30. The micromachined optomechanical switch according to claim 29 further comprising:

microhinges serving to hinge the electrically conductive micromachined plate to the substrate.

31. The micromachined optomechanical switch according to claim 30

wherein the microhinges are surface micromachined upon the substrate.

32. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an electrically conductive micromachined plate;

that is mechanically hinged and pivoting to

a substrate;

a three-dimensional surface-micromachined structure physically supporting the micromachined plate off the substrate regardless that the electrical force which pivots the micromachined plate relative to the substrate should be absent;

wherein micromachined plate is biased in position off the substrate, diminishing the possibility of stiction of the micromachined plate to the substrate; and

electrical means for developing an electrical force between the micromachined plate and the substrate so that the micromachined plate, and the micromirror mounted thereto, is caused to pivot and to move in position;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in position by action of the electrical force selectively developed in the substrate by the electrical means, making thus an optomechanical switch.

33. A structure micromachined upon a substrate for both (i) mechanically receiving, and for (ii) making electrical connection to, a distal end region of micromachined plate that is pivoting about the substrate from its proximal end region to selectively land upon the structure, thus a micromachined landing electrode structure, the micromachined landing electrode structure comprising:

an electrically conductive buckled beam that is buckled above a plane of the substrate in location under the distal end region of the micromachined plate, the buckled beam serving as (i) a spring to the pivoting movement of the micromachined plate, and as (ii) an electrode for making electrical contact to the micromachined plate when the micromachined plate is pivoted into pressured contact therewith, and as (iii) a stop helping to prevent stiction between the pivoting micromachined plate and the substrate;

wherein the buckled beam is contacted and depressed by the micromachined plate only when the micromachined plate is almost contacting the substrate;

wherein an additional spring force provided by the spring action of the buckled beam does appreciably increase a force is required to pivot the micromachined plate relative to the substrate over most of its pivot range; and

wherein the micromachined plate is biased in angular position by a torsion spring and wherein a spring constant of the buckled beam is much larger than that of the torsion spring so that a force on the micromachined plate by the buckled beam when the micromachined plate is in contact therewith is much stronger than an opposite force on the micromachined plate arising from the torsion spring.

34. A structure micromachined upon a substrate for both (i) mechanically receiving, and for (ii) making electrical connection to, a distal end region of micromachined plate that is pivoting about the substrate from its proximal end region to selectively land upon the structure, thus a micromachined landing electrode structure, the micromachined landing electrode structure comprising:

an electrically conductive buckled beam that is buckled above a plane of the substrate in location under the distal end region of the micromachined plate, the buckled beam serving as (i) a spring to the pivoting movement of the micromachined plate, and as (ii) an electrode for making electrical contact to the micromachined plate when the micromachined plate is pivoted into pressured contact therewith, and as (iii) a stop helping to prevent stiction between the pivoting micromachined plate and the substrate;

a cantilever bending spring cantilevered from the approximate center of the buckled beam so as to contact the micromachined plate when it pivots close to the substrate;

wherein this cantilever bending spring provides a spring force to angularly kick back the torsion plate from off the substrate when any force holding it proximate to the substrate is released; and

wherein the micromachined plate is biased in angular position by a torsion spring and wherein a spring constant of the buckled beam is much larger than that of the torsion spring so that a force on the micromachined plate by the buckled beam when the micromachined plate is in contact therewith is much stronger than an opposite force on the micromachined plate arising from the torsion spring.

35. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an electrically conductive micromachined plate;

that is mechanically hinged and pivoting to

a substrate;

wherein the micromachined plate is bent about an axis, and pivots about the substrate along this axis so that, as a consequence of the bend, only a portion of the micromachined plate that is upon a one side of the axis may be against the substrate at any one time, the portion of the micromachined plate that is upon the other side of the axis being angled away from the substrate;

wherein the micromirror is mounted to one portion of the micromachined plate; and

electrical means for developing an electrical force between the micromachined plate and the substrate so that the micromachined plate, and the micromirror mounted thereto, is caused to pivot and to move in position;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in position by action of the electrical force selectively developed in the substrate by the electrical means, making thus an optomechanical switch.

36. The micromachined optomechanical switch according to claim 35

wherein the electrical force that serves to pivot the bent micromachined plate relative to the substrate is electrically separately developed between the substrate and each portion of the micromachined plate;

wherein the electrical forces between the substrate and each portion of the bent micromachined plate are temporally sequenced so as to positively force the micromachined plate to pivot in position in a push-the-first-portion followed by a push-the-second-portion, or a push-push operation.

37. The micromachined optomechanical switch according to claim 35

wherein the electrical force that serves to pivot the bent micromachined plate relative to the substrate is electrically separately developed between the substrate and each portion of the micromachined plate;

wherein the electrical forces between the substrate and each portion of the bent micromachined plate are temporally sequenced so as to positively force the micromachined plate to pivot in position in a push-the-first-portion and pull-the-second-portion, followed by a pull-the-first-portion and push-the-second-portion, or a push-pull operation.

38. A structure micromachined upon a substrate for both (i) mechanically receiving, and for (ii) making electrical connection to, a distal end region of micromachined plate that is pivoting about the substrate from its proximal end region to selectively land upon the structure, thus a micromachined landing electrode structure, the micromachined landing electrode structure comprising:

an electrically conductive buckled beam that is buckled above a plane of the substrate in location under the distal end region of the micromachined plate, the buckled beam serving as (i) a spring to the pivoting movement of the micromachined plate, and as (ii) an electrode for making electrical contact to the micromachined plate when the micromachined plate is pivoted into pressured contact therewith, and as (iii) a stop helping to prevent stiction between the pivoting micromachined plate and the substrate.

39. The micromachined landing electrode structure according to claim 38 wherein the electrically conductive buckled beam comprises:

a polysilicon beam pushed until it buckles, locked in its buckled position into

a micromachined structure.

40. The micromachined landing electrode structure according to claim 38

wherein the micromachined plate is biased in angular position by a torsion spring;

and

wherein a spring constant of the buckled beam is much larger than that of the torsion spring so that a force on the micromachined plate by the buckled beam when the micromachined plate is in contact therewith is much stronger than an opposite force on the micromachined plate arising from the torsion spring.

41. A micromachined optomechanical switch comprising:

a micromirror;

mounted to

an electrically conductive micromachined plate;

that is mechanically hinged and pivoting to

a substrate;

an electromagnet located in one of (i) the substrate and the (ii) micromachined plate;

a permanent magnet in the other one of (i) the substrate and the (ii) micromachined plate; and

electrical means for developing an electrical force between the micromachined plate and the substrate so that the micromachined plate, and the micromirror mounted thereto, is caused to pivot and to move in position, and wherein the electrical means comprises;

electrical current means for selectively energizing the electromagnet so as to produce an electromagnetic force that will serve to forcibly pivot the micromachined plate and the micromirror mounted thereon relative to the substrate;

wherein a radiation beam will selectively intercept the micromirror dependent upon whether the micromachined plate is, or is not, moved in position by action of the electrical force selectively developed in the substrate by the electrical means, making thus an optomechanical switch.

42. The micromachined optomechanical switch according to claim 41 further comprising;

wherein the electromagnet is in the substrate; and

wherein permanent magnet is in the micromachined plate.

43. The micromachined optomechanical switch according to claim 42 wherein the permanent magnet comprises:

a magnetic material integrated within the micromachined plate.

44. The micromachined optomechanical switch according to claim 41 further comprising;

wherein the permanent magnet is located in the micromachined plate and serves to bias the micromachined plate in position off the substrate regardless that the electrical current means should not be producing such current as gives rise to the electromagnetic force;

wherein micromachined plate is biased in position off the substrate, diminishing the possibility of stiction of the micromachined plate to the substrate.

45. A micromachined plate angularly hinged for pivoting upon and relative to a substrate, the hinged pivoting micromachined plate comprising:

a micromachined plate having at least one substantially straight side adjacent to which straight side is relieved at least one hole so that but a narrow strip of the plate remains between the holes and the straight side edge;

a micromachined hinge for permitting the micromachined plate to angularly pivot on its straight side about the substrate, the micromachined hinge including

one or more torsion springs attached between the substrate and a straight side pivoting end region of the micromachined plate, the torsion springs serving to bias the micromachined plate in angular position towards the substrate, and into but an acute angular separation therefrom, and

at least so many micromachined staples, attached to the substrate, as there are holes, each staple spanning over the narrow strip of the micromachined plate and into a hole so as to connect at both ends to the substrate, forming thus a mechanism holding the micromachined plate to angularly pivot about its narrow strips, which strips serve as hinge pins, about the substrate;

wherein displacement of the narrow strip of the micromachined plate, or the hinge pins, is limited by the one or more torsion springs.

46. The hinged pivoting micromachined plate according to claim 45

wherein the micromachined plate is relieved so as to form a plurality of holes;

wherein the micromachined hinge includes a plurality of torsion springs; and

wherein the micromachined hinge includes a plurality of staples as do fit within the plurality of holes.

47. The hinged pivoting micromachined plate according to claim 45

wherein arrangement of the at least one torsion spring and the at least one staple imparts a well-defined angular direction of rotation of the pivoting micromachined plate.

48. An optomechanical matrix switch, comprising:

a substrate defining an upper surface;

a plurality of optomechanical switching cells, each of said plurality of optomechanical switching cells including a mirror disposed to move between reflecting and non-reflecting states in a plane substantially perpendicular to said upper surface.

49. The optomechanical matrix switch of claim 48, wherein said plane forms an angle of approximately forty five degrees with a direction traversed by an optical beam incident upon said switch.

50. An optimechanical switching cell, comprising:

an actuator positioned on a substrate;

a mirror coupled to said actuator; and

a landing structure disposed on the substrate under an end region of said actuator.