Optical cross-connect switch using electrostatic surface actuators

• US 6,215,222 B1
• Filed: 03/30/1999
• Issued: 04/10/2001
• Est. Priority Date: 03/30/1999
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Hoen, Storrs T.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/281,698
• Time in Patent Office: 742 Days
• Field of Search: 310/309
• US Class Current: 310/309
• 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 6/3566 involving bending a beam, e.g. with cantilever
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• 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: H02N 1/006 of the gap-closing type H02N1/004 takes precedence

Abstract

A system and a method of steering optical beams utilize a surface electrostatic actuator to mechanically pivot a micromirror to selectively redirect a received optical beam to a predetermined destination. In a preferred application, the system is an optical switch that can optically couple a number of first optical fibers to a number of second optical fibers in one of many configurations. As an optical switch, the system includes a number of switching devices that operate to couple the optical fibers. Each switching device includes a surface electrostatic actuator and a micromirror to reflect a received optical signal to a selected optical fiber. The electrostatic actuator includes a translator and a stator that are separated by a short distance. The opposing surfaces of the translator and stator include a number of drive electrodes. These electrodes generate electrostatic forces between the translator and the stator. The translator is laterally displaced when the electrostatic forces are modified. The modification of the electrostatic forces is accomplished by reconfiguring a voltage pattern of the drive electrodes on the translator and/or the stator. The lateral displacement of the translator pivots the micromirror, which is mechanically attached to the translator. Pivoting the micromirror from a non-reflective orientation to a reflective orientation equates to activating the switching device. When activated, the micromirror of the switching device reflects the received optical signal to the selected optical fiber. In the preferred embodiment, the translator and the stator further include levitator electrodes that generate repulsive forces to negate any attractive forces between the translator and the stator.

Claims

1. An optical micromachine for steering optical beams comprising:

a reflective element having a reflecting surface to redirect an optical beam from an original direction to a second direction; and

a surface electrostatic actuator operatively coupled to said reflective element to selectively manipulate said reflective element in a path of said optical beam, said surface electrostatic actuator including a movable member that can be displaced with respect to a stationary member of said electrostatic actuator in response to electrostatic forces, said movable member having a first plurality of electrodes on a first surface of said movable member, said stationary member having a second plurality of electrodes on a second surface of said stationary member that opposes said first surface of said movable member, said first and second pluralities of said electrodes configured to generate said electrostatic forces to laterally displace said movable member in a direction generally parallel to said first and second surfaces, said movable member being mechanically attached to said reflective element such that said reflective element is selectively manipulated in said path of said optical beam by displacement of said movable member.

2. The micromachine of claim 1 wherein said reflective element is configured to be pivotable by said surface electrostatic actuator to at least a relaxed orientation and a reflective orientation such that said optical beam is redirected to said second direction when said reflective element is positioned in said reflective orientation.

3. The micromachine of claim 2 wherein said reflective element is configured to be pivoted between an initial orientation in which said reflecting surface of said reflective element is generally parallel to a propagation path of said optical beam and a final orientation in which said reflecting surface of said reflective element is generally perpendicular to said propagation path of said optical beam, said initial orientation being said relaxed orientation and said final orientation being said reflective orientation.

4. The micromachine of claim 2 wherein said reflective element is partially affixed to said stationary member such that said reflective element is able to pivot about one side of said reflective element in response to said displacement of said movable member.

5. The micromachine of claim 1 wherein said movable member of said electrostatic actuator is positioned above said stationary member such that a lower surface of said movable member faces an upper surface of said stationary member, said lower surface of said movable member being said first surface of said movable member and said upper surface of said stationary member being said second surface of said stationary member.

6. The micromachine of claim 1 wherein said first plurality of said electrodes is positioned on said first surface of said movable member such that a repeat distance associated with said first plurality of said electrodes divided by a gap distance between said first plurality of said electrodes and said second plurality of said electrodes is less than approximately sixteen.

7. The micromachine of claim 1 wherein said electrodes of said first and second pluralities are thin strips of conductive material that are positioned substantially in parallel on said first surface of said movable member and said second surface of said stationary member.

8. The micromachine of claim 1 further comprising a voltage controller that is electrically coupled to said second plurality of said electrodes on said stationary member to selectively vary voltages along said second plurality such that predetermined voltage patterns are established, said predetermined voltage patterns defining said electrostatic forces between said movable member and said stationary member.

9. The micromachine of claim 1 further comprising a voltage source that is electrically coupled to said first plurality of said electrodes on said movable member, said voltage source being configured to apply a repeating spatially alternating voltage pattern to said first plurality of said electrodes.

10. The micromachine of claim 1 further comprising a first plurality of levitator electrodes on said first surface of said movable member and a second plurality of levitator electrodes on said second surface of said stationary member, said levitator electrodes being configured to generate repulsive electrostatic forces between said movable member and said stationary member.

11. The micromachine of claim 1 wherein said movable member includes a plurality of flexures that are attached to said stationary member, said flexures having a structural property to yield to movement of said movable member such that said movable member may be displaced in said direction.

12. A method of steering optical beams using a surface electrostatic actuator comprising steps of:

receiving an optical beam;

displacing a movable member of said surface electrostatic actuator in a direction generally parallel to a surface of said movable member facing a stationary member of said surface electrostatic actuator;

selectively manipulating a reflective element in a path of said optical beam in response to displacement of said movable member of said surface electrostatic actuator in said direction generally parallel to said surface of said movable member facing said stationary member of said surface electrostatic actuator; and

redirecting said optical beam by reflecting said optical beam from said reflective element to a destination that is at least partially defined by said selective manipulation of said reflective element.

13. The method of claim 12 wherein said step of selectively manipulating said reflective element includes a step of selectively pivoting said reflective element to a particular orientation by said surface electrostatic actuator.

14. The method of claim 13 wherein said step of selectively pivoting said reflective element is a step of selectively pivoting said reflective element by approximately ninety degrees from an initial orientation.

15. The method of claim 13 wherein said step of selectively pivoting said reflective element includes incrementally pivoting said reflective element such that said reflective element makes a predefined angle with respect to said surface of said movable member, said predefi ned angle defining said particular orientation of said reflective element.

16. The method of claim 12 wherein said step of redirecting said optical beam to said destination is a step of redirecting said optical beam to one of a plurality of waveguides, said optical beam being an optical signal.

17. The method of claim 12 wherein said step of displacing said movable member of said surface electrostatic actuator further includes modifying drive electrostatic forces that are generated between said movable member and a stationary member of said electrostatic actuator to displace said movable member.

18. The method of claim 12 further comprising a step of generating repulsive electrostatic forces that are generally normal to opposing surfaces of said movable member and said stationary member to offset induced attractive forces between said movable member and said stationary member of said electrostatic actuator.

19. An optical switch comprising:

a switching element positioned to selectively direct a received optical signal to one of a plurality of waveguides, said switching element having a reflective surface to reflect said received optical signal to said one of said plurality of said waveguides; and

an electrostatic actuator operatively coupled to said switching element to selectively manipulate said reflective surface to reflect said received optical signal, said electrostatic actuator including a movable member having a first plurality of electrodes on a first surface of said movable member and a stationary member having a second plurality of electrodes on a second surface of said stationary member to generate electrostatic forces between said movable member and said stationary member, said first surface and second surface being opposed surfaces such that said movable member is able to be displaced in a direction generally parallel to said first and second surfaces, said movable member being mechanically attached to said switching element such that said reflective surface of said switching element is manipulated when said movable member of said electrostatic actuator is displaced.

20. The optical switch of claim 19 wherein said switching element is configured to be pivotable by said electrostatic actuator such that said reflective surface can be orientated to selectively reflect said received optical signal to one of said waveguides.

21. The optical switch of claim 19 wherein said movable member of said electrostatic actuator further includes a plurality of flexures that are attached to said stationary member, said flexures being flexible in said direction generally parallel to said first and second surfaces such that said movable member is able to be displaced in said direction.

22. The optical switch of claim 19 wherein said second plurality of said electrodes on said stationary member is electrically connected to a voltage controller to provide voltages to said second plurality of said electrodes in a voltage pattern, said voltage controller being able to reconfigure said voltage pattern of said second plurality of said electrodes to change said electrostatic forces between said movable member and said stationary member to displace said movable member.

23. The optical switch of claim 19 wherein said first plurality of said electrodes is positioned on said first surface of said movable member such that a repeat distance associated with said first plurality of said electrodes divided by a gap distance between said first plurality of said electrodes and said second plurality of said electrodes is less than approximately sixteen.

24. The optical switch of claim 19 further comprising a voltage source that is electrically coupled to said first plurality of said electrode on said movable member, said voltage source being configured to apply a repeating spatially alternating voltage pattern to said first plurality of said electrodes.

25. The optical switch of claim 19 wherein said movable member further includes a first plurality of levitator electrodes and wherein said stationary member includes a second plurality of levitator electrodes, said levitator electrodes being located on said first and second surfaces to generate repulsive electrostatic forces between said movable member and said stationary member.