Bi-stable micro-actuator and optical switch

• US 6,788,840 B2
• Filed: 02/12/2003
• Issued: 09/07/2004
• Est. Priority Date: 02/27/2001
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Hall, David B., Stewart, Robert E., Cherbettchian, Agop H., Fersht, Samuel
• Primary Examiner(s): Palmer, Phan T. H.
• Assistant Examiner(s): Doan, Jennifer
• Application Number:
  US10/365,370
• Publication Number:
  US 20030210849A1
• Time in Patent Office: 573 Days
• Field of Search: 385/15-19, 359/872, 359/876
• US Class Current: 385/16
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 3/0024 Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators electric motors using thermal effects H02N10/00
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• 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 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• 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 6/3584 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: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet

Abstract

A bi-stable micro-actuator is formed from a first and a second silicon-on-insulator wafer fused together at an electrical contact layer. A cover with a V-groove defines an optical axis. A collimated optical signal source in the V-groove couples an optical signal to an optical port in the V-groove. A mirror surface on a transfer member blocks or reflects the optical signal. The transfer member has a point of support at the first and second end. The mirror blocks or reflects the optical axis. An expandable structure applies a compressive force between the first and second point of support of the transfer member along a compressive axis to hold the transfer member in a bowed first state or a bowed second state. A control signal applied to a heating element in the expandable structure reduces the compressive force, switching the transfer member to a second state.

Claims

1. A micro-actuator responsive to a control signal having a first state and a second state comprising:

a flexible transfer member having a central portion and first and second ends located along a compressive axis, the flexible transfer member being in a first or second bowed state; and

an expandable structure response to the control signal coupled to the first and second ends of the transfer member, the expandable structure applying a compressive force to the flexible transfer member substantially along the compression axis, the expandable structure adapted to toggle the flexible transfer member between the first and second bowed states as determined by the control signal.

2. The micro-actuator of claim 1, wherein said expandable structure comprises:

a frame coupled to the flexible transfer member and adapted to expand and reduce the compressive force applied to the flexible transfer member in response to the control signal, whereby the central portion of the flexible transfer member moves from an initial first or bowed state past the coinpressive axis into a second bowed state with restoration of the compressive force by the expandable structure.

3. A micro-actuator comprising:

a flexible transfer member having a first and second point of support at a first end and a second end of a compressive axis, the flexible transfer member having a central portion displaced from the compressive axis;

a control signal having a first state and second state,

an expandable structure having a first and second end coupled to the transfer member'"'"'s first and second point of support, the expandable structure adapted to apply a compressive force between the first and second point of support along the compressive axis of the flexible transfer member to hold the flexible transfer member in compression in a bowed first state, the expandable structure response to the control signal to reduce the compressive force applied to the flexible transfer member, whereby a central portion of the flexible transfer member moves past the compressive axis into a bowed second state upon restoration of compressive force by the expandable structure.

4. The micro-actuator of claim 3 wherein a first and second end of the expandable structure further comprises:

at least a first support post extending from the expandable structure to a point of support on the flexible transfer member.

5. The micro-actuator of claim 3 wherein the first and second end of the expandable structure further comprises:

a first support post extending from the first end of the expandable structure to the first point of support on the flexible transfer member; and

a second support post extending from the second end of the expandable structure to the second point of support on the flexible transfer member.