Connection-verification in optical MEMS crossconnects via mirror-dither

• US 6,243,507 B1
• Filed: 12/27/1999
• Issued: 06/05/2001
• Est. Priority Date: 06/07/1999
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Lin, Lih-Yuan, Goldstein, Evan Lee, Lunardi, Leda Maria
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): ASSAF, FAYEZ G
• Application Number:
  US09/472,682
• Time in Patent Office: 526 Days
• Field of Search: 385/16-19, 385/12-14, 359/212, 359/223, 359/225, 250/216, 250/234
• US Class Current: 385/13
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• 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 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52

Abstract

Integrated connection-verification system for use in a micro-electro-mechanical system (MEMS) crossconnect device. The system uses application of a dithering signal such as a sinusoidal bias to an electrode plate associated with a micro-mirror switching element to dither the micro-mirror. The optical signal from the dithering micro-mirror is fed through a beam splitter, a portion of the optical signal thus being directed to a photodetector. If intensity modulation in the optical signal corresponding to the frequency of the dithering signal is detected by the photodetector associated with the micro-mirror, the connection path between the desired input and output ports is verified.

Claims

1. A connection verification system comprising

a micro-mirror having an optical signal input side and an optical signal output side, the micro-mirror connected to a substrate,

an electrode plate in association with the micro-mirror and capable of dithering the micro-mirror upon application of a dithering signal to the electrode plate,

a beam splitter located on the substrate at the optical signal output side of the micro-mirror, and

a photodetector positioned beneath the beam splitter.

2. The connection verification system according to claim 1, wherein the system is within an optical micro-electro-mechanical crossconnect device.

3. The connection verification system according to claim 2, wherein the optical micro-electro-mechanical crossconnect device includes at least one input port and at least one output port, the micro-mirror being located on the substrate in a line of travel of an incoming optical signal from one of the at least one input ports and at a point of intersection of a path from the one input port and one of the at least one output ports when in a reflective position.

4. The connection verification system according to claim 1, wherein the electrode plate is connected to a source of the dithering signal via conductive wiring.

5. The connection verification system according to claim 1, wherein the micro-mirror is connected to the substrate via hinge joints permitting free rotation of the micro-mirror.

6. The connection verification system according to claim 1, wherein one or more of the micro-mirror, the electrode plate and the beam splitter are comprised of a surface-micromachined polysilicon.

7. A connection verification system of an optical micro-electro-mechanical crossconnect device, comprising

at least one input port and at least one output port,

a micro-mirror for one of the at least one input ports and having an optical signal input side and an optical signal output side, the micro-mirror connected to a substrate, and capable of being moved to a reflective position so as to switch an incoming optical signal from the one input port to a predetermined output port when the micro-mirror is in a reflective position,

an electrode plate in association with the micro-mirror and capable of dithering the micro-mirror upon application of a dithering signal to the electrode plate,

a beam splitter located on the substrate at the optical signal output side of the micro-mirror, and

a photodetector positioned beneath the beam splitter.

8. A method of verifying the connection path of an optical signal from an input port to a desired output port, comprising

switching an optical signal from the input port to the desired output port with a micro-mirror having an optical signal input side and an optical signal output side, the micro-mirror connected to a substrate,

applying a dithering signal to an electrode plate in association with the micro-mirror to dither the micro-mirror, and

splitting the optical signal on the optical signal output side of the micro-mirror into a detection portion and an output portion with a beam splitter located on the substrate at the optical signal output side of the micro-mirror, the beam splitter directing the detection portion to a photodetector located beneath the beam splitter.

9. The method according to claim 8, wherein the dithering signal is a sinusoidal bias.

10. The method according to claim 8, wherein the connection path is verified when the photodetector detects alterations in intensity of the detection portion of the optical beam corresponding to the dithering signal applied to the electrode plate.

11. The method according to claim 8, wherein the optical signal from the input port includes a pilot tone.