Fast switching method for a micro-mirror device for optical switching applications

• US 6,771,851 B1
• Filed: 06/19/2001
• Issued: 08/03/2004
• Est. Priority Date: 06/19/2001
• Status: Expired due to Fees

• Current Assignee: Nayna Networks, Inc.
• Original Assignee: Nayna Networks, Inc.
• Inventors: Yang, Xiao
• Primary Examiner(s): Ullah, Akm Enayet
• Assistant Examiner(s): Rahll, Jerry T.
• Application Number:
  US09/884,692
• Time in Patent Office: 1,141 Days
• Field of Search: 385/15-18, 385/39-41, 359/872, 359/874
• US Class Current: 385/18
• 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 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/359 of the position of the moving element itself during switching, i.e. without monitoring the switched beams

Abstract

A fast method of switching optical signals using micro-mirror structures and control. The method selects an optical path for a micro-mirror device, the mirror device being coupled to a torsion bar device. The micro-mirror device is moved or pivoted about a torsion bar device, the micro-mirror device being operated about the torsion bar device through an operating range. The micro-mirror device is subjected to a mechanical force from the torsion bar and being subjected an electro-static force applied to the micro-mirror device. The method positions the micro-mirror device to a selected switching location within the operating range a selected region within a predetermined time. The micro-mirror device is controlled during a portion of time during the moving by receiving position signals periodically at a predetermined frequency from a sensing device coupled to the micro-mirror device. The position signals are indicative of a position of the operating range and selectively applying an electrostatic force based upon one or more of the position signals such that the micro-mirror device is moved to the selected switching location without substantial oscillation of the micro-mirror device within the predetermined time of less than 10 milliseconds.

Claims

1. A method of switching optical signals using micro-mirror structures and control, the method comprising:

selecting an optical path for a micro-mirror device, the mirror device being coupled to a torsion bar device;

moving the micro-mirror device about a torsion bar device, the micro-mirror device being operated about the torsion bar device through an operating range, the micro-mirror device being subjected to a mechanical force from the torsion bar and being subjected to an electro-static force applied to the micro-mirror device and positioning the micro-mirror device to a selected switching location within the operating range to a selected region within a predetermined time; and

controlling the micro-mirror device during a portion of time during the moving by receiving position signals periodically at a predetermined frequency from a sensing device coupled to the micro-mirror device, the position signals being indicative of a position of the operating range and selectively applying an electro-static force based upon one or more of the position signals such that the micro-mirror device is moved to the selected switching location to form the optical path without substantial oscillation of the micro-mirror device within the predetermined time of less than 10 milliseconds, wherein the electro-static force and the torsion force are equal to zero at the selected switching location.

2. The method of claim 1 wherein the controlling reduces the electro-static forces from an electrode coupled to the micro-mirror device.

3. The method of claim 1 wherein the predetermined time is less than about 1 millisecond.

4. The method of claim 1 wherein the sensing device is selected from an optical sensor, mechanical sensor, or an electrical sensor.

5. The method of claim 1 Wherein the selected frequency is 6 kHz and greater.

6. The method of claim 1 wherein the micro-mirror device has a mirror surface having a diameter of less than 3 millimeters.

7. The method of claim 1 wherein the controlling is provided at a time period of less than 20 microseconds.

8. The method of claim 1 wherein the operating range includes an unstable region, the unstable region being characterized as a pull-in condition.

9. The method of claim 1 wherein the predetermined time is a minimized time for the controlling and wherein the mirror device is subjected to a back bias voltage of 200 volts and less.

10. The method of claim 1 wherein the predetermined time is less than 5 milliseconds or less.

11. A method of switching optical signals using micro-mirror structures and control, the method comprising:

selecting an optical path for a micro-mirror device, the mirror device being coupled to a torsion bar device;

moving the micro-mirror device about a torsion bar device, the micro-mirror device being operated about the torsion bar device through an operating range, the micro-mirror device being subjected to a mechanical force from the torsion bar and being subjected to an electro-static force applied to the micro-mirror device and positioning the micro-mirror device to a selected switching location within the operating range to a selected region within a predetermined time; and

controlling the micro-mirror device during a portion of time during the moving by receiving position signals periodically at a predetermined frequency from a sensing device coupled to the micro-mirror device, the position signals being indicative of a position of the operating range and selectively applying an electro-static force based upon one or more of the position signals such that the micro-mirror device is moved to the selected switching location to form the optical path without substantial oscillation of the micro-mirror device within the predetermined time of less than 10 milliseconds, wherein the substantial oscillation includes a predetermined frequency that may be damped and continues for an amount of time that exceeds milliseconds.

12. The method of claim 11 wherein the predetermined time is less than about 1 millisecond.

13. The method of claim 11 wherein the controlling reduces the electro-static forces from an electrode coupled to the micro-mirror device.

14. The method of claim 11 wherein the electro-static force and the torsion force are equal to zero at the selected switching location.

15. The method of claim 11 wherein the sensing device is selected from an optical sensor, mechanical sensor, or an electrical sensor.

16. The method of claim 11 wherein the selected frequency is 6 kHz and greater.

17. The method of claim 11 wherein the micro-mirror device has a mirror surface having a diameter of less than 3 millimeters.

18. The method of claim 11 wherein the controlling is provided at a time period of less than 20 microseconds.

19. The method of claim 11 wherein the operating range includes an unstable region, the unstable region being characterized as a pull-in condition.

20. The method of claim 11 wherein the predetermined time is a minimized time for the controlling and wherein the mirror device is subjected to a back bias voltage of 200 volts and less.

21. The method of claim 11 wherein the predetermined time is less than 5 milliseconds or less.