Angular-precision enhancement in free-space micromachined optical switches

• US 6,606,428 B2
• Filed: 08/22/2001
• Issued: 08/12/2003
• 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, Tkach, Robert William
• Primary Examiner(s): Phan, James
• Application Number:
  US09/933,726
• Publication Number:
  US 20010053261A1
• Time in Patent Office: 720 Days
• Field of Search: 359/198-199, 359/212, 359/223-226, 359/871, 359/872, 385/15-23, 385/147
• US Class Current: 385/18
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• 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 6/3518 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 6/3584 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

Integrated mechanical angular alignment-enhancement structures for incorporation into free-space micromachined optical switches are capable of achieving better than 0.1° micro-mirror angular precision and repeatability with the optical switches. The structures open the path to high port-count crossconnects with sufficiently low loss for deployment in practical optical-communications networks.

Claims

1. An optical switching device comprising:

a matrix of input and output ports, and

an optical micro-mirror switching element located at an intersection of each path from an input port to an output port, the optical micro-mirror switching element comprising;

a micro-mirror attached to a substrate through one or mote hinge joints comprised of a hinge pin and a hinge staple, the hinge staple being attached to he substrate,

one or more pushrods associated with the micro-miror, and capable of rotating the micro-mirror upon movement of a translation stage, and

at least one mechanical angular alignment-enhancement structure coupled to the one or more pushrods.

2. The optical switching device according to claim 1, wherein the matrix comprises N input ports and M output ports, N and M being any integer greater than 1.

3. The optical switching device according to claim 1, wherein the optical micro-mirror switching element is positioned at a 45°

angle to a path from the input port.

4. The optical switching device according to claim 1, wherein the micro-mirror moves between a rest position and reflecting position.

5. The optical switching device according to claim 4, wherein in the switching position, the micro-mirror is at an angle of about 90°

from the substrate.

6. The optical switching device according to claim 1, wherein the micro-mirror is mounted within a frame integral with the hinge joints.

7. The optical switching device according to claim 1, wherein the pushrods are attached at one end to the micro-mirror by a hinge joint and are attached at an opposite end to the translation stage by a hinge joint.

8. The optical switching device according to claim 1, wherein the at least one mechanical angular alignment-enhancement structure is selected from the group consisting of one or more push-bars upon the substrate, one or more scratch drive actuators having a bushing abutting an end edge of the actuator, and one or more hinge pins having a width in portions of the hinge pin outside of the hinge staples greater than a width of portions of the hinge pin inside of the hinge staples.

9. The optical switching device according to claim 1, wherein the at least one mechanical angular alignment-enhancement structure is one or more push-bars upon the substrate.

10. The optical switching device according to claim 9, wherein the one or more push-bars are movable upon movement of the translation stage.

11. The optical switching device according to claim 9, wherein the one or more push-bars move to press one or more hinge pins of the micro-mirror against a forward inner wall of one or more of the hinge staples.

12. The optical switching device according to claim 1, wherein the at least one mechanical angular alignment-enhancement structure is one or more scratch drive actuators having a bushing at an end edge of the actuator.

13. The optical switching device according to claim 1, wherein the at least one mechanical angular alignment-enhancement structure is one or more hinge pins having a width in portions of the hinge pin outside of the hinge staples greater than a width of portions of the hinge pin inside of the hinge staples.

14. The optical switching device according to claim 13, wherein the portions of the hinge pin outside of the hinge staples have a width greater than the width of portions of the hinge pin inside of the hinge staples by 0.3 μ

m or more.

15. The optical switching device according to claim 13, wherein the portions of the hinge pin outside of the hinge staples have a width greater than the width of portions of the hinge pin inside of the hinge staples by 0.5 μ

m or more.

16. The optical switching device according to claim 1, wherein the input ports comprise input optical fibers and the output ports comprise output optical fibers.