Angular-precision enhancement in free-space micromachined optical switches

• US 6,292,600 B1
• Filed: 12/27/1999
• Issued: 09/18/2001
• 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: Goldstein, Evan Lee, Lin, Lih-Yuan, Tkach, Robert William
• Primary Examiner(s): Phan, James
• Application Number:
  US09/472,724
• Time in Patent Office: 631 Days
• Field of Search: 385/15-23, 385/147, 359/198, 359/199, 359/212, 359/223, 359/226, 359/871, 359/872
• 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 element comprising:

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

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

at least one mechanical angular alignment-enhancement structure.

2. The optical switching element of claim 1, wherein the micro-mirror is mounted within a frame integral with the hinge joints.

3. The optical switching element of 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.

4. The optical switching element of 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.

5. The optical switching element of claim 1, wherein the at least one mechanical angular alignment-enhancement structure is one or more push-bars upon the substrate.

6. The optical switching element of claim 5, wherein the one or more push-bars are movable upon movement of the translation stage.

7. The optical switching element of claim 5, 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.

8. The optical switching element of 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.

9. The optical switching element of 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.

10. The optical switching element of claim 9, 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.

11. The optical switching element of claim 10, 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.

12. A method of achieving angular alignment precision of at least 0.1°

with a micro-mirror of an optical switching element at a predetermined angle from a substrate upon which the micro-mirror is mounted when rotating the micro-mirror to the predetermined angle, the optical switching element comprising the micro-mirror attached to a substrate through one or more hinge joints comprised of a hinge pin and a hinge staple, the hinge staple being attached to the substrate, one or more pushrods associated with the micro-mirror, and capable of rotating the micro-mirror upon movement of a translation stage, and at least one mechanical angular alignment-enhancement structure, the method comprising

moving the translation stage with one or more scratch drive actuators to move the pushrods and rotate the micro-mirror via the one or more hinge joints, and

positioning the micro-mirror at the predetermined angle within 0.1°

precision, the precision achieved via the at least one mechanical alignment-enhancement structure.

13. The method according to claim 12, 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 at 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.

14. The method according to claim 12, wherein the at least one mechanical angular alignment-enhancement structure is one or more push-bars upon the substrate, the one or more push-bars moving upon movement of the translation stage to press one or more hinge pins of the hinge joints against a forward inner wall of one or more of the hinge staples.

15. The method according to claim 12, wherein the at least one mechanical angular alignment-enhancement structure is one or more scratch drive actuators having a bushing at the end edge of the actuator, the scratch drive actuators effecting precise movement of the translation stage to achieve the precision in the positioning of the micro-mirror.

16. The method according to claim 12, 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 by 0.5 μ

m or more.

17. A method of rotating a micro-mirror of an optical switching element to a predetermined position from a substrate upon which the micro-mirror is mounted, the optical switching element comprising the micro-mirror attached to a substrate through one or more hinge joints comprised of a hinge pin and a hinge staple, the hinge staple being attached to the substrate, one or more pushrods associated with the micro-mirror, and capable of rotating the micro-mirror upon movement of a translation stage, and at least one mechanical angular alignment-enhancement structure, the method comprising

moving the translation stage with one or more scratch drive actuators to move the pushrods and rotate the micro-mirror via the one or more hinge joints, and

positioning the micro-mirror at the predetermined position within 0.1°

precision, the precision achieved via the at least one mechanical alignment-enhancement structure.