Angular-precision enhancement in free-space micromachined optical switches

• US 20010053261A1
• Filed: 08/22/2001
• Published: 12/20/2001
• Est. Priority Date: 06/07/1999
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Goldstein, Evan Lee, Tkach, Robert William, Lin, Lih-Yuan
• Granted Patent: US 6,606,428 B2
• Time in Patent Office: Days
• 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.