Protection for MEMS cross-bar switch

• US 6,292,281 B1
• Filed: 03/24/1999
• Issued: 09/18/2001
• Est. Priority Date: 03/24/1999
• Status: Expired due to Fees

• Current Assignee: Rembrandt Communications LP (Rembrandt IP Management, LLC)
• Original Assignee: Tellium, Inc. (DZS, Inc.)
• Inventors: Bala, Krishna, Tomlinson, W. John
• Primary Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US09/275,414
• Time in Patent Office: 909 Days
• Field of Search: 359/110, 359/117, 359/128, 385/16-18
• US Class Current: 398/2
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3546 NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3562 Switch of the bypass type, i.e. enabling a change of path in a network, e.g. to bypass a failed element in the network

Abstract

A protection system for a micro electro-mechanical system (MEMS) cross-bar switch is described. Optical signals that are cross-connected by a N×N optical matrix switch are routed through alternative protection paths using protection switch elements. The protection switch elements are incorporated as part of the silicon wafer based fabricated structure that forms the N×N optical matrix. The protection switch elements enable the N×N optical matrix switch to recover from one or more failures in switch elements of the N×N optical matrix using alternative protection paths that have the same path length as the original optical path.

Claims

1. An optical switch system having a protection optical path, comprising:

a plurality of optical input lines for carrying optical signals;

a plurality of optical output lines; and

an optical switch for directing light beams from the optical input lines to selected optical output lines, said optical switch comprising a plurality of miniature working mirrors for reflecting light beams in optical paths from the optical input lines to the selected optical output lines and a plurality of miniature protection mirrors movable into the optical paths in the event of a fault in light communication of one or more light beams from the input optical lines to the selected output optical lines, said miniature protection mirrors for directing light beams ultimately to the selected optical output lines.

2. An optical system according to claim 1, wherein said miniature mirrors are fabricated on a silicon wafer.

3. An optical switch system according to claim 1, wherein said miniature mirrors are micro electro-mechanical system (MEMS) elements.

4. An optical switch system according to claim 1, wherein said miniature protection mirrors are individually movable into the optical paths.

5. An optical switch system according to claim 1, further comprising additional miniature mirrors for reflecting light beams received from said miniature protection mirrors.

6. An optical switch system according to claim 1, further comprising additional miniature protection mirrors for reflecting light beams received from said miniature protection mirrors.

7. An optical switch system according to claim 1, further comprising a first plurality of additional miniature protection mirrors and a second plurality of additional protection mirrors, wherein, when one of said miniature protection mirrors is moved into an optical path, the miniature protection mirror directs the light beam to one of said first plurality of additional miniature protection mirrors, which directs the light beam to one of the second plurality of additional protection mirrors.

8. An optical switch system according to claim 1, wherein one of said miniature protection mirrors is moved into an optical path in the event of fault of light communication through that optical path.

9. An optical switch system according to claim 1, wherein multiple miniature protection mirrors are moved into multiple optical paths in the event of fault of light communications through one of the multiple optical paths.

10. A method of switching light beams from input optical fibers to output optical fibers in an optical switch system, the method comprising:

directing light beams in first optical paths from input optical fibers to selected output optical fibers using miniature mirrors, and

in the event of a fault in light communication of a light beam from an input optical fiber to its selected output optical fiber, redirecting the light beam using an additional miniature mirror, wherein the redirected light beam traverses a protection optical path from the input optical fiber to the selected output optical fiber.

11. The method according to claim 10, wherein said miniature mirrors are fabricated on a silicon wafer.

12. The method according to claim 10, wherein said miniature are micro electro-mechanical systems (MEMS) elements.

13. A method of switching light beams between input optical fibers and output optical fibers in an optical switch system, the method comprising:

directing light beams in first optical paths from input optical fibers to selected output optical fibers using miniature mirrors, and

in the event of a fault in light communication of a light beam from an input optical fiber to its selected output optical fiber, redirecting the light beam from the first optical path to a protection miniature mirror in a protection optical path to the selected output optical fiber.

14. The method according to claim 13, wherein said miniature mirrors and said protection miniature mirror are fabricated on a silicon substrate.

15. The method according to claim 13, wherein said miniature mirrors and said protection miniature mirror are micro electro-mechanical system (MEMS) elements.

16. A method of switching light beams between input optical fibers and output optical fibers in an optical switch system, the method comprising:

directing light beams in first optical paths from input optical fibers to selected output optical fibers using miniature mirrors, and

in the event of a fault in light communication of a light beam from an input optical fiber to its selected output optical fiber, moving a protection miniature mirror into the first optical path of the light beam, said protection miniature mirror directing the light beam ultimately to its selected optical output fiber.

17. The method according to claim 16, wherein said miniature mirrors and said protection miniature mirror are fabricated on a silicon substrate.

18. The method according to claim 16, wherein said miniature mirrors and said protection miniature mirror are micro electro-mechanical system (MEMS) elements.

19. A protection optical switching method in an optical switch that directs light beams in first optical paths from input optical fibers to output optical fibers using miniature mirrors, the protection optical switching method used in the event of a fault in light communication of a light beam from an input optical fiber to its selected output optical fiber, the method comprising:

directing the light beam from the first optical path to a first protection optical path link using a miniature mirror;

directing the light beam from the first protection optical path link to a second optical path link using a miniature mirror; and

directing the light beam from the second protection optical path link to the selected output optical fiber using a miniature mirror.

20. The method according to claim 19, wherein said miniature mirrors are fabricated on a silicon substrate.

21. The method according to claim 19, wherein said miniature mirrors are micro electro-mechanical system (MEMS) elements.

22. A protection optical switching method in an optical switch that directs light beams in first optical paths from input optical fibers to output optical fibers using miniature mirrors, the protection optical switching method used in the event of a fault in light communication of a light beam from an input optical fiber to its selected output optical fiber, the method comprising:

moving a miniature mirror into the first optical path; and

directing the light beam ultimately to the selected optical output fiber.

23. The method according to claim 22, wherein said miniature mirror is fabricated on a silicon substrate.

24. The method according to claim 22, wherein said miniature mirror is a micro electro-mechanical system (MEMS) element.

25. An optical switch system having a protection optical path, comprising:

a plurality of optical input lines for carrying light beams carrying optical signals;

a plurality of optical output lines; and

an optical switch for directing light beams from the optical input lines to selected optical output lines, said optical switch comprising a plurality of miniature working mirrors for reflecting the light beams in optical paths from the optical input lines to the selected optical output lines and a plurality of miniature protection mirrors receiving one or more of the light beams in the event of a fault in light communication of one or more light beams from input optical fibers to output optical fibers, said miniature protection mirrors for directing the one or more received light beams ultimately to the selected optical output fibers.

26. An optical switch according to claim 25, wherein said miniature mirrors are fabricated on a silicon wafer.

27. An optical switch according to claim 25, wherein said miniature mirrors are micro electro-mechanical system (MEMS) elements.

28. An optical switch according to claim 25, wherein a miniature protection mirror of said plurality of miniature protection mirrors receives one light beam in the event of the fault in light communication.

29. An optical switch according to claim 25, further comprising additional miniature protection mirrors movable into said optical paths to receive said lights beams, said additional miniature protection mirrors for directing one or more of the light beams to said miniature protection mirrors.

30. An optical switch system having a protection optical path, comprising:

a plurality of input optical waveguides for carrying input optical signals traveling in a first direction;

a plurality of output optical waveguides for receiving reflected input optical signals traveling in a second direction different than the first direction;

a matrix of switch elements arranged in multiple rows and columns and selectably providing a reflective surface to enable the input optical signals to be selectably coupled to each output optical waveguide;

a protection column of protection switch elements;

a protection row of protection switch elements;

an optical reflector provided at the intersection of the column of protection switch elements and the row of protection switch elements, wherein in the event of failure of optical communication of an optical signal from one of the input optical waveguide to its selected one of the output optical waveguides, wherein a protection switch element of the protection column reflects the optical signal to the optical reflector, the optical reflector reflects the optical signals to a protection switch element of the protection row, and the protection switch element of the protection row reflects the optical signal to the selected one of the output optical waveguides, thereby providing at least a portion of a protection optical path.

31. An optical switch system having a protection optical path, comprising:

a plurality of first optical waveguides carrying optical signals;

a plurality of second optical waveguides for receiving reflected optical signals;

a switch matrix including (a) optical switch elements for selectably reflecting the optical signals from the first optical waveguides to selected second optical waveguides to provide optical communication between the first optical waveguides and the second optical waveguides, and (b) a plurality of optical protection switch elements including first protection switch elements, second protection switch elements, and an optical reflector that provide a protection optical path for the optical signals between a first optical waveguide and its selected second optical waveguide, the optical protection path bypassing the optical switch elements.

32. An optical switch system having a protection optical path comprising:

a plurality of input optical waveguides and a plurality of output optical waveguides;

an optical switching matrix for selectively coupling optical signals from each of the input optical waveguides to selected output optical waveguides, said matrix including rows and columns of multiple optical switch elements for selectively reflecting the optical signals from each input optical waveguide to its selected output optical waveguide, wherein the rows of the optical switching elements correspond to the input optical waveguides and the columns of optical switch elements correspond to the output optical waveguides, said matrix further including a column of first optical protection switch elements, a row of second protection switch elements, and an optical reflector that together provide at least a portion of a protection optical path in the event of a fault in optical communication of the optical signals from an input optical waveguide to its selected output optical waveguide, wherein a first optical protection switch element is configured to reflect the optical signal to the optical reflector, the optical reflector is arranged to reflect the optical signal to a second optical protection switch element, and the second optical protection switch element is configured to reflect the optical signal to its selected output waveguide.