Optical cross-connect with magnetic micro-electro-mechanical actuator cells

• US 6,785,038 B2
• Filed: 01/17/2001
• Issued: 08/31/2004
• Est. Priority Date: 01/17/2001
• Status: Expired due to Fees

• Current Assignee: Innovative Micro Technology Incorporated, Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Inventors: Foster, John S., Summers, Jeffery F., Rubel, Paul J., Martin, Richard T., Stocker, John W., Hichwa, Bryant P.
• Primary Examiner(s): Schwartz, Jordan M.
• Assistant Examiner(s): STULTZ, JESSICA T
• Application Number:
  US09/765,522
• Publication Number:
  US 20020093720A1
• Time in Patent Office: 1,322 Days
• Field of Search: 359/224, 359/221, 359/230, 359/231, 359/252, 359/290, 359/291, 250/231.1, 250/231.18, 310/306, 310/307, 372/92, 385/14, 385/47, 385/49
• US Class Current: 359/290
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• 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 6/3564 Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• 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
• CPC Class Codes: G02B 6/4226 Positioning means for moving the elements into alignment, e.g. alignment screws, deformation of the mount

Abstract

An optical cross-connect is fabricated on a substrate using individual MEMs dice with mirrors that rotate into and out of an optical beam path. Each die can be aligned to a single (input-output) pair of collimators in a fiber-optic switching system. An individually accessible magnetic drive on each die provides low power consumption when re-configuring the array in addition to fast switching speeds. The state of each die can be electronically sensed to verify proper array configuration and operation of each die.

Claims

1. An optical switch comprising:

a mounting substrate

a micro-electro-mechanical system (“

MEMs”

) die mounted on an edge to the mounting substrate, the MEMs die including a mirror movably attached to a base portion of the MEMs die with a flexure hinge, the mirror moving from a first position to a second position in a plane essentially normal to a major surface of the mounting substrate;

an input port disposed to couple an optical signal to

a first output port when the mirror is in the first position and to couple the optical signal to

a second output port when the mirror is in the second position wherein the mirror is formed on a smoothed major crystal plane of a layer of single-crystal silicon and has a reflectivity greater than 96%.

2. The optical switch of claim 1 wherein the input port provides the optical signal to the mirror in the second position at an angle of between about 15-45 degrees from a normal of the mirror.

3. The optical switch of claim 1 wherein the input port provides the optical signal to the mirror in the second position at an angle of less than about 22.5 degrees from a normal of the mirror.

4. An optical switch comprising:

a mounting substrate

a micro-electro-mechanical system (“

MEMs”

) die mounted on an edge to the mounting substrate, the MEMs die including a mirror rotatably attached to a base portion of the MEMs die with a flexure hinge, the mirror rotating from a first position to a second position in a plane essentially parallel to a major surface of the MEMs die;

an input port disposed to couple an optical signal to

a first output port when the mirror is in the first position and to couple the optical signal to

a second output port when the mirror is in the second position, wherein the mirror has a first mirrored surface and a second mirrored surface, the second mirrored surface being opposite the first mirrored surface, and further comprising

a second input port disposed to optically couple a second optical signal to the first output port when the mirror is in the second position.

5. A micro-electro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first MEMs optical switch cell affixed to the mounting surface on an edge of the first MEMs optical switch cell and aligned to direct a first optical beam propagating along a beam path from a first optical input to a first optical output when a first metallic mirror of the first MEMs optical switch cell is in the beam path; and

a second MEMs optical switch cell affixed to the mounting surface and aligned to direct the first optical beam from the first optical input to a second optical output when a second metallic mirror of the second MEMs optical switch cell is in the beam path and the first optical switching element is rotated in a plane essentially normal to the mounting surface out of the beam path wherein at least one of the first metallic mirror and the second metallic mirror has a minimum face dimension greater than about 400 microns.

6. The MEMs optical cross connect of claim 5 wherein the metallic mirror has an oval shape of about 550 microns by about 780 microns.

7. The MEMs optical cross connect of claim 5 wherein the metallic mirror has an oval shape of about 1.0 mm by about 1.4mm.

8. A micro-electro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first MEMs optical switch die having a major surface and an edge, the first MEMs optical switch die being affixed to the mounting surface on the edge and aligned to direct a first optical beam propagating along a beam path from a first optical input to a first optical output when a first optical switching element of the first MEMs optical switch die is in the beam path; and

a second MEMs optical switch die affixed to the mounting surface and aligned to direct the first optical beam from the first optical input to a second optical output when a second optical switching element of the second MEMs optical switch die is in the beam path and the first optical switching element is rotated in a plane essentially parallel to the major surface of the first MEMs optical switch die out of the beam path, wherein the first optical switching element is a two-sided mirror having a first mirrored side and a second mirrored side, the first optical beam reflecting off the first mirrored side of the two-sided mirror when the two-sided mirror is in the beam path and further comprising

a second optical input disposed to provide a second optical beam to the second mirrored side of the two-sided mirror when the two-sided mirror is in the beam path, the second optical beam being reflected off the second mirrored side to

a third optical output wherein the first optical beam optically couples to the third optical output when the first optical element and the second optical element are both switched out of the beam path.

9. A micro-electro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first MEMs optical switch cell affixed to the mounting surface on an edge of the first MEMs optical switch cell and aligned to direct a first optical beam propagating along a beam path from a first optical input to a first optical output when a first optical switching element of the first MEMs optical switch cell is in the beam path; and

a second MEMs optical switch cell affixed to the mounting surface and aligned to direct the first optical beam from the first optical input to a second optical output when a second optical switching element of the second MEMs optical switch cell is in the beam path and the first optical switching element is rotated in a plane essentially normal to the mounting surface out of the beam path

wherein the first optical switching element is a two-sided mirror having a first mirrored side and a second mirrored side, the first optical beam reflecting off the first mirrored side of the two-sided mirror when the two-sided mirror is in the beam path and further comprising

a second optical input disposed to provide a second optical beam to the second mirrored side of the two-sided mirror when the two-sided mirror is in the beam path, the second optical beam being reflected off the second mirrored side to

a third optical output wherein the first optical beam optically couples to the third optical output when the first optical element and the second optical element are both switched out of the beam path

wherein the first mirrored side has a reflectivity greater than 96% and the second mirrored side has a reflectivity greater than 96%, each of the first mirrored side and the second mirrored side being formed on a smoothed major crystal plane of a layer of single-crystal silicon.

10. A micro-electro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first MEMs optical switch cell affixed to the mounting surface on an edge of the first MEMs optical switch cell and aligned to direct a first optical beam propagating along a beam path from a first optical input to a first optical output when a first optical switching element of the first MEMs optical switch cell is in the beam path; and

a second MEMs optical switch cell affixed to the mounting surface and aligned to direct the first optical beam from the first optical input to a second optical output when a second optical switching element of the second MEMs optical switch cell is in the beam path and the first optical switching element is rotated in a plane essentially normal to the mounting surface out of the beam path wherein the first optical input is disposed between 12-57 mm from the first optical output.

11. A micro-eletro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first MEMs die mounted on a first edge to the mounting surface and having a first mirror disposed to rotate in a plane essentially normal to the mounting surface and extending at least about 400 microns above a second edge of the first MEMs die when the mirror is in a first position and being retracted below the second edge of the first MEMs die when the first mirror is in a second position, the first mirror reflecting a first optical beam from

a first optical input to

a first optical output when the first mirror is in the first position, the first optical beam coupling to

a second optical output when the first mirror is in the second position; and

a second MEMs die mounted on a third edge to the mounting surface and having a second mirror disposed to rotate in a plane essentially normal to the mounting surface and extending at least about 400 microns above a fourth edge of the second MEMs die when the mirror is in a third position and being retracted below the fourth edge of the second MEMs die when the second mirror is in a fourth position, the second mirror reflecting the first optical beam front the first optical input to

a third optical output when the second mirror is in the fourth position and the optical beam coupling to the second optical output when the first mirror is in the second position and the second mirror is in the fourth position, the first optical input being separated from the second optical output by about 12-57 mm.

12. The optical cross connect of claim 11 wherein the first mirror is a two-sided mirror and further comprising a second optical input wherein the first mirror reflects a second optical beam from the second optical input to the second optical output when the first mirror is in the first position.

13. A micro-electro-mechanical system (“

MEMs”

) optical cross connect comprising;

a mounting substrate having a mounting surface;

a first latching MEMs optical switch cell affixed to the mounting surface and aligned to direct a first optical beam from a first optical input to a first optical output when a first mirror of the first MEMs optical switch cell is latched in an extended position; and

a second MEMs optical switch cell affixed to the mounting surface and aligned to direct the first optical beam from the first optical input to a second optical output when a second mirror of the second MEMs optical switch cell is latched in a second extended position and the first mirror is rotated in a plane essentially normal to the mounting surface out of the beam path to latch in a retracted position wherein the first mirror in the extended position extends above an edge of the first latching MEMS optical switch cell at least 400 microns.

14. An optical cross connect comprising:

N optical input ports where N is a first integer;

M optical output ports where M is a second integer; and

N times M micro-electro-mechanical system optical switch dice, each of the micro-electro-mechanical system optical switch dice having a magnetic drive capable of switching a mirror from a first position to a second position in response to a switching signal provided to the micro-electro-mechanical switch die wherein the switching signal has a maximum voltage less than 10 Volts.

15. An optical cross connect comprising:

N optical input ports where N is an integer;

N optical output ports where; and

N times N micro-electro-mechanical system optical switch dice, each of the micro-electro-mechanical system optical switch dice having a drive capable of switching a mirror from a first position to a second position in response to a switching signal provided to the micro-electro-mechanical switch die wherein the optical cross connect switches 2N optical switch dice in less than about 50 mS with an average power consumption of less than about 2N/50 Watts.

16. A method for operating an optical cross connect, the method comprising:

measuring an impedance of a first circuit of a first optical switch in the optical cross connect;

comparing the impedance to a reference value to determine a switch state of the first optical switch;

providing a switch state output; and

comparing the switch state output to an expected switch state.

17. The method of claim 16 further comprising a step, after the comparing the switch state output, if the switch state output is not the expected switch state, of providing a switching signal to the first optical switch.

18. The method of claim 16 further comprising a step, after the comparing the switch state output, if the switch state output is not the expected switch state, of generating an error signal identifying the first optical switch in the optical cross connect.

19. The method of claim 18 further comprising a step of, after the comparing the switch state output, if the switch state output is the expected switch state, measuring a second impedance of a second circuit of a second optical switch in the optical cross connect.

20. A method for operating an optical cross connect having a plurality of optical switches, each of the optical switches having a magnetic drive, the method comprising:

measuring an impedance of a first circuit of a first optical switch in the optical cross connect;

comparing the impedance to a reference value to determine a state of the first optical switch;

providing a switch state output; and

comparing the switch state output to an expected switch state; and

, if the switch state output is not the expected switch state,

providing a switching signal to the first optical switch.

21. A method for operating an optical cross connect having a plurality of optical switches, each of the optical switches having a magnetic drive, the method comprising:

measuring an impedance of a first circuit of a first optical switch in the optical cross connect;

comparing the impedance to a reference value to determine a state of the first optical switch;

providing a switch state output; and

comparing the switch state output to an expected switch state; and

, if the switch state output is not the expected switch state,

providing a switching signal to the first optical switch; and

generating an error signal identifying the first optical switch in the optical cross connect.

22. A method of determining a configuration of an optical cross connect having N optical inputs, M optical outputs, and N×

M optical switching cells where N and M are integers, the method comprising;

measuring an impedance for each of the N×

M optical switching cells;

comparing the measured impedance of each of the N×

M optical switching cells against a reference value; and

generating a switch state signal for each of the N×

M optical switching cells.

23. The method of claim 22 further comprising steps of:

comparing each of the switch state signals against a corresponding expected switch state; and

, if an optical switching cell is not in an expected state,

generating an error signal identifying the optical switching cell that is not in the expected state.

24. A method of operating an optical cross connect, the method comprising:

providing a plurality of electronic control signals to a plurality of micro-electro-mechanical system optical switch dice in the optical cross connect to configure the optical cross connect to a selected configuration;

removing electrical input to the optical cross connect; and

maintaining the selected configuration.