Multiple element controlled optical coupling

• US 6,850,661 B2
• Filed: 08/16/2002
• Issued: 02/01/2005
• Est. Priority Date: 03/11/2002
• Status: Expired due to Fees

• Current Assignee: Microsemi Communications, Inc. (Microchip Technology Incorporated)
• Original Assignee: Vitesse Semiconductor Sales Corp. (Microchip Technology Incorporated)
• Inventors: Singh, Daljeet
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US10/222,341
• Publication Number:
  US 20030170023A1
• Time in Patent Office: 900 Days
• Field of Search: 385/17, 385/25, 385/75, 385/101, 385/18, 385/33, 385/20, 385/21, 356/138, 356/141.3, 356/141.1, 356/141.4, 356/139.5, 356/149
• US Class Current: 385/17
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0024 using space switching
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]
• CPC Class Codes: H04Q 2011/0043 Fault tolerance
• CPC Class Codes: H04Q 2011/0049 Crosstalk reduction; Noise; Power budget

Abstract

An optical cross connect with simultaneous correction of multiple mirror angles to achieve desired output power. In one embodiment beam offset and pointing angle are changed and output power is measured to determine changes to mirror angles.

Claims

1. A process of coupling inputs and outputs in an optical cross connect, a particular input and a particular output being coupled by a first mirror moveable in azimuth and elevation and a second mirror moveable in azimuth and elevation, the process comprising:

selecting a desired output beam power;

traversing a number of points by a beam provided by the particular input by changing the azimuth and elevation of the first and second mirrors;

measuring output power provided to the particular output;

comparing the measured output power to the desired output power; and

adjusting changes in the azimuth and elevation of the first and second mirrors based on the measured output power.

2. The process in claim 1 wherein traversing a number of points by a beam location comprises moving the beam in a circular path on the surface of output optics associated with the particular output while varying the pointing angle of the beam on the surface of the output optics.

3. The process of claim 2 wherein moving the beam in a circular path comprises moving the beam over a discrete set of points, each point being positioned on the circular path.

4. The process of claim 3 wherein the location of the points on the circular path in the azimuth dimension are defined by ${\mathrm{OF}}_{\mathrm{AZ}}=R_{\mathrm{OF}}·$

cos⁡

(h·

N8·

2·

π

)

and where the location of the points on the circular path in the elevation dimension are defined by ${\mathrm{OF}}_{\mathrm{EL}}=R_{\mathrm{OF}}·<br><br>\sin <br><br>\left(\frac{h·<br><br>N}{8}·<br><br>2·<br><br>\mathrm{\pi <br><br>}\right)$

for chosen integer or non-integer values of N and integer value of h greater than 1.

5. The process of claim 2 wherein the pointing angle varies over a chosen range of angles at a frequency that is orthogonal to the frequency at which the beam is traced in a circle on the surface of the output optics.

6. The process of claim 2 wherein the pointing angle varies over a chosen range of angles at a frequency that is a harmonic of the frequency at which the beam is traced in a circle on the surface of the output optics.

7. The process of claim 6 wherein the azimuth component of the pointing angle varies according to ${\mathrm{AN}}_{\mathrm{AZ}}=R_{\mathrm{AN}}·$

cos⁡

(N8·

2·

π

)

and the elevation component of the pointing angle varies according to ${\mathrm{AN}}_{\mathrm{EL}}=R_{\mathrm{AN}}·<br><br>\sin <br><br>\left(\frac{N}{8}·<br><br>2·<br><br>\mathrm{\pi <br><br>}\right)$

for chosen integer or non-integer values of N.

8. The process of claim 1 wherein altering the beam location comprises moving the beam over a circular path a predetermined number of times, the circular path being defined by a discrete set of points.

9. The process of claim 8 wherein measuring the output power comprises summing the output power provided by the beam at each point on the circular path for the predetermined number of times the beam traverses the circular path to determine the total power delivered by the beam.

10. The process of claim 1 wherein the beam location is altered if the measured power is not within a specified range of the desired output power.

11. The process of claim 2 wherein the beam location is altered by reducing the radius of the circular path that the beam traverses on the surface of the output optics.

12. The process of claim 1 wherein the process of comparing the measured output power to the desired output power comprises calculating error values indicative of the difference between the measured output power and the desired output power.

13. The process of claim 12 wherein the error values are calculated after the beam has traversed a circle on the surface of the output optics a predetermined number of times.

14. The process of claim 12 wherein the error value in the pointing angle in the azimuth direction is calculated according to:

${\mathrm{ER}}_{{\mathrm{AN}}_{\mathrm{AZ}}}=\frac{P_{{\mathrm{AN}}_{\mathrm{AZ}}}}{p_{\mathrm{TOTAL}}}·<br><br>\frac{{\mathrm{ANO}}^2}{R_{\mathrm{AN}}};<br><br>$

where the error value in the pointing angle in the elevation direction is calculated according to;

${\mathrm{ER}}_{{\mathrm{AN}}_{\mathrm{EL}}}=\frac{P_{{\mathrm{AN}}_{\mathrm{EL}}}}{p_{\mathrm{TOTAL}}}·<br><br>\frac{{\mathrm{ANO}}^2}{R_{\mathrm{AN}}};<br><br>$

where the error value in the offset distance in the azimuth direction is calculated according to;

${\mathrm{ER}}_{{\mathrm{OF}}_{\mathrm{AZ}}}=\frac{P_{{\mathrm{OF}}_{\mathrm{AZ}}}}{P_{\mathrm{TOTAL}}}·<br><br>\frac{{\mathrm{OFO}}^2}{R_{\mathrm{OF}}};<br><br>$

and where the error value in the offset distance in the elevation direction is calculated according to;

${\mathrm{ER}}_{{\mathrm{OF}}_{\mathrm{EL}}}=\frac{P_{{\mathrm{OF}}_{\mathrm{EZ}}}}{P_{\mathrm{TOTAL}}}·<br><br>\frac{{\mathrm{OFO}}^2}{R_{\mathrm{OF}}}$

15. The process of claim 14 wherein for targeted output power level searches, P_Total is calculated by using P_Target−

Px if the monitored power is greater than the target power.

16. The process of claim 14 wherein altering the beam location comprises moving the beam in such a way as to compensate for a portion of the calculated error values.

17. A device for selectively coupling light between an input and an output, the device comprising:

a plurality of inputs and outputs, the inputs and outputs adapted to receive and transmit light, respectively;

a plurality of moveable mirrors, the moveable mirrors moveable in an azimuth direction and an elevation direction;

a power monitor, the power monitor measuring the intensity of a beam at at least one of the outputs; and

a controller, the controller receiving data from the power monitor, and adjusting the positions of the moveable mirrors in response to intensity data received from the power monitor.

18. The device of claim 17 wherein the controller is a digital signal processor based controller.

19. The device of claim 17 wherein the power monitor is a photo receiver.

20. The device of claim 17 wherein the power monitor is a wavelength locker.

21. The device of claim 17 wherein a moveable input mirror receives light from an input port, and directs the light to a moveable output mirror.

22. The device of claim 21 wherein the moveable output mirror directs the light to an output port.

23. The device of claim 21 wherein the input port includes input optics.

24. The device of claim 22 wherein the output port includes output optics.

25. The device of claim 23 wherein the input optics includes a collimating lens.

26. The device of claim 24 wherein the output optics includes a collimating lens.

27. The device of claim 21 wherein the input port receives light from a fiber.

28. The device of claim 22 wherein the output port provides light to a fiber.

29. The device of claim 17 wherein the plurality of moveable mirrors are micro electro mechanical mirrors.

30. The device of claim 17 wherein at least some of the plurality of moveable mirrors are discrete mirror assemblies.