OPTICAL SWITCH FABRIC WITH BIAS CONTROL

• US 20200137467A1
• Filed: 06/08/2018
• Published: 04/30/2020
• Est. Priority Date: 01/28/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dupuis, Nicolas, Kuchta, Daniel M., Lee, Benjamin G., Rylyakov, Alexander, Schow, Clint L.
• Granted Patent: US 10,687,126 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04Q 11/0001 using optical switching
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0039 Electrical control
• CPC Class Codes: H04Q 2011/0049 Crosstalk reduction; Noise; Power budget
• CPC Class Codes: H04Q 2011/0058 Crossbar; Matrix

Abstract

Methods and systems for bias control in an optical switch fabric include monitoring optical power at outputs of a plurality of switch elements in an N×N switch fabric that has N inputs, N outputs, and M≥2 stages, each switch element having a respective unique radio frequency tone. A bias control of each of the plurality of switch elements is adjusted. It is determined whether the optical power at the outputs of each respective switch element after bias control adjustment conform more closely to a predetermined criterion relative to the monitored optical power at the outputs of the respective switch element prior to adjustment.

Claims

1. A method for bias control in an optical switch fabric, comprising:

monitoring optical power at outputs of a plurality of switch elements in an N×

N switch fabric that has N inputs, N outputs, and M≥

2 stages, each switch element having a respective unique radio frequency tone;

adjusting a bias control of each of the plurality of switch elements; and

determining, using a processor, whether the optical power at the outputs of each respective switch element after bias control adjustment conform more closely to a predetermined criterion relative to the monitored optical power at the outputs of the respective switch element prior to adjustment.

2. The method of claim 1, wherein each switch element comprises a Mach-Zehnder interferometer.

3. The method of claim 2, wherein determining the optical power at an output of a switch element comprises tapping one or more outputs of the Mach-Zehnder interferometer and measuring the tapped one or more outputs using a photodetector.

4. The method of claim 1, wherein monitoring the optical power at the outputs comprises tone demultiplexing N multi-tone outputs.

5. The method of claim 1, further comprising repeating said adjusting and determining until the monitored optical power at the outputs of each switch element converge on an optimal value according to the predetermined criterion.

6. The method of claim 1, wherein monitoring the optical power at the outputs of a plurality of switch elements comprises monitoring individual optical power at the outputs of every switch element in the switch fabric.

7. The method of claim 1, wherein monitoring optical power at the outputs of a plurality of switch elements comprises monitoring aggregate optical power from only those switch elements in a final stage of the switch fabric.

8. A non-transitory computer readable storage medium comprising a computer readable program for bias control in an optical switch fabric, wherein the computer readable program when executed on a computer causes the computer to perform the steps of:

monitoring optical power at outputs of a plurality of switch elements in an N×

N switch fabric that has N inputs, N outputs, and M≥

2 stages, each switch element having a respective unique radio frequency tone;

adjusting a bias control of each of the plurality of switch elements; and

determining, using a processor, whether the optical power at the outputs of each respective switch element after bias control adjustment conform more closely to a predetermined criterion relative to the monitored optical power at the outputs of the respective switch element prior to adjustment.

9. An optical switch fabric, comprising:

a plurality of switch elements, wherein each switch element comprises a bias control configured to adjust a bias of the respective switch element and has a respective unique radio frequency tone;

a plurality of photodetectors configured to measure optical power at outputs of the plurality of switch elements;

a processor configured to trigger adjustment by the respective bias controls and to determine, for each respective switch element, whether the optical power at the output of each switch element conforms more closely to a predetermined criterion than does the optical power at the output of the respective switch element after an adjustment of the respective switch element.

10. The optical switch fabric of claim 9, wherein each switch element comprises a Mach-Zehnder interferometer.

11. The optical switch fabric of claim 10, wherein the photodetectors are configured to tap and measure one or more outputs of the plurality of the Mach-Zehnder interferometers.

12. The optical switch fabric of claim 9, wherein the processor is further configured to demultiplex multi-tone outputs to determine an optical power at an output of each switch element.

13. The optical switch fabric of claim 9, wherein the processor is further configured to repeat said adjustment and determination until the monitored optical power at the outputs of the each switch element converge on an optimal value according to the predetermined criterion.

14. The optical switch fabric of claim 9, wherein the plurality of photodetectors are configured to monitor individual optical power at the outputs of every switch element in the switch fabric.

15. The optical switch fabric of claim 9, wherein the plurality of photodetectors are configured to monitor aggregate optical power outputs from only those switch elements in a final stage of the switch fabric.