Control system for an optical fiber switch

• US 6,925,221 B2
• Filed: 05/07/2004
• Issued: 08/02/2005
• Est. Priority Date: 10/24/2001
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Maitan, Jacek
• Primary Examiner(s): KIANNI, KAVEH C
• Application Number:
  US10/842,033
• Publication Number:
  US 20040208425A1
• Time in Patent Office: 452 Days
• Field of Search: 385/17, 385/16, 385/18, 385/25, 385/27, 385/31, 385/40, 385/52, 372/70, 372/20
• 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 6/359 of the position of the moving element itself during switching, i.e. without monitoring the switched beams
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]
• CPC Class Codes: H04Q 2011/0039 Electrical control
• CPC Class Codes: H04Q 2011/0083 Testing; Monitoring

Abstract

An optical switching fabric enables an optical signal entering the device on any one of multiple input ports to be directed to any one of multiple output ports. Light entering the switching fabric on an input port is reflected by individual mirrors on one or more mirror arrays to an output port. Methods of controlling optical switching fabrics compensate for distortions due to mechanical and environmental changes without the need to measure losses along all optical paths linking input ports and output ports. Reference input ports are interspersed among signal input ports and reference output ports are interspersed among signal output ports. Periodically, the positions of mirrors which maximize the intensity of light deflected from reference input ports and reference output ports, are measured. The measured positions are used to predict mirror positions to maximize the intensity of light deflected from signal input ports to signal output ports.

Claims

1. An optical switch comprising:

a first plurality of ports comprising signal input ports and reference input ports;

a second plurality of ports comprising signal output ports and reference output ports;

a first plurality of mirrors disposed on a first surface;

a second plurality of mirrors disposed on a second surface;

wherein each one of the first plurality of mirrors is individually controllable to direct light incident from a corresponding one of the first plurality of ports to any one of the second plurality of mirrors, and

wherein each one of the second plurality of mirrors is individually controllable to direct to a corresponding one of the second plurality of ports, light incident from any one of the first plurality of mirrors;

a reference light source coupled to provide reference light to the reference input ports;

a reference detector coupled to the reference output ports;

wherein measured changes in optimal positions of mirrors in the first plurality of mirrors and of mirrors in the second plurality of mirrors for directing reference light from reference input ports to reference output ports can be used to determine changes in optimal positions of mirrors in the first plurality of mirrors and of mirrors in the second plurality of mirrors for directing signal light from signal input ports to signal output ports; and

a look-up table associated with the first plurality of mirrors, the look-up table including data describing an optimal position of each mirror of the first plurality of mirrors to connect signal light between any signal input port and any signal output port.

2. The optical switch of claim 1 wherein the first plurality of ports comprise a two-dimensional array and wherein the reference input ports are interspersed among the signal input ports in two dimensions, and wherein the second plurality of ports comprise a two-dimensional array and wherein the reference output ports are interspersed among the signal output ports in two dimensions.

3. The optical switch of claim 1 further comprising:

a first control light source located to illuminate the first plurality of mirrors with control light;

a first position sensing detector located to detect control light that has been reflected by the first plurality of mirrors, wherein signals provided by the first position sensing detector correspond to the positions of the first plurality of mirrors;

a second control light source located to illuminate the second plurality of mirrors with control light; and

a second position sensing detector located to detect control light that has been reflected by the second plurality of mirrors, wherein signals provided by the second position sensing detector correspond to the positions of the second plurality of mirrors.

4. The optical switch of claim 3, further comprising:

a third position sensing detector located to detect control light from the first control light source that has been reflected by the first plurality of mirrors and the second plurality of mirrors.

5. The optical switch of claim 1, further comprising:

a first infrared sensor optically coupled to the first plurality of ports to monitor intensity of signal light at the signal input ports; and

a second infrared sensor optically coupled to the second plurality of ports to monitor intensity of signal light at the signal output ports.

6. The optical switch of claim 1, further comprising a second look-up table associated with the second plurality of mirrors, the second look-up table including data describing an optimal position of each mirror of the second plurality of mirrors to connect signal light between any signal input port and any signal output port.

7. The optical switch of claim 1, further comprising a dichroic flat beamsplitter to reflect signal light and reference light between the first plurality of mirrors and the second plurality of mirrors.

8. An optical switch, comprising:

a first plurality of ports comprising signal input ports and reference input ports;

a second plurality of ports comprising signal output ports and reference output ports;

a first plurality of mirrors disposed on a first surface;

a second plurality of mirrors disposed on a second surface;

wherein each one of the first plurality of mirrors is individually controllable to direct light incident from a corresponding one of the first plurality of ports to any one of the second plurality of mirrors, and

wherein each one of the second plurality of mirrors is individually controllable to direct to a corresponding one of the second plurality of ports, light incident from any one of the first plurality of mirrors;

a reference light source coupled to provide reference light to the reference input ports;

a reference detector coupled to the reference output ports;

wherein measured changes in optimal positions of mirrors in the first plurality of mirrors and of mirrors in the second plurality of mirrors for directing reference light from reference input ports to reference output ports can be used to determine changes in optimal positions of mirrors in the first plurality of mirrors and of mirrors in the second plurality of mirrors for directing signal light from signal input ports to signal output ports; and

a dichroic flat beamsplitter to reflect signal light and reference light between the first plurality of mirrors and the second plurality of mirrors.

9. The optical switch of claim 8, wherein the first plurality of ports comprise a two-dimensional array and wherein the reference input ports are interspersed among the signal input ports in two dimensions, and wherein the second plurality of ports comprise a two-dimensional array and wherein the reference output ports are interspersed among the signal output ports in two dimensions.

10. The optical switch of claim 8, further comprising:

a first control light source located to illuminate the first plurality of mirrors with control light;

a first position sensing detector located to detect control light that has been reflected by the first plurality of mirrors, wherein signals provided by the first position sensing detector correspond to the positions of the first plurality of mirrors;

a second control light source located to illuminate the second plurality of mirrors with control light; and

a second position sensing detector located to detect control light that has been reflected by the second plurality of mirrors, wherein signals provided by the second position sensing detector correspond to the positions of the second plurality of mirrors.

11. The optical switch of claim 10, further comprising:

a third position sensing detector located to detect control light from the first control light source that has been reflected by the first plurality of mirrors and the second plurality of mirrors.

12. The optical switch of claim 8, further comprising:

a first infrared sensor optically coupled to the first plurality of ports to monitor intensity of signal light at the signal input ports; and

a second infrared sensor optically coupled to the second plurality of ports to monitor intensity of signal light at the signal output ports.

13. The optical switch of claim 8, further comprising:

a look-up table associated with the first plurality of mirrors, the look-up table including data describing an optimal position of each minor of the first plurality of mirrors to connect signal light between any signal input port and any signal output port.