Feedback stabilization of a loss optimized switch

• US 6,728,433 B1
• Filed: 05/24/2002
• Issued: 04/27/2004
• Est. Priority Date: 04/13/2000
• Status: Expired due to Term

• Current Assignee: Calient Networks Incorporated
• Original Assignee: Calient Networks Incorporated
• Inventors: Bowers, John Edward, Helkey, Roger Jonathon
• Primary Examiner(s): ULLAH, AKM E
• Application Number:
  US10/155,047
• Time in Patent Office: 704 Days
• Field of Search: 385/16-18, 385/20-24, 385/30-33, 385/39, 385/52, 385/1, 385/26, 385/42, 385/48, 385/127, 250/227.14, 250/227.19, 250/227.24, 398/143-147
• US Class Current: 385/16
• 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 6/3588 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: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams
• CPC Class Codes: G02B 6/422 Active alignment, i.e. moving the elements in response to the detected degree of coupling or position of the elements G02B6/4233, G02B6/4234 take precedence
• CPC Class Codes: G02B 6/4225 by a direct measurement of the degree of coupling, e.g. the amount of light power coupled to the fibre or the opto-electronic element

Abstract

A system is provided to obtain loss optimized output optical power by way of feedback control and stabilization in an optical signal switching or routing system. The optical signal switching or routing system includes at least two input optical fibers and at least two output optical fibers, a controllable mechanism for directing an optical beam from one of the input optical fibers to one of the output optical fibers, and a mechanism for measuring the optical power applied to output optical fiber. The measuring mechanism provides a measure of the output optical power through a signal processing apparatus to a control apparatus. Possible other inputs to the signal processing apparatus include the input optical power, test optical power, etc. The inputs to the signal processing apparatus are compared and the signal processing apparatus outputs a signal to the control apparatus to provide optimized output power.

Claims

1. A method of optimizing the output power of an optical system of the type in which an input light beam is steered by a controllable beam steering apparatus, comprising:

determining the output optical power of the optical system;

performing a comparison of the output optical power to a reference optical power; and

controlling the beam steering apparatus as a function of the comparison to optimize the output optical power, wherein the beam steering apparatus is comprises an array of independently moveable mirrors, each mirror of the array being moved by a control apparatus applying a control level to one or more electrodes associated with the mirror under control of a controller, further wherein controlling the beam steering apparatus comprises producing a control signal and providing said control signal to the control apparatus, the control apparatus causing the control level to be applied to the one or more electrodes in response to the control signal.

2. A method of optimizing a fiber-coupled output power of an optical switch comprising:

inputting a plurality of input optical signals from a plurality of input optical fibers;

collimating the plurality of input optical signals to form a plurality of free-space input optical beams;

using a controllable beam steering apparatus to steer the plurality of free-space input optical beams to form a plurality of free-space output optical beams;

coupling the plurality of free-space output optical beams into a plurality of output optical fibers to form a plurality of output optical signals;

measuring the optical power of the output optical signals; and

controlling the beam steering apparatus as a function of the measured optical power of the output optical signals.

3. The method of claim 2, where measuring the optical power of the output optical signals includes performing a comparison of the output powers of the plurality of optical signals to a plurality of reference optical powers.

4. The method of claim 2, wherein measuring the optical power of the output optical signals includes performing a comparison of the power of the plurality of output optical signals to the power of the plurality of input optical signals.

5. The method of claim 4, wherein performing a comparison includes taking a ratio of the power of an output optical signal to the power of input optical signal, and wherein controlling the beam steering apparatus includes maximizing the ratio of output signal optical power to input signal optical power.

6. The method of claim 2, wherein the beam steering apparatus comprises an array of independently moveable mirrors, each mirror of the array being moved by a control apparatus applying a control level to one or more electrodes associated with the mirror under control of a controller, further wherein controlling the beam steering apparatus comprises producing a control signal and proving said control signal to the control apparatus, the control apparatus causing the control level to be applied to one or more electrodes in response to the control signal.

7. A method of optimizing a fiber-coupled output power of an optical switch comprising:

inputting at least a first and second input optical signal;

converting the input optical signals to free-space optical beams, using mirrors that rotate in two axes to steer the input optical beams to output mirrors that rotate in two axes forming output optical beams;

steering the output optical beams with the output mirrors, coupling the optical beams into output optical fibers to form at least a first and second output optical signal;

measuring the optical power of the output optical signals; and

controlling angles of the input mirrors and output mirrors to optimize the measured optical power of the output optical signals.

8. The method of claim 7, where the input mirrors are part of an input mirror array, and the output mirrors are part of an output mirror array.

9. The method of claim 7, where the input mirrors and output mirrors are part of a single mirror array.

10. The method of claim 7, where optimizing the measured optical power of the output optical signals comprises measuring the power of the input optical signals, taking the ratio of the output optical powers to the respective input optical powers, and maximizing the ratios of output optical power to input optical power.

11. A method of optimizing a fiber-coupled output power of an output switch comprising:

inputting at least a first and second input optical signal;

converting the input optical signals to free-space optical beams;

using mirrors that rotate in two axes to steer the input optical beams to output mirrors that rotate in two axes forming output optical beams;

steering the output optical beams with the output mirrors;

coupling the optical beams into output optical fibers to form at least a first and second output optical signal;

measuring the optical power of the output optical signals;

receiving the output optical power measurements with a signal processing apparatus;

controlling of the input mirrors and output mirrors with the signal processing apparatus; and

optimizing angles of the input mirrors and output mirrors with the signal processing apparatus to optimize the measured optical power of the output optical signals.

12. The method of claim 11, where the signal processing apparatus also receives the input optical power measurements.

13. The method of claim 12, wherein optimizing the measured optical power of the output optical signals includes taking a ratio of the power of an output optical signal to the power of input optical signal, and optimizing the angles of the input and output mirrors includes maximizing this ratio of output signal optical power to input signal optical power.

15. The method of claim 11, where the signal processing apparatus also receives the input optical power measurements, after these levels are converted to digital values.

16. The method of claim 12, wherein optimizing the measured optical power of the output optical signals includes taking a ratio of the power of an output optical signal to the power of input optical signal, and optimizing the angles of the input and output mirrors includes maximizing this ratio of output signal optical power to input signal optical power.

17. The method of claim 12, wherein generating the control signals for the input mirrors and output mirrors is performed by a microprocessor.

14. A method of optimizing fiber-coupled output power of an optical switch comprising:

inputting at least a first and second input optical signal;

converting the input optical signals to free-space optical beams;

using mirrors that rotate in two axes to steer the input optical beams to output mirrors that rotate in two axes forming output optical beams;

steering the output optical beams with the output mirrors;

coupling the optical beams into output optical fibers to form at least a first and second output optical signal;

measuring the optical power of the output optical signals;

converting the measurement of optical power to digital values;

receiving the output optical power measurements with a signal processing apparatus;

generating control signals for the input mirrors and output mirrors;

converting the control signals to analog control levels;

controlling the input mirrors and output mirrors with the analog control levels; and

optimizing the angles of the input mirrors and output mirrors with the analog control levels to optimize the measured optical power of the output optical signals.