Claims
- 1. A fiber optic control system comprising:
an optical input waveguide for providing an emitted optical beam; a beam direction control element, for controllably directing the optical beam emitted from the input optical waveguide; a plurality of output elements, each for coupling the directed optical beam into an associated output optical waveguide; control inputs, associated with at least one beam direction control element, to effect a change in direction of the optical beam towards a selected one of the output elements; a detector, for determining a level of optical power coupled thereby to the selected output optical waveguide; and a controller, for applying control signals to the control inputs, the controller having a first and second mode, the first mode generating the control signals without feedback from the optical power detector, and the second mode generating control signals that are determined by monitoring a desired detected optical power level and changing the control signals in response thereto.
- 2. A fiber optic control system as in claim 1 wherein the beam direction control element operates on the optical beam as emitted by the input optical waveguide.
- 3. A fiber optic control system as in claim 1 wherein the beam direction control element operates on the optical beam as received by the output elements.
- 4. A fiber optic control system as in claim 1 wherein the beam direction control element moves an optic fiber end relative to an optical lens.
- 5. A fiber optic control system as in claim 1 wherein the input optical waveguide and output optical waveguide are optical fibers.
- 6. A fiber optic control system as in claim 1 wherein a transition occurs from the first mode to the second mode upon detecting a predetermined optical power.
- 7. A fiber optic control system as in claim 1 wherein the first mode uses stored predetermined calibration settings to generate the control signals.
- 8. A fiber optic control system as in claim 1 wherein the control signals generated in the second mode comprise a dither signal.
- 9. A fiber optic control system as in claim 8 wherein the dither signal additionally comprises a pair of orthogonal signals applied to respective pair of control inputs.
- 10. A fiber optic control system as in claim 9 wherein
the beam direction control element operates on the optical beam as emitted by the input optical waveguide as well as wherein the beam direction control element operates on the optical beam as received by the output elements, with the control signals applied to both the input side beam direction control elements and the output side beam direction control elements; and a frequency of the orthogonal modulation signals applied to the input side beam direction control elements is different from a frequency of the orthogonal modulation signals applied to the output side beam direction control elements.
- 11. A fiber optic control system as in claim 8 wherein the dither signal comprises a pair of orthogonal sinusoids.
- 12. A fiber optic control system as in claim 1 wherein the detector includes a capacitive sensor.
- 13. A method for controlling an optical beam from an input optical waveguide to one of multiple output optical waveguides, the method comprising:
controllably directing the optical beam emitted from the input optical waveguide; effecting a change in direction of an optical beam emitted by an input optical waveguide to couple the optical beam with a selected one of multiple output optical waveguides; determining a level of optical power coupled to the selected output optical waveguide; generating control signals to control the change in direction of the optical beam based upon a predetermined level of light being coupled to the selected output optical waveguide; and changing the control signals by monitoring a desired detected optical power level.
- 14. A method as in claim 13 wherein effecting a change in direction includes operating on the optical beam at the input optical waveguide.
- 15. A method as in claim 13 wherein effecting a change in direction includes operating on the optical beam at the selected output optical waveguide.
- 16. A method as in claim 13 wherein effecting a change in direction includes moving an optic fiber end relative to an optical lens.
- 17. A method as in claim 13 wherein the input optical waveguide and output optical waveguide are optical fibers.
- 18. A method as in claim 13 further including the step of:
transitioning from generating the control signals to changing the control signals upon detecting a predetermined optical power.
- 19. A method as in claim 13 wherein the step of generating the control signals additionally comprises:
using stored predetermined calibration settings.
- 20. A method as in claim 13 wherein the step of changing the control signals additionally comprises:
applying a dither signal.
- 21. A method as in claim 20 wherein the dither signal additionally comprises a pair of orthogonal signals.
- 22. A fiber optic control system as in claim 21 wherein the step of effecting a change in direction additionally comprises the steps of:
operating on the optical beam at the input optical waveguide; operating on the optical beam at the selected output optical waveguide; and where in the step of operating on the optical beam at the input optical waveguide comprises applying a first dither signal; wherein the step of operating on the optical beam at the output optical waveguide comprises applying a second dither signal.
- 23. A method as in claim 21 wherein the orthogonal dither signals are a pair of sinusoids.
- 24. A fiber optic control system comprising:
means for effecting a change in direction of an optical beam emitted by an input optical waveguide to couple the optical beam with a selected one of multiple output optical waveguides; means for determining a level of optical power coupled to the selected output optical waveguide; means for generating control signals to control the change in direction of the optical beam based upon a predetermined level of light being coupled to the selected output optical waveguide; and means for changing the control signals by monitoring a desired detected optical power level.
- 25. A fiber optic control system comprising:
a physical plant comprising:
an optical input waveguide for providing an emitted optical beam; a beam direction control element for controllably directing the optical beam emitted from the input optical waveguide; a plurality of output elements, each for coupling the directed optical beam into an associated output optical waveguide; control inputs, associated with the beam direction control element, to effect a change in direction of the optical beam towards a selected one of the output elements; a detector, for determining a level of optical power coupled thereby to the selected output optical waveguide; and a controller, for generating control signals applied to the control inputs, the controller generating control signals that have been compensated for a dynamic response of the physical plant that results from an application of control signals thereto.
- 26. A fiber optic control system as in clam 25 wherein the controller additionally comprises:
a compensator, for compensating for at least one of phase lag, phase lead, or amplitude change in response of the physical plant.
- 27. A fiber optic control system as in claim 26 wherein the compensator additionally comprises:
a filter, for receiving an applied control signal, and having a transfer function that depends upon the expected dynamic response of the physical plant.
- 28. A fiber optic control system as in claim 26 wherein the compensator additionally comprises:
a dither filter, for receiving a dither signal, and having a transfer function that depends upon the expected dynamic response of the physical plant to the dither signal.
- 29. A fiber optic control system as in claim 28 wherein the compensator additionally comprises:
a multiplier, connected for multiplying the filtered dither signal and the detected optical power signal.
- 30. A fiber optic control system as in claim 29 wherein the compensator additionally comprises:
a filter, for filtering the multiplier output.
- 31. A fiber optic control system as in claim 29 wherein the compensator additionally comprises:
an integrator, for integrating the multiplier output, to produce at least one control input.
- 32. A fiber optic control system as in claim 31 wherein the applied control signal is a sum of a mean signal and a dither signal.
- 33. A fiber optic control system as in claim 25 wherein the dither signal additionally comprises a pair of orthogonal signals applied to respective control inputs.
- 34. A fiber optic control system as in claim 33 wherein:
the beam direction control element operates on the optical beam as emitted by the input optical waveguide; the beam direction control element operates on the optical beam as received by the output elements; the control signals are applied to both the input side beam direction control elements and the output side beam direction control elements; and a frequency of the dither signals applied to the input side beam direction control elements is different from a frequency of the dither signals applied to the output side beam direction control elements.
- 35. A fiber optic control system as in claim 34 wherein the compensator additionally comprises:
a set of filters, each for receiving a respective one of four applied control signals, each filter having a transfer function that depends upon the expected dynamic response of the physical plant along a corresponding orthogonal control axis.
- 36. A fiber optic control system as in claim 25 wherein the control inputs are determined from time histories of the optical power level as determined by the sensor.
- 37. A fiber optic control system as in claim 25 wherein the control inputs are determined from time histories of the optical power as determined by a capacitive sensor.
- 38. A fiber optic control system as in claim 25 wherein the central inputs excite dynamic behavior of the physical plant.
- 39. A method for controlling an optical beam from an input optical waveguide to one of multiple output optical waveguides, the method comprising the steps of:
controllably directing the optical beam emitted from the input optical waveguide; effecting a change in direction of the optical beam to couple the optical beam with a selected one of the multiple output optical waveguides; determining a level of optical power coupled to the second one of the output optical waveguides; generating control signals that have been compensated for a dynamic response determined during the step of controllably directing the optical beam; and using the control signals to controllably direct the optical beam.
- 40. A method as in claim 39 wherein the step of controllably directing the optical beam additionally comprises:
compensating for at least one of phase lag, phase lead, or amplitude change in response.
- 41. A method as in claim 40 wherein the step of compensating additionally comprises:
filtering an applied control signal according to a transfer function that depends upon the expected dynamic response associated with the step of controllably directing the optical beam.
- 42. A method as in claim 41 wherein the step of compensating additionally comprises:
multiplying the filtered applied control signal and the detected optical power signal.
- 43. A method as in claim 42 wherein the step of compensating additionally comprises:
filtering the multiplier output.
- 44. A method as in claim 42 wherein the step of compensating additionally comprises:
integrating the multiplier output to produce at least one control signal.
- 45. A method as in claim 41 wherein the applied control signal is a sum of a mean signal and a dither signal.
- 46. A method as in claim 45 wherein the dither signal additionally comprises a pair of orthogonal signals.
- 47. A method as in claim 46 wherein the step of effecting a change in direction of the optical beam additionally comprises:
operating on the optical beam at the input optical waveguide as well as operating on the optical beam at the selected output optical waveguide; operating on the optical beam at the input optical waveguide; applying a first frequency to an associated orthogonal modulation signals; and operating on the optical beam at the output optical waveguide by applying a second frequency to the associated orthogonal modulation signals.
- 48. A method as in claim 47 wherein the step of compensating additionally comprises:
filtering each of a respective one of four applied control signals according to respective transfer functions that depend upon the expected dynamic response in directing the optical beam along a corresponding orthogonal control axis.
- 49. A method as in claim 39 wherein the dynamic changes in the response result from at least one of a phase lead, phase lag, or amplitude change associated with application of a control signal to an actuator used for controllably directing the optical beam and the eventual positioning of the beam.
- 50. A method as in claim 39 further comprising the step of:
determining time histories of control inputs for changing the direction of the optical signal as a function of the determined optical power level.
- 51. A method as in claim 39 wherein a time constant of internal states for changing the direction of the optical beam are similar to the time interval for changes in the command inputs.
- 52. A fiber optic control system comprising:
means for controllably directing the optical beam emitted from the input optical waveguide to a first one of the multiple output optical waveguides; means for effecting a change in direction of the optical beam emitted by the input optical waveguide to couple the optical beam with a second one of the multiple output optical waveguides; means for determining a level of optical power coupled to the second one of the output optical waveguides; means for generating control signals that have been compensated for a dynamic response determined by the means for controllably directing the beam; and means for using the control signals to controllably direct the optical beam.
- 53. A method for controlling optical coupling between ports in an optical switch, the method comprising:
closing a feedback loop using dither control at an initial signal level; dynamically compensating for error in the optical coupling between the initial signal level and a desired signal level; and causing the amplitude of the dithering to change as the error is changed.
- 54. A method as in claim 53 wherein causing the amplitude to change includes causing the amplitude to increase and decrease on a time schedule.
- 55. A method as in claim 53 wherein the step of causing the amplitude to change comprises increasing and decreasing the amplitude of the dithering as a function of the gradient of the optical power with respect to a control input.
- 56. A method as in claim 53 wherein closing the loop includes engaging an optical sensor.
- 57. A method as in claim 53 wherein closing the loop includes detecting an angle of at least one of the ports in the optical switch.
- 58. A method as in claim 57 wherein detecting the angle includes engaging a capacitance sensor.
- 59. A fiber optic control system comprising:
an optical input waveguide for providing an emitted optical beam; a beam direction control element for controllably directing the optical beam emitted from the input optical waveguide; a plurality of output elements, each for coupling the directed optical beam into an associated output optical waveguide; control inputs, associated with the beam direction control element, to effect a change in direction of the optical beam towards a selected one of the output elements; a detector, for determining a level of optical power coupled thereby to the selected output optical waveguide; and a controller, coupled to the detector, to determine an error in output power between an initial output power level and a desired output power level and to generate control signals, which include a dither signal having a selectable amplitude, in a manner causing the amplitude of the dither signal to change.
- 60. A control system as in claim 59 wherein the controller causes the amplitude of the dither signal to increase and decrease on a time schedule.
- 61. A control system as in claim 59 wherein the optical power is modeled as a three-dimensional shape, and wherein the controller causes the amplitude of the dither signal to change as a function of the gradient along the three-dimensional shape.
- 62. A control system as in claim 59 wherein the detector includes an optical sensor.
- 63. A control system as in claim 59 wherein the detector includes a non-contact position sensor to determine an angle of the beam control element.
- 64. A control system as in claim 63 wherein the non-contact position sensor is a capacitance sensor.
- 65. A fiber optic control system comprising:
an optical input waveguide for providing an emitted optical beam; a beam direction control element for controllably directing the optical beam emitted from the input optical waveguide; a plurality of output elements, each for coupling the directed optical beam into an associated output optical waveguide; control inputs, associated with the beam direction control element, to affect a change in direction of the optical beam towards a selected one of the output elements; means for determining a level of optical power coupled thereby to the selected output optical waveguide; and means for determining an error in output power between an initial output power level and a desired output power level and for generating control signals, which include a dither signal having a selectable amplitude, in a manner causing the amplitude of the dither signal to change.
- 66. A fiber optic control system comprising:
an optical input waveguide for providing an emitted optical beam; a beam direction control element for controllably directing the optical beam emitted from the input optical waveguide; a plurality of output elements, each for coupling the directed optical beam into an associated output optical waveguide; control inputs, associated with the beam direction control element, to affect a change in direction of the optical beam towards a selected one of the output elements; a detector, for determining a level of optical power coupled thereby to the selected output optical waveguide; and a controller coupled to the detector, to generate control signals that include a dither signal having a selectable amplitude applied to the control inputs, the controller selecting the amplitude of the dither signals to provide a variable level of attenuation of optical power between the input optical waveguide and the selected output optical waveguide.
- 67. A fiber optic control system as in claim 66 wherein the controller selects the amplitude of the dither signal according to a function describing coupled optical power between the input optical waveguide and the selected output optical waveguide.
- 68. A fiber optic control system as in claim 67 wherein the controller selects the amplitude and/or phase of the dither signals to produce a constant optical power level at the selected output optical waveguide.
- 69. A fiber optic control system as in claim 66 wherein the amplitude of the dither signal is proportionally related to the attenuation level of optical power at the output optical waveguide.
- 70. A fiber optic control system as in claim 66 used in an optical switch having multiple input optical waveguides, output optical waveguides, and associated controllers, wherein a given controller selects the amplitude of the dither signal to attenuate the optical power at the selected output optical waveguide to equalize the optical power with the optical power on other output optical waveguides.
- 71. A method for controlling optical coupling between ports in an optical switch, the method comprising:
dynamically compensating for error in the optical coupling using a feedback loop employing amplitude selectable dither control; and selecting the amplitude of the dithering to variably attenuate the optical coupling.
- 72. A method as in claim 71 wherein selecting the amplitude of the dithering is done according to a function describing coupled optical power.
- 73. A method as in claim 71 wherein selecting the amplitude of the dithering includes setting the amplitude to a constant level to produce a constant coupled optical power level.
- 74. A method as in claim 71 wherein the amplitude of the dithering is proportionally related to the attenuation level of the optical coupling.
- 75. A method as in claim 71 used in an optical switch having multiple input optical waveguides and output optical waveguides, and associated methods for controlling the optical coupling between them, wherein selecting the amplitude of the dithering to attenuate the optical power includes equalizing the optical coupling to balance an associated output optical power on a respective output optical waveguide with the optical power on other output optical waveguides.
- 76. An apparatus for controlling optical coupling between ports in an optical switch, the apparatus comprising:
means for dynamically compensating for error in the optical coupling using a feedback loop employing amplitude selectable dither control; and means for selecting the amplitude of the dithering to variably attenuate the optical coupling.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No. 60/326,775 entitled “Method and Apparatus for Switching or Attenuating Optical Signals”, filed Mar. 18, 2002, and U.S. Provisional Application No. 60/326,780 entitled “Method and Apparatus for Positioning Optical Elements”, also filed Mar. 18, 2002. The entire teachings of these applications, each of which are assigned to Continuum Photonics, Inc., are hereby incorporated herein by reference.