US4960319A — Active polarization control servo and method

Claim 1

Independent Claim 180 words

A system for controlling the polarization of light guided by an optical waveguide, comprising: means for controlling the birefringence of the optical waveguide comprising a first transducer and a second transducer arranged to act on the optical waveguide along parallel axes and a third transducer being on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; means for applying a first control signal to each of the first and second transducers; means for applying a second control signal to the third transducer, the first and second control signals being in time quadrature; means for forming and electrical signal indicative of the intensity of light guided by the optical waveguide; means for processing the electrical signal to form an error signal indicative of differences between the polarization state of light guided by the optical waveguide and a predetermined desired polarization state; and means for combining the error signal with the first and second control signals to minimize the different between the polarization state of light guided by the optical waveguide and the desired polarization state.

Claim 2

Independent Claim 180 words

A system for controlling the polarization of light guided by an optical waveguide, comprising: means for controlling the birefringence of the optical waveguide comprising a first transducer and a second transducer arranged to act on the optical waveguide along parallel axes and a third transducer being on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; means for applying a first control signal to each of the first and second transducers; means for applying a second control signal to the third transducer, the first and second control signals being in time quadrature; means for forming and electrical signal indicative of the intensity of light guided by the optical waveguide; means for processing the electrical signal to form an error signal indicative of differences between the polarization state of light guided by the optical waveguide and a predetermined desired polarization state; and means for combining the error signal with the first and second control signals to minimize the different between the polarization state of light guided by the optical waveguide and the desired polarization state.

Claim 3

Dependent Claim 29 words

The system of claim 1 wherein each of the transducers comprises a piezoelectric fiber squeezer that adjusts the birefringence of the optical waveguide by means of the photoelastic effect.

Claim 4

Dependent Claim 19 words

The system of claim 1, further comprising a polarizer arranged to provide a reference polarization in the optical waveguide.

Claim 5

Dependent Claim 55 words

The system of claim 1, further comprising: a first oscillator for producing the first control signal; first means for amplifying the first control signal; a second oscillator for producing the second control signal; second means for amplifying the second control signal; and means for providing independent gain control for the first and second amplifying means.

Claim 6

Dependent Claim 36 words

The system of claim 1, further comprising a dual channel phase sensitive detector responsive to both in-phase and quadrature signals for demodulating the electrical signal indicative of the intensity of light guided by the optical waveguide.

Claim 7

Dependent Claim 67 words

A fiber optic rotation sensor, comprising: a length of optical fiber formed to include a sensing loop; means for introducing counterpropagating optical waves into the sensing loop; means for processing the counterpropagating optical waves to produce a signal indicative of rotation of the sensing loop; and means for processing the signal indicative of rotation of the sensing loop to control the polarization of the counterpropagating light waves.

Claim 8

Dependent Claim 67 words

A fiber optic rotation sensor, comprising: a length of optical fiber formed to include a sensing loop; means for introducing counterpropagating optical waves into the sensing loop; means for processing the counterpropagating optical waves to produce a signal indicative of rotation of the sensing loop; and means for processing the signal indicative of rotation of the sensing loop to control the polarization of the counterpropagating light waves.

Claim 9

Dependent Claim 148 words

The fiber optic rotation sensor of claim 6, further comprising: means for controlling the birefringence of the sensing loop comprising a first transducer and a second transducer arranged to act on the optical fiber along parallel axes and a third transducer being on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; means for applying a first control signal to each of the first and second transducers; means for applying a second control signal to the third transducer, the first and second control signals being in time quadrature; means for processing the signal indicative of rotation of the sensing loop to form an error signal indicative of differences between the polarization states of the counterpropagating waves; and means for combining the error signal with the first and second control signals to minimize the differences between the polarization states of the counterpropagating waves.

Claim 10

Dependent Claim 23 words

The system of claim 7 wherein each of the transducers comprises a piezoelectric fiber squeezer that adjusts the birefringence of the optical fiber.

Claim 11

Dependent Claim 20 words

The system of claim 7, further comprising a polarizer arranged to provide a reference polarization for the counterpropagating optical waves.

Claim 12

Dependent Claim 55 words

The system of claim 7, further comprising: a first oscillator for producing the first control signal; first means for amplifying the first control signal; a second oscillator for producing the second control signal; second means for amplifying the second control signal; and means for providing independent gain control for the first and second amplifying means.

Claim 13

Dependent Claim 44 words

The system of claim 7, further comprising a dual channel phase sensitive detector responsive to both in-phase and quadrature signals for demodulating the electrical signal indicative of the intensity of light guided by the means for introducing counterpropagating optical waves into the sensing loop.

Claim 14

Dependent Claim 22 words

The system of claim 7, further comprising a source polarization controller for controlling the polarization of light input to the sensing loop.

Claim 15

Dependent Claim 80 words

A coherent optical communications system, comprising: means for producing a first optical signal that includes an optical carrier signal with a data signal superimposed thereon; means for producing a second optical signal for demodulating the data signal; means for optically mixing the first and second optical signals; and means for processing the mixed optical signals to control the polarization of the second optical signal so that the first and second optical signals have the same polarization when they are mixed.

Claim 16

Dependent Claim 80 words

A coherent optical communications system, comprising: means for producing a first optical signal that includes an optical carrier signal with a data signal superimposed thereon; means for producing a second optical signal for demodulating the data signal; means for optically mixing the first and second optical signals; and means for processing the mixed optical signals to control the polarization of the second optical signal so that the first and second optical signals have the same polarization when they are mixed.

Claim 17

Dependent Claim 89 words

The coherent optical communications system of claim 13, further comprising: a first optical waveguiding means for guiding the first optical signal; a second optical waveguiding means for guiding the second optical signal; optical coupler means for combining the first and second optical signals; detector means for producing an electrical signal indicative of the intensity of the combined optical signals; and means for processing the electrical signal to produce an error signal indicative of differences between the polarization state of light guided by the first and second optical waveguiding means.

Claim 18

Independent Claim 174 words

A method for controlling the polarization of light guided by an optical waveguide, comprising the steps of: controlling the birefringence of the optical waveguide by the steps of arranging a first transducer and a second transducer to act on the optical waveguide along parallel axes and placing a third transducer on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; applying a first control signal to each of the first and second transducers; applying a second control signal to the third transducer, the first and second control signals being in time quadrature; forming an electrical signal indicative of the intensity of light guided by the optical waveguide; processing the electrical signal to form an error signal indicative of differences between the polarization state of light guided by the optical waveguide and a predetermined desired polarization state; and combining the error signal with the first and second control signals to minimize the difference between the polarization state of light guided by the optical waveguide and the desired polarization state.

Claim 19

Independent Claim 174 words

A method for controlling the polarization of light guided by an optical waveguide, comprising the steps of: controlling the birefringence of the optical waveguide by the steps of arranging a first transducer and a second transducer to act on the optical waveguide along parallel axes and placing a third transducer on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; applying a first control signal to each of the first and second transducers; applying a second control signal to the third transducer, the first and second control signals being in time quadrature; forming an electrical signal indicative of the intensity of light guided by the optical waveguide; processing the electrical signal to form an error signal indicative of differences between the polarization state of light guided by the optical waveguide and a predetermined desired polarization state; and combining the error signal with the first and second control signals to minimize the difference between the polarization state of light guided by the optical waveguide and the desired polarization state.

Claim 20

Dependent Claim 34 words

The method of claim 15 including the step of forming each of the transducers to comprise a piezoelectric fiber squeezer that adjusts the birefringence of the optical waveguide by means of the photoelastic effect.

Claim 21

Dependent Claim 18 words

The method of claim 15, further comprising the step of providing a reference polarization in the optical waveguide.

Claim 22

Dependent Claim 50 words

The method of claim 15, further comprising the steps of: producing the first control signal with a first oscillator; amplifying the first control signal; producing the second control signal with a first oscillator; amplifying the second control signal; and providing independent gain control for the first and second amplifying means.

Claim 23

Dependent Claim 40 words

The method of claim 15, further comprising the step of detecting the in-phase and quadrature signals with a dual channel phase sensitive detector responsive for demodulating the electrical signal indicative of the intensity of light guided by the optical waveguide.

Claim 24

Independent Claim 66 words

A method for forming a rotation sensor, comprising the steps of: forming a length of optical fiber to include a sensing loop; introducing counterpropagating optical waves into the sensing loop; processing the counterpropagating optical waves to produce a signal indicative of rotation of the sensing loop; and processing the signal indicative of rotation of the sensing loop to control the polarization of the counterpropagating light waves.

Claim 25

Independent Claim 66 words

A method for forming a rotation sensor, comprising the steps of: forming a length of optical fiber to include a sensing loop; introducing counterpropagating optical waves into the sensing loop; processing the counterpropagating optical waves to produce a signal indicative of rotation of the sensing loop; and processing the signal indicative of rotation of the sensing loop to control the polarization of the counterpropagating light waves.

Claim 26

Dependent Claim 141 words

The method of claim 20, further comprising the steps of: controlling the birefringence of the sensing loop comprising a first transducer and a second transducer arranged to act on the optical fiber along parallel axes and a third transducer being on an axis that is placed between the parallel axes and angularly displaced by 45° therefrom; applying a first control signal to each of the first and second transducers; applying a second control signal to the third transducer, the first and second control signals being in time quadrature; processing the signal indicative of rotation of the sensing loop to form an error signal indicative of differences between the polarization states of the counterpropagating waves; and combining the error signal with the first and second control signals to minimize the differences between the polarization states of the counterpropagating waves at the detector.

Claim 27

Dependent Claim 28 words

The method of claim 21 including the steps of forming each of the transducers to comprise a piezoelectric fiber squeezer that adjusts the birefringence of the optical fiber.

Claim 28

Dependent Claim 23 words

The method of claim 21, further comprising the step of providing a polarizer arranged as a reference polarization for the counterpropagating optical waves.

Claim 29

Dependent Claim 50 words

The method of claim 21, further comprising the steps of: producing the first control signal with a first oscillator; amplifying the first control signal; producing the second control signal with a first oscillator; amplifying the second control signal; and providing independent gain control for the first and second amplifying means.

Claim 30

Dependent Claim 48 words

The method of claim 21, further including the step of forming a dual channel phase sensitive detector responsive to both in-phase and quadrature signals for demodulating the electrical signal indicative of the intensity of light guided by the means for introducing counterpropagating optical waves into the sensing loop.

Claim 31

Dependent Claim 26 words

The system of claim 21, further comprising including the step of controlling the polarization of light input to the sensing loop with a source polarization controller.

Claim 32

Independent Claim 76 words

A method for forming a coherent optical communications system, comprising: producing a first optical signal that includes an optical carrier signal with a data signal superimposed thereon; producing a second optical signal for demodulating the data signal; optically mixing the first and second optical signals; and processing the mixed optical signals to control the polarization of the second optical signal so that the first and second optical signals have the same polarization when they are mixed.

Claim 33

Independent Claim 76 words

A method for forming a coherent optical communications system, comprising: producing a first optical signal that includes an optical carrier signal with a data signal superimposed thereon; producing a second optical signal for demodulating the data signal; optically mixing the first and second optical signals; and processing the mixed optical signals to control the polarization of the second optical signal so that the first and second optical signals have the same polarization when they are mixed.

Claim 34

Dependent Claim 82 words

The method of claim 30, further comprising: guiding the first optical signal with a first optical waveguiding means; guiding the first optical signal with a second optical waveguiding means; combining the first and second optical signals with an optical coupler means; producing an electrical signal indicative of the intensity of the combined optical signals; and processing the electrical signal to produce an error signal indicative of differences between the polarization state of light guided by the first and second optical waveguiding means.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-10-01	1994-04-02	1994-10-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-10-01	1998-04-02	1998-10-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-10-01	2002-04-02	2002-10-02	$7700.00	Window Closed / Lapsed

Active polarization control servo and method

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag