Polarization maintaining fiber interferometer and method for source stabilization
First Claim
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1. A device for stabilizing the frequency of an optical signal output from a optical source, comprising:
- a length of polarization maintaining optical fiber for guiding an optical signal while maintaining the polarization thereof;
means for introducing an optical signal having a pair of linear polarization components from the light source into the length of polarization maintaining optical fiber, the polarization components having different propagation times therein;
fiber optic phase modulator means for modulating at a reference frequency the phase difference of the two linear polarization components guided by the length of polarization maintaining optical fiber;
means for producing an error signal indicative of the intensity as a function of the reference frequency of an optical signal output from the length of polarization maintaining optical fiber; and
means for applying the error signal to the optical source to servo the frequency of the optical signal output from the optical source to a predetermined value.
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Abstract
The frequency of an optical signal output from an optical source is controlled while maintaining the polarization of the signal by guiding the signal with either a polarization maintaining optical fiber or an integrated optics waveguide. A portion of the signal output from the light source is input to the light guiding structure. The optical signals are phase modulated, and an electrical signal indicative of the intensity of an optical signal output from the polarization maintaining light guiding device is applied to the optical source for controlling the frequency of the optical signal output therefrom.
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Citations
28 Claims
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1. A device for stabilizing the frequency of an optical signal output from a optical source, comprising:
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a length of polarization maintaining optical fiber for guiding an optical signal while maintaining the polarization thereof; means for introducing an optical signal having a pair of linear polarization components from the light source into the length of polarization maintaining optical fiber, the polarization components having different propagation times therein; fiber optic phase modulator means for modulating at a reference frequency the phase difference of the two linear polarization components guided by the length of polarization maintaining optical fiber; means for producing an error signal indicative of the intensity as a function of the reference frequency of an optical signal output from the length of polarization maintaining optical fiber; and means for applying the error signal to the optical source to servo the frequency of the optical signal output from the optical source to a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for stabilizing the frequency of an optical signal output from a optical source, comprising the steps of:
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guiding an optical signal with a length of polarization maintaining optical fiber to maintain the polarization of the optical signal; introducing an optical signal having a pair of linear polarization components from the light source into the length of polarization maintaining optical fiber, the polarization components having different propagation times therein; modulating the phase difference of the two polarization components guided by the length of polarization maintaining optical fiber with a signal having a predetermined reference frequency; producing an error signal indicative of the intensity as a function of the reference frequency of an optical signal output from the length of polarization maintaining optical fiber; and applying the error signal to the optical source to servo the frequency of the optical signal output from the optical source to a predetermined value. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A fiber optic rotation sensing system, comprising:
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an optical source; a first fiber for receiving light from the optical source; a second optical fiber having a sensing coil formed therein; optical coupling means for coupling light between the first and second optical fibers; means optically coupled to the optical source for stabilizing the frequency of an optical signal output from the optical source, including; a length of polarization maintaining optical fiber for guiding an optical signal while maintaining the polarization thereof; means for introducing an optical signal having a pair of linear polarization components from the light source into the length of polarization maintaining optical fiber, the polarization components having different propagation times therein; fiber optic phase modulator means for modulating at a reference frequency the phase difference of the two linear polarization components guided by the length of polarization maintaining optical fiber; means for producing an error signal indicative of the intensity as a function of the reference frequency of an optical signal output from the length of polarization maintaining optical fiber; and means for applying the error signal to the optical source to servo the frequency of the optical signal output from the optical source to a predetermined value; means for producing a pair of counterpropagating waves in the sensing coil so that the waves interfere and produce an interference pattern indicative of the rotation rate of the sensing coil; and means for processing optical signals output from the sensing coil to determine its rotation rate. - View Dependent Claims (14, 15, 16, 17)
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21. A method for sensing rotations, comprising the steps of:
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producing a light beam with an optical source; receiving light from the optical source with a first optical fiber; forming a sensing coil in a second optical fiber; coupling light between the first and second optical fibers; and controlling the frequency of an optical signal output from a optical source with means optically coupled to the optical source, including the steps of; guiding an optical signal with a length of polarization maintaining optical fiber to maintain the polarization of the optical signal; introducing an optical signal having a pair of linear polarization components from the light source into the length of polarization maintaining optical fiber, the polarization components having different propagation times therein; modulating the phase difference of the two polarization components guided by the length of polarization maintaining optical fiber with a signal having a predetermined reference frequency; producing an error signal indicative of the intensity as a function of the reference frequency of an optical signal output from the length of polarization maintaining optical fiber; and applying the error signal to the optical source to servo the frequency of the optical signal output from the optical source to a predetermined value; producing a pair of counterpropagating waves in the sensing coil so that the waves interfere and produce an interference pattern indicative of the rotation rate of the sensing coil; and processing optical signals output from the sensing coil to determine its rotation rate. - View Dependent Claims (18, 19, 20, 22, 23, 24, 25, 26, 27, 28)
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Specification