Monitoring for disturbance of optical fiber
First Claim
1. A method of monitoring an optical fiber, comprising:
- launching a probe light flux into the fiber, wherein the probe light flux includes a first portion and a second portion in respective launch polarization states that are characterized by linearly independent launch Stokes vectors;
analyzing a received light associated with propagation of the probe light flux in the fiber based on at least two analyzer polarization states that are characterized by Stokes vectors that are linearly independent;
processing detected signals associated with the analyzed received light to determine a measure of change in the fiber, over a period of time that is substantially invariant under a non-reflecting unitary transformation of either the launch polarization states or the analyzer polarization states; and
reporting a disturbance of the fiber based on the determined measure of change.
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Accused Products
Abstract
Problems of excessive fading in systems for monitoring single-mode optical fiber for disturbances are addressed by launching into the fiber polarized light having at least two different predetermined launch states of polarization whose respective Stokes vectors are linearly-independent of each other; downstream from the first location, receiving the light from the fiber; analyzing the received light using polarization state analyzer having at least two different analyzer states of polarization that are characterized by respective Stokes vectors that are linearly-independent and detecting the analyzed light to provide corresponding detection signals; deriving from the detection signals measures of changes in polarization transformation properties of the fiber between different times that are invariant under a non-reflective unitary transformation on either the launch states or the detection states; and, on the basis of predefined acceptable physical disturbance criteria determining whether or not the measures are indicative of a reportable physical disturbance.
154 Citations
34 Claims
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1. A method of monitoring an optical fiber, comprising:
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launching a probe light flux into the fiber, wherein the probe light flux includes a first portion and a second portion in respective launch polarization states that are characterized by linearly independent launch Stokes vectors; analyzing a received light associated with propagation of the probe light flux in the fiber based on at least two analyzer polarization states that are characterized by Stokes vectors that are linearly independent; processing detected signals associated with the analyzed received light to determine a measure of change in the fiber, over a period of time that is substantially invariant under a non-reflecting unitary transformation of either the launch polarization states or the analyzer polarization states; and reporting a disturbance of the fiber based on the determined measure of change. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus for monitoring an optical fiber, comprising:
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a probe light source coupled to launch a probe light flux into the optical fiber, wherein the probe light flux includes a first portion and a second portion in respective launch polarization states that are characterized by linearly independent launch Stokes vectors; a polarization analyzer situated to receive a light flux associated with propagation of the probe light flux in the optical fiber and analyze the received light flux based on at least two analyzer polarization states that are characterized by Stokes vectors that are linearly independent; and a processor configured to receive detected signals associated with the analyzed received light and determine a measure of change in the fiber over a period of time, wherein the measure of change is substantially invariant under a non-reflecting unitary transformation of either the launch polarization states or the analyzer polarization states, wherein the processor is configured to report a disturbance of the optical fiber based on the determined measure of change. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification