System and method for fiber sensing

1. A network element (NE), comprising:

a first wavelength coupler configured to separate a first optical supervisory channel (OSC) signal from a data-carrying signal received from a fiber span;

a polarization-measurement unit having an input coupled to an output of the first wavelength coupler, wherein the polarization-measurement unit is configured to perform a polarization measurement on the first OSC signal to obtain a state of polarization of the first OSC signal; and

an OSC unit comprising a receiver and a transmitter, wherein the receiver is configured to receive the first OSC signal and the transmitter is configured to transmit a second OSC signal that includes the state of polarization of the first OSC signal to a control-and-management unit, thereby facilitating distributed fiber sensing.

2. The NE of claim 1 , wherein the polarization-measurement unit comprises a polarimeter.

3. The NE of claim 1 , wherein the polarization measurement comprises a measurement of changes in the state of polarization of the first OSC signal, and wherein the polarization-measurement unit comprises a linear polarizer followed by a photodetector.

4. The NE of claim 1 , further comprising:

a second wavelength coupler configured to combine the second OSC signal and an outgoing data-carrying signal such that the second OSC signal is transmitted to a next NE in an optical transport network (OTN).

5. The NE of claim 1 , wherein the NE is an inline NE coupled to two fiber spans, and wherein the inline NE comprises two polarization-measurement units, with each polarization-measurement unit configured to perform a polarization measurement on an OSC signal received from a particular fiber span.

6. A system for distributed fiber sensing, comprising:

a plurality of network elements (NEs) in an optical transport network (OTN) and a control-and-management unit coupled to the NEs;

wherein a respective network element (NE) comprises:

a first wavelength coupler configured to separate a first optical supervisory channel (OSC) signal from a data-carrying signal received from a fiber span;

a polarization-measurement unit having an input coupled to an output of the first wavelength coupler, wherein the polarization-measurement unit is configured to perform a polarization measurement on the first OSC signal to obtain a state of polarization of the first OSC signal; and

an OSC unit comprising a receiver and a transmitter, wherein the receiver is configured to receive the first OSC signal and the transmitter is configured to transmit a second OSC signal that includes the state of polarization of the first OSC signal to the control-and-management unit, thereby facilitating distributed fiber sensing.

7. The system of claim 6 , wherein the polarization-measurement unit comprises a polarimeter.

8. The system of claim 6 , wherein the polarization measurement comprises a measurement of changes in the state of polarization of the first OSC signal, and wherein the polarization-measurement unit comprises a linear polarizer followed by a photodetector.

9. The system of claim 6 , wherein the NE further comprises:

a second wavelength coupler configured to combine the second OSC signal and an outgoing data-carrying signal such that the second OSC signal is transmitted to a next NE in the OTN.

10. The system of claim 6 , wherein the respective NE is an inline NE, wherein the inline NE is coupled to two fiber spans, and wherein the inline NE comprises two polarization-measurement units, with each polarization-measurement unit configured to perform a polarization measurement on an OSC signal received from a particular fiber span.

11. The system of claim 6 , wherein the control-and-management unit comprises a polarization-data-processing unit configured to process data associated with the state of polarization of the first OSC signal.

12. The system of claim 11 , wherein the control-and-management unit comprises an environmental-factor-determination unit configured to determine environmental factors surrounding the fiber span based on the processed outcome data.

13. The system of claim 12 , wherein the environmental factors comprise one or more of: mechanical disturbance and temperature changes.

14. The system of claim 13 , wherein the control-and-management unit comprises an overlapping-route-determination unit configured to determine whether the fiber span shares a route with a corresponding backup fiber.

15. A method for distributed fiber sensing, comprising:

receiving, at a network element (NE), optical signals from a fiber span coupled to the NE;

separating a first optical supervisory channel (OSC) signal from a data-carrying signal in the received optical signals;

performing a polarization measurement on the first OSC signal to obtain a state of polarization of the first OSC signal;

generating a second OSC signal that includes the state of polarization of the first OSC signal; and

transmitting the second OSC signal to a control-and-management unit; and

determining environmental factors surrounding the fiber span based on the state of polarization of the first OSC signal.

16. The method of claim 15 , wherein performing the polarization measurement comprises one of:

using a polarimeter to measure the state of polarization of the first OSC signal; and

using a linear polarizer followed by a photodetector to measure changes in the state of polarization of the first OSC signal.

17. The method of claim 15 , further comprising:

combining the second OSC signal and an outgoing data-carrying signal such that the second OSC signal is transmitted to a next NE.

18. The method of claim 15 , further comprising:

processing, by a polarization-data-processing unit, data associated with the state of polarization of the first OSC signal.

19. The method of claim 18 , further comprising determining whether the fiber span shares a route with a corresponding backup fiber.