Interrogator unit for multi-span distributed acoustic sensing

1 . An optical communication system, comprising:

a distributed acoustic sensing (DAS) interrogation unit, the DAS interrogation unit includes a single DAS transmitting device and a plurality of DAS receiving devices;

the single DAS transmitting device

generates one or more optical signals for determining a status of one or more portions of an optical communication path;

modulates the one or more optical signals using one or more measurement pulses and generates one or more modulated optical signals; and

transmits the one or more modulated optical signals to the one or more portions of the optical communication path;

the plurality of DAS receiving devices

receives one or more reflected signals in response to the one or more modulated optical signals reflected by the one or more portions, wherein each DAS receiving device in the plurality of DAS receiving devices receives at least one of the one or more reflected signals in accordance with a predetermined wavelength of signals that the DAS receiving device is configured to receive; and

determines the status of the one or more portions of the optical communication path based on the one or more reflected signals.

2 . The system of claim 1 , wherein the optical communication path is a distributed acoustic sensing optical transmission path.

3 . The system of claim 2 , wherein the single DAS transmitting device includes a laser source configured to generate the one or more optical signals for determining the status of the one or more portions of the optical communication path.

4 . The system of claim 3 , wherein the laser source includes at least one of the following: a sweeping laser, a continuous wave laser, a multi-tone frequency laser, or any combination thereof.

5 . The system of claim 2 , wherein the single DAS transmitting device includes a pulse generator configured to generate the one or more measurement pulses for modulating the one or more optical signals.

6 . The system of claim 5 , wherein the single DAS transmitting device includes a modulator configured to modulate the one or more optical signals using the one or more measurement pulses generated by the pulse generator.

7 . The system of claim 6 , wherein the modulator includes at least one of the following: an acousto-optic modulator, an electrical absorption modulator, an electric-optic modulator (EOM), or any combination thereof.

8 . The system of claim 5 , wherein a frequency of at least one modulated optical signal in the one or more modulated optical signals is determined in accordance with at least one portion of the optical communication path in the one or more portions of the optical communication path, wherein the at least one modulated optical signal is used to determine status of the at least one portion.

9 . The system of claim 1 , wherein the one or more optical signals include an interrogation signal.

10 . A method for monitoring an optical transmission path in an optical transmission system, the optical transmission system includes a distributed acoustic sensing (DAS) interrogation unit having a single DAS transmitting device and a plurality of DAS receiving devices, the method comprising:

generating, by the single DAS transmitting device, one or more optical signals for determining a status of one or more portions of an optical communication path;

modulating, by the single DAS transmitting device, the one or more optical signals using one or more measurement pulses and generating one or more modulated optical signals;

transmitting, by the single DAS transmitting device, the one or more modulated optical signals to the one or more portions of the optical communication path;

receiving, by the plurality of the DAS receiving devices, one or more reflected signals in response to the one or more modulated optical signals reflected by the one or more portions, wherein each DAS receiving device in the plurality of DAS receiving devices receives at least one of the one or more reflected signals in accordance with a predetermined wavelength of signals that the DAS receiving device is configured to receive; and

determining, by plurality of DAS receiving devices, the status of the one or more portions of the optical communication path based on the one or more reflected signals.

11 . The method of claim 10 , wherein the optical communication path is a distributed acoustic sensing optical transmission path.

12 . The method of claim 10 , wherein the single DAS transmitting device includes a laser source configured to generate the one or more optical signals for determining the status of the one or more portions of the optical communication path.

13 . The method of claim 12 , wherein the laser source includes at least one of the following: a sweeping laser, a continuous wave laser, a multi-tone frequency laser, or any combination thereof.

14 . The method of claim 10 , wherein the single DAS transmitting device includes

a pulse generator configured to generate the one or more measurement pulses for modulating the one or more optical signals; and

a modulator configured to modulate the one or more optical signals using the one or more measurement pulses generated by the pulse generator, wherein the modulator includes at least one of the following: an acousto-optic modulator, an electrical absorption modulator, an electric-optic modulator (EOM), or any combination thereof.

15 . The method of claim 14 , wherein a frequency of at least one modulated optical signal in the one or more modulated optical signals is determined in accordance with at least one portion of the optical communication path in the one or more portions of the optical communication path, wherein the at least one modulated optical signal is used to determine status of the at least one portion.

16 . The method of claim 10 , wherein the one or more optical signals include an interrogation signal.