A long-distance transmission array system and method for optical fiber hydrophone based on compensation interference

Abstract

The invention discloses an optical fiber hydrophone remote transmission array system and method based on compensation interference, comprising: a signal transmitting unit for inputting a pulse signal; a compensation interference unit having an unbalanced arm difference for converting the pulse signal into a The delayed pulse signal pair is output in parallel; the optical ring unit is used to transmit the pulse signal pair; the time-division multiplexing array unit has a time-division multiplexing array, which is used to split and delay the pulse signal pair, and will obtain the sensing signal The delay signals of the beams are combined, and the time-division multiplexing interference pulse signal with the sensing signal is transmitted from the input and output ports to the second port of the optical ring unit; the signal receiving unit analyzes the time-division multiplexing interference pulse signal to obtain sensing signal. It can greatly improve the comprehensive performance of the long-range transmission array of large-scale optical fiber hydrophones, so that it can meet the application requirements of related fields such as fixed arrays of optical fiber hydrophones on the seabed and shore.

Description

technical field [0001] The invention relates to the technical field of optical fiber hydrophones, in particular to an optical fiber hydrophone remote transmission array system and method based on compensation interference. Background technique [0002] Optical fiber hydrophone is a fiber optic sensor based on optical fiber and photoelectric technology, which uses sound waves to detect, locate and identify underwater acoustic targets. Optical fiber hydrophones have the advantages of small size and light weight, and can easily form various underwater optical fiber sensing networks, providing an ideal technical approach for solving problems related to marine development strategies such as underwater acoustic detection and oil exploration. Typical applications of fiber optic hydrophones include submarine shore-based fixed arrays, towed arrays, and snorkeling buoys. Among them, shore-based arrays have the advantages of stable formation, long-term continuous duty, and low self-noi...

AI Technical Summary

Problems solved by technology

[0004] (2) In terms of long-distance transmission technology of fiber optic hydrophones, with the increase of the transmission distance of analog optical signals, it is also accompanied by coherent Rayleigh scattering noise (Rayleigh), stimulated Brillouin scattering (stimulated Brillouin scattering, SBS), four The intensification of linear and nonlinear noises such as Four-Wave Mixing (FWM) will affect the weak acoustic signal detection ability of fiber optic hydrophones

[0008] 1. In the equi-arm compensation interference structure using heterodyne demodulation, the round-trip length of the array delay fiber is equal to the arm difference of the horse-increasing compensation interferometer, that is, the interference delay after compensation Δτ=0, resulting in Δf 2 ×Δτ≡0, unable to satisfy the phase modulation scheme Δf 2 ×Δτ=k (k is a positive integer) requirements

Therefore, the suppression of SBS noise in remote transmission can only be achieved by controlling the optical power injected into the remote fiber below the SBS threshold.

Compared with the phase modulation stimulated Brillouin scattering suppression scheme, the total optical power budget of the system will be reduced by more than 10dB, and the long-distance transmission distance and array scale are greatly limited

[0009] 2. The equi-arm compensation interference structure of heterodyne demodulation introduces a fixed frequency difference Δf into the two beams of interference light field, and extracts signals of related frequencies to demodulate the phase information of the hydrophone. The heterodyne demodulation scheme Does not have the ability to suppress noise

However, the disadvantage of this solution is that each probe of the array is an independent Michelson interferometer, and the number of couplers, optical fibers, mirrors, and fusion points used in the time-division multiplexing array is 2 to 3 times that of the compensation interference structure.

Therefore, in the actual production process of large-scale arrays, the independent probe scheme greatly increases the complexity of the process compared with the compensation interference scheme, and also increases the optical loss and cost of the array, which has obvious disadvantages

Images