Abstract

Underwater acoustic surveillance with fiber optic hydrophones offers electrically passive systems with minimum cablings. This in turn makes them highly desirable for sea bed arrays, towed arrays and Flank arrays. Distributed Feed-Back Fiber Laser (DFB-FL) based hydrophones are the advanced one in this category. Packaging of such DFB-FL for such applications is still an exploring area of research to obtain desired sensitivity and bandwidth. For array formation, multiple DFBFLs are needed to be coupled in a single lead fiber with common pump source and make the task difficult one. Here we report, the realization of an eight element array in a single lead fiber pumped with a 500mW pump source and an eight channel DWDM with 400GHz separation with a high sensitive low noise Mach Zehnder interferometer with 50m optical path difference. Simultaneous phase demodulation is carried out with an eight channel optical phase demodulator. Sensitivity of the hydrophones are found to be −155±5dB ref. 1V/µPa for the frequency band up to 4000Hz.

© 2016 Optical Society of America