Polarization diversity receivers with heterodyne demodulation for eliminating the polarization-induced fading of interferometric hydrophone

A method of adding squared signals of three polarization diversity receiver to overcome the polarization induced fading (PIF) in the optical fibre hydrophone is proposed and experimentally verified. This triple polarization diversity receiver (tri-PDR) is first analysed and theoretically demonstrated. Then, a Mach-Zehnder interferometric sensor with polarization rotator in the reference arm is fabricated and tested. Experimental results show that PIF can be efficiently eliminated with the adding squared signals of tri-PDR. It's also found that background noise of high frequency (>500Hz) can be also suppressed.