Deep-water fiber-optic hydrophone

A prototype hydrophone was constructed using a He–Ne laser coupled optically to a single-mode fiber waveguide. An active homodyne system for recording of the signal was developed and tested. This system utilized control of the laser emission frequency and its phase sensitivity limit was 10 ^– 5 rad/Hz^1/2. Winding of the waveguide on an elastic mandrel increased the hydrophone sensitivity by 45 dB.