Abstract: A pump light source provides pump light to an optical fiber arranged to guide the pump light to a first optical isolation device. Light output by the first optical isolation device is input to a wavelength division multiplexer. A gain fiber is connected to the wavelength division multiplexer and arranged to be optically pumped by the pump light such that the gain fiber emits broadband light that propagates to the wavelength division multiplexer. An output optical fiber is connected to the wavelength division multiplexer and arranged to guide a portion of the broadband light emitted by the gain fiber to a second optical isolation device for input to a fiber optic rotation sensor.

Abstract: A fiber optic interferometric sensor for use in a hydrophone system at high pressures includes a reference fiber wrapped around a rigid inner cylinder. A solid layer of compliant material is applied over the reference fiber. The sensing arm of the interferometer is wound over the layer of material applied over the reference fiber. The outer material is sufficiently compliant to provide acoustic sensitivity comparable to that of air-backed hydrophones.

Abstract: A wet end termination for a towed cable. An elongated cylindrical structure includes a bellows surface that is extendable under towing force. The cylindrical structure includes opposed tapered ends, the rear ends encapsulated the region of splice between the optical fiber conductor of the cable and the optical circuit of the towed array.