The design of an air-backed fiber-optic hydrophone is presented. With respect to the previous models this prototype is optimized to provide a bandwidth sufficiently large to detect acoustic signals produced by high energy hadronic showers in water. In addiction to the geometrical configuration and to the choice of the materials, the preliminary results of the measured performances in air are presented.

We describe how we have realized the prototype of an optic fiber air backed mandrel hydrophone designed to measure frequencies up to 20 kHz. The characteristics of the materials we have selected, the procedure of winding the optic fibers and the coating process are described in detail.

We have studied the design of an air-backed optic fiber hydrophone. With respect to the previous models, this prototype is optimized to provide a band width sufficiently large to detect acoustic signals produced by high energy hadronic showers in water. After a discussion on the geometrical configuration and on the choice of the materials we evaluate the expected performances on the basis of simple analytical calculations.