A fiber optic hydrophone array with four sensor elements ofthe air-backed mandrel type has been manufactured and tested. Frequency response, crosstalk, noise and directional response have been measured in an acoustic tank.
G. B. Havsgaard, G. B. Havsgaard,
"Four channel fiber optic hydrophone system", Proc. SPIE 4185, Fourteenth International Conference on Optical Fiber Sensors, 41851B (9 November 2000); doi: 10.1117/12.2302190; https://doi.org/10.1117/12.2302190