High sensitivity and wide dynamic measurement range can be achieved with these detectors These properties make fiber lasers suitable for acoustic detection of seismic risks, tsunami prevention, oil prospection with large deep-sea detectors. But the free running relative intensity and frequency optical noise of the laser can limit the performance of deep-sea detector systems. In this work, the dependence on relative intensity and frequency optical noise versus acoustic frequency is discussed as a function of the acousto-optic sensitivity SAO(nm/Pa).