Fiber-optic hydrophone (FOH) is a significant type of acoustic sensor, which can be used in both military and civilian fields such as underwater target detection, oil and natural gas prospecting, and earthquake inspection. The recent progress of FOH is introduced from five aspects, including large-scale FOH array, very-low-frequency detection, fiber-optic vector hydrophone (FOVH), towed linear array, and deep-sea and long-haul transmission. The above five aspects indicate the future development trends in the FOH research field, and they also provide a guideline for the practical applications of FOH as well as its array.
The noise floor is a vital specification that determines the minimum detectable signal in the phase measurement. However, the noise floor in optical phase measurement conducted via conventional optical interferometry tends to approach the intrinsic limit. In this study, a low noise phase measurement of a fiber optic sensor conducted via weak value amplification is experimentally demonstrated. The system has a flat, wideband frequency response from 0.1 Hz to 10 kHz, as well as adequate linearity. The operating band is wider than the present sensor using the same mechanism. In particular, the system noise floor is measured to be -98 dB at 1 Hz and -155 dB at 1 kHz. The results indicate that the minimum detectable signal can reach as low as 5.6 × 10−6 rad at 1 Hz and 8 × 10−9 rad at 1 kHz. In addition, it is demonstrated that the noise result of the proposed system is two-order of magnitude lower than that of the typical interferometric fiber optic sensors through the comparison experiment. With the characteristic of low-noise, the system is promising in the field of weak signal detection such as underwater acoustic signal detection, seismic wave detection, and mineral resource exploration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.