Micro quasi-Michelson interferometric fiber-optics hydrophone based on refractive index modulation

The exploration and utilization of marine resources is one of the most important topics in human development. In this paper, a fiber-optic hydrophone was proposed and demonstrated experimentally for submarine ultrasonic detection. The device contained a refractive index modification window in the cladding of tapered fiber-optics tip, making it as a quasi-Michelson interferometer. Moreover, a plastic cone structure was formed and employed to focus the ultrasonic field on the fiber, which highly promote the coupling efficiency of ultrasonic-to-interferometer. Using the spectral-side band filtering technology, the hydrophone was working well for ultrasonic wave detection.