Research on the reflectivity of the end face of film-coated optic fiber for application in fiber optic Fabry-Perot cavity hydrophone

Abstract

Fiber optic Fabry-Perot cavity hydrophones have the advantages of high sensitivity, simple structure and the resistance to electromagnetic interference, making them a research hotspot. Filling the Fabry-Perot cavity with water media would lead to a decrease in the reflectivity of the fiber end face, thus causing a decrease in the sensitivity of the fiber FP cavity hydrophone. In this work, the magnetron sputtering technology was utilized with alumina as the sputtering target. A thin film was deposited to the end face of the optical fiber to improve the reflectivity of the end face of the fiber. Coated fibers with varied film thicknesses were prepared and their reflectivity was characterized. The experimental results showed that the reflectivity of the end face of the optical fiber in water media can be increased by an order of magnitude to 2.61%, which is an excellent basis for the development of a highly sensitive optical fiber Fabry-Perot cavity hydrophone.