Structure Design of Disposable Ocean Temperature Depth Sensing Probe Based on F-P Cavity and FBG

The basic principle of sensing is the combination of F-P cavity interference and fiber grating reflection. A hybrid structure sensor probe has been designed based on the combination of an F-P cavity of liquid-filled thermometer structure, and a fiber grating with an elastic diaphragm, herein F-P cavity is used for temperature sensing, and the fiber grating is used for pressure sensing. By adopting the dual optical path structure, the dual-parameter detection of temperature and depth is realized, which solves the problem of low accuracy caused by the cross response of temperature and pressure of a single sensor device and the calculation of the depth information of the ocean with empirical formulas. Compared with traditional sensors, the sensitivity is effectively improved. Theoretical analysis shows that the sensitivity of the F-P cavity with a thermometer structure filled with kerosene reaches 1.334 nm/?C, and the depth sensitivity of the fiber grating is 284.6 pm/Mpa within the ocean depth range of 0 - 400 m.