Cantilever deflection optical fiber sensor based on a chirped fiber grating Fabry-Perot cavity.

A cantilever deflection fiber-optic sensor based on chirped fiber grating (CFG) Fabry-Perot (FP) cavity had been proposed and experimental demonstrated. Two CFBGs with the same chirped coefficient direction and grating parameters are written in one single-mode fiber by UV mask exposure to form the CFG-FP cavity. The central wavelength of two CFGs is 1549.6072 nm, the 3 dB bandwidth is 2.9897 nm, and the physical cavity length of two CFGs is 1 cm. The grating region of two CFGs are straightness fixed on a cantilever beam, forming a sensor. Then the optical properties of this sensor are tested with different stresses at different positions of the cantilever beam. The experimental results show that this sensor can obtain linear displacement of a cantilever beam, overcoming the abilities of the FBG sensor, which only performed point measurement defect. The wavelength drift sensitivity of the sensor is 2.31 pm/g, and linearity is 0.99916. This sensor has great application value in the precise measurement of cantilever beam type and two-dimensional scale strain.