A Displacement Sensor Based on a Temperature-Insensitive Double Trapezoidal Structure With Fiber Bragg Grating

A novel temperature-insensitive displacement sensor based on a fiber Bragg grating (FBG) is presented. A FBG was glued into a V-shaped groove, which lies on the lower surface of a double trapezoidal beam. It is found that the 3-dB bandwidth of the reflection spectra and output optical power of the FBG changed linearly with the variation of the displacement of the beam. High sensitivity of 0.25 and 3.70 were achieved. The sensor is temperature-insensitive through measuring the bandwidths of the reflection spectra and optical power of the reflected signal.