Temperature-insensitive fiber-Bragg-grating-based vibration sensor

We propose a simple optical fiber sensor for the measurement of vibration. The sensor consists of two fiber Bragg gratings that have partially overlapped reflection spectra and are mounted on the opposite sides of a flexible beam. With this setting, the light intensity reflected by the gratings is modulated in accord with the vibration of the beam and adverse thermal effects can be largely eliminated. Experimental results are presented to demonstrate the feasibility of the sensor.