Fiber strain sensor based on a π-phase-shifted Bragg grating and the Pound-Drever-Hall technique

A fiber strain sensor based on a pi-phase-shifted Bragg grating and an extended cavity diode laser is proposed. Locking the laser frequency to grating resonance by the Pound-Drever-Hall technique results in a strain power spectral density S-epsilon(f) = (3 x 10(-19) f(-1) + 2.6 x 10(-23)) epsilon(2)/Hz in the Fourier frequency range from 1 kHz to 10 MHz (epsilon being the applied strain), corresponding to a minimum sensitivity of 5 p epsilon Hz(-1/2) for frequencies larger than 100 kHz. (C) 2008 Optical Society of America.