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

A fiber strain sensor based on a p-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 Se ( f ) = (3X10^-19 f^-1 +2.6x10^-23) in the Fourier frequency range from 1 kHz to 10 MHz (e being the applied strain), corresponding to a minimum sensitivity of 5 peHz^(1/2) for frequencies larger than 100 kHz.