Impulse response measurements of phase-retardation change in a birefringent fiber sensor

An impulse response of phase retardation in an externally stretching fiber sensor is measured. Correlation processing, made for the phase retardation obtained from optical heterodyne interferometry, gives a transfer function for the fiber sensor system which is computed from a cross-power spectrum between the input and the output together with a power spectrum of the input. The sensing system with a stretching apparatus is shown to measure the impulse response. Its response becomes sensitive and quick with an increase in the bias tension added to the dynamic stretching.