Strain measurement in a Mach-Zehnder fiber interferometer using genetic algorithm

A fiber optic strain sensing method based on genetic algorithm (GA) is presented in a Mach-Zehnder type fiber interferometer. The interferogram recorded from the interferometer has been demodulated using GA and the phase data of the pattern has been represented by a suitable grade polynomial fitting function. A population set of chromosomes is used to codify the coefficients of the polynomial function that estimates the phase. The modulation of group delay and dispersion caused by the measurand has been obtained from the phase curve where no unwrapping process is required. Results for different applied low strains (≤20 μstrain) are presented. The values are compared with those obtained by data dependent system (DDS) method and Fourier transform method.