Compact system of dispersion spectroscopy for interrogating fiber Bragg grating sensors using multi-wavelength phase shift interferometry

In this paper an all-fiber compact instrumentation system for dispersion spectroscopy is presented. This system is designed to interrogate fiber Bragg grating (FBG) sensors obtaining wavelength measurements with high-resolution. Instead of using the reflection profile of the FBG sensor to obtain the Bragg wavelength, we propose the phase shift interferometry technique applied to the readout of the FBG dispersion profile. The interrogation is done with an optical frequency comb based on dual-electro-optic modulators for compactness and stability, that can be exploited on site the applications. This comb allows to detect simultaneously five samples of the spectra and apply a five step algorithm to recover the optical phase variation due to the dispersion and therefore the correspondent strain applied to the FBG sensor.