Interrogation of fiber Bragg grating sensors using a VCSEL and correlation techniques

We describe a demodulation technique for optical fiber Bragg grating (FBG) sensors based in the utilization of a long wavelength Vertical Cavity Surface Emitting Laser (VCSEL). The identification of the FBG wavelength is performed by sweeping the VCSEL wavelength over the operation range of the sensors and correlating its raising and falling periods in order to automatically determine the initial and final points of the wavelength to time mapping readout. The process is carried out by a simple computational routine, which allows the identification of the FBGs' spectral position leading to a cost-effective scheme.