Fiber Bragg grating sensor interrogation using edge-filtering with long period grating modulated light source

We propose an Fiber Bragg Grating (FBG) peak detection method using edge-filtering technique with Long Period Grating (LPG)-modulated light source. A low loss-band of LPG is chosen, where the intensity varies linearly over a certain wavelength range. The broadband light source is passed through the Long Period Grating and split using a 3 dB coupler. The modulated light is separately fed to two FBG using Y-couplers. The reflected lights from FBG are measured using optical power meter. The variation in the FBG peak wavelength due to measurand will cause change in the light power detected by the power meter. The proposed method of FBG peak detection is simple, dynamic, and cost-effective. The technique has been experimentally implemented for measurement of strain and temperature and the corresponding sensitivities are obtained as 1.01 pm/με and 9.8 pm/°C.