Temperature Compensated High-Resolution Interrogation of FBG Strain Sensor Based on Four Wave Mixing

Realization of temperature compensation and high sensitivity is a challenging task in the field of FBG based strain sensor. A unique scheme of high sensitive temperature compensated interrogation technique for FBG strain sensors is proposed. Two chirped FBGs are designed in such a way that effect of temperature on one FBG is compensated by the other FBG. The strain sensitivity is enhanced by a factor of sixteen compared to the signal reflected from the edge of the FBG using only third order Four wave mixing (FWM) product. The third order FWM product generated in the 1
^st
stage FWM process is filtered and utilized in the 2
^nd
stage FWM process to enhance the sensitivity. The proposed scheme attains high sensitivity of 0.312 dBm/με with strain resolution of 0.032με using only 3
^rd
order FWM product.