Electronic technique for temperature compensation of fibre Bragg gratings sensors

Optical sensors composed of fibre Bragg gratings (FBG) are becoming a choice for a wide range of sensing applications. However, in order to manufacture temperature independent sensors, it is necessary to compensate for the intrinsic temperature dependence of the FBG. In this letter we present an extremely effective, simple and low cost novel technique for stabilising the bias point of an interrogation current amplitude detection system which uses a laser diode source and a pair of matched FBGs. An electronic feedback control circuit measures the wavelength shift due to temperature variations in a reference FBG and actuates on the laser diode temperature, to induce changes in its wavelength output and compensate for the temperature dependence of the FBG sensor.