Sensor interrogation technique using chirped fibre grating based Sagnac loop

A novel and simple sensor interrogation scheme for fibre Bragg grating (FBG)-based sensing systems is demonstrated. In this scheme, a chirped FBG-based Sagnac loop is used as a wavelength-dependent receiver, and a stable and linear readout response is realised. It is a significant advantage of this scheme that the sensitivity and the measurement wavelength range can be easily adjusted by controlling the chirp of the FBG or using an optical delay line in the Sagnac loop.