Novel frequency-agile interrogating system for fibre Bragg grating sensors

We have demonstrated a new frequency-agile system for the interrogation of in-fibre Bragg grating sensors. The scheme involves frequency shift keying (FSK) of the RF drive to an acousto-optic tunable filter (AOTF) to track the wavelength shifts of a Bragg grating. Theoretical studies to derive the optimum frequency deviation for achieving maximum sensitivity are given, and experimental results are presented for temperature measurement. This technique is capable of rapid, random access and very wide tuning range, showing the potential for interrogating multiplexed arrays of Bragg-grating-based sensor