All-fibre interrogation technique for fibreBragg sensors using a biconical fibre filter

Abstract

A passive self-referencing all-fibre technique for Bragg wavelength shift detection using a biconical fibre filter is described. This filter, basically a tapered depressed-cladding fibre, exhibits a periodic spectral power dependence which permits direct tracking of wavelength shifts in a 20 nm unambiguous range. Dynamic strain resolution of 1.5 µstrain/√Hz has been achieved.