Interrogation of a fibre Fabry–Perot interferometer using a π-shifted Bragg grating

Abstract

A robust all-fibre interferometric interrogation technique based on the wavelength modulation of a π-shifted fibre Bragg grating is proposed. The concept is demonstrated for strain measurement using a Bragg-grating-based Fabry–Perot interferometer. The strain–phase relationship is shown to be linear with a sensitivity slope of (2.19 ± 0.02)°/με. A strain resolution of ≈2.4 µε is demonstrated.