Dynamic fiber Bragg grating sensor array with increased wavelength-division multiplexing density and low crosstalk

Abstract

This paper describes a dense wavelength-division multiplexing scheme with low crosstalk for fiber Bragg grating (FBG) sensors based on interferometric detection. The scheme uses a 100-GHz spacing dense wavelength-division multiplexer with two-level optical filters to separate the returned wavelengths from FBG sensor array, enabling a high-resolution interferometric dynamic wavelength demodulation for each sensor with narrow spacing. An array with three gratings was demonstrated, and a dynamic wavelength resolution of ∼7×10−4 pm/√Hz was tested, with a bandwidth of 1 Hz to 1 kHz for each sensor. The FBGs have an operating range approaching 0.6 nm with a crosstalk level below −80 dB. The multiplexing scheme demonstrates the potential to address up to 50 FBG sensors through a single fiber with a 40-nm bandwidth optical source.