Absolute wavelength calibration technique for multiplexing interferometric fibre Bragg grating sensor interrogation systems

The advent of multiplexing interferometric schemes for fibre Bragg grating (FBG) sensor interrogation has enabled the combination of large-scale multiplexing and high-resolution measurement. In this letter, we describe a fast and simple technique to add absolute wavelength measurement capabilities to any passive-interferometric multiplexer. Through simulation we demonstrate a wavelength accuracy of <10 pm using common system specifications. The technique allows high-resolution interferometric interrogation to be applied to many key industrial applications requiring precise knowledge of absolute values, such as static temperature, without trading off high interrogation rate or resolution.