Fundamental experiment of wavelength-shift detection for strain measurement using fiber Bragg grating

We describe detection of Bragg wavelength shift in dynamic strain measurement by combining a fiber Bragg grating (FBG) with an unbalanced Mach-Zehnder interferometer using serrodyne modulation. We also use a serrodyne coefficient to describe the effects of a pseudo-heterodyne interferometry based on serrodyne modulation when measuring the Bragg wavelength-shift as a phase change.