Optical fiber axial micro-displacement sensor based on Mach-Zehnder interferometer

A Mach-Zehnder interferometer (MZI) based fiber axial microdisplacement sensor was proposed. The MZI was constructed by a bowknot-type taper (BTT) combining with a fiber core-offset between two single mode fibers (SMFs). The axial micro-displacement of the core offset is correlated with the MZI transmission spectrum and varied with the interferometer arm length. For the arm length L of 12, 18, 24 and 30 mm, the proposed sensors showed high sensitivity of -0.362 dB/mu m, -0.385 dB/mu m, -0.332 dB/mu m and -0.235dB/mu m, and temperature errors of -0.056 dB/degrees C, -0.036 dB/degrees C, -0.044 dB/degrees C, -0.048 dB/degrees C, respectively. The theoretical simulations of the energy distributions were also given. The obtained sensitivity of -0.385 dB/mu m is about 150 times high than that of the current similar existing axial micro-displacement sensor. (C) 2014 Optical Society of America