The arms arrangement influence on the sensitivity of Mach–Zehnder fiber optic interferometer

Fiber-optic sensors based on phase shift measurements are one of the most sensitive sensors at all. In general they are capable to measure various phenomena, for example displacement, rotation, temperature, acoustic pressure, liquid flow and level, strain etc. In our paper we have used interferometer configuration based on the Mach–Zehnder principle with polarization maintaining components and narrowband DFB laser operating at a wavelength of 1550 nm. In this configuration it is important to isolate the reference arm against measured phenomena and on the other hand to increase the sensitivity of the measuring arm to maximize phase shift induced by the measured phenomenon. The paper describes various measurement arrangements of measuring and reference arm and their influence on the measurement sensitivity. The obtained frequency ranges are evaluated for all mentioned combinations.