Simulation of interferometric sensors for pressure and temperature measurements

A Mach–Zehnder type fiber optic sensor is modeled and the phase change for this device as a result of pressure or temperature variation is studied. Different parameters involved in the sensing process such as Young's modulus, Poisson's ratio, light wavelength, index of refraction, and stress–optic coefficients are changed and their effects investigated. Our results show that Young's modulus, Poisson's ratio, light wavelength, and stress–optic coefficients have the major roles for pressure sensing. On the other hand for temperature sensing, light wavelength, thermal expansion coefficient, and temperature dependence of the index of refraction are the important parameters. For a typical silica glass fiber at 0.6328 μm wavelength, the calculated phase change due a pressure change of 1 Pa for the 1 m length is $4.08×10−5$ rad. This phase change for 1 m of a similar probe fiber corresponding to 1 °C temperature change is found to be 107 rad.