Birefringence manipulation in tapered polarization-maintaining photonic crystal fiber Mach-Zehnder interferometer for refractive index sensing

A temperature insensitive, compact and high resolution refractive index measurement system using tapered polarization maintaining photonic crystal fiber (PM-PCF) Mach-Zehnder interferometer (MZI) is proposed. The sensor exhibits sensitivity of 20.53 nm/RIU with very high refractive index resolution of 1.2175 × 10−5 RIU and 252.6906 dBm/RIU within the refractive index range from 1.33 to 1.37. The birefringence value varied from 1.90619 × 10−5 to 1.86978 × 10−5 with the corresponding change in refractive index. The core and clad having different propagation constant and the changes in the optical path length and hence a change in interference pattern is correlated with the minute changes in refractive index of the subjected sample.