A novel fiber in-line Michelson interferometer based on end face packaging for temperature and refractive index measurement

A novel fiber in-line Michelson interferometer based on end face packaging fabricated by fusion splicing single mode fiber (SMF) and hollow core silica tube (HCST) is proposed and experimentally demonstrated for measurements of refractive index (RI) and temperature. This proposed fiber end face packaging scheme enables in-line Michelson interferometer to sense the liquid refractive index and protect fiber ends from influences of external liquid. Temperature and refractive index (RI) can be demodulated by utilizing the phase-shift tracking scheme in the Fast Fourier Transform (FFT) spectra with advantages of low noise and high resolution. Experimental results show that the refractive index and temperature sensitivities are 8.1498rad/RIU (the RI range of 1.331-1.387) and -0.05rad/°C (the temperature range of 20 °C-90 °C), respectively. In addition, the proposed sensor is attractive due to its simple production process, compact size and low cost.