Dynamic Refractive Index Sensing of Water-Ice Phase Transition with a Single Fiber Grating

We show that a single titled fiber Bragg grating (TFBG) can perform in-situ monitoring of refractive index changes during a water-ice phase transition process. The resonant wavelengths of TFBG modes are sensitive to temperature, strain, and surrounding refractive index (SRI) variations, induced by the phase transition. Based on the differential wavelength shifts of different TFBG resonances, the temperature and strain effects can be calibrated and eliminated. Thus, the remaining wavelength shifts induced by SRI can be obtained for monitoring the water-ice phase transition.