Highly Sensitive Nonlinear Temperature Sensor Based on Modulational Instability Technique in Liquid Infiltrated Photonic Crystal Fiber

A highly sensitive nonlinear temperature sensor, which is based on modulational instability (MI) process, is theoretically demonstrated for the first time using a CS2-filled photonic crystal fiber (CSPCF). The proposed novel temperature sensor works on the principle of measurement of a temperature-dependent wavelength shift of generated Stokes and anti-Stokes MI Sidebands. Based on the notion of MI dynamics, the performance of the proposed temperature sensor is studied in both anomalous and normal dispersion regimes of an appropriately designed CSPCF. It is found that the sensitivity of the proposed nonlinear temperature sensor is very low when the CSPCF is pumped in the anomalous dispersive region. However, the sensitivity is enhanced by more than 66 times using Stokes line in the normal dispersion regime. The proposed sensor is optimized by varying the structural parameters and pump parameters, such as pitch, air-hole diameter, pump wavelength, and pump power. The proposed nonlinear temperature sensor, which is made up of an appropriate structure of CSPCF having a length of 13 cm exhibits a sensitivity of -82 nm/°C using Stokes line and 435 nm/°C using anti-Stokes line while pumped with a power of 100 W in the normal dispersive region.