A Refractive Index Sensor Based on Four-Wave Mixing in D-Shaped Tellurite Photonic Crystal Fiber

In this study, we design a refractive index (RI) sensor using a novel cadmium telluride photonic crystal fiber (TPCF). Based on four-wave mixing (FWM), the changes in RI can be accurately detected, and RI sensing in the mid-infrared region (MIR) can be achieved by detecting wavelength shifts in the Stokes and anti-Stokes spectra caused by the changes in RI of the liquid to be measured. When the pump wavelength of FWM lies in the normal and abnormal dispersion regions of the TPCF, the RI response of the idler frequency wave and the signal wave are analyzed by numerical simulation methods. The simulation results show that the RI sensitivity of the sensor can be as high as 7692 nm/RIU with a linearity is up to 99.9% at the pump wavelength of 3380 nm. To our knowledge, the RI sensing sensitivity of the MIR is presented for the first time in this study by using FWM in the non-silicon PCF.