Terahertz refractive index sensor with high sensitivity based on two‐core photonic crystal fiber

This article contributes a highly sensitive novel refractive index (RI) sensor based on two‐core photonic crystal fiber (PCF) is proposed in the terahertz (THz) frequency regime. The sensing performance of the proposed RI sensor is based on the mode‐coupling theory. Two vertical cores of the PCF divided by the central air hole, act as two separate waveguides. The analyte whose refractive index being sensed is filled in the central air hole of the PCF. A full‐vector finite element method (FEM) approach is used to investigate the sensor. Numerical data reveal that the sensitivities of the proposed PCF are 672 600, 940480, 1035300, 1332200, and 1 827 300 nm/RIU for the RI sensing range of analyte from 1.30 to 1.33, 1.34 to 1.37, 1.38 to 1.40, 1.41 to 1.43, and 1.44 to 1.46, respectively. This indicates that the proposed RI sensor is highly sensitive to the refractive index of the analyte.