Theoretical analysis of a refractive index sensor based on a photonic crystal fiber with a rectangular core

In this study, a photonic crystal fiber (PCF) sensor is proposed for refractometric sensing. The proposed PCF sensor includes a single rectangular core and 32 rectangular air holes in the cladding region that have the same width and height as the core rectangle. The fiber substance used is Zeonex. The finite element-based COMSOL 5.6 program is used to numerically analyze the model. The simulation confirms the suggested PCF capability to identify the analyte samples with extremely high sensitivity. A frequency range of 1.5–3.0 THz was adopted. At an operating frequency of 2.8 THz, many performance metrics are calculated. Extremely low effective area (6.3575 × 10 4 µm 2 ), effective material loss (0.00222 cm − 1 ) and confinement loss (0.52772 × 10 − 14 ) have been obtained with the proposed sensor. Extremely high-power factor (98.128%), birefringence (3.3 × 10 − 3 ), numerical aperture (0.23319) and relative sensitivity (98.876%) have been also obtained with the current PCF sensor. Moreover, the fabrication possibility of the proposed sensor is further assured by the PCF design’s simplicity.