Optimization and enhancement of liquid analyte sensing performance based on square-cored octagonal photonic crystal fiber

This paper presents an optimum design for highly sensitive square-cored octagonal photonic crystal fiber (S-OPCF) based liquid sensor. Full vectorial finite element method (FEM) with perfectly matched layer (PML) circular boundary has been applied to investigate propagation characteristics of proposed structure, in which both core and cladding are microstructured. Ring numbers, air filling ratios both in core and cladding area and structural shapes in core region are varied to examine sensitivity and confinement loss. According to simulation, five-ring S-OPCF structure is designed and optimized different parameters. The proposed S-OPCF significantly enhances sensitivity and reduces confinement loss for the optimized parameters. Finally the S-OPCF structure improves the sensitivity 1.16, 1.21 and 1.24 times for water, Ethanol and Benzyne analytes respectively compare to prior structure. In addition to this, the proposed structure operates for a wide range of wavelength from 0.6 μm to 2.2 μm with larger effective area and also suitable for nonlinear applications.