Modelling and simulation of novel liquid-infiltrated PCF biosensor in Terahertz frequencies

The liquid-infiltrated photonic crystal fibre (LI-PCF) is proposed for guiding terahertz radiation. Geometrical asymmetry is achieved by introducing a large ellipse in the core. By filling the ellipse with liquid cocaine, the optical properties of the photonic crystal fibre (PCF) are theoretically examined using finite element method-based COMSOL multiphysics software. At an operating frequency of 1 THz, the proposed LI-PCF demonstrates a sensitivity of 87.02% and confinement loss in the order of 10(-4) cm(-1). The PCF also demonstrates extremely low effective material loss <0.01 cm(-1), a birefringence of 0.018, large effective mode area of 1.11 x 10(5) mu m(2), a high numerical aperture of 0.45 and near-zero ultra-flattened chromatic dispersion of 1.4351 +/- 0.5883 ps/THz/cm. The design simplicity and high sensitivity, strong confinement factor, low material losses and high birefringence of the fibre suggest that the proposed fibre may be convenient for PCF-based cocaine sensing, for application in the security and defence industries.