Optimization and analysis of rectangular photonic crystal fiber sensor for detection of methanol, ethanol, propanol and water in THz regime

Abstract

The rectangular hollow core Photonic Crystal Fiber (PCF) sensor is designed for sensing and detection of various chemical compounds in terahertz regime. The hollow rectangular core of the proposed sensor is surrounded by 12 different types of hollow rectangles and two types of 8 squares configuring the cladding region of PCF. The simulation results of the proposed PCF sensor design are obtained from COMSOL Multiphysics v6.0 software which is based on finite element method. The shape, size, position, pitch and number of rectangles used in configuring the core and cladding regions of the design including fiber radius are taken into consideration for optimization of the sensor performance. The performance evaluation of the proposed sensor model is based on the analysis of effective loss of material, birefringence, confinement loss, effective surface area, numerical aperture and relative sensitivity in (1.0–2.5) THz frequency band. All these optical parameters are evaluated at operating frequency of 2.5 THz corresponding to both x- and y- polarizations for analytes methanol, ethanol, propanol and water loaded separately into fiber core except birefringence. This sensor can detect and classify the various chemical compounds based on their refractive indices. Simulation results demonstrate that the proposed sensor loaded separately with methanol, ethanol, propanol and water possess the maximum relatively sensitivity of 96.709%, 97.61%, 98.05% and 97.05% at 2.5 THz, respectively corresponding to y-polarization. Moreover, the confinement loss of the sensor reaches to nearly zero for both polarizations under the influence of all samples between frequency range 1.2 THz to 2.5 THz. Furthermore, a superficial effective loss of material is noticed for sensing of three varieties of alcohols investigated here. The geometry of the proposed PCF sensor design can be a better alternative of developing suitable sensors in the field of biological sample detection, construction, miming, alcohol industry, micro-optics and other THz related technologies.