Characterization and Design of a Porous Core Photonic Crystal Fiber for THz Wave Guiding and Sensing

Abstract

In this work, the main attention is to develop Photonic Crystal Fiber (PCF) geometry that is applicable for THz wave propagation as well as in analytes sensing applications. Recently lots of researchers have developed their PCFs with low losses and high sensitivity. Optical properties of PCF based devices depend on the geometrical properties. So it can be said that there is a huge scope to develop the properties by changing the geometrical parameters. Based on the above mentioned situation, a PCF with sectored roundabout core is proposed. The cladding region follows the same sectored circular design also. Topas is used as a background material for both cladding and core region of designed fiber because Topas contains low material absorption loss with a consistent refractive index inside at a wide range of frequency. Guiding properties of developed PCF are investigated through Comsol Multiphysics v5.3 a with finite element method. Due to the strategic geometrical optimization, it renders improved performances in most of the crucial cases. It exhibits ultra-low effective material loss of 0.022 cm-1 at 0.9 THz, besides, near-zero flatten dispersion is observed in the wide THz spectrum. Moreover, to ensure the suitability of proposed PCF, other significant guiding properties such as confinement loss, effective area, and v-parameter, etc. are observed in the same THz frequency range. Lots of recent researches proved that PCF has the huge potentiality in analytes sensing cases. For example biomedical, gas sensing, analyte sensing, blood component sensing, alcohol and toxic sensing applications with high sensitivity and it is proved that PCF is a strong candidate in the field of sensing. Considering the above mentioned fact, our developed PCF structure has also been investigated for THz sensing cases with different analytes of various refractive indices. Cladding holes of the proposed geometry are filled with only air and core holes are filled with different liquid analytes having different refractive indices. At optimal design condition a high sensitivity of 91.8% , 92.0% , 92.2%, 92.3% and 92.4% and low confinement loss of 2.88 × 10-9cm-1, 2.69 × 10-9cm-1, 2.502 × 10-9cm-1, 2.308 × 10-9cm-1, 2.11 × 10-9cm-1 have been achieved for refractive indices of 1.33,1.34, 1.35, 1.36, and 1.37 respectively. Besides, a moderate effective area and low EML have also been achieved. Fabrication feasibility of the demonstrated design is a key concern for any researcher. The proposed PCF based waveguide and sensor is constructed by circular sectored core and cladding. By using extrusion technique, various types of structure have been fabricated by Max Plank Institute and the procedures of fabrication of the proposed design have been discussed in details. Finally, the outcomes and contribution of proposed design is highlighted in this research. The proposed design is applicable in both waveguide application for data transmission and in sensing application for detecting a wide variety of chemicals in industrial and chemical sector 1