Methane Gas Sensor Based on Microstructured Highly Sensitive Hybrid Porous Core Photonic Crystal Fiber

Md Ranju Sardar,Mohammad Faisal

doi:10.4236/jst.2019.91002

Abstract

We have demonstrated and analyzed the methane gas sensor based on octagonal cladding and hexagonal hybrid porous core photonic crystal fiber (HPC-PCF) for gas detection purpose. The proposed design of HPC-PCF has been numerically investigated by COMSOL Multiphysics software through utilizing the full vectorial finite element method (FEM). The optical characteristics of HPC-PCF as well as confinement loss, relative sensitivity and refractive index, effective area, nonlinearity and numerical aperture are optimized properly by changing the geometrical parameters as well as air filling ratio, air hole diameter, pitch constant of cladding and porosity of the core. In this simulation work, we have achieved optimum relative sensitivity of 21.2%, and confinement loss of 0.000025 dB/m at 3 μm pitch, 0.7 air filling ratio of the cladding and 29% porosity of the core for 3.5 μm absorption wavelength of CH4 gas. This proposed design of HPC-PCF will keep exclusive contribution for detecting the CH4 gas accurately.

Highlights

Conventional optical fiber technology provides greater bandwidth services and excellent data accuracy than copper wire in telecommunication systems
We have demonstrated and analyzed the methane gas sensor based on octagonal cladding and hexagonal hybrid porous core photonic crystal fiber (HPC-PCF) for gas detection purpose
When the refractive index of the core is large with respect to cladding, the HPC-PCF confines the optical signal in the core by utilizing modified total internal reflection (MTIR) technique [5]

Summary

Introduction

Conventional optical fiber technology provides greater bandwidth services and excellent data accuracy than copper wire in telecommunication systems. On the other hand, when the refractive index of the core is low with respect to cladding, HPC-PCF confines the optical signal in the core by utilizing PBG effects [6] [7] where length of wavelength is greater than silica gap between two air holes of cladding. The HPC-PCF is optimized by changing the geometrical parameters like air hole diameter, air filling fractions, pitch constant and porosity of the core In this design, 3 μm pitches, 0.7 air filling ratio of cladding and 29% porosity of the core are chosen as optimum value, since in these values, we have obtained the highest relative sensitivity of 21.2%, and minimum confinement loss of 0.000025 dB/m at 3.5 μm absorption wavelength of CH4 gas than other values. The prime dream of proposed design of HPC-PCF is to improve relative sensitivity and decrease confinement loss at minimum level that will sense CH4 gas accurately

Experimental Set up and Sensing Mechanism of Proposed HPC-PCF

Signal Confinement Technique of HPC-PCF

Equations

Simulations

Findings

Conclusion