Design and Sensitivity Improvement of Microstructured-Core Photonic Crystal Fiber Based Sensor for Methane and Hydrogen Fluoride Detection

Abstract

This paper describes a gas detection sensor that is based on a microstructured-core photonic crystal fiber (PCF). The finite element method (FEM) is used to analyze the quantitative dependence of guiding properties on geometrical parameters along wavelength. The result shows that the structure provides high relativity sensitivity with minimal confinement loss for detecting various gases such as methane (CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) and hydrogen fluoride (HF) because the proposed PCF introduces microstructured-core. According to the results of this simulation, an absorptive line of CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> /HF gases could have a maximum relative sensitivity of about 44.47% at wavelength of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.33 ~\mu \text{m}$ </tex-math></inline-formula> with the optimal design of the PCF. The proposed sensor has a confinement loss of around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.83\times 10}^{-8}$ </tex-math></inline-formula> dB/m, that is very low and suitable for use as a gas sensor. Furthermore, numerical aperture (NA), V-parameter, Marcuse spot size (MSS), and beam divergence (BD) are extensively investigated in the wavelength range of 1.3 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.2 ~\mu \text{m}$ </tex-math></inline-formula> . These findings should aid in the development of a high-efficiency PCF for gas sensing and monitoring air pollution.

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