提出一种基于纳米铜/石墨烯包覆光子晶体光纤的硫化氢传感方法.将两根单模光纤分别与实心光子晶体光纤进行粗锥熔接, 形成马赫-曾德干涉结构.先在光子晶体光纤表面包覆石墨烯薄膜, 再在石墨烯薄膜的表面沉积纳米铜形成复合敏感薄.当复合敏感薄膜吸附硫化氢气体时, 其自身折射率发生改变, 导致光子晶体光纤中纤芯与包层的光程差发生变化, 干涉波谷发生偏移.建立气体浓度与波长偏移关系, 实现硫化氢的低浓度检测.研究表明：该传感器的灵敏度为8.5 pm/ppm, 检测限为3.85 ppm, 在硫化氢浓度为0~80 ppm范围内呈现良好的线性和选择性, 其输出光谱呈现蓝移, 响应时间和恢复时间分别约为92 s和119 s.该传感器成本低、结构简单、制作容易, 有望应用于硫化氢气体的探测.

A hydrogen sulfide gas sensor based on Cu/Graphene composite membrane coated waist-enlarged tapered Photonic Crystal Fiber (PCF) is proposed and fabricated. The Mach-Zehnder Interferometer (MZI) is formed by fusion splicing a section of PCF which is sandwiched between two Single-Mode Fibers (SMF), and the air holes of PCF in the splicing regions are fully collapsed and formed two waist-enlarged tapers. The outside surface of PCF is coated with a layer of nano-Cu-deposited graphene by using a dip-coating technique. Cu-deposited graphene-coated PCF is to make the sensor produce high sensitivity. With the increasing concentration of hydrogen sulfide, the output wavelengths appear blue shift. In addition, a high hydrogen sulfide gas sensitivity of 8.5 pm/ppm, the limit of detection of 3.85 ppm and good linear relationship and selectivity are obtained within a measurement range of 0~80 ppm for H2S gas. The response and recovery time of the sensor are 92 s and 119 s, respectively. The experimental results show that the sensor has the advantages of low cost, high sensitivity and simple structure, especially suitable for low concentration and high sensitivity detection of hydrogen sulfide gas.