A Methane and Hydrogen sensor with Surface Plasmon Resonance-Based Photonic Crystal Fiber

A photonic crystal fiber (PQF) sensor based on surface plasmon resonance (SPR) is designed for simultaneous detection of methane and hydrogen. In the sensor, Pd-WO3 and cryptophane $\mathbf{E}$ doped polysiloxane films deposited on gold films are the hydrogen and methane sensing materials, respectively. The PQF -SPR sensor is analyzed numerically by the full-vector finite element method and excellent sensing performance is demonstrated. By studying the resonance effect of different thickness of gold layer and sensitive material and different position of gas passing through, we found the thickness of gold layer and sensitive material and the ventilation position of hydrogen and methane that make the sensitivity of hydrogen and methane the highest under the condition of keeping a low loss. In the concentration range of 0% ~ 5%, the average sensitivity of hydrogen is about 0.02nm/%, and that of methane is about 0.005nm/% in the concentration range of 0% ~10%. The sensor has the ability to detect multiple gases simultaneously, which has great potential for equipment miniaturization and remote monitoring and is suitable for compact optical fiber communication systems.