Simultaneous measurement of hydrogen and methane based on PCF-SPR structure with compound film-coated side-holes

A special photonic crystal fiber based Surface Plasmon Resonance (PCF-SPR) sensor having ability of polarization filtering is designed for the simultaneous measurement of methane and hydrogen. In order to enhance the spectral response to the target gas, four ultra-large side-holes are symmetrically introduced into the cladding layer and two of them are coated with different compound thin-films. All geometrical parameters would be optimized for the selective detection of specific gas. Combined with the side-hole structure and polarization filtering, the gas mixture of methane and hydrogen can be accurately measured without interfering with each other. The approach also can be broadened to the qualitative identification of multiple gases.