Hybrid Graphene-Microfiber Waveguide for Chemical Gas Sensing

Graphene has been attracting great interest as the basis of novel photonic devices and sensors due to its many unique optical and electric properties that are quite different from conventional film materials. In this paper, we propose and demonstrate a novel hybrid graphene-microfiber waveguide structure and its application to chemical gas sensing for the first time to our knowledge. As the complex refractive index of the extremely thin graphene film (<1 nm) can be easily modified by chemical gas molecules distributing on its surface, the transverse electric mode surface wave intensity is sensitive to gas concentration. Such an intensity modulation induced by gas molecules can be detected via the coupling of evanescent field between the graphene waveguide and the microfiber. A sensitivity of 0.31 dB/100 ppm and good reversibility are observed experimentally for acetone vapor gas sensing. It is believed that this hybrid waveguide structure could open a new window to realize a variety of graphene-based photonic sensors, for potential applications in the fields of biology, medicine, and chemistry.