▎ 摘　　要

Graphene and its derivative graphene oxide (GO) have been the focus of attention in the field of chemical and biological sensing. In this paper, we report a fiber-optic sensor for chemical gas sensing by using graphene oxide coated microfiber knot resonator (GMKR). The refractive index of GO was changed when the gas molecules were adsorbed to the surface of GO, and the gas concentration varying induced refractive index change can be detected by measuring the interference fringes shift of the GMKR. The experimental results show the sensitivities of similar to 0.35pm/ppm for NH3 and similar to 0.17pm/ppm for CO detection, due to the different adsorption energy and charge transfer ability between the gas molecules and GO. Experimental results show GO is a promising candidate for gas sensing and can be combined with various fiber-optic devices due to the easy transfer process. (C) 2016 Optical Society of America