Research On Fiber Gas Sensors Based Ongraphene Oxide

As a new sensor detection technology,optical fiber sensing technology has become one of the key technologies in the field of sensor research.The evanescent wave propagation characteristics of micro-nanofibers make it highly sensitive and extremely short response time in sensor detection,so it has a wide application prospect in optical sensor application.Meanwhile,graphene and its derivatives graphene oxide?GO?has also become a new type of sensitive material in the field of biological and chemical sensing research.In this thesis,the research on the optical fiber gas sensor is based on graphene oxide.The main contents are as follows:It is proposed to coat the graphene oxide film on the surface of the micro-nano fiber to form a hybrid waveguide structure.In this thesis,the mode field distribution of the optical signal transmitted in the composite waveguide structure and the transmission characteristics of the graphene oxide-micro fiber hybrid waveguide structure are discussed in detail.The composite waveguide structure is applied to the gas sensing area.In this thesis,the characteristics,transmission principle and preparation method of graphene oxide and micro-nano fiber are firstly introduced in detail,and the bonding method and specific steps of the graphene oxide and micro-nano fiber are discussed.Then,we analyze the sensing characteristics of this hybrid waveguide structure and analyze the effect of graphene oxide in the hybrid waveguide.Finally,the simulation software is used to simulate the mode field distribution of the hybrid waveguide.Lastly,this composite waveguide structure is applied to the optical fiber sensing experiment.The experiment of temperature sensing characteristics and gas sensing characteristics of graphene oxide-micro fiber hybrid waveguides were carried out respectively.The experimental results show the effectiveness and unique advantages of graphene-micro fiber composite waveguide sensor.This thesis also proposed an optical fiber sensor based on microfiber knot resonator?GMKR?coated with graphene oxide.When the gas molecules are adsorbed to the surface of GO,the refractive index of GO is changed,and then the change in refractive index due to gas concentration changes can be detected by measuring the interference fringe drift of GMKR.Because of the difference of adsorption energy and charge transfer between gas molecules and GO,the experimental results show that the sensitivity of NH₃ and CO is ⁰.34pm/ppm and ⁰.16pm/ppm respectively.Meanwhile,the experimental results show that GO is a promising material for gas detection and that it is very easy to combine with various fiber optic devices due to the simple preparation process,high transfer success rate and good consistency.