Study Of Optical Spectrum Characteristics Of GQDs-FBG

In recent years,according to a variety of coating technology,researchers combine the films formed by different materials with fiber Bragg gratings,the fiber Bragg grating on the cladding coating layer of the uniform symmetric or asymmetric periodic change of thin film to change the transmission properties of fiber Bragg grating in order to make new type of optical fiber sensor.For different occasions,people in the fiber grating coated dielectric film,metal film and nano-materials produced a different type of high sensitivity,good stability of the sensor,in the field of optical fiber communication and sensing to show their talents.And coating the nanometer material film on the fiber grating has become the research hotspot at this stage.Graphene quantum dots(GQDs),the formation of quasi zero hour graphene size carbon nano-materials,not only has the fastest conductive rate of graphene,the large specific surface area,the strongest thermal conductivity,the maximum mechanical strength,but also has high light absorption and luminous efficiency,unique,tunable optical properties and low toxicity,safety and environmental protection and so on.Although there are many researches on the coating of graphene and the carbon nanotubes on the fiber gratings,no reports have been reported on the research of coated polystyrene quantum dots on fiber gratings.Because of graphene quantum dots(GQDs)are compared with graphene and carbon nanotubes unique optical physical characteristics,so will the graphene quantum dot coating on the fiber Bragg grating,the spectral will show the special change.This thesis mainly studies coating fiber grating theoretically and experimentally,A kind of graphene quantum dots(GQDs)coating fiber grating is obtained and its spectral character is studied.This thesis mainly includes the following chapters:In the first chapter,the principle and development of coated fiber grating at home and abroad are summarized.Besides,the relevant knowledge of fiber grating and graphene quantum dot is introduced.In the second chapter,from the optical fiber theory to the fiber grating theory and the sensing theory,the parameters of the grating are analyzed in detail and verified by MATLAB software.In the third chapter,the principle of coated fiber grating is described in detail,and the photoelectric properties and adsorption characteristics of the graphene quantum dots are studied especially.The cladding anisotropic crystal grating model and cladding etched fiber grating were analyzed,and the simulation analysis was carried out by using MATLAB,OPtiGratting and Rsoft optical software.In the fourth chapter,the fiber grating of corrosive cladding is obtained in the preparation stage of the experiment,and the coating solution of the graphene quantum dots(GQDs)is prepared.Finally,the optical spectrum characteristics of GDs-FBG is studied and shows that the reflectivity first decrease and then increase,while the central wavelength has been redshift.And it is proposed to make the GQDs-FBG humidity sensor.This is a preliminary exploration for the production of new fiber grating sensors.