The Fabrication Of Gold Nanoparticles Based On Optical Fiber Sensor And Its Optical Characteristics

The surface plasmon polariton can be formed when the photon interact with the free electrons on the surface of the metal.This behavior can makes the energy of the incident light field being limited to the surface of metal nanostructures,which result in a large local field enhancement effect.This feature can improve the sensitivity of optical fiber sensing or broaden the application field of optical fiber sensing.Therefore,the optic fiber sensors combined with metal nano materials have obtained a wide spread concern in the field of biological/chemical sensing.General methods of gold nanoparticles preparation have expensive etching method based on semiconductor micro processing technology and the easy impurities introduction of chemical method.In this paper,aiming at the shortcomings of the existing gold nanoparticles synthesis technology,new methods of gold nanoparticles preparation were attempted.The gold nanoparticles'optical properties were also studied.At last,optical fiber Raman sensing prober based on gold nanoparticles was produced.In the first chapter of this paper,the preparation methods of gold nanoparticles and the research progress of Au nanoparticles and optical fiber composite structures are briefly introduced.In the second chapter of this paper,based on the traditional buffer layer assisted growth metal nanoparticle method?buffer layer assisted growth,BLAG?,a new method was developed by using organic thin film as buffer layer.Gold nanoparticles and their aggregates were obtained using thermal annealing substrate-poly?PMMA?-Au film structure,the sizes of gold nanoparticles and the degree of nanoparticles'aggregation were controlled by the annealing temperature and the thickness of PMMA.The surface enhanced Raman scattering spectra of aggregated gold nanoparticles were detected,which results showed that the greater degree of gold nanoparticles aggregation,the stronger Raman peak intensity.In the third chapter of this paper,we developed a new self-assembly method to fabricate periodic Au nanoparticle arrays via pulsed laser induced dewetting.Different from the existing preparations of gold nanoparticles array which carried out on the thin film surface boundary modulation,the cyclical concave and convex substrate introduced an additional angle tilting when it was coated.This method achieved the same purpose the vertical direction of the thickness of the periodic modulation of the gold film.When it was annealed by pulsed laser,ordered gold nanoparticles arrays were obtained.Furthermore,experimental dates demonstrated that the self-assembly process was drived by the Rayleigh instability and the diameters and spacings of the periodic particles were all controlled by the initial period of template.In the fourth chapter,single crystal gold nanowires were grown on the MgO?110?lattice plane because of the mismatch of magnesium oxide?110?lattice plane with gold crystals?110?lattice plane.Then making the nanowires coupled with optical fiber tip,it showed significant optical conduction characteristics.In the fifth chapter,combined with the BLAG method and Wet etching transfer,composite film of graphene and gold nanoparticles were obtained.The composite film were obtained by heating copper-grapheme-PMMA-gold film.Then the buffer layer of PMMA assisted transfer the composite film to the multi-mode fiber end,which could be used as the fiber Raman sensing probe.The R6G Raman spectrum showed that the composite film can detect 10^-8mol/L concentration,which transferred to the optical fiber end face can detect 10^-77 mol/L molecules concentration.