Study On Holographic Characteristics Of Au-nanoparticle/Photopolymer Compound Materials

The excellent holographic storage properties of acrylamide based photopolymer materials havemade them become the hot spot of current research in high-density holographic storage field. In recentyears, a variety of nanoparticles were dispersed into the photopolymer system by researchers in order tofurther enhance the holographic performance parameters of materials such as diffraction efficiency,refraction modulation, exposure sensitivity and dynamic range. Gold nanoparticles was one of the mostwidely used nanomaterials, and with a high electron density, high dielectric properties and catalysis, can becombined with a variety of biological macromolecules. In this paper, the gold nanoparticles were dispersedinto hydrophilic acrylamide based photopolymer, the preparation method of gold nanoparticle sol and theholographic characteristics of gold nanoparticle dispersed photopolymer were studied and discussed.At first, the gold nanoparticles coated with citrate ions were fabricated by the method of sodiumcitrate reduction of gold chloride acid. SEM image display that the gold nanoparticles with goodmonodisperse and the particle size uniformity. Compared with the XRD data of gold bulk material wefound that gold grain is still the face-centered cubic structure. According to Scherrer’ s formula, the averagegrain diameter19nm can be estimated by the each half-height peak width and the Bragg angle. The goldnanoparticles were dispersed into photopolymer uniformly by the improved preparation method. A optimalgold nanoparticles doping concentration was obtained by test the holographic performance parameters ofsamples doped with different concentrations of gold nanoparticles. The experimental results wereconsistent with thermodynamic equilibrium conditions. With the8.463×10-5mol/L doping concentrationsof gold nanoparticles, the diffraction efficiency of the sample have a improvement of15%, the shrinkagerate can be reduced to0.8%.Secondly, Five particle size of gold nanoparticles were manufactured by single-step reduction,two-step reduction and seeding method, respectively. The average particle diameter of five types of goldnanoparticles can be estimated by analyzing the absorption spectrum, they are6nm,12nm,19nm,26nmand40nm, respectively. Different particle size gold nanoparticles were dispersed into the photopolymersamples, the holographic parameter of each samples was tested, and the results showed that the maximum diffraction efficiency of photopolymer doping with12nm gold nanoparticles were increased to90%, theBragg mismatch were reduced to0.04°. compared to the pure sample, the shrinkage phenomenon of dopingsamples were suppressed significantly during exposure. The experimental results were analysed by theRayleigh scattering formula and the square wave particle size formula.Finally, the analog holographic storage and digital holographic storage were experimented on theoptimized photopolymer samples. The experimental results show that the diffraction reconstructed imagewas clear, signal to noise ratio and bit error rate of the data page within the acceptable range, this showsthat the materials of photopolymer doped with gold nanoparticles is expected to be applied in high densitydigitized holographic storage.