Study On Paper-based Reflective Random Laser Coated With Metal Particles

Random laser is caused by the incident light scattering through the scattering system,so it doesn’t need a fixed resonant cavity.Through the observation of real life,it is found that sandpaper particles meet the conditions of providing disordered structure,so sandpaper is used instead of resonant cavity.Gold nanostructures are deposited on sandpaper by evaporation,and the electromagnetic mode of free electron collective oscillation will be formed between metal and dielectric material by using the strong plasmon scattering characteristic of precious metal,which can produce significant electric field enhancement.Moreover,the strong constraint of active waveguide has the characteristic of reducing the pumping threshold.Based on the above properties,this paper mainly focuses on the characteristics of paper-based reflective thin film random laser coated with metal particles.The main research contents are as follows:1.Make a reflective random laser based on sandpaper.Select Rhodamine 6G(R6G)as the fluorescent dye,distilled water as the solvent,mix the curing agent and polyvinyl alcohol(PVA)oligomer in a ratio of 10:1 to form R6 G with a concentration of 3 mg/m L and PVA with 30 mg/m L mixture.The reflective random laser was pumped with 532 nm incident light,and the characteristics of the random laser emission spectrum under different energy densities were studied.The center wavelength of the random laser output was about 575 nm,and the full width at half maximum of the spectrum was stable at 5.nm,the threshold is about 14 m J/cm2.In order to detect the sandpaper meshes with the best random laser effect,a systematic experimental study was carried out on sandpaper with different meshes.Firstly,several experiments were carried out on sandpaper with different meshes,and it was concluded that the R6G-PVA waveguide layer was prepared on 7000 mesh sandpaper,and the laser output could be obtained.The experiment was carried out by changing the sandpaper mesh number for many times,and it was obtained that when pumped with a532 nm laser,8000 mesh sandpaper can get a low threshold,narrow linewidth laser output,while the spectrum of samples with other mesh sandpaper as the base is the ASE spectrum,which is not a real laser.By exploring the impact of sand on the laser scattering,a reasonable analysis of the experimental results is made.3.In order to further study the influence of local plasmon characteristics on the preparation of plasmon feedback random laser,the feedback random laser coated with gold nanoparticles was prepared by spin coating method.Sandpaper(mainly composed of Si C)was used as substrate,and then PVA and R6 G mixed solvent was spin coated on Au NPs by spin coating.At this time,some sandpaper which can’t emit laser can emit laser,but the output threshold of sandpaper which can emit laser is lower,which is because metal nanoparticles provide plasmon feedback mechanism and enhance the fluorescence emission of gain materials.2.In order to further study the influence of local plasmon characteristics on the preparation of plasmon feedback random lasers,this paper uses spin coating to prepare feedback random lasers covered with gold nanoparticles,using sandpaper(the main component is Si C)as the substrate,Au NPs was vapor-deposited on the sandpaper,and then PVA and R6 G mixed solvent was spin-coated on the film by spin coating.A layer of metal film is vapor-deposited on the surface of the sandpaper.The localized surface plasmon properties of metal nanoparticles are sensitive to their size,material type,and refractive index of the external environment.Among them,under the influence of incident light,the metal particles will show obvious dipole resonance,and an enhanced electromagnetic field will be generated around the particles.This paper simulates the electric field distribution of metal nanoparticles and analyzes the different shapes of sandpaper particles,the different particle diameters,the different spacing between the two particles,and the different arrangements of the sandpaper particles,and the conclusions are that these factors are all Will affect the corresponding electric field distribution.