Polarization Control Of Random Laser Based On Plasmonic Feedback

Since random lasers provide feedback loops through a disordered system to achieve multiple scattering,a fixed cavity is not required.The characteristics of strong plasmon scattering in gold nanostructures on silicon rubbers,as well as the strong confinement properties of active waveguides,lower the pumping threshold and improve the conversion efficiency of random lasers.Its potential functions have been applied in the fields of cancer diagnosis and biosensing.Polarized light plays a very important role in human life.After the polarized light source propagates through the medium,we can still extract the polarization information such as the intensity,phase and spectrum of the original polarized light source in the output emission.Based on this,this paper is devoted to the mechanism research of random lasers,focusing on the regulation of polarization states,and has done the following research:(1)Due to the water-soluble properties of rhodamine 6G and PVA,we have made soluble and reusable random lasers based on metal nanoparticles and water-soluble polymers,which combine the properties of metal nanoparticles and organic semiconductors to study water solubility,sensing characteristics and repeatability of random lasers.Its low threshold center is 591 nm and the threshold is about 9.9 mJ/cm~2.As the immersion time is extended,the output emission intensity of the water-soluble random laser decreases,and the center wavelength is blue-shifted from 591 nm to 575nm.The performance of reconstructed water-soluble random lasers shows great potential in sensor applications.(2)In the fields of ocean optics,atmospheric optics,biology and medicine,polarization technology plays a very important role.A wavelength tunable random laser was prepared by spin coating method.The silicon rubber was used as the substrate,and the film was prepared by PVA,R6G and metal nanoparticle ternary composite process.Metal nanoparticles provide a plasmonic feedback mechanism that enhances photoluminescence of the gain material.The wavelength of the random laser emission is tuned by mechanical stretching,wherein the rearrangement of the metal nanoparticles has a large influence on the wavelength and polarization characteristics of the output spectrum.(3)The Localized Surface Plasmon Resonance of metal nanoparticles are sensitive to their size,material type,structural characteristics and refractive index of the external environment.Based on this characteristic,various sensing and signal enhancement studies can be performed.In this paper,the electric field distribution of gold nanoparticles is simulated.Among them,the discrete gold nanoparticles show obvious dipole resonance under the influence of incident light,and generate enhanced electromagnetic field around the nanostructure.At the same time,the corresponding electric field distribution is analyzed when the particle size of the gold nanoparticles is different,the spacing between the two gold nanoparticles is different,and when the plurality of gold nanoparticles are arranged in different ways.Under different illumination states,the polarization state of gold nanoparticles under the illumination of Gaussian beam is also affected,which provides a theoretical basis for the concentration of different gold nanoparticles in the experiment.