Study On Localization And Controllable Localization Of Photons In Disordered Media

Light localization in disordered medium, which is based on Andersonlocalization, has attracted much attention in the world since1980s. The research oflight localization includes coherent backscattering, random laser, anisotropic lightlocalization, time-resolved measurements in disordered medium and so on. As theresearch of light localization goes deeper, scientists have found it very helpful inunderstanding the essential concept of condensed physics. At the same time it haswide potential in applications of laser physics, display technology, micro-/nano-photonic devices, biomedical fields and so on. As a new photonics technology, thelight localization has many difficult problems to be studied and solved in the basictheory and experiment technology fields. In this dissertation, we will focus on theexisting essential problems of light localization and do the relative researches. Theinnovative points, main contents, and results of the dissertation are concluded asfollows:(1) We experimentally studied light-controllable coherent backscattering of lightfrom a water suspension of uniaxial microcrystalline particles. Light-controllablecoherent backscattering of light from a water suspension of uniaxial positivemicrocrystalline particles was demonstrated for the first time. These effects were dueto the uniaxial positive microcrystalline particles’ reorientation behaviors induced bya linearly polarized pump beam. We also analyzed their reorientation behaviorstheoretically. They concluded the same trend as the experimental results. Thisresearch widely extends the materials which can be used in the light-controllablecoherent backscattering, and proves the regime of the reorientation behaviors ofuniaxial positive microcrystalline particles in a water suspension.(2) We experimentally studied wavelength dependence of light propagation in awater suspension of anisotropic microcrystalline particles. Firstly, the ballistictransmission in the visible range of the suspension was measured. The nonlinearrelationship was observed between the transport mean free path and wavelength ofthe incident light. Secondly, we measured the coherent backscattering of the sample at different wavelength. The full width at half maximum of the coherent backscatteringcone at532nm was about1.24times as large as that at671nm. The results indicatethat the light with long wavelength propagates further than the short wavelength lightand the localization state of the short one is stronger. Finally, we investigated thelight-controllable CBS experiments in the disordered material of anisotropicscatterers, which showed that the configuration of pump light with longer wavelengthand the probe one with shorter wavelength performed better.(3) A visible tri-wavelength upconversion luminescence macroporouserbium-doped lithium niobate was fabricated. The emission bands excited by a980nm diode laser were centered at660,550and450nm, respectively. Furthermore,coherent backscattering measurement showed that its transport mean free path was ona submicrometer scale. It indicates that macroporous LN:Er is a promising candidatematerial for developing visible multi-wavelength emission upconversion randomlaser.(4) We explored the development of an upconversion green light emittingrandom laser. The system was designed based on the macroporous erbium-dopedlithium niobate. We measured the spectral properties, thresholds and size dependence.Furthermore, we compared the experimental results and theoretical analysis, andsupposed that there were random lasing actions in the experiments. These workssupply a steady foundation for the development and application of upconversiongreen light emitting random laser.