The Relation Between The Random Laser Of ZnO Powder And The Density Of Scatterers

The random laser is a new kind of laser that has special theorem which people have discovered in recent years.Up to now,there are two opinions about the formation of the random laser:one is random laser with coherent feedback;the other is random laser with incoherent feedback.And there are many kinds of ways and means to research the random laser which has unusual optic characteristic and will be applied widely.This thesis is based on the National Natural Science Foundation of China "a relevant study of the new mechanism on lasing in random media","nonlinear effects at the low light levels" and "single photo laser",we have researched the relation between ZnO powder and the density of scatterers.In this paper we focused on the density of scatterers which is an important parameter in researching the random laser and researched the restriction on the density of scatterers,the relation between laser about different of the modes and the density of scatterers,the spatial of optical field in random media with different filling densities of the same material particles.The key points of this thesis are presented as follows:1.The history of the random laser and the comparer between the random laser and conventional laser.2.The actuality of the random laser including the evolving of the random laser,the optic characteristic,and the view of application.3.Based on the theory of random laser with coherent feedback and taken the ZnO powder for example,we found that the laser would appear only when the density of scatterers exceed a critical value,and the more scatterers,the easier to achieve laser radiation after researching the relation between random laser and the density of scatterers.The relation between the density of scatterers and the laser of different modes was also studied;we found that the laser whose mode in the center of plus would be radiated earlier.4.The spatial of optical field in random media with different filling densities of the same material particles.Results show that when the scattering mean free path is close to the wavelength,the optical fields are localized obviously in the random media.And with the particle filing density increasing,the localization becomes stronger.So with the same pump beam,it is easier to achieve laser radiation for random media with higher filling densities of scattering particles.