Research On Several Current Theoretical Subjects In Random Lasers

Random lasers, which deal with lasing phenomenon due to interaction between the optical wave and the amplifying random media, have become a hot subject in physics world. The investigations on random lasers present an important value both in theory and application. Several experiments of random lasers, especially coherent-feedback random lasers, have been reported in the past few years, thus many theoretical models have been developed to explain the experimental results. In this paper, we give our model to explain the experimental results following the previous experimental results and theoretical results. The paper is organized as follows.First we summarize the experimental results of random lasers, which include the preparation of sample, measurement of parameter and the lasing under different environments. The influence of lasing due to the change of sample configuration will be intensively discussed.In the second part we give a summary of the current development of the theoretical results in random lasers. The diffusion model, time-dependent theory and Anderson localization model will be introduced in details.Thirdly the quasistate-mode theory will be presented. After discussing the principle of quasistate-mode theory, we use this theory to investigate the 1-D and 2-D random lasers. By incorporating a well-established FDTD (finite-difference time-domain) method, we calculate series results including the temporal evolution of quasistate-mode, spatial and spectral distribution of amplitude and the quasistate-mode enhancement. Our theoretical results can explain the experimental results perfectly.In the last section based diffusion model, we study the temporal evolution and the saturation of the emission from two-photon pumping random lasers. From the results we present an idea that the random laser can be used in as an anti-forge device.