二维随机介质中的能量分布和频谱特性

研究了二维随机介质中能量的空间分布和一些特定区域的频谱特性.结果显示介质中能量呈局域化分布，其分布与介质中颗粒的随机分布有关，还与激发光的波长有密切的关系，介质中能量聚集的区域和介质的准封闭区域有一定关系但并非一一对应.所考察的各准封闭区域的频谱均随时间变化，在同一激发光的激励下各准封闭区域的频谱均不相同，而同一区域在不同的激发光的激励下频谱也不相同.当激发波长与准封闭区域的结构参数偏差较大时，频谱中谱峰会出现此消彼涨的模式竞争现象，而且能量衰减得较快；而当激发波长与该结构参数较接近时，相应的频谱中存在一 关键词： 激光物理 有限时域差分法 局域化 频谱特性

The spatial energy distribution and the spectrum characteristics in a two-dimensional random medium

The spatial distributions of energy in a random medium and the spectrum characteristics of some regions in this medium are studied and the results show that the energy is localized in some regions and the spatial distribution of the energy is both related with positions of the particles in the medium and the wavelength of excitation light. And the regions of energy congregation are related with the quasi-closed structures formed from the particles but no one to one correspondence exists between them. Under the stimulating of the same excitation light, different spectra appear in different quasi-closed structures and they change with time. And under the stimulating of different excitation light sources, the spectra of the same quasi-closed structure are different. When the wavelength of exci tation light does not match the configuration parameter of a quasi-closed structure, the peaks of its spectrum will change frequently and the energies of the peaks are attenuated quickly. When the wavelength of the light be ther matches the configuration parameter of the quasi-closed structure, a certain peak will retain its leading position in height in the spectrums and its energy attenuate but slowly. So photon-localization is both related with the configuration of medium and the wavelength of excitation light, and the random lasing can be regarded as the result of the general scattering effect of the excitation light by the random medium.