Laser phenomena in random media have been studied based on the localized theory for lightwave in random media. The relationship between random lasing modes and localized modes has been investigated by directly solving Maxwell equations numerically via the finite difference time domain method. The spatial distribution and the spectra of localized modes are obtained for both passive and active random media. The results show that random lasing modes directly originate from the localized modes inside the random medium. In the presence of gain, any one of the localized modes can be amplified and can serve as random lasing mode.
传统系统不能在水中对振动频率和声辐射进行分析,存在分析效果差的问题,提出基于模态模型方法对船体薄板辐射响应变异性分析系统进行设计。架构船体薄板辐射响应变异性系统硬件框图,为了解决振动频率问题,需对结构中报警电路进行设计;针对硬件中的RS232转换器需对内部软件功能展开分析,利用模态模型分析声辐射耦合结果。由实验结果表明,该系统比传统系统辐射声功率等级高35 d B,分析效果较好,可在水中对振动频率和声辐射进行分析。
