飞秒激光与基于安德森局域效应的无序介质相互作用的机理研究

项目名称： 飞秒激光与基于安德森局域效应的无序介质相互作用的机理研究

项目编号： No.10876010

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 无线电电子学、电信技术

项目作者： 王可嘉

作者单位： 华中科技大学

项目金额： 33万元

中文摘要： 在本项目中，我们提出并研究了随机激光辐射作为惯性约束核聚变系统中(ICF)种子光的探索性方案。随机激光来源于具有增益的无序介质，产生的物理机制是安德森局域效应。绝大多数的实验中，提供增益的泵浦光为纳秒级的脉冲激光。但在ICF中，产生种子光的光源为飞秒激光，因此必须从基本物理机理出发研究超短脉冲与无序介质相互作用产生随机激光行为。研究结果表明：飞秒级泵浦光的超短特性会影响随机激光辐射的特性：当激励脉冲峰值功率超过某个阈值时，受激辐射就会进入饱和输出状态，从而使输出光具有较高的稳定性；脉宽的增加会使输出光脉宽会变窄，可以达到飞秒级，峰值强度增加；由于激励光是超短脉冲，谱宽很宽，因此介质色散效不可忽略，计算结果表明色散效应使得随机激光拥有更多可能的输出模式。以上的结果为控制随机激光的输出特性提供了手段，表明如果采用随机激光作为ICF中的种子光，其输出特性可以由飞秒激励光直接控制，这就避免了现有产生种子光方案中需要经过产生、选频和再放大等复杂过程以及系统体积较大等问题。另外，本项目还研究了具有三能级结构红宝石颗粒构成的无序介质产生太赫兹随机激光行为。为获取新型太赫兹辐射源提供了一种技术方案。

中文关键词： 无序介质；飞秒激光；随机激光；色散；种子光

英文摘要： A proposal about using random lasing (RL) as the seed in the Inertial Confinement Fusion (ICF) system is presented and investigated in this project. RL origins from Anderson localization in a disordered media which is pumped by nanosecond pulsed lasers in previous experiments. As the source in ICF is femtosecond laser (fs-laser), the physical mechanism of RL generated from the interaction between fs-laser and disordered media, if used as see in RCF, must be fully investigated. Our research results showed that the characteristic of RL emission could be influenced and controlled by fs-laser. The intensity of RL, for example, will be saturated and stable when the peak power of fs-laser is over a threshold. To narrow the pulse width of RL, even to femtosecond, one can choose a proper pulse width of pump laser with a certain high peak power. Further analysis showed that the dispersion could generate more RL out mode since a fs-laser pulse has a wide bandwidth.Our results,generally,could provid a new method to generate a seed in RCF and overcome some shortcomings of traditional method, such as complicated generation process and huge size. In addition, we also demonstrated that a ruby disordered medium could support the THz wave to form random lasing under suitable conditions, indicating that it is possible to form terahertz random lasing, providing a way to obtain a new type of terahertz emitter.

英文关键词： Disordered media;Femtosecond laser;Random lasing; Dispersion; Seed