Wave phenomena in nonlinear disordered optical media

非线性无序光学介质中的波动现象

基本信息

批准号：
11640373
负责人：
TOMITA Makoto
金额：
$ 2.3万
依托单位：
Shizuoka university
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We investigated both experimentally and theoretically the wave phenomena in nonlinear disordered optical media.[1] Two-beam pump-probe method in space and time domainsWe proposed and theoretically analyzed a new method of two-beam pump-probe method in space and time domains. As a result, besides the signal term, which reflects the temporal and spatial response of material, we found parametric coupling phenomena that suggest that two laser beams injected onto the nonlinear disordered optical media are coupled through the fluctuation effect.[2] Stimulated emission and absorption in disordered mediumWe applied the above new technique to investigate the gain volume of random laser. In this experiment, two excitation laser beams just below the threshold of the random laser were injected on the disordered medium and the spectral width of the luminescence was monitor as a function of the spatial distance of two beams. We experimentally found that the gain volume is relevant to the transport mean free path and the absorption length and the volume is uniquely represented using an equation which includes these parameters. The computer simulation was also performed and the simulation well explains the experimental results.[3] Observation of the memory effect by using the parametric coupling phenomenaWe examined the memory effect, which means that waves in disordered medium still retain the information on the wavefront, using the above parametric coupling phenomena. We have clearly demonstrated the coupling phenomena by a series of detailed experiments on LiNbO3 as the nonlinear disordered medium.

我们从实验和理论上研究了非线性无序光学介质中的波动现象。[1]空时域双光束泵浦探测方法提出了一种空时域双光束泵浦探测方法并进行了理论分析。结果，除了反映材料的时间和空间响应的信号项之外，我们还发现了参数耦合现象，表明注入到非线性无序光学介质上的两束激光通过涨落效应耦合。 [2]无序介质中的受激发射和吸收我们应用上述新技术来研究随机激光的增益体积。在该实验中，将两束刚好低于随机激光阈值的激发激光束注入到无序介质上，并监测发光的光谱宽度作为两束空间距离的函数。我们通过实验发现增益体积与传输平均自由程和吸收长度相关，并且使用包含这些参数的方程唯一地表示增益体积。还进行了计算机模拟，模拟很好地解释了实验结果。[3]利用参量耦合现象观察记忆效应我们利用上述参量耦合现象研究了记忆效应，即无序介质中的波仍然保留了波前的信息。我们通过一系列详细的实验，以 LiNbO3 作为非线性无序介质，清楚地证明了耦合现象。