Studies for estimation method of nonlinear optical crystals by using phonon imaging technique

声子成像技术非线性光学晶体估计方法的研究

基本信息

批准号：
13554009
负责人：
ADACHI Satoru
金额：
$ 9.15万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Im present work, we aimed the estimation of the crystal quality via the detection of the phonon scattering by the defect and so on by using our developed phonon-polariton imaging technique. We have performed the imaging experiment for the LiTaO_3. The phonon generation and monitoring of the propagating polariton wavepackets have been imaged. Illuminating the delayed pulse into the crystal in order to probe the generated phonon-polariton wavepackets, we could construct the image of the wavepackets at the real time within the temporal resolution of the used pulse. The phonon polariotn is really the modulation of the refractive indices and therefore the phase object. Although it is impossible usually to detect the phase of the scattered light since our detection ability is sensitive only to the intensity of the light, the conversion from the phase information to the intensity information can be achieved by using Talbot effect. We have succeeded to capture the interference of the phonon polariotn wavepackets at the real time via the special arrangement. Also we could control the amplitude of the propagating phonon polariton wavepacket within some extent. The obtained results can contribute greatly to the phonon spectroscopy and indicated the new direction of the research. By using the similar four-wave mixing technique, we could estimate the sample quality of the bulk GaN, which is the promising material for the laser diode and so on, via the phonon scattering and exciton-exciton interaction, and found the heterobiexciton. The hetero biexciton consists of the heavy-hole and light-hole excitons and we found the heterobiexciton in GaN for the first time.

在目前的工作中，我们的目标是利用我们开发的声子极化子成像技术，通过缺陷等引起的声子散射的检测来估计晶体质量。我们对LiTaO_3进行了成像实验。声子的产生和传播极化子波包的监测已经被成像。将延迟脉冲照射到晶体中以探测生成的声子极化子波包，我们可以在所用脉冲的时间分辨率内实时构建波包图像。声子极化实际上是折射率的调制，因此也是相位物体的调制。虽然我们的检测能力只对光的强度敏感，通常不可能检测到散射光的相位，但利用塔尔伯特效应可以实现相位信息到强度信息的转换。通过特殊的布置，我们成功地实时捕获了声子极化波包的干涉。我们还可以在一定程度上控制传播的声子极化子波包的幅度。所得结果对声子光谱学有很大贡献，并指明了研究的新方向。通过使用类似的四波混频技术，我们可以通过声子散射和激子-激子相互作用来估计块状GaN（激光二极管等有前景的材料）的样品质量，并发现异质双激子。异质双激子由重空穴激子和轻空穴激子组成，我们首次在GaN中发现异质双激子。