权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Generation of electrical signals in THz band from coherent charge dipoles in microcavities

从微腔中的相干电荷偶极子生成太赫兹波段的电信号

基本信息

批准号：
12305006
负责人：
YAMANISHI Masamichi
金额：
$ 28.7万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In this project, we aimed at the generation of THz-electrical signals from coherent charge dipoles in semiconductor quantum wells (QWs) by exciting them with sub-picosecond laser pulses, and also at applying THz electrical signals to the semiconductor microcavities, where polariton mode oscillation is excited. For this purpose, after preparatory experiments for the building a measurement setup using co-planer microstrip lines, we designed a microstrip line structure, where dc and THz electric fields can be applied perpendicularly to the QW plane. From the numerical analysis based on finite difference time domain (FDTD) method, we found that an in-line gap structure can be used for this purpose. Using the fabricated such kind of devices, we successfully observed THz electrical signals, whose rise-time is about 400 fs, using a QW as a detector. Then, we searched the conducting line materials, which allow us a optical access through the line. We decided to use ITO films as a candidate of such a material. After the establishment of fabrication process, we successfully formed a microstrip line device based on ITO. Although the properties are not satisfactory, we could observe an electrical signal perpendicularly applied to the QW plane. During the investigation, we found that even with a single microstrip line, THz signals can be guided if the propagation distance is not too long. Such a guiding mode may be useful in some kind of applications. We also investigated the polariton mode oscillation in semiconductor microcavities under static electric field, and found that the phase of the oscillations vary with the change of the electric field and that the phase change suggests strongly that the variation of exciton-exciton interactions, which is a key factor in excitonic nonlinearity. To the best of our knowledge, this is the first observation of the alteration of exciton-exciton interactions.

在这个项目中，我们的目标是通过用亚皮秒激光脉冲激励半导体量子井(QW)中的相干电荷偶极子来产生THz电信号，并将THz电信号施加到半导体微腔中，在那里激发偏振子模振荡。为此，在利用共面微带线构建测量装置的前期实验后，我们设计了一种可以垂直于量子波平面施加直流和太赫兹电场的微带线结构。从基于时域有限差分(FDTD)方法的数值分析中，我们发现可以使用串联间隙结构来实现这一目的。利用这种器件，我们成功地观测到了上升时间约为400ps的太赫兹电信号，并用量子阱作为探测器。然后，我们搜索了导线材料，这些材料允许我们通过这条线路进行光学访问。我们决定使用ITO薄膜作为这种材料的候选材料。在确定了制作工艺后，我们成功地形成了基于ITO的微带线器件。虽然性质并不令人满意，但我们可以观察到垂直于量子波面的电信号。在研究过程中，我们发现，即使只有一条微带线，在传输距离不太长的情况下，也可以引导太赫兹信号。这样的引导模式可能在某些类型的应用中有用。我们还研究了静电场作用下半导体微腔中的极化激子模振荡，发现振荡的相位随着电场的变化而变化，并且这种相位变化强烈地表明激子-激子相互作用的变化是激子非线性的一个关键因素。据我们所知，这是第一次观察到激子-激子相互作用的变化。