Polarization independent and ultra-fast optical response in quantum dot nanostructures for optical amplifier

用于光学放大器的量子点纳米结构中的偏振无关和超快光学响应

基本信息

批准号：
17360142
负责人：
KITA Takashi
金额：
$ 8.77万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360142/
关键词：
Quantum dot Columnar quantum dot Stacked growth Polarization independence Ultra fast optical responce Optical communication Epitaxial growth

项目摘要

Optical amplifier is indispensable for future optical communication systems. Semiconductor optical amplifier (SOA) is desirable in low cost and compactness, but it has a serious problem of optical polarization anisotropy. We must realize polarization-independent characteristics for their use in real systems. To overcome the optical polarization anisotropy problem, we focus on the columnar QDs that can be grown by closely stacking Stranski-Krastanow-mode InAs-QD layers. The aspect ratio of the QDs can be controlled by changing the stacking layer number (SLN). It is expected to enable polarization-independent SOA by using this technique.SLN dependence of the polarization characteristics in edge-luminescence has already been investigated in columnar QDs. From this research it was found that TM mode intensity is being dominated with increasing SLN. This TE mode and TM mode intensity ratio is turned over between 7 and 9 layers, so polarization-independent characteristics is realized in this region. The polarization-independent characteristics must be achieved not only in luminescence but also in gain characteristics for practical use in real systems. So we have investigated optical gain of columnar QDs by using variable stripe length (VSL) method in which optical excitation length is varied with monitoring the amplified luminescence from the sample edge. The optical gain has been found to sensitively depend on the SLN. With increasing the SLN, the TM-sensitive optical gain has been demonstrated. Furthermore, we have obtained almost polarization insensitive optical gain sample with seven staking layers.

光放大器对于未来的光通信系统来说是不可或缺的。半导体光放大器（SOA）具有低成本和紧凑的优点，但它存在严重的光学偏振各向异性问题。我们必须实现偏振无关的特性才能在实际系统中使用。为了克服光学偏振各向异性问题，我们重点研究可以通过紧密堆叠 Stranski-Krastanow 模式 InAs-QD 层来生长的柱状 QD。量子点的长宽比可以通过改变堆叠层数（SLN）来控制。预计通过使用该技术能够实现与偏振无关的 SOA。边缘发光中偏振特性的 SLN 依赖性已经在柱状 QD 中进行了研究。这项研究发现，TM 模式强度随着 SLN 的增加而占主导地位。该TE模式和TM模式强度比在7层和9层之间翻转，因此在该区域实现了与偏振无关的特性。不仅在发光方面而且在实际系统中实际使用的增益特性方面都必须实现与偏振无关的特性。因此，我们通过使用可变条纹长度（VSL）方法研究了柱状量子点的光学增益，其中光学激发长度随着监测样品边缘的放大发光而变化。已发现光学增益敏感地取决于 SLN。随着SLN的增加，TM敏感的光学增益已经被证明。此外，我们还获得了具有七个堆叠层的几乎偏振不敏感的光学增益样品。