Microscopic description of tunnel-injection quantum-dot lasers

该项目的目标是推进半导体激光器的设计，这有可能大大改善用于互联网的基于光纤的光数据通信。该设计是基于隧道注入（TI）结构与量子点（QD）作为活性材料，并承诺大大提高调制速度。设计的挑战在于不同纳米结构组件之间的相互作用：非均匀加宽的QD系综，TI势垒和用于载流子注入的体势垒材料。 这种设备的物理基础有几个要求很高的方面。载流子输运连接了三维、二维和零维结构，这些结构之间的载流子散射过程受多体效应控制，器件性能取决于隧道势垒存在时载流子动力学和增益特性之间的相互作用。由Johann Peter Reithmaier（卡塞尔大学）、Grzegorz Szirk（弗罗茨瓦夫理工大学）和Gadi Eisenstein（以色列理工学院）代表的该领域领先科学家联盟目前正致力于高速TI-QD激光器的实验实现及其各种光谱方法的表征。申请人已被邀请加入该联盟，该项目的结构目标是建立与所有三个团体直接合作的新框架。在第一个资助期内，发现了TI-QD激光器物理学的新的和意想不到的结果。量子点能级排列的LO-声子共振条件被证明是由纳米结构中的电子态混合和多体效应（极化子）引起的。相反，发现了TI屏障的光谱滤波器效应。只有将这种光谱滤波器与QD发射器的不均匀加宽分布适当对准，才有望改善TI-QD激光器的调制特性。根据这些新的见解，在第二个应用期间，将生长和表征新的激光结构。与此同时，理论模型将扩大进行直接的实验理论比较。我们的目标是一个微观的理解相关的物理基础的设备操作在TI-QD激光器和改进的发射过程的演示。

The goal of this project is to advance the design of semiconductor lasers, which have the potential to strongly improve fiber-based optical data communication as used for the internet. The design is based on a tunnel-injection (TI) structure with quantum dots (QDs) as active material and promises strongly improved modulation speed. The challenge for the design lies in the interplay between different nanostructure components: the inhomogeneously broadened QD ensemble, the TI barrier, and the bulk barrier material used for carrier injection. The physics underlying such a device has several demanding aspects. Carrier transport connects three-, two-, and zero-dimensional structures, the carrier scattering processes between these structures is governed by many-body effects, and the device performance depends on the interplay between carrier dynamics and gain properties in the presence of a tunnel barrier. A consortium of leading scientists in this field, represented by Johann Peter Reithmaier (Univ. Kassel), Grzegorz Sęk (Wroclaw University of Technology) and Gadi Eisenstein (Technion, Israel Institute of Technology) is presently working on the experimental realization of high-speed TI-QD lasers and their characterization with various spectroscopic methods. The applicant has been invited to join this consortium and the structural goal of this project is to establish the framework for a new direct collaboration with all three groups. In the first funding period, new and unexpected results for the physics of TI-QD-lasers were discovered. The LO-phonon resonance condition for the alignment of QD levels turns out to be suspended by electronic state mixing in the nanostructure and many-body effects (polarons). Instead, a spectral filter effect of the TI-barrier was discovered. Only with proper alignment of this spectral filter to the inhomogeneous broadening distribution of the QD emitters the improved modulation properties of TI-QD lasers are expected. According to these new insights, during the second application period, new laser structures will be grown and characterized. In parallel, theoretical models will be expanded to conduct direct experiment-theory comparisons. Our goal is a microscopic understanding of the relevant physics underlying the device operation in TI-QD lasers and the demonstration of improved emission processes.