Kainz Martin Alexander, Schönhuber Sebastian, Andrews Aaron Maxwell, Detz Hermann, Limbacher Benedikt, Strasser Gottfried, Unterrainer Karl
Photonics Institut, TU Wien, 1040 Vienna, Austria.
Center for Micro- and Nanostructures, TU Wien, 1040 Vienna, Austria.
ACS Photonics. 2018 Nov 21;5(11):4687-4693. doi: 10.1021/acsphotonics.8b01280. Epub 2018 Oct 17.
Terahertz quantum cascade lasers (QCLs) are excellent coherent light sources, but are still limited to an operating temperature below 200 K. To tackle this, we analyze the influence of the barrier height for the identical three-well terahertz QCL layer sequence by comparing different aluminum concentrations ( = 0.12-0.24) in the GaAs/Al Ga As material system, and then we present an optimized structure based on these findings. Electron injection and extraction mechanisms as well as LO-phonon depopulation processes play crucial roles in the efficient operation of these lasers and are investigated in this study. Experimental results of the barrier height study show the highest operating temperature of 186.5 K for the structure with 21% aluminum barriers, with a record /ℏω value of 1.36 for a three-well active region design. An optimized heterostructure with 21% aluminum concentration and reduced cavity waveguide losses is designed and enables a record operating temperature of 196 K for a 3.8 THz QCL.
太赫兹量子级联激光器（QCL）是出色的相干光源，但仍局限于在200 K以下的温度工作。为解决这一问题，我们通过比较GaAs/AlGaAs材料系统中不同铝浓度（= 0.12 - 0.24），分析了相同三阱太赫兹QCL层序列的势垒高度的影响，然后基于这些发现提出了一种优化结构。电子注入和提取机制以及LO声子去布居过程在这些激光器的高效运行中起着关键作用，本研究对其进行了探讨。势垒高度研究的实验结果表明，铝势垒为21%的结构的最高工作温度为186.5 K，对于三阱有源区设计，其记录的/ℏω值为1.36。设计了一种铝浓度为21%且腔波导损耗降低的优化异质结构，对于3.8太赫兹QCL，其记录的工作温度为196 K。
