Sheikhey Mohammad Mohsen, Mahjoory Ali, Baghban Hamed, Golmohammadi Saeed
Appl Opt. 2022 Feb 20;61(6):1523-1530. doi: 10.1364/AO.447648.
Quantum cascade lasers with quantum dot (QD) active regions have been developed to overcome the drawbacks of quantum-well-based cascade lasers. Low threshold current and enhanced bandwidth characteristics of QD lasers can be combined with promising energy-efficient features of vertical cavity surface emitting lasers (VCSELs) through introducing the novel, to the best of our knowledge, concept of a QD cascade VCSEL (QDC-VCSEL). Design steps and predicted features of a QDC-VCSEL operating at 4.5 µm wavelength are discussed in this paper, where the cavity and active region are optimized for TE mode using a high contrast grating design. Laser characteristics are investigated by developing rate equations for the cascade scheme. Threshold and L-I characteristics are obtained at different temperatures. Also, the dependency of threshold current, slope efficiency, and modulation bandwidth on design parameters, mainly the carrier tunneling time, is studied. Results exhibit output peak powers of ∼2 and ∼0.5 at 150 and 273 K, respectively. In addition, threshold current increment and modulation bandwidth reduction are observed with the increase in tunneling time.
已开发出具有量子点（QD）有源区的量子级联激光器，以克服基于量子阱的级联激光器的缺点。通过引入据我们所知新颖的量子点级联垂直腔面发射激光器（QDC-VCSEL）概念，量子点激光器的低阈值电流和增强的带宽特性可与垂直腔面发射激光器（VCSEL）有前景的节能特性相结合。本文讨论了工作在4.5 µm波长的QDC-VCSEL的设计步骤和预测特性，其中使用高对比度光栅设计对腔和有源区进行了TE模式优化。通过为级联方案建立速率方程来研究激光特性。在不同温度下获得阈值和L-I特性。此外，还研究了阈值电流、斜率效率和调制带宽对设计参数（主要是载流子隧穿时间）的依赖性。结果表明，在150 K和273 K时输出峰值功率分别约为2和0.5。此外，随着隧穿时间的增加，观察到阈值电流增加和调制带宽减小。
