Self-consistent analysis of quantum transport in a split-well resonant-phonon terahertz quantum cascade laser.

IF 3.2 2区 物理与天体物理 Q2 OPTICS
Optics express Pub Date : 2025-06-02 DOI:10.1364/OE.559242
Shiran Levy, Nathalie Lander Gower, Silvia Piperno, Asaf Albo
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Abstract

The split-well resonant phonon (SWRP) THz quantum cascade laser (QCL) is a novel design scheme introduced in previous studies, demonstrating significant potential due to its reduced overlap between doped regions and active laser states. This structural advantage was expected to mitigate ionized impurity scattering (IIS) and improve overall device performance, motivating a detailed investigation of the transport mechanisms. Here, we analyze the SWRP design using nonequilibrium Green's function (NEGF) simulations. Our analysis of the SWRP-based THz QCL design reveals key mechanisms limiting its high-temperature performance and provides a pathway for significant improvement. In our study, we found that the injector level and the upper laser level (ULL) exhibit different population distributions, suggesting that injection coupling can be further enhanced to improve the temperature performance. Additionally, backfilling remains a limiting factor, which could be mitigated by increasing the energy separation between the lower laser level (LLL) and the injector level beyond 36 meV. Furthermore, our analysis highlights that interface roughness (IFR) significantly impacts optical gain and spectral broadening. We propose improving the design by reducing Al content in the barriers to reduce the interface roughness scattering, for example, by implementing mixed potential barriers, maintaining the injector at 30% aluminum while reducing other barriers to 15%. Our findings provide valuable insights into the high-temperature performance of SWRP-based THz QCLs and establish clear guidelines for further optimization, potentially pushing the design beyond the current state-of-the-art.

分裂阱共振-声子太赫兹量子级联激光器中量子输运的自洽分析。
裂阱共振声子(SWRP)太赫兹量子级联激光器(QCL)是以往研究中引入的一种新颖的设计方案,由于其减少了掺杂区域和主动激光状态之间的重叠,显示出巨大的潜力。这种结构优势有望减轻电离杂质散射(IIS)并提高整体器件性能,从而激发对传输机制的详细研究。本文采用非平衡格林函数(NEGF)模拟分析了SWRP的设计。我们对基于swrp的太赫兹QCL设计的分析揭示了限制其高温性能的关键机制,并为显著改进提供了途径。在我们的研究中,我们发现注入器能级和上激光能级(ULL)呈现不同的种群分布,这表明可以进一步增强注入耦合以改善温度性能。此外,回填仍然是一个限制因素,可以通过增加较低激光电平(LLL)和注入器电平之间的能量间隔来缓解。此外,我们的分析强调,界面粗糙度(IFR)显著影响光学增益和光谱展宽。我们建议通过减少屏障中的Al含量来改善设计,以减少界面粗糙度散射,例如,通过实施混合电位屏障,将注入器中的铝含量保持在30%,同时将其他屏障减少到15%。我们的研究结果为基于swrp的太赫兹qcl的高温性能提供了有价值的见解,并为进一步优化建立了明确的指导方针,有可能推动设计超越当前的最先进水平。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Optics express
Optics express 物理-光学
CiteScore
6.60
自引率
15.80%
发文量
5182
审稿时长
2.1 months
期刊介绍: Optics Express is the all-electronic, open access journal for optics providing rapid publication for peer-reviewed articles that emphasize scientific and technology innovations in all aspects of optics and photonics.
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