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Terahertz generation in quantum-cascade lasers through down-conversion optical nonlinearity: Design and modeling
Optics Communications ( IF 2.4 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.optcom.2020.125792
Mohammad Reza Kazemi-Tesieh , Hossein Reza Yousefvand , Abbas Ghadimi , Azadeh Kiani-Sarkaleh

Abstract In this paper, we propose an electrically driven optically excited laser structure for terahertz (THz) generation in quantum cascade lasers (QCLs) through frequency down-conversion optical nonlinearity. In our distinct design, both the pump and THz radiations are generated simultaneously by optical and electronic intersubband transitions (ISTs) between the quantized states within the conduction band of the same active region of a QCL. The modeling of laser bandstructure is achieved using a self-consistent solution of Schrodinger–Poisson equations, and the detailed analysis of electronic transport of the proposed structure is performed using the density matrix approach and energy-density balance equation that self-consistently consider the optical, electrical and thermal interactions in the structure. Additionally, the waveguide loss for the THz optical mode is considered using the bulk Drude model. Using a stationary solution of the density matrix equations, an expression for the THz intensity gain is derived as a function of pump field intensity, carrier distributions and quantum coherence contributions. Using the presented model, we analyze the steady-state and transient characteristics of the device for two different heatsink temperatures, 220 and 300 K. Simulation results show that the proposed structure has a potential to generate room-temperature THz radiation in QCLs.

中文翻译:

通过下转换光学非线性在量子级联激光器中产生太赫兹:设计和建模

摘要 在本文中,我们提出了一种电驱动的光激发激光器结构,用于通过下变频光学非线性在量子级联激光器 (QCL) 中产生太赫兹 (THz)。在我们独特的设计中,泵浦辐射和太赫兹辐射都是由 QCL 的相同有源区域的导带内的量化状态之间的光学和电子子带间跃迁 (IST) 同时产生的。激光能带结构的建模是使用薛定谔-泊松方程的自洽解来实现的,并且使用密度矩阵方法和能量密度平衡方程对所提出结构的电子输运进行了详细分析,这些方程自洽地考虑了光学, 结构中的电和热相互作用。此外,使用体德鲁德模型考虑太赫兹光模式的波导损耗。使用密度矩阵方程的平稳解,THz 强度增益的表达式被推导出为泵场强度、载流子分布和量子相干贡献的函数。使用所提出的模型,我们分析了器件在两种不同散热器温度(220 和 300 K)下的稳态和瞬态特性。仿真结果表明,所提出的结构有可能在 QCL 中产生室温太赫兹辐射。
更新日期:2020-08-01
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