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通过改进的三能级多模态速率方程,运用电路建模方法,建立了太赫兹(THz)量子级联激光器(QCL)的一种等效电路模型。由于基于多模态效应进行建模,所建模型能够有效表征多模态效应对THz QCL光电性能的影响。模型中,涉及的非辐射散射时间、自激发射弛豫时间以及电子逃逸时间均根据器件有源层结构参数通过自洽数值求解获得。采用所建模型,可运用通用电路仿真工具实现对THz QCL光电特性的模拟分析,克服了数值分析方法计算复杂、模拟时间长的缺点。运用电路仿真工具PSPICE对2.47THz QCL的稳态特性和输出光谱特性进行了模拟分析,并讨论了温度变化对器件阈值电流、输出光功率以及输出频谱的影响,分析结果与已报道的理论和实验结果一致,验证了本文方法的适用性和准确性。
An equivalent circuit model of THz quantum cascade laser (QCL) is established by using the improved three-level multi-modal rate equation and the circuit modeling method. Due to the modeling based on multi-mode effects, the proposed model can effectively characterize the effect of multi-mode effects on the THz QCL optoelectronic performance. In the model, the involved non-radiative scattering time, self-excited emission relaxation time and electron escape time are obtained by self-consistent numerical solution according to the structural parameters of the device active layer. The model can be used to simulate the THz QCL photoelectric characteristics by using general circuit simulation tools, which overcomes the shortcomings of complex numerical simulation and long simulation time. The circuit simulation tool PSPICE is used to simulate the steady-state characteristics and output spectral characteristics of 2.47 THz QCL. The influence of temperature on the threshold current, output optical power and output spectrum of the device is discussed. The results are in good agreement with the published theories and experiments The results are consistent, verifying the applicability and accuracy of this method.