In this paper, a theoretical model is proposed to investigate and analyze an ultra-fast cross gain modulation (XGM) in quantum dot semiconductor optical amplifiers (QDSOAs). The proposed model is based on a set of carrier’s rate equations, propagation equations for pump and probe signals and phase equations. To investigate the XGM mechanism, nonreturn-to-zero (NRZ) pulse trains with various bitrates are supposed to propagate as the input pump signals through the QDSOA’s active layer. The probe signal is assumed to be a continuous wave (CW) signal. Furthermore, optical gain of quantum dots (QDs) is calculated using a density matrix approach. For the first time, to the best of our knowledge, a second excited state is considered in the band diagram of QDs, to obtain the ultra-fast XGM in QDSOAs. Therefore, in the presented model, the rate equations are written for the carriers in the ground state, first and second excited states (ES2), continuum state and the wetting layer. In the ...

中文翻译：

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量子点半导体光放大器：在第二激发态存在下的超快速交叉增益调制研究

本文提出了一个理论模型来研究和分析量子点半导体光放大器（QDSOA）中的超快速交叉增益调制（XGM）。所提出的模型基于一组载波速率方程，泵和探针信号的传播方程以及相位方程。为了研究XGM机制，假定具有各种比特率的不归零（NRZ）脉冲序列作为输入泵浦信号通过QDSOA的活动层传播。探测信号假定为连续波（CW）信号。此外，使用密度矩阵方法计算量子点（QD）的光学增益。据我们所知，这是第一次在QD的能带图中考虑了第二个激发态，以获得QDSOA中的超快XGM。因此，在提出的模型中，为基态，第一和第二激发态（ES2），连续态和润湿层的载流子写出速率方程。在里面 ...