An infinite order perturbation approach to gain calculation in injection semiconductor lasers
An infinite order perturbation approach to gain calculation in injection semiconductor lasers
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DOI：
10.1063/1.368453
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发表时间：
1998-09-15
影响因子：
3.2
通讯作者：
Yamada, M
中科院分区：
文献类型：
--
作者：
Ahmed, M;Yamada, M
通过对密度矩阵分析应用无限阶微扰处理并考虑单模操作中的电子弛豫过程来分析注入半导体激光器的非线性增益。无限扩展的增益可应用于阈值电流低得多的未来激光器开发。研究了扩展密度矩阵元素的线性和高阶公式以及它们相应的增益系数阶数。无限扩展的增益以封闭形式获得，通常无法通过分析处理。这种封闭形式在平面波场的简单情况下得到了简化，并且在完全均匀和非均匀增益展宽的范围内近似于先前报道的增益公式。给出了具有特定带内弛豫时间的 GaAs 激光器情况的数值示例。基于这些数值结果，根据注入载流子数量，给出了线性和高阶增益系数的简化表达式。此外，根据激光功率值研究了截断不同高阶无限增益扩展的数值标准。在传统半导体激光器的情况下，注入电流高达其阈值的三倍，三阶增益扩展对应于无限扩展的增益。然而，五阶展开在高达阈值十倍的较高电流下给出了更准确的描述。在更高的注入电流范围内进行更精确的增益分析需要更高阶的增益扩展。 (C) 1998 美国物理研究所..
Nonlinear gain in injection semiconductor lasers is analyzed by applying an infinite order perturbation treatment to the density matrix analysis and taking in account the electron relaxation processes in single-mode operation. The infinitely expanded gain can be applied to future laser developments having much lower threshold current. Formulas for linear and higher orders of the expanded density matrix element and for their corresponding orders of the gain coefficient are investigated. The infinitely expanded gain is obtained in closed form which, in general, cannot be handled analytically. This closed form is simplified in the simple case of plane-wave fields and is approximated to the previously reported gain formulas within limits of perfectly homogeneous and inhomogeneous gain broadening. Numerical examples are given for the case of GaAs lasers having a specified intraband relaxation time. Based on these numerical results, simplified expressions are presented for linear and higher orders of the gain coefficient in terms of the injected carrier number. Furthermore, numerical criteria to truncate the infinite gain expansion for different higher orders are investigated based on the values of the lasing power. In the case of conventional semiconductor lasers, where the injection current is up to three times its threshold value, the third-order gain expansion corresponds to the infinitely expanded gain. However, the fifth-order expansion gives a more accurate description at higher current up to ten times the threshold. More exact gain analysis at higher ranges of the injection current requires higher orders in the gain expansion. (C) 1998 American Institute of Physics..