Spectral hole-burning and nonlinear-gain decrease in a band-to-level transition semiconductor laser
Spectral hole-burning and nonlinear-gain decrease in a band-to-level transition semiconductor laser
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带级跃迁半导体激光器中的光谱烧孔和非线性增益下降
DOI：
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发表时间：
1973
期刊：
影响因子：
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通讯作者：
Y. Nishimura
中科院分区：
文献类型：
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作者：
Y. Nishimura
基于半导体激光器的能带跃迁模型（不考虑k选择规则），理论上得到了固定频率激光振荡条件下非线性激光增益的频率特性。这种非线性增益在振荡频率附近表现出频谱烧孔，并且在整个频谱区域上相对于相应的线性增益有所下降。该分析使用半经典密度矩阵形式和微扰方法。假设激光跃迁发生在导带布洛赫态和局域受主能级之间。上述定义的非线性增益是通过三阶扰动计算获得的。在激光频率附近，理论上会发现增益被烧毁的窄光谱区域（烧孔效应）。这个“洞”的宽度随着受主态的弛豫率而增加，并且几乎与激发能级无关。整个光谱区域的增益下降是由于缺乏 k 选择规则造成的，并且对应于激光发射后自发发射的饱和。导带的快速弛豫和较低的受主浓度使得在远离激光频率的频率处增益下降更显着。在某些情况下，这种效应使得单轴向模式操作成为可能。
Frequency characteristics of a nonlinear lasing gain under the condition that a laser oscillation exists at a fixed frequency are theoretically obtained on the basis of a band-to-level transition model (without the k - selection rule) of semiconductor lasers. This nonlinear gain exhibits a spectral hole-burning in the vicinity of oscillation frequency as well as a decrease from the corresponding linear gain over the entire spectral region. The analysis uses a semiclassical density-matrix formalism and a perturbation method. The lasing transitions are assumed to occur between a conduction-band Bloch state and a localized acceptor level. The above-defined nonlinear gain is obtained from a third-order perturbation calculation. In the neighborhood of a lasing frequency, a narrow spectral region where the gain is burned is theoretically found (hole-burning effect). The width of this "hole" increases with the relaxation rate at acceptor states, and is almost independent of excitation level. The gain decrease over the entire spectral region results from the absence of the k -selection rule, and corresponds to the saturation of spontaneous emission after the onset of lasing. Rapid relaxations in the conduction band and lower acceptor concentrations make more significant gain decreases at a frequency sufficiently apart from the lasing frequency. This effect makes possible a single axial-mode operation in some cases.