Radiative coupling of A and B excitons in ZnO
Radiative coupling of A and B excitons in ZnO
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ZnO 中 A 和 B 激子的辐射耦合
DOI：
10.1103/physrevb.94.045441
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发表时间：
2016
影响因子：
3.7
通讯作者：
T. Kinoshita and H. Ishihara
中科院分区：
文献类型：
--
作者：
Yoshiki Osaka;Nobuhiko Yokoshi;and Hajime Ishihara;T. Kinoshita and H. Ishihara
从理论上研究了ZnO中A、B激子的辐射诱导耦合。考虑到激子在体和薄膜结构中的质心运动，我们计算了激子-辐射耦合系统的本征模，并揭示了各本征模中各激子分量的比值，该比值由极化与麦克斯韦电场之间的自一致方程的对角化决定。特别是，在纳米-体交叉尺寸下，多极型激子波与辐射波之间的大相互作用体积导致来自不同价带的激子之间的辐射耦合，从而导致辐射校正增强。本研究的结果与ZnO中激子的光学响应的传统观点形成鲜明对比，其中A和B激子独立分配到各自的光谱结构。我们通过聚焦于简并的四波混频，展示了非线性光信号的另一种频谱分配。
Radiation-induced coupling between A and B excitons in ZnO is theoretically studied. Considering the center-of-mass motion of excitons in bulk and thin-film structures, we calculate the eigenmodes of an exciton–radiation coupled system and reveal the ratio of each excitonic component in the respective eigenmodes, which is determined from diagonalization of the self-consistent equation between the polarization and the Maxwell electric field. In particular, in a nano-to-bulk crossover size regime, the large interaction volume between multipole-type excitonic waves and radiation waves causes radiative coupling between excitons from different valence bands, which leads to an enhancement of the radiative correction. The results presented in this study are in striking contrast with the conventional view of the optical response of excitons in ZnO, where A and B excitons are independently assigned to their respective spectral structures. We demonstrate an alternative spectral assignment of nonlinear optical signals by focusing on the degenerate four-wave mixing.