Irregular oscillatory patterns in the early-time region of coherent phonon generation in silicon
Irregular oscillatory patterns in the early-time region of coherent phonon generation in silicon
复制标题
硅相干声子产生早期区域的不规则振荡模式
DOI：
10.1103/physrevb.96.125204
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
and Nobuya Maeshima
中科院分区：
文献类型：
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作者：
Yohei Watanabe;Ken-ichi Hino;Muneaki Hase;and Nobuya Maeshima
从理论上研究了超短激光脉冲辐照后，未掺杂Si晶体中相干声子（CP）的产生，揭示了未被探索的早期量子力学效应。我们检查归因于离子核的感应电荷密度的时间信号，将焦点放在Rabi频率对信号的影响上;该频率对应于脉冲的峰值电场。结果表明，在特定的s，当光激载流子引起的等离子体激元能量与光-光声子能量相一致时，这两种模式之间的能量共振相互作用导致了显著的反交叉，揭示了在所观察到的时间信号中振幅急剧增强的不规则振荡。此外，振荡模式还受到受控制的激发载流子密度的拉比振荡的影响。这些研究结果表明，早期的时间区域是丰富的CP生成中固有的量子力学效应，虽然实验信号或多或少掩盖了所谓的相干伪影，由于非线性光学效应。
Coherent phonon (CP) generation in an undoped Si crystal is theoretically investigated to shed light on unexplored quantum-mechanical effects in the early-time region immediately after the irradiation of ultrashort laser pulses. We examine time signals attributed to an induced charge density of an ionic core, placing the focus on the effects of the Rabi frequencyon the signals; this frequency corresponds to the peak electric-field of the pulse. It is found that at specific's, where the energy of plasmon caused by photoexcited carriers coincides with the longitudinal-optical phonon energy, the energeticallyresonantinteraction between these two modes leads to striking anticrossings, revealing irregular oscillations with anomalously enhanced amplitudes in the observed time signals. Also, the oscillatory pattern is subject to the Rabi flopping of the excited carrier density that is controlled by. These findings show that the early-time region is enriched with quantum-mechanical effects inherent in the CP generation, though experimental signals are more or less masked by the so-called coherent artifact due to nonlinear optical effects.