Frequency Upshift of the Transverse Optical Phonon Resonance in GaAs by Femtosecond Electron-Hole Excitation.,Physical Review Letters

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Frequency Upshift of the Transverse Optical Phonon Resonance in GaAs by Femtosecond Electron-Hole Excitation.
Physical Review Letters ( IF 8.1 ) Pub Date : 2020-07-10 , DOI: 10.1103/physrevlett.125.027401
Ahmed Ghalgaoui ₁ , Klaus Reimann ₁ , Michael Woerner ₁ , Thomas Elsaesser ₁ , Christos Flytzanis ₂ , Klaus Biermann ₃

Affiliation

The impact of transient electric currents on the transverse optical (TO) phonon resonance is studied after excitation by two femtosecond near-infrared pulses via the fourth-order nonlinear terahertz emission. Nonlinear signals due to interband shift currents and heavy-hole–light-hole polarizations are separated from Raman-induced TO phonon coherences. The latter display a frequency upshift by some 100 GHz upon interband excitation of an electron-hole plasma. The frequency shift is caused by transverse electronic shift currents, which modify the dielectric function. A local-field model based on microscopic current densities reproduces the observed frequency upshift.

中文翻译：

飞秒电子空穴激励在GaAs中实现横向声子共振的频率上移。

在两个飞秒近红外脉冲通过四阶非线性太赫兹发射激发之后，研究了瞬态电流对横向光学（TO）声子共振的影响。由于带间移位电流和重空穴-轻空穴极化引起的非线性信号与拉曼诱导的TO声子相干相分离。后者在电子空穴等离子体的带间激励下显示出约100 GHz的频率上移。频率偏移是由横向电子偏移电流引起的，该电流会改变介电功能。基于微观电流密度的局部场模型可再现观察到的频率上移。

更新日期：2020-07-10

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