Eidmann K, Kawachi T, Marcinkevicius A, Bartlome R, Tsakiris G D, Witte K, Teubner U
Max-Planck Institute für Quantenoptik, Hans-Kopfermann Str. 1, D-85748 Garching, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Sep;72(3 Pt 2):036413. doi: 10.1103/PhysRevE.72.036413. Epub 2005 Sep 26.
The emission of fundamental and harmonic radiation from the rear side of thin foils in the thickness range 50-460 nm irradiated by intense frequency doubled Ti:sapphire laser pulses of the duration of 150 fs and intensities up to a few 10(18) W/cm(2) was investigated. Following up a previous study of the rear side harmonic emission [Teubner, Phys. Rev. Lett. 92, 185001 (2004)], we measured the emission efficiencies, polarization properties, and the spectral shapes of the fundamental frequency and the second harmonic. Rear side emission is only observed when the obliquely incident laser light is p -polarized. Particle-in-cell (PIC) simulations indicate that the foils remain strongly overdense during the interaction with the laser pulse and that the rear side emission is caused by energetic electron bunches which are generated at the front side by resonance absorption. They are accelerated into the foil and drive strong plasma oscillations at the fundamental and higher harmonic frequencies.
研究了在50 - 460纳米厚度范围内的薄箔背面，由持续时间为150飞秒、强度高达几10(18)瓦/平方厘米的强倍频钛宝石激光脉冲辐照时产生的基波和谐波辐射。继之前对背面谐波发射的研究[特布纳，《物理评论快报》92, 185001 (2004)]之后，我们测量了发射效率、偏振特性以及基频和二次谐波的光谱形状。仅当斜入射激光为p偏振时才观察到背面发射。粒子模拟表明，箔在与激光脉冲相互作用期间仍保持强烈的过密状态，并且背面发射是由在前表面通过共振吸收产生的高能电子束引起的。它们被加速进入箔中，并在基频和更高谐波频率上驱动强烈的等离子体振荡。
