Noninstantaneous polarization dynamics in dielectric media
Noninstantaneous polarization dynamics in dielectric media
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DOI：
10.1364/optica.2.000151
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发表时间：
2014-06
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通讯作者：
M. Hofmann;J. Hyyti;S. Birkholz;M. Bock;S. Das;R. Grunwald;Mathias Hoffmann;T. Nagy;A. Demircan;M. Jupé;D. Ristau;U. Morgner;C. Brée;M. Woerner;T. Elsaesser;G. Steinmeyer
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文献类型：
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作者：
M. Hofmann;J. Hyyti;S. Birkholz;M. Bock;S. Das;R. Grunwald;Mathias Hoffmann;T. Nagy;A. Demircan;M. Jupé;D. Ristau;U. Morgner;C. Brée;M. Woerner;T. Elsaesser;G. Steinmeyer
三阶光学非线性对超短光脉冲的产生和表征起着至关重要的作用。一种特殊的表征方法是频率分辨光学选通，它可以基于各种各样的三阶非线性效应。这些变体中的任何一个都以瞬时时间响应为前提，因为它是预期的非共振。在本文中，我们表明，共振激发的第三谐波产生了令人惊讶的大衰减时间，这是迄今为止产生的最短的振荡器脉冲的持续时间的顺序。为此，我们测量了干涉三次谐波频率分辨光门轨迹在二氧化钛和二氧化硅，证实了偏振衰减时间高达6.5 fs的二氧化钛。这种效应是在超快光谱学中观察到的最快的效应之一。含时薛定谔方程的数值解与实验观测非常吻合。我们的工作（实验和模拟）证实，一个非瞬时的偏振衰减可能会出现在一个3光子共振的存在。反过来，在紫外线的脉冲产生和表征可能会受到严重影响，这种以前未报道的效果。
Third-order optical nonlinearities play a vital role for the generation and characterization of ultrashort optical pulses. One particular characterization method is frequency-resolved optical gating, which can be based on a large variety of third-order nonlinear effects. Any of these variants presupposes an instantaneous temporal response, as it is expected off resonance. In this paper we show that resonant excitation of the third harmonic gives rise to surprisingly large decay times, which are on the order of the duration of the shortest oscillator pulses generated to date. To this end, we measured interferometric third-harmonic frequency-resolved optical gating traces in TiO2 and SiO2, corroborating polarization decay times up to 6.5 fs in TiO2. This effect is among the fastest effects observed in ultrafast spectroscopy. Numerical solutions of the time-dependent Schrodinger equation are in excellent agreement with experimental observations. Our work (experiments and simulations) corroborates that a noninstantaneous polarization decay may appear in the presence of a 3-photon resonance. In turn, pulse generation and characterization in the ultraviolet may be severely affected by this previously unreported effect.