Morimoto T, Miyamoto T, Yamakawa H, Terashige T, Ono T, Kida N, Okamoto H
Department of Advanced Materials Science, University of Tokyo, Kashiwa 5-1-5, Chiba 277-8561, Japan.
Phys Rev Lett. 2017 Mar 10;118(10):107602. doi: 10.1103/PhysRevLett.118.107602.
A rapid polarization control in paraelectric materials is important for an ultrafast optical switching useful in the future optical communication. In this study, we applied terahertz-pump second-harmonic-generation-probe and optical-reflectivity-probe spectroscopies to the paraelectric neutral phase of an organic molecular dielectric, tetrathiafulvalene-p-chloranil and revealed that a terahertz pulse with the electric-field amplitude of ∼400 kV/cm produces in the subpicosecond time scale a large macroscopic polarization whose magnitude reaches ∼20% of that in the ferroelectric ionic phase. Such a large polarization generation is attributed to the intermolecular charge transfers and breathing motions of domain walls between microscopic neutral and ionic domains induced by the terahertz electric field.
对于未来光通信中有用的超快光开关而言，顺电材料中的快速极化控制至关重要。在本研究中，我们将太赫兹泵浦二次谐波产生探测和光反射率探测光谱应用于有机分子电介质四硫富瓦烯 - 对氯苯醌的顺电中性相，并揭示出电场幅度约为400 kV/cm的太赫兹脉冲在亚皮秒时间尺度内产生了一个大的宏观极化，其幅度达到铁电离子相极化幅度的约20%。如此大的极化产生归因于太赫兹电场诱导的微观中性和离子域之间的分子间电荷转移以及畴壁的呼吸运动。
