近日，中国科学院精密测量科学与技术创新研究院的卞学滨及其研究小组取得一项新进展。经过不懈努力，他们揭示液体中由位移电流引起的太赫兹辐射过程。相关研究成果已于2024年2月20日在国际知名学术期刊《美国科学院院刊》上发表。

该研究团队提出了一个位移电流模型。该理论模型成功地再现了实验结果。此外，该理论可以进一步用于研究H₂O和D₂O中太赫兹辐射的核量子效应。这项研究工作为体积液体中太赫兹辐射的起源提供了基本的见解。

据悉，液体中激光诱导太赫兹(THz)辐射的实验研究取得了很大进展。液体太赫兹表现出许多不同于气体和等离子体太赫兹的独特特征。例如，液体太赫兹可以有效地由单色激光产生。它的产额最大化且具有较长的驱动脉冲持续时间。它也线性依赖于激发脉冲能量。在双色激光场中，人们测量到一个意想不到的未调制太赫兹场，其对驱动激光的能量依赖与调制太赫兹波的能量依赖完全不同。然而，由于复杂无序液体的超快动力学描述困难，其微观机制尚不清楚。

附：英文原文

Title: Terahertz radiation induced by shift currents in liquids

Author: Li, Zheng-Liang, Bian, Xue-Bin

Issue&Volume: 2024-2-20

Abstract: Considerable progress has been made in the experimental studies on laser-induced terahertz (THz) radiation in liquids. Liquid THz demonstrates many unique features different from the gas and plasma THz. For example, the liquid THz can be efficiently produced by a monochromatic laser. Its yield is maximized with a longer driving-pulse duration. It is also linearly dependent on the excitation pulse energy. In two-color laser fields, an unexpected unmodulated THz field was measured, and its energy dependence of the driving laser is completely different from that of the modulated THz waves. However, the underlying microscopic mechanism is still unclear due to the difficulties in the description of ultrafast dynamics in complex disordered liquids. Here we propose a shift-current model. The experimental observations could be reproduced by our theory successfully. In addition, our theory could be further utilized to investigate the nuclear quantum effect in the THz radiation in H₂O and D₂O. This work provides fundamental insights into the origin of the THz radiation in bulk liquids.

DOI: 10.1073/pnas.2315297121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2315297121