近日，韩国先进光子学研究所的Chul Kang及其研究小组与美国马里兰大学的Ki-Yong Kim等人合作并取得一项新进展。经过不懈努力，他们实现从可扩展的光学整流中以260MV/cm电场强度电离太赫兹波。相关研究成果已于2024年5月27日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队成功演示了通过150太瓦激光脉冲的相位匹配光学整流技术，从大面积铌酸锂晶体中发射出多周期、15太赫兹波的电离过程。对所产生的太赫兹波进行全面表征，包括能量、脉冲持续时间和焦点光斑大小，结果显示场强可达到每厘米260兆伏特。特别地，研究团队利用单次太赫兹干涉仪精准测量了太赫兹脉冲的持续时间和频谱，并通过互补的数值模拟进行验证。

此外，这种高强度的太赫兹脉冲被照射到多种固体靶上，成功证明了太赫兹诱导的隧道电离和等离子体的形成。本研究还探讨了气体中无扰动太赫兹驱动电离的潜力，这将为等离子体中的非线性和相对论太赫兹物理研究开辟新领域。

据悉，太赫兹(THz)波，由于其光子能量低而被称为非电离辐射，当足够多的太赫兹光子集中在时间和空间中时，实际上可以电离原子和分子。

附：英文原文

Title: Ionizing terahertz waves with 260MV/cm from scalable optical rectification

Author: Kim, Hyeongmun, Kang, Chul, Jang, Dogeun, Roh, Yulan, Lee, Sang Hwa, Lee, Joong Wook, Sung, Jae Hee, Lee, Seong Ku, Kim, Ki-Yong

Issue&Volume: 2024-05-27

Abstract: Terahertz (THz) waves, known as non-ionizing radiation owing to their low photon energies, can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and space. Here, we demonstrate the generation of ionizing, multicycle, 15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses. A complete characterization of the generated THz waves in energy, pulse duration, and focal spot size shows that the field strength can reach up to 260 megavolts per centimeter. In particular, a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical simulations. Such intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma formation. This study also discusses the potential of nonperturbative THz-driven ionization in gases, which will open up new opportunities, including nonlinear and relativistic THz physics in plasma.

DOI: 10.1038/s41377-024-01462-w

Source: https://www.nature.com/articles/s41377-024-01462-w