近日，中国科学院上海高等研究院赵振堂团队报道了在自由电子激光器中通过精确的电子束裁剪实现连续的太赫兹波段覆盖。该研究于2025年10月20日发表在《自然—光子学》杂志上。

高功率、连续可调谐的窄带太赫兹（THz）传感器对于推进非线性光学、太赫兹驱动的材料动力学和超快光谱学至关重要。传统技术通常在脉冲能量和频率可调性之间进行权衡。

研究组展示了一种新的自由电子激光方法，通过用频率跳动的激光脉冲预调制相对论电子束，并利用束压缩和集体效应来增强微束，从而克服了这些限制。实验结果表明，该技术产生的窄带太赫兹辐射具有7.8 ~ 30.8太赫兹，使脉冲能量达到385 μJ，使频谱带宽保持在7.7% ~ 14.7%之间。此外，该方法表现出卓越的稳定性和可扩展性，突出了其弥合长期存在的太赫兹差距的独特能力，并为各种尖端科学应用提供了有前景的解决方案。

附：英文原文

Title: Continuous terahertz band coverage through precise electron-beam tailoring in free-electron lasers

Author: Kang, Yin, Li, Tong, Wang, Zhen, Wang, Yue, Yu, Cheng, Yin, Weiyi, Gao, Zhangfeng, Xu, Hanghua, Luo, Hang, Wang, Xiaofan, Chen, Jian, Lan, Taihe, Liu, Xiaoqing, Wang, Jinguo, Zhao, Huan, Gao, Fei, Sun, Liping, Zhu, YanYan, Wen, Yongmei, Tian, Qili, Xu, Chenye, Wang, Xingtao, Xu, Jiaqiang, Qi, Zheng, Liu, Tao, Li, Bin, Yan, Lixin, Zhang, Kaiqing, Feng, Chao, Liu, Bo, Zhao, Zhentang

Issue&Volume: 2025-10-20

Abstract: High-power, continuously tunable narrowband terahertz (THz) sources are essential for advancing nonlinear optics, THz-driven material dynamics and ultrafast spectroscopy. Conventional techniques typically impose a trade-off between pulse energy and frequency tunability. Here we demonstrate a novel free-electron laser approach that overcomes these limitations by premodulating a relativistic electron beam with a frequency-beating laser pulse and leveraging bunch compression along with collective effects to enhance microbunching. Experimental results demonstrate that this technique generates narrowband THz emission with continuous frequency tunability from 7.8 to 30.8THz, achieving pulse energies up to 385upmu {rm{J}} and maintaining spectral bandwidths between 7.7% and 14.7%. Moreover, the method exhibits exceptional robustness and scalability, highlighting its unique ability to bridge the long-standing THz gap and offering a promising solution for diverse cutting-edge scientific applications.

DOI: 10.1038/s41566-025-01775-1

Source: https://www.nature.com/articles/s41566-025-01775-1