Enabling Continuous THz Band Coverage via Precise Electron Beam Tailoring in Free-electron Lasers
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 introduce a novel free-electron laser approach that overcomes these limitations by pre-modulating 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 385{\mu}J while 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.
Cite
@article{arxiv.2504.01391,
title = {Enabling Continuous THz Band Coverage via Precise Electron Beam Tailoring in Free-electron Lasers},
author = {Yin Kang and Tong Li and Zhen Wang and Yue Wang and Cheng Yu and Weiyi Yin and Zhangfeng Gao and Hanghua Xu and Hang Luo and Xiaofan Wang and Jian Chen and Taihe Lan and Xiaoqing Liu and Jinguo Wang and Huan Zhao and Fei Gao and Liping Sun and YanYan Zhu and Yongmei Wen and Qili Tian and Chenye Xu and Xingtao Wang and Jiaqiang Xu and Zheng Qi and Tao Liu and Bin Li and Lixin Yan and Kaiqing Zhang and Chao Feng and Bo Liu and Zhentang Zhao},
journal= {arXiv preprint arXiv:2504.01391},
year = {2025}
}