Highly efficient terahertz radiation from a thin foil irradiated by a high-contrast laser pulse

Jin, Z. and Zhuo, H. B. and Nakazawa, T. and Shin, J. H. and Wakamatsu, S. and Yugami, N. and Hosokai, T. and Zou, D. B. and Yu, M. Y. and Sheng, Z. M. and Kodama, R. (2016) Highly efficient terahertz radiation from a thin foil irradiated by a high-contrast laser pulse. Physical Review E, 94. 03320. ISSN 2470-0053 (https://doi.org/10.1103/PhysRevE.94.033206)

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Abstract

Radially polarized intense terahertz (THz) radiation behind a thin foil irradiated by ultrahigh-contrast ultrashort relativistic laser pulse is recorded by a single-shot THz time-domain spectroscopy system. As the thickness of the target is reduced from 30 to 2 µm, the duration of the THz emission increases from 5 to over 20 ps and the radiation energy increases dramatically, reaching ~10.5 mJ per pulse, corresponding to laser-to-THz radiation energy conversion efficiency of 1.7%. The efficient THz emission can be attributed to reflection (deceleration and acceleration) of the laser driven hot electrons by the target-rear sheath electric field. The experimental results are consistent with that of a simple model as well as particle-in-cell simulation.