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Tuesday, June 23, 2015
Abstract-Bursts of Terahertz Radiation from Large-Scale Plasmas Irradiated by Relativistic Picosecond Laser Pulses
G. Q. Liao (廖国前), Y. T. Li (李玉同), C. Li (李春), L. N. Su (苏鲁宁), Y. Zheng (郑轶), M. Liu (刘梦), W. M. Wang (王伟民), Z. D. Hu (胡志丹), W. C. Yan (闫文超), J. Dunn, J. Nilsen, J. Hunter, Y. Liu (刘越), X. Wang (王瑄), L. M. Chen (陈黎明), J. L. Ma (马景龙), X. Lu (鲁欣), Z. Jin (金展), R. Kodama (兒玉了祐), Z. M. Sheng (盛政明), and J. Zhang (张杰)
Phys. Rev. Lett. 114, 255001 – Published 23 June 2015
Powerful terahertz (THz) radiation is observed from large-scale underdense preplasmas in front of a solid target irradiated obliquely with picosecond relativistic intense laser pulses. The radiation covers an extremely broad spectrum with about 70% of its energy located in the high frequency regime over 10 THz. The pulse energy of the radiation is found to be above 100μJ per steradian in the laser specular direction at an optimal preplasma scale length around 40–50μm. Particle-in-cell simulations indicate that the radiation is mainly produced by linear mode conversion from electron plasma waves, which are excited successively via stimulated Raman scattering instability and self-modulated laser wakefields during the laser propagation in the preplasma. This radiation can be used not only as a powerful source for applications, but also as a unique diagnostic of parametric instabilities of laser propagation in plasmas.