title: Effects of laser-plasma interactions on terahertz radiation from solid targets irradiated by ultrashort intense laser pulses.
abstract: Interactions of 100-fs laser pulses with solid targets at intensities of 10(18) W/cm(2) and resultant terahertz (THz) radiation are studied under different laser contrast ratio conditions. THz emission is measured in the specular reflection direction, which appears to decrease as the laser contrast ratio varies from 10(-8) to 10(-6). Correspondingly, the frequency spectra of the reflected light are observed changing from second harmonic dominant, three-halves harmonic dominant, to vanishing of both harmonics. Two-dimensional particle-in-cell simulation also suggests that this observation is correlated with the plasma density scale length change. The results demonstrate that the THz emission is closely related to the laser-plasma interaction processes. The emission is strong when resonance absorption is a key feature of the interaction, and becomes much weaker when parametric instabilities dominate.
authors: Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190, China.
authors: Chun
authors: C
authors: Li
authors: Mu-Lin
authors: ML
authors: Zhou
authors: Wen-Jun
authors: WJ
authors: Ding
authors: Fei
authors: F
authors: Du
authors: Feng
authors: F
authors: Liu
authors: Yu-Tong
authors: YT
authors: Li
authors: Wei-Min
authors: WM
authors: Wang
authors: Zheng-Ming
authors: ZM
authors: Sheng
authors: Jing-Long
authors: JL
authors: Ma
authors: Li-Ming
authors: LM
authors: Chen
authors: Xin
authors: X
authors: Lu
authors: Quan-Li
authors: QL
authors: Dong
authors: Zhao-Hua
authors: ZH
authors: Wang
authors: Zheng
authors: Z
authors: Lou
authors: Sheng-Cai
authors: SC
authors: Shi
authors: Zhi-Yi
authors: ZY
authors: Wei
authors: Jie
authors: J
authors: Zhang