Abstract-Terahertz emission from two-plasmon-decay induced transient currents in laser-solid interactions

G.-Q. Liao¹, Y.-T. Li^1,2,a), C. Li¹, S. Mondal³, H. A. Hafez³, M. A. Fareed³, T. Ozaki³, W.-M. Wang^1,2, Z.-M. Sheng^2,4,5,a) and J. Zhang^2,5
 http://scitation.aip.org/content/aip/journal/pop/23/1/10.1063/1.4939605?TRACK=RSS
a) Authors to whom correspondence should be addressed. Electronic addresses:ytli@iphy.ac.cn and zmsheng@sjtu.edu.cn
Phys. Plasmas 23, 013104 (2016); http://dx.doi.org/10.1063/1.4939605

We have studied the generation of terahertz (THz) radiation via the interaction of intense femtosecond laser pulses with solid targets at a small incidence angle. It is found that preplasma with a moderate density gradient can enhance the emission. We also observe saturation of the THz output with the driving laser energy. We find that THz emission is closely related to the 3/2 harmonics of the driving laser. Particle-in-cell simulations indicate that under the present experimental conditions, the THz emission could be attributed to the transientcurrents at the plasma-vacuum interface, mainly formed by the two-plasmon-decay instability.