Non-linear plasma effects on laser-induced terahertz emission from the atmosphere

作者：Shin J H^*; Zhidkov A; Jin Z; Hosokai T; Kodama R

来源：Physics of Plasmas, 2012, 19(2): 023117.

DOI：10.1063/1.3685736

Power, spectral characteristics, and angle distribution of terahertz (THz) radiation from air irradiated by a single (omega) or coupled (omega, 2 omega) femtosecond laser pulses are analyzed for higher intensities, for which non-linear plasma effects on the pulse propagation become essential, by means of multidimensional particle-in-cell simulations exploiting the self-consistent plasma kinetics. THz radiation is shown to be a result of beat waves generated at ionization front with fundamental and second harmonic waves. At lower intensities, the THz power growth is far faster than the linear; at pulse intensities over I > 10(15) W/cm(2), the power increases slower than the linear. Along with the forward emission, strong power in around 30 degrees angles occurs at high intensities. Ionization of air results in poor focusing of laser pulses and, therefore, lower efficiency of THz emission.

• 出版日期2012-2