1School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 2Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 3School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 4Innovative Collaboration Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240 5University of Chinese Academy of Sciences, Beijing 100864
Abstract：Generation of attosecond electromagnetic (EM) pulses and the associated electron dynamics are studied using particle-in-cell simulations of relativistic laser pulses interacting with over-dense plasma foil targets. The interaction process is found to be so complicated even in the situation of utilizing driving laser pulses of only one cycle. Two electron bunches closely involved in the laser-driven wavebreaking process contribute to attosecond EM pulses through the coherent synchrotron emission process whose spectra are found to follow an exponential decay rule. Detailed investigations of electron dynamics indicate that the early part of the reflected EM emission is the high-harmonics produced through the relativistic oscillating mirror mechanism. High harmonics are also found to be generated through the Bremsstrahlung radiation by one electron bunch that participates in the wavebreaking process and decelerates when it experiences the local wavebreaking-generated high electrostatic field in the moving direction.
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2018, Vol. 35 
