Efficient generation of isolated attosecond pulses with high   beam-quality by two-color Bessel-Gauss beams
  The generation of isolated attosecond pulses with high efficiency and high beam quality is essential for attosec- ond spectroscopy. We numerically investigate the supercontinuum generation in a neutral rare-gas medium driven by a two-color Bessel-Gauss beam. The results show that an efficient smooth supercontinuum in the plateau is obtained after propagation, and the spatial profile of the generated attosecond pulse is Gaussian-like with the divergence angle of 0.1 degree in the far field. This bright source with high beam quality is beneficial for detecting and controlling the microscopic processes on attosecond time scale. 
Zhe Wang, Weiyi Hong, Qingbin Zhang, Shaoyi Wang, and Peixiang Lu
physics.optics