Spatiotemporal steering of photoelectron emission in multiphoton   above-threshold ionization
  We experimentally demonstrate spatiotemporal steering of photoelectron emission in multiphoton above-threshold single ionization of atoms exposed to a phase-controlled orthogonally polarized two-color (OTC) laser pulse. Spatial and energy resolved photoelectron angular distributions are measured as a function of the laser phase, allowing us to look into the fine structures and emission dynamics. The slow and fast photoelectrons, distinguished by the energy larger or smaller than 2Up with Up being the ponderomotive energy of a free electron in the laser field, have distinct spatiotemporal dependences of the laser waveform. The phase-of-phase of the slow electron oscillates as functions of both the energy and emission direction, however, the fast electron present rather flat phase structure which merely depends on its emission direction. Three-dimensional generalized quantum trajectory Monte Carlo simulations are performed to explore the sub-cycle dynamics of the electron emission in the phase-controlled OTC pulse. 
Xiaochun Gong, Cheng Lin, Mingming Liu, Qiying Song, Kang Lin, Qinying   Ji, Wenbin Zhang, Junyang Ma, Peifen Lu, Yunquan Li...
physics.optics