Abstract-All-optical attoclock: accessing exahertz dynamics of optical tunnelling through terahertz emission

I. Babushkin, A. J. Galan, A. Husakou, F. Morales, A. Demircan, J. R. C. Andrade, U. Morgner, M. Ivanov

https://arxiv.org/abs/1803.04187

The hot debate regarding attosecond dynamics of optical tunneling has, so far, been focused on the presence, or absence, of time delays associated to the electron tunnelling through the classically forbidden region during atomic ionization in intense infrared laser fields. Strong theoretical and experimental arguments have been put forward to advocate the polar opposite points of view. The underlying dynamics are richer. Here we propose to use the nonlinear optical responses of the tunnelling electrons to tailored light fields to track these dynamics in full complexity. Using the combination of single-color and two-color fields, we resolve not only ionization delays, but also temporal re-shaping and spatial re-focusing of the tunnelling wavepacket as it emerges from the classically forbidden region. Access to these details of the dynamics is facilitated by the near-instantaneous nature of the nonlinear optical response driven by ionization, and by using tailored laser pulses to induce this response. Our work introduces a new type of attoclock for optical tunnelling, one that is based on measuring light rather than photo-electrons. Our conclusions suggest a possible middle ground between the two conflicting points of view.