Abstract

The effects of very intense lasers on atoms have been the subject of active experimental and theoretical investigation over the past several years. Two intriguing experimental results emerged recently which have excited new developments and debate on the theory of these processes. Since the laser intensities have become large enough that the electric field is comparable to the interelectronic forces, the question has arisen as to whether new atomic physics has been or can be observed. The first of the two discoveries is called above threshold ionization (ATI). It was observed that the energy spectrum of the electrons emitted from multiphoton ionization experiments exhibited a large number of peaks separated by photon energy. This means that many more than the minimum number of photons required for ionization have been absorbed. Additionally, as the intensity increases, the lowest peaks in this spectrum sequentially disappear.

© 1987 Optical Society of America