  With the appearance of superpower laser sources of
relativistic/ultrarelativistic intensities in the last decade, the
laser-QED-vacuum-matter interaction physics has entered a new phase that makes
real the observation of many nonlinear quantum electrodynamic (QED) and
classical-quantum- mechanical phenomena revealed more than fore-five decades
ago, serious advance in new generation of laser-plasma accelerators of
ultrahigh energies, nuclear fusion etc. Hence, the present review article will
help explorers-experimentalists in this field to attract attention on the
fundamental properties and peculiarities of the dynamics of induced free-free
transitions at high and superhigh intensities of stimulated radiation fields.
In this connection it is of special interest the induced Cherenkov, Compton,
undulator/wiggler coherent processes, as well as cyclotron resonance in a
medium -- possessing with nonlinear resonances of threshold nature and leading
to many important nonlinear effects or applications, which are considered in
this review.
