EXCITATION OF ULTRASHORT BURSTS OF HARMONICS OF THE RADIATION DURING IONIZATION OF A GAS BY AN INTENSE LIGHT-PULSE

A self-consistent model for a nonlinear interaction of an intense femt osecond-range light pulse with a gas of quantum particles (atoms) is d iscussed. During fast multiphoton ionization of the gas, the spectral lines of harmonics of the radiation undergo a substantial broadening a nd a blue shift. A pulse of the third harmonic with a duration equal t o less than three periods of the exciting optical field can be generat ed at an efficiency approximately 10% in terms of the field amplitude.