Tailoring the waveforms to extend the high-order harmonic generation cut-off

Increase of the cut-off value in the high order harmonics generation process is demonstrated for a special case of the driving field composed of several harmonics of a given frequency. It is shown that a moderate, of the order of 20%, increase in the cut-off value can be achieved. This result possibly constitutes an upper limit for the increase in the cut-off value, attainable for a class of the waveforms considered in the paper.