Sub-10 fs unipolar pulses of a tailored waveshape from a multilevel resonant medium

We theoretically demonstrate the possibility to tune the temporal waveform of unipolar pulses of femtosecond duration emitted from a multilevel resonant medium. This is achieved through the control of the medium response by a properly adjusted sequence of half-cycle unipolar or quasi-unipolar driving pulses and the spatial density profile of resonant centers along the medium layer. We show the production of unipolar optical pulses of varying profiles, like rectangular or triangular ones, from an extended layer of a multilevel medium.