  We study optical response of a resonant medium possessing nonlinear coupling
to external field driven by a few-cycle pump pulse sequence. We demonstrate the
possibility to directly produce unipolar half-cycle pulses from the medium
possessing an arbitrary nonlinearity, by choosing the proper pulse-to-pulse
distance of the pump pulses in the sequence. We examine the various ways of the
shaping of the medium response using different geometrical configurations of
nonlinear oscillators and different wavefront shapes for the excitation pulse
sequence. Our approach defines a general framework to produce unipolar pulses
of controllable form.
