All-optical control of unipolar pulse generation in a resonant medium   with nonlinear field coupling
  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. 
A.V. Pakhomov, R.M. Arkhipov, I.V. Babushkin, M.V. Arkhipov, Yu.A.   Tolmachev and N.N. Rosanov
physics.optics