Generation of femtosecond mid/far-infrared pulses in quantum-well heterostructures under femtosecond laser pumping

We propose to use the resonant nonlinear-wave mixing due to the second-order electron (hole) nonlinearity in the semiconductor asymmetric quantum wells under a femtosecond optical pulse excitation for the generation of the utmost short mid/far-infrared pulses with a few- or even single-cycle duration defined by the pump duration. We analyze emission of the mid/far-infrared pulses for the planar multiple quantum-well structure optically pumped at the Brewster´s angle. The explicit formula for the mid/far-infrared electric field is derived, and its peak value is estimated as 1 V/m (for the Al(In)GaAs heterostructures) that is high enough for many applications, in particular, in the THz frequency range.