Efficient amplification of mid- to far-infrared pulses due to optical pulse conversion in waveguiding quantum-well heterostructures

A method is suggested of efficient mid- to far-infrared (ir) pulse amplification via driving optical pulse energy conversion in waveguiding quantum well (QW) heterostructures at room temperature. It is based on the optical pulse creating transient population inversion at a long-wavelength transition in the three-level scheme formed by QW levels of dimensional quantization. As a result, efficient amplification of a weak mid- to far-ir pulse, propagating simultaneously with the driving one, becomes possible. A waveguide and QW heterostructure design that is optimal for optical-long-wavelength pulse conversion is proposed and shown to be much simpler than that used in quantum cascade lasers. For the typical input peak power of a picosecond driving pulse and mid- to far-ir pulse of ∼100 W and 100–0.1 mW, respectively, the present scheme is able to produce output ir pulses with peak powers of at least several tens of watts or several tens of milliwatts in the mid- or far-ir range, respectively, i.e., to convert an appreciable part of the optical pulse energy into the mid-ir signal.