Amplification of terahertz radiation on transitions between Wannier–Stark ladders in weak-barrier superlattices

The experimental and numerical studies of the transport properties and wave functions of electrons in GaAs/Al_xGa_1-xAs superlattices with weak barriers in a strong electric field demonstrate the possibility of terahertz lasing on transitions between Wannier–Stark ladders, which can be tuned by applying voltage. The calculated gain can be as high as 500 cm^-1, which exceeds several times the values characteristic of modern THz quantum cascade lasers. Thus, one would expect lasing to occur in a simple n⁺ – superlattice – n⁺ stripe structure. Such lasers, due to the possibility of wide tuning and simplicity of the superlattices they are based on, could compete with cascade lasers.