Optically driven tuning of gain spectra in quantum-cascade structures

In this work, new approach to gain spectra tuning have been developed for quantum-cascade structures. The spectral tuning is based on the phase space filling effect evoked by optical driving signals inducing interband electron transitions and populating of conduction lasing subbands. For three-well THz GaAs/AlGaAs quantum-cascade structure, mathematical modeling show that gain spectra can be shifted up to 2 meV without significant change of the gain magnitude at the maximum of spectral characteristic. Tuning ranges are defined by subbands' non-parabolicity.