Potential‐inserted quantum well design for quantum cascade terahertz lasers

We report on a new design of terahertz quantum cascade laser based on a single, potential‐inserted quantum well active region. The quantum well properties are engineered through single monolayer InAs inserts. The modeling is based on atomistic, spds* tight‐binding calculations, and performances are compared to that of the classical three‐well design. We obtain a 100% increase of the oscillator strength per unit length, while maintaining a high, nearly temperature‐independent contrast between phonon‐induced relaxation times of the upper and lower lasing states. The improved performances are expected to allow THz lasing at room temperature.