The Significance of Carrier Leakage for Stable Lasing in Split-Well Direct Phonon Terahertz Quantum Cascade Lasers

We studied the temperature performance of split-well direct phonon terahertz quantum cascade lasers and found that it is limited by a lasing instability that becomes significant as the temperature increases. When the hot electrons of the upper laser level cannot scatter effectively to excited states due to the high radiative barriers of the structures, a lasing instability occurs, which limits the temperature performance.