A population inversion study of GaAs/Al<sub>x</sub>Ga<sub>1-x</sub>As three-quantum-well quantum cascade structures is presented. We derive the population inversion condition (PIC) of the active region (AR) and discuss the PICs on different structures by changing structural parameters such as the widths of quantum wells or barriers in the AR. For some instances, the PIC can be simplified and is proportional to the spontaneous emission lifetime between the second and the first excited states, whereas some other instances imply that the PIC is proportional to the state lifetime of the second excited state.
© 2013 Chinese Optics Letters
Lasers and Laser Optics
Jinlong Liu, Xiaoli Zhang, Jian Wang, Yanwu Lv, and Suqing Duan, "Population inversion study of GaAs/AlGaAs three-quantum-well quantum cascade structures," Chin. Opt. Lett. 11, 041409- (2013)