temperature effect on thz quantum cascade lasers

a simple semi-phenomenological model, which accurately predicts the dependence of thresholdcurrent for temperature of resonant-phonon three well quantum cascade laser based on verticaltransitions is offered. we found that, the longitude optical phonon scattering of thermally excitedelectrons is the most important limiting factor for thermal performance of high frequency thz qcls.in low frequency region, parasitic current increases the threshold current. based on our model the useof materials with higher longitude optical phonon energy such as ingaas/gaassb and decreasing thelower laser level lifetime can increase the maximum performance temperature. our observations maycan be used to understand the notion of the effects of thermal electrons on reduction of laserperformance.