Extremely temperature-insensitive continuous-wave quantum cascade lasers

Conspicuous temperature performances of λ ∼ 8.7 μm quantum cascade lasers with anticrossed dual-upper laser states are reported. The lasers characterized by strong super-linear current-light output curves exhibit an extremely high characteristic temperature for the threshold current density above 330 K (T0 ∼ 750 K). The slope efficiency grows with increasing temperature (a negative T1-value). In addition, for the pulsed operation of a short 1 mm length laser, the T0-value reaches a value of 1085 K above 340 K. These distinctive characteristics are attributable to optical absorption quenching in the injector as well as to suppression of carrier leakage in the active region.