Improved performance of GaAs-AlGaAs superlattice quantum cascade lasers beyond lambda=13 mu m

Highly improved quantum cascade lasers based on intraband transitions in a chirped AlGaAs-GaAs superlattice have been realized. Lasing in a liquid nit rogen environment with a laser wavelength centered at 13 mu m and with a pe ak optical power per facet exceeding 80 mW is achieved. A threshold current density of 8.6 kA/cm(2) at 80 K has been measured. Multimode lasing spectr a ranging from 12.4 to 13.3 mu m and single mode spectra in a short cavity at 13 mu m are obtained. To improve the gain in the structure, the design o f the injector is optimized, The minibands in the active region are more st rongly confined beneath the conduction band edge of the barriers to decreas e electron losses into the continuum. The maximum operating temperature exc eeds 230 K with T-0 values of 170 K.