Quantum dot cascade laser

We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode and two-step strain compensation active region design. The prototype generates stimulated emission at lambda similar to 6.15 mu m and a broad electroluminescence band with full width at half maximum over 3 mu m. The characteristic temperature for the threshold current density within the temperature range of 82 to 162 K is up to 400 K. Moreover, our materials show the strong perpendicular mid-infrared response at about 1,900 cm(-1). These results are very promising for extending the present laser concept to terahertz quantum cascade laser, which would lead to room temperature operation.