Recent progress in the development of type II interband cascade lasers

Type-II interband cascade lasers combine the advantage of an interband optical transition with interband tunneling to enable the cascading of type-II quantum well active regions as is done in type-I quantum cascade laser. The relatively high radiative efficiency resulting from interband optical transitions translates into very low-threshold current densities, and when combined with the high quantum efficiency of cascade lasers, this diode laser design has the potential to operate under cw conditions at room temperature with high output power. Experimental results have already demonstrated some of this potential including high differential external quantum efficiency (>600%), high peak output power (View the MathML source at View the MathML source), high cw power conversion efficiency (>17% at View the MathML source), and operation at View the MathML source under pulsed conditions. Recent work aimed at reducing device thermal resistance and increasing cw operating temperature is reviewed including the demonstration of significant reductions in thermal resistance (averaging View the MathML source or 40% for 1-mm-long devices), View the MathML source cw operation at View the MathML source with high-power conversion efficiency (23%) and high differential external quantum efficiency (532%), and cw operation up to View the MathML source.