Room temperature continuous wave operation of quantum cascade lasers with 12.5% wall plug efficiency

An InP based quantum cascade laser heterostructure emitting at 4.6 mu m was grown with gas-source molecular beam epitaxy. The wafer was processed into a conventional double-channel ridge waveguide geometry with ridge widths of 19.7 and 10.6 mu m without semi-insulating InP regrowth. An uncoated, narrow ridge device with a 4.8 mm cavity length was epilayer down bonded to a diamond submount and exhibits 2.5 W maximum output power with a wall plug efficiency of 12.5% at room temperature in continuous wave operation. (C) 2008 American Institute of Physics.