High power 3-12 mu m infrared lasers: recent improvements and future trends

In this paper, we discuss the progress of quantum cascade lasers (QCLs) gro wn by gas-source molecular beam epitaxy. Room temperature QCL operation has been reported for lasers emitting between 5-11 mum, with 9-11 mum lasers o perating up to 425 K. Laser technology for the 3-5 mum range takes advantag e of a strain-balanced active layer design. We also demonstrate record room temperature peak output powers at 9 and 11 mum (2.5 and 1 W, respectively) as well as record low 80 K threshold current densities (250 A/cm(2)) for s ome laser designs. Preliminary distributed feedback (DFB) results are also presented and exhibit single mode operation for 9 mum lasers at room temper ature. (C) 2001 Elsevier Science B.V. All rights reserved.