GSMBE grown infrared quantum cascade laser structures

In this paper we show the evaluated results of a quantum cascade laser (QCL ) structure with a vertical transition and a Bragg reflector grown by gas s ource molecular beam epitaxy (GSMBE). The Al0.48In0.52As/Ga0.47In0.53As QCL structures lattice matched to the InP substrate consists of alternating 25 periods of undoped coupled-quantum-well active regions with compositionall y graded layers, a superlattice graded region to provide strong electron co nfinement in the upper state using a Bragg reflector and an InP buffer laye r. The laser operates in the temperature range from 8 to 250 K with measure d integrated optical powers up to 70 mW at 8 K, and 5 mW at 250 K. The high -resolution emission spectrum of the laser at 250 K provides direct evidenc e of laser action from the narrowing of the strong line and clearly illustr ating the longitudinal mode structure. (C) 1999 Elsevier Science B.V. All r ights reserved.