Vertical beam divergence of double-barrier multiquantum well (DBMQW) (AlGa)As heterostructure lasers

A theoretical analysis of vertical beam divergence of a modified (AlGa)As laser heterostructure with thin, wide energy-gap barrier layers inserted at interfaces of MQW active region and cladding layers is presented. The barrier layers were intended to achieve the separate control of the carrier and optical confinements. This allowed for weak optical confinement and thereby reduction of beam divergence, without weakening of the carrier confinement and excessive increase of the threshold current density. An efficient antiguiding contribution of the barriers to the original waveguiding properties of a MQW structure has been proved. This results in significant beam divergence reduction down to from 11 to 80 depending on cladding layers thicknesses, Influence of other features of this double-barrier multiquantum well" (DBMQW) structure on the beam divergence is also analyzed.