Optical-field profiles in InxGa1−xN -MQW laser structures

In this paper, we calculated the optical fields for InxGa1−xN-multiquantum well (MQW) laser structures. Two different optical cavities are compared, the conventional step separate confinement heterostructure (Step) and a graded-index (GRIN) structure with a parabolic variation of the Al content in the AlxGa1−xN guide layers. A comparison is made regarding the confinement factor, near- and far-field patterns. An anomalous behavior for the confinement factor is observed in the structure, and it can be eliminated by choosing an appropriated combination of the layer’s thicknesses forming the waveguide. For AlxGa1−xN, an improved expression for the refractive index is presented, which shows better agreement with experimental data than previously reported expressions.