Influence of mass-transported layers on threshold current and mode behavior in InGaAsP BH semiconductor lasers

The junction voltage distributions in InGaAsP mass-transported (MT) BH lasers are calculated by Schwarz-Christoffel transformation technique. The effects of MT layer thickness, active layer thickness, the hole concentration in upper confining layer, and of injected current through active layer on the leakage current through MT layer homojunction are analyzed. The guiding modes are divided into classes A and B according to a proposed ''transition mode'' by which the mode behavior of a symmetrical five-layer slab waveguide is analyzed in a rather comprehensive way. It is shown that the requirement for decreasing the threshold current and the requirement for lasing in a single fundamental lateral mode are somewhat contradictory, so that the thickness of MT layer should have the optimum value in a certain sense.