Tweaking the Modal Properties of 1.3 µm Short-Cavity VCSEL - Simulation and Experiment

A modal analysis of both molecular beam epitaxy (MBE)- and metal-organic vapor phase epitaxy (MOVPE)- planarized short-cavity (SC) vertical-cavity surface-emitting lasers (VCSELs) emitting at 1.3 ?m is presented. The comparison of simulated threshold gains with experimental threshold current densities, as well as modal gain difference with sidemode suppression ratios, allows the clear identification of designrelated limitations with respect to single-mode emission for different active diameters. In particular, the influence of the radial profile of the effective refractive index on the strength of index-guiding is found to depend on the regrowth-type (MBE or MOVPE). Moreover, the impact of strongly absorbing contact layers and surface relief structures on the modal properties of the fundamental mode is investigated. A design proposal for a MOVPE-regrown SC-VCSEL with optimized surface relief structure is given, predicting reduced threshold current densities and increased single-mode optical output powers.