The growing demand of VCSEL-based 3D imaging system requires the development of high-power AlGaAs-based VCSELs. In this context, the purpose of this Master’s thesis is to contribute to the optimization of efficient multijunction AlGaAs VCSELs, overcoming the power limitations of conventional pin configurations. These designs comprise multiple active regions (ARs), electrically coupled by tunnel junctions (TJs). TJs are reversely biased pn junctions where, due to high doping levels, the conduction band (CB) overlooks the valence band (VB), enabling current flow through band-to-band tunneling (BTBT) [1]. Multistage VCSELs exploit BTBT across TJs to re-promote the recombined electrons in the quantum wells (QWs) back into the CB, making them available for further recombinations.