A model tool for single polarization VCSEL design

Polarization control in vertical-cavity surface-emitting lasers (VCSELs) has attracted a lot of interest and different techniques have been proposed to achieve it. Among them, one of the most attractive relies on slight modifications of existing and well behaving devices, i.e. by introducing a non-circular transverse layer section somewhere in the device. Even though experimental verifications. of this principle have already been carried out, a theoretical framework to better understand and possibly optimize such devices is still missing. This mainly originates from the need of a fully vectorial and three-dimensional approach. In this paper we will undertake a joint experimental and theoretical effort: first we give experimental evidence of polarization control by applying elliptical surface etching. Then, after having validated the vectorial electromagnetic model by comparing numerical and experimental results, we are able to better explain the polarization selection mechanisms and consequently to provide suggestions for optimized structures.