Possibilities for polarisation control in vertical cavity surface emitting lasers for optical interconnects

VCSELs are expected to play an important role in short distance optical interconnects like fast reconfigurable or free-space interconnects. Besides the current modulation for data transmission, polarisation adds an extra parameter, which can be used for routing purposes. In this presentation we shall briefly describe the processing of intra-cavity contacted VCSELs including a seating method for the dry-etched DBR mesa. Asymmetric current injection in the active region was used. It reduces the current crowding problem along the edges of the oxide aperture. This has been confirmed using simple 2D electrical modelling. Moreover, asymmetric current injection showed the potential of stabilising the polarisation by introducing an anisotropy in the gain and loss resulting in a beam polarisation perpendicular to the direction at which the p- and n-contacts are placed.