Modelling the transverse mode behaviour of surface modified VCSELs

We have modelled the effects of modifying the surface of an oxide-confined top emitting VCSEL by etching a shallow circular surface relief, for the purpose of understanding and subsequently controlling the transverse mode behaviour. Using only generic VCSEL parameters, and a single fitting parameter, good agreement with the experimental results was achieved. By using measured device-specific parameters even higher agreement is expected. These results suggest that by further optimisation of the relief diameter and depth several mWs of single mode power can be achieved with a simple surface modification of a standard oxide confined VCSEL.