Spatial mode structure of bottom-emitting broad-area vertical-cavity surface-emitting lasers

The spatial mode structure of circular broad-area bottom-emitting vertical- cavity surface-emitting lasers is investigated close to threshold. The devi ces display very high-order flower-like Laguerre modes as well as structure s with a Cartesian symmetry in spite of the original O(2) symmetry. In some cases the latter resemble tilted waves more than Hermite-Gaussian modes. S patial structures appear for both sides of the detuning between the gain pe ak and the cavity resonance. The results indicate the necessity to refine t he theoretical models to include realistic boundary conditions and inhomoge neities.