Symmetry considerations in vertical-cavity surface-emitting lasers: Prediction of removal of polarization isotropicity on (001) substrates

The effects of crystalline and structural symmetry on the performance of vertical-cavity surface-emitting laser structures are studied by group theoretical techniques. It is shown that an asymmetrically designed active region (i.e., saw-tooth quantum wells) will make the gain anisotropic with respect to the two different transverse polarization on (001) substrates with eigenvectors along [110] and [11̄0] directions. Removal of gain degeneracies is also shown for tilted substrates with the corresponding tabulation of the eigendirections. The gain/loss anisotropicity is required to make polarization stablized lasers.