Polarization and transverse mode selection in birefringent Vertical-Cavity Surface Emitting Lasers

Calculations are reported of the eeect of birefringence on the selection of polarization states for the case of a weakly index guided Vertical-Cavity Surface Emitting Laser supporting both a fundamental and a higher-order transverse mode. The innuence of the refraction index step of the waveguide on the polarization behaviour of the laser is elucidated. It is found that for large refraction index steps higher-order modes can emerge which are orthogonally polarized to the dominant polarization of the fundamental mode. It is also shown that for smaller index steps polarization switching due to spatial-hole burning eeects can occur. This polarisation switching behaviour is analysed when current spreading eeects and higher order transverse mode discrimination mechanisms are present.