Polarization and transverse-mode selection in birefringent vertical-cavity surface-emitting lasers

Calculations are reported of the effect of birefringence on the selection of polarization states for the case of a weekly index guided vertical-cavity surface emitting laser supporting both a fundamental and a higher-order transverse mode. The influence of the refraction index step of the waveguide on the polarization behavior 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 effects can occur. This polarization switching behavior is analyzed when current spreading effects and higher order transverse mode discrimination mechanisms are present.