Dynamics and polarization of conventional and spin-VCSELs in the presence of an axial magnetic field

The spin flip model is used to investigate the effects of an axial magnetic field on the polarization and dynamics of conventional vertical cavity surface-emitting lasers (VCSELs) and spin-VCSELs where polarized optical pumping is used to inject a spin-polarized electron population. It is found that the ratio of the circular birefringence caused by the magnetic field to the intrinsic linear birefringence plays an important role in exciting oscillations in the intensities and polarization of the VCSELs studied. For a conventional VCSEL, higher values of the linear birefringence require larger axial magnetic fields to cause output power and polarization oscillations. In the case of spin-VCSELs, it is found that both magnitude and sign of the magnetic field can affect the stability and dynamics, as represented on maps in the plane of polarization ellipticity versus magnitude of the pump. A reversal in the sign of the field is equivalent to reversing the sign of the pump ellipticity. Potential applications of these effects in terms of optical oscillators and magnetic field sensors are identified.