Study of polarization properties of VCSELs subject to optical feedback from an extremely short external cavity

In this paper, we present a rate equation model for VCSELs subject to optical feedback from an extremely short external cavity (ESEC) to develop a map of bystability. This allows us to investigate the parametric dependence of polarization properties of VCSELs in ESEC configuration, finding out a strong periodic dependence of the polarisation switching (PS) current on the external cavity length. By increasing the external mirror reflectivity we can make this periodic dependence not only stronger but also asymmetric providing the possibility of preventing PS for any injection current, which constitutes a new way to achieve polarization stabilization in VCSELs.