Polarization dynamics in a multi-transverse-mode vertical-cavity surface-emitting laser subject to optical feedback

We experimentally study the polarization dynamics in the multi-transverse-mode regime of a vertical-cavity surface-emitting laser under isotropic optical feedback. Simultaneous measurements of orthogonally polarized states are conducted for both the total output and several spatial positions on the beam pattern. When the total output is detected, both slow and fast fluctuations of the two orthogonally polarized states are anticorrelated. For a chosen spatial position, slow fluctuations of the two polarizations are anticorrelated; fast fluctuations at the time scale of the external cavity round-trip time do not show fixed correlation properties when transverse modes have similar strengths.