Robust Irreversible Polarization Switching in Optically Injected VCSELs

We report experimental observations of robust irreversible polarization switching (IPS) in vertical cavity surface emitting lasers (VCSELs) subject to external optical injection. It is shown that, when operated in a two-mode regime, the VCSEL exhibits IPS for both parallel and orthogonal optical injection. The polarization switching is maintained for a wide range of values of control parameters, including frequency detuning, injected power $({\rm P}_{\rm \inj})$ , bias current, and device operating temperature.