Criticalities and Phase Transitions in the Polarization Switching of Vertical-Cavity Surface-Emitting Lasers

This letter reports on four criticalities observed in the polarization switching (PS) of vertical-cavity surface-emitting lasers (VCSELs). These are a critical slowing down nearing PS, a power law and scaling law of the relaxation time, and an adiabatic no-go, which indicates that the critical point can not be reached adiabatically. The critical exponent of the relaxation time, $\Delta$ , is measured about 2.3. To our knowledge, this is the first investigation of these criticalities in the VCSEL\´s PS (VPS). The phase transition characteristics of VPS are also discussed, including the possible connection with the quantum phase transitions.