The inhibition mechanism in polarization bistable semiconductor lasers

The polarization bistability between TE00and TM00eigenstates in InGaAsP/InP lasers is shown to be due to the mode inhibition mechanism. A theoretical analysis shows that the switching is governed by two current-dependent competing terms. One term represents the self-stabilization for the existing lasing mode to resist the onset of a new mode. The other term is the gain recovering term of the nonlasing mode. The major contribution to the latter is the relative current dependence of the TE and TM gains. By making proper assumptions for the device parameters based on experimental data, the observed hysteresis loops have been successfully modeled. The conditions for the existence of polarization bistability are discussed.