Dynamics of a driven lower polariton mode in resonantly excited planar GaAs microcavities

摘要

Instabilities in a driven lower polariton (LP) mode in planar GaAs microcavities are investigated under the resonant optical pumping near the magic angle, with the use of a time-resolved technique. A qualitatively different hysteresis behavior has been observed for the intracavity field ε_(QW) and for the resonance energy of the driven LP mode. Self-instability of the driven nonlinear LP oscillator, which develops with increasing pumping, results in a sharp increase in both ε_(QW) and the LP energy. The steplike increase in ε_(QW) transfers the LP system in a region of its strong parametric instability with respect to the intermode scattering. The instability mainly results in a redistribution of LPs in the momentum space, which causes a strong decrease in ε_(QW) for the driven mode but weakly affects the resonance energy. The results are qualitatively explained within a coherent many-mode approximation based on the Gross-Pitaevskii equations.