Self-shaping of cavity-polariton systems created by resonant broadband excitation

Abstract

The dynamics of a pure low polariton (LP) system created by resonant broadband excitation in a wide range of wave vectors was investigated in a high-$Q$ GaAs-based microcavity. The LP system is shown to inherit the high spatial coherence from the laser pulse and does not lose it during decay. As a result, its dynamics is well controlled by the spatial and momentum distributions of photons in the exciting pulse and described by the Gross-Pitaevskii equations. In particular, the purely dynamic formation of the highly populated coherent LP state was implemented at the LP band bottom in the cavity excited in a large spot by converging ps-long Gaussian laser pulses when the active region of the cavity is in front of its waist. The formed state is found to persist for several picoseconds until the LP-LP repulsion leads to the creation of high-energy LPs dissipating from the ground state with high velocities.