Polariton lasing in high-quality Selenide-based micropillars in the strong coupling regime

T. Klein, S. Klembt, E. Durupt, C. Kruse, D. Hommel, M. Richard

Published 2015-04-29Version 1

We have designed and fabricated all-epitaxial ZnSe-based micropillars exhibiting the strong coupling regime between the excitonic transition and the confined cavity modes. At cryogenic temperatures, we demonstrate pulsed, single transverse mode polariton lasing operation in the micropillars. Owing to their high crystalline quality, low sidewall roughness, and a quality factor in excess of 5000, we find a particularly low optical excitation threshold, ranging from P$_{\text{thr}}$=2.11\,$\mu$J/cm$^2$ for a diameter of $10\,\mu$m to P$_{\text{thr}}$=2.41\,$\mu$J/cm$^2$ for a diameter of $1.5\,\mu$m. These values are comparable or lower than what is reported so far in planar microcavities made of other large bandgap materials, or in GaAs micropillars. By a careful analysis of P$_{\text{thr}}$ versus diameter we could trace back the conservation of a low polariton lasing threshold in small diameter micropillars to a sidewall roughness length scale as low as $(2\pm 1)\,$nm.