Eur. Phys. J. B 84, 381-384 (2011)
https://doi.org/10.1140/epjb/e2011-20551-9

Regular Article

Optical polariton properties in ZnSe-based planar and pillar structured microcavities

¹ Semiconductor Optics, Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany
² CEA-CNRS-UJF group Nanophysique et Semiconducteurs, Institut Néel, Grenoble, France
³ Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany

^a e-mail: ksebald@ifp.uni-bremen.de

Received: 7 July 2011
Received in final form: 12 October 2011
Published online: 28 November 2011

Abstract

Strong coupling is demonstrated in monolithic ZnSe-based microcavities. Under nonresonant excitation the polariton dispersion has been investigated in dependence on the photon-exciton detuning for different excitation densities at low temperatures. For zero detuning indications of a polariton lasing threshold are observed like a k-space and energy dispersion narrowing of the lower polariton branch with increasing excitation density. Furthermore, it is observed that this effect is hampered for measurements at negative detunings as a result of the less effective polariton relaxation to the ground state. Latter results in the formation of a discrete polariton distribution at finite k values as known for the polariton bottleneck. In order to investigate the influence of a three-dimensional optical confinement on the polariton relaxation, pillar structured microcavities were fabricated. The formation of discrete polariton states in the k-space distribution is observed. Furthermore, indications for a softening of the k-conservation arising from the structural confinement are found leading to a more effective polariton relaxation. This process would be beneficial for the realization of efficient polariton lasing processes.