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
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.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2011