Coexistence of exciton and polariton-lasing in an m-plane GaN-based microcavity

Full text: GaN-based heterostructures grown along polar orientation suffer from the presence of the quantum-confined Stark effect. The latter weakens the excitonic transition which is detrimental for achievement of strong coupling regime. For this reason, growth of non-polar microcavities (MCs) looks suitable. Here, we present results obtained on such a non-polar III-nitride MC grown on m-plane bulk GaN substrate. The optical response, Probed by means of photoluminescence (PL) and reflectivity, shows linear and non-linear features in combination with a pronounced anisotropy. More precisely, different selection rules and optical constants for light polarization perpendicular and parallel to the optical axis lead to the coexistence of weak and strong coupling regime at the same sample position. Excitation power dependent PL-studies reveal different thresholds for exciton and polariton lasing and give access to simultaneous observation of the renormalization behavior of the exciton and the lower polariton branch. (author)