Strong exciton-photon coupling in ZnO based resonators

The authors report on the fabrication of high quality all-oxide Bragg reflectors (BRs) and ZnO based resonators. The resonator consists of a bulk half-wavelength ZnO microcavity embedded between two BRs, each made of 10.5 layer pairs of yttria stabilized zirconia and Al2O3. Scanning transmission electron microscopy and atomic force microscopy, yield smooth interfaces and low surface roughness for the BR as well as the resonator. For the BR with 10.5 layer pairs the authors obtain reflectivities up to 99.2% within the Bragg stop band. The exciton-polariton dispersion was determined by both, polarization- and angle-resolved photoluminescence (PL) and reflectivity (R) measurements. The detuning between the uncoupled exciton mode and photon mode was changed by shifting the exciton mode energy in the temperature range of 10–290 K. Thereby we observed that a strong exciton-photon coupling regime up to room temperature is present in our resonators with maximum values of the Rabi splitting of about 68 meV (PL, T=...