Toward polariton lasing in a zinc oxide microcavity: Design and preliminary results

Fabrication and Optical Properties of a Fully-Hybrid Epitaxial ZnO-Based Microcavity in the Strong-Coupling Regime

“…The increase of the Rabi splitting at low temperature can be simply explained by the reduction of the exciton linewidth, which approaches that of the photonic mode [15]. The detection at 5 K of A, B, and C excitons at 3376±3, 3382±3, and 3427±2 meV, respectively, in agreement with previous measurements [8], confirms the high quality of the active layer. The dispersion of the polaritonic modes deduced from reflectivity (solid squares) and PL (open circles) data at 300 K is plotted in Fig.…”

“…Thanks to the large binding energy (60 meV) and the small Bohr radius (1.8 nm) of ZnO excitons, the achievement of a polariton laser working at room temperature based on the coherent emission from exciton-polaritons in their ground state is expected [3,4]. A strong coupling regime (SCR) up to 410 K [2,[5][6][7][8][9] is demonstrated but the lasing threshold is not crossed, mainly due to the low photon lifetime. Two different conceptions of ZnO microcavities have been reported: all oxide structures with high quality factors but polycrystalline zinc oxide layers [5][6][7], or hybrid cavities with a better quality of the active layer but a reduced photonic confinement [2,[8][9].…”

“…A strong coupling regime (SCR) up to 410 K [2,[5][6][7][8][9] is demonstrated but the lasing threshold is not crossed, mainly due to the low photon lifetime. Two different conceptions of ZnO microcavities have been reported: all oxide structures with high quality factors but polycrystalline zinc oxide layers [5][6][7], or hybrid cavities with a better quality of the active layer but a reduced photonic confinement [2,[8][9]. Similar to previous works on GaN-based microcavities [10,11] a third approach can be followed using two dielectric mirrors after removal of the substrate used for the epitaxy of the active layer for a high quality factor and a reduced inhomogeneous broadening of the ZnO excitons.…”

Laser emission with excitonic gain in a ZnO planar microcavity

“…The study of the angle-resolved reflectivity of the half-cavity, i.e. without the top dielectric DBR, revealed a large Rabi splitting of 130meV at 300K [14]. A smaller value (105±10 meV) is deduced from the analysis of the angle-resolved photoluminescence of the actual full cavity, the diminution of the Rabi splitting being due to the larger penetration length in the dielectric DBR than in air.…”

“…The microcavity consists in a 5λ/4 ZnO active layer embedded between a bottom (Ga,Al)N/AlN DBR and a top (Si,O)/(Si,N) DBR. The nitride DBR and the ZnO layer are grown by MBE on a Si(111) substrate, whereas the dielectric DBR is realized by PECVD [13,14]. The number of pairs of each mirror is respectively 13 and 12, leading to a nominal quality factor of about 500 for the cavity mode.…”