Room-temperature polariton luminescence from a bulk GaN microcavity

We report strong exciton-photon coupling at room temperature in a hybrid high quality bulk $3\lambda ∕2$ GaN cavity with a bottom lattice-matched $\mathrm{Al}\mathrm{In}\mathrm{N}∕\mathrm{Al}\mathrm{Ga}\mathrm{N}$ distributed Bragg reflector through angle-resolved polarized photoluminescence (PL). Coupling of the optically active free excitons ($X_A$, $X_B$, and $X_C$) to the cavity mode is demonstrated, with their contribution to the PL spectra varying with polarization. Under TE polarization, exciton oscillator strengths for $X_A$ and $X_B$ are about one order of magnitude larger than in bulk GaAs. Photoluminescence exhibits a strong bottleneck effect despite its thermal lineshape.