We report the experimental observation of the strong-coupling regime in a nitride-based microcavity. The active layer in the optical cavity consists of a λ/2 GaN layer sandwiched between a dielectric mirror and the silicon substrate, which acts as the bottom mirror. Reflectivity measurements have been performed under various angles of incidence at $T=5\mathrm{}\mathrm{K},$ producing evidence of strong-coupling behavior between the exciton and the cavity mode. A Rabi splitting of 31 meV is obtained experimentally. Transfer-matrix simulations have allowed us to account for the exciton-photon interaction. From these calculations, the oscillator strengths of the $A$ and $B$ excitons are evaluated and these values are in good agreement with those previously determined in bulk GaN.

• Received 22 June 2003

DOI:https://doi.org/10.1103/PhysRevB.68.153313