Experimental observation of strong light-matter coupling in ZnO microcavities: Influence of large excitonic absorption

We present experimental observation of the strong light-matter coupling regime in ZnO bulk microcavities grown on silicon. Angle-resolved reflectivity measurements, corroborated by transfer-matrix simulations, show that Rabi splittings in the order of 70 meV are achieved even for low finesse cavities. The impact of the large excitonic absorption, which enables a ZnO bulklike behavior to be observed even in the strong-coupling regime, is illustrated both experimentally and theoretically by considering cavities with increasing thickness.