Rabi splitting in CuCl microcavity with DBR consisting of PbCl₂/NaF multilayers

Abstract

We have investigated exciton‐photon coupling phenomena in bulk CuCl microcavities with distributed Bragg reflectors consisting of PbCl2 and NaF multilayers. The CuCl microcavities, which have the cavity‐length of half‐integer multiples of Z3 exciton wavelength, were fabricated by the vacuum deposition in the consistent process. From angle‐resolved reflectance spectra, the cavity polaritons originating from Z3, Z1,2 excitons and cavity photon were clearly obtained in each sample. We assumed the three polariton modes derived from 3×3 phenomenological Hamiltonian with two vacuum Rabi splitting energies. From the analysis, the obtained Rabi splitting energies for λ‐cavity are 110 and 195 meV for Z3 and Z1,2 excitons, respectively. On the other hand, we have determined the complex refractive indices of PbCl2/NaF layers by spectral ellipsometry. Using these optical constants, the reflectance spectrum of the sample was calculated by nonlocal theory with spatial structures of wavefunction of excitons. The spectrum and Rabi splitting energies estimated by the calculations agree well with the experimental results (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)