Exciton-light coupling in single and coupled semiconductor microcavities: Polariton dispersion and polarization splitting

TLDR

Dielectric mirrors exhibit angle‑ and polarization‑dependent phase delay, and coupling two identical cavities via a central mirror produces an optical splitting between symmetric and antisymmetric modes. The study investigates linear exciton‑light coupling in single and coupled semiconductor microcavities, focusing on angular dispersion and polarization effects in the strong‑coupling regime. The authors model the system as coupled oscillators, showing that cavity mode polarization splitting scales with sin²(θ_eff) and that embedding quantum‑well excitons in both cavities at antinodes yields four coupled oscillators, producing exciton state splitting and separate anticrossings of symmetric and antisymmetric modes. Experimental data on GaAs‑based single and coupled cavities confirm that polariton dispersion and polarization splitting follow the theoretical predictions, with good agreement between measured and modeled anticrossings and polarization splittings.

Abstract

A comprehensive theoretical and experimental study of linear exciton-light coupling in single and coupled semiconductor microcavities is presented: emphasis is given to angular dispersion and polarization effects in the strong-coupling regime. The phase delay in the dielectric mirrors carries a nontrivial angle and polarization dependence. The polarization splitting of cavity modes increases with internal angle as ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{\mathrm{eff}}.$ Comparison with experimental results on a GaAs-based cavity with ${\mathrm{In}}_{0.13}{\mathrm{Ga}}_{0.87}\mathrm{As}$ QW's shows that a quantitative understanding of polariton dispersion and polarization splitting has been achieved. Coupling of two identical cavities through a central dielectric mirror induces an optical splitting between symmetric and antisymmetric modes. When QW excitons are embedded in both cavities at antinode positions, the system behaves as four coupled oscillators, leading to a splitting of otherwise degenerate exciton states and to separate anticrossing of symmetric and antisymmetric modes. These features are confirmed by experimental results on coupled GaAs cavities with ${\mathrm{In}}_{0.06}{\mathrm{Ga}}_{0.94}\mathrm{As}$ QW's. Finally, the polarization splitting in a coupled cavity is analyzed in detail and is in good agreement with the experimental findings.