Exciton-polaritons and nanoscale cavities in photonic crystal slabs

Recent theoretical work on exciton–light coupling in waveguide-embedded photonic crystals is reviewed. After a short description of the theory of photonic crystal slabs, the following issues are discussed: (i) a quantum-mechanical formulation of the interaction between photonic modes and quantum-well excitons, leading to a description of photonic crystal polaritons; (ii) calculations of variable-angle reflectance spectra, which show that radiative polaritons can be excited by an optical beam incident on the slab surface; (iii) a description of nanoscale cavities with extremely high Q-factors and low mode volumes in photonic crystal slabs; (iv) a quantum-mechanical model of the interaction between confined nanocavity modes and single quantum-dot transitions, leading again to a strong-coupling regime of light–matter interaction.