STRONG-COUPLING PHENOMENA IN QUANTUM MICROCAVITY STRUCTURES

The physics of strong coupling phenomena in semiconductor quantum micr ocavities is reviewed. This is a relatively new field with most import ant developments having occurred in the last 5 years. We describe how such microcavities enable both electronic and photonic properties oi s emiconductors, and the interaction between them, to be controlled in t he same structure. The resulting coupled exciton-photon eigenstates, c avity polaritons, have many interesting properties including very low mass for small in-plane wavevectors, and can be studied easily and dir ectly in optical experiments, unlike exciton-polaritons in bulk semico nductors. A wealth of new optical phenomena has been reported in this field in the last few years. This review describes the most important of these phenomena. We discuss the reasons why polaritons have fundame ntally different properties in microcavities as compared with those in bulk materials or quantum wells. We explain the factors which control the strength of the exciton-photon coupling and how the resulting opt ical spectra can be modelled. We then emphasize, in the main body of t he review, the particularly important results of reflectivity experime nts at both normal and oblique angles of incidence, the effects of ext ernal electric and magnetic fields, the results of coherent Raman scat tering experiments, the effects of disorder on microcavity spectra, in cluding the observation of motional narrowing over the exciton disorde r potential, studies of coupled microcavities, and photoluminescence a nd time-resolved phenomena.