Strong coupling phenomena in quantum microcavity structures

Abstract

The physics of strong coupling phenomena in semiconductor quantum microcavities is reviewed. This is a relatively new field with most important developments having occurred in the last 5 years. We describe how such microcavities enable both electronic and photonic properties of semiconductors, and the interaction between them, to be controlled in the same structure. The resulting coupled exciton-photon eigenstates, cavity polaritons, have many interesting properties including very low mass for small in-plane wavevectors, and can be studied easily and directly in optical experiments, unlike exciton-polaritons in bulk semiconductors. 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 fundamentally 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 optical spectra can be modelled. We then emphasize, in the main body of the review, the particularly important results of reflectivity experiments at both normal and oblique angles of incidence, the effects of external electric and magnetic fields, the results of coherent Raman scattering experiments, the effects of disorder on microcavity spectra, including the observation of motional narrowing over the exciton disorder potential, studies of coupled microcavities, and photoluminescence and time-resolved phenomena.

Vortices in Polariton OPO Superfluids

“…As discussed in the next section, by using a pulsed LG beam (25), vorticity has been shown to persist not only in absence of the rotating drive, but also longer than the gain induced by the probe, and therefore to be transferred to the OPO signal, demonstrating metastability of quantised vortices and persistence of currents in OPO. Experiments and theory will be discussed in the next Sec.…”

“…F pb (r,t) = f pb |r − r pb | |m| e imϕ e −|r−r pb | 2 /(2σ 2 pb ) e i(k pb ·r−ω pb t) e −(t−t pb ) 2 /(2σ 2 t ) , (25) with {k pb , ω pb } can be tuned resonantly to either the OPO signal or idler. As discussed in the next section, by using a pulsed LG beam (25), vorticity has been shown to persist not only in absence of the rotating drive, but also longer than the gain induced by the probe, and therefore to be transferred to the OPO signal, demonstrating metastability of quantised vortices and persistence of currents in OPO.…”

“…From a theoretical point of view, metastable solutions can be equally induced by either a vortex probe pulse (25) or a noise pulse. However, differently from the case of stable vortices, metastable solutions require a threshold in the perturbation breaking the system y → −y symmetry.…”

“…A more complete introduction can be found in several review articles [25,26,27,28,29,14] and books [30,31,32,33] on microcavity polaritons.…”

Coupling of exciton-polaritons inlow−Qcoupled microcavities beyond the rotating wave approximation

“…Coupled microcavities introduce additional degrees of freedom, both for materials and the cavity interactions, and have attracted increasing attention. Quantum well based coupled inorganic microcavites (MCs) have been well studied for theory and optical devices [4][5][6][7][8][9][10][11] . Cavity polariton-induced splitting of excitonic states and optical reflection asymmetry were reported by Armitage et al in quantum well based coupled inorganic MCs 6,7 .…”