Biexcitons in semiconductor microcavities

Abstract

In this paper, the present status of the experimental study of the optical properties of biexcitons in semiconductor microcavities is reviewed. In particular, a detailed investigation of a polariton-biexciton transition in a high-quality single quantum well GaAs/AlGaAs microcavity is reported. The binding energy and the coherent dynamics of the biexciton state are measured at low temperature using differential reflectivity and transient four-wave mixing spectroscopy, respectively. It is found that the biexciton binding energy is not strongly influenced by the exciton-photon coupling in the microcavity, even if the vacuum Rabi splitting exceeds the biexciton binding energy. However, the presence of a longitudinal built-in electric field that results in a Stark effect slightly reducing the binding energy compared to the value measured on a reference bare quantum well is experimentally pointed out and compared with calculations. Additionally, the polarization decay of the transition from the crystal ground state to the biexciton is measured and is shown to be larger by approximately a factor of two compared to the value measured on the reference quantum well.

Polariton correlation in microcavities produced by parametric scattering

“…It is therefore to be expected that the pump-polaritons experience a negative renormalization by this state, which is not present for the cross-linearly polarized signal and idler polaritons. A similar behaviour was measured for co-and cross-circularly polarized polaritons in a pump-probe experiment 1 on the same sample [19], and has been used in the theoretical analysis of polarization dependent polariton amplification measurements [20]. The appearance of such a renormalization is even more evident from the results of the dual pump geometries discussed in the next section.…”

Influence of multi-exciton correlations on nonlinear polariton dynamics in semiconductor microcavities

“…Additionally, the possibility exists that the biexciton can couple to two-photon cavity modes, forming what is often described as a bipolariton. Normally, such coupling does not lead to significant changes in biexciton energy or linewidth since the biexciton interaction occurs over a much larger k-space range than that within which the cavity light field is coupled to the exciton [34,35]. However, some work has demonstrated the existence of a bipolariton state when the biexciton binding energy is equal to the Rabi splitting of the cavity [30,31], as mentioned above.…”

Impact of biexcitons on the relaxation mechanisms of polaritons in III-nitride based multiple quantum well microcavities

“…Note that the equality sign might not hold exactly as the MC biexciton binding energy was shown to be slightly modified by the light-matter interaction, 23 (ii) the radiative dissociation of a cavity biexciton can also directly feed the LPB. Neglecting the dispersion of biexcitons, we get that the biexciton emission energy is 245308-7 …”

“…20 The latter have indeed been shown to be instrumental in analyzing four-wave mixing experiments performed on GaAs MCs. [21][22][23] The SCR between the biexciton transition and the cavity photon might even be observed in MCs submitted to intense circularly polarized excitation. 24 Compared to III-As or II-VI MQW MCs, disorder and biexcitons should play an even more important role in nitride-based systems.…”