Cavity Emission and Photon Statistics in Exciton-Cavity Coupled Systems
Takehiko Tawara, Hidehiko Kamada, and Stephen Hughes*
Optical Science Research Laboratory, *Queen’s University
Interaction between single exciton and single cavity mode are fundamentally interesting and useful in the context of single-photon source for quantum information processing. A curious feature in recent studies using semiconductor photonic-crystal (PhC) is much brighter cavity emission under large detuning than theoretically expected from standard emission formulas . Here, we undertake an experimental study to identify the cavity mode emission at non-zero detuning and its influence on single photon statistics .
We use PhC cavities which consist of a GaAs membrane containing a single InAs dot layer. The left panel of Fig. 1 is image of PL intensity mapping with cavity mode detuning at 4 K. The GaAs barrier was excited by Ar-ion laser (2.54 eV) in this measurement. We found that this system show the bright cavity emission even under fairly-large detunings. The integrated PL intensity when the cavity mode and the exciton are resonant (zero detuning), increases by a factor of about 9 compared with the off resonant case.
To explore the influence of the cavity emission on the photon statistics, we measured the second-order autocorrelation function of the photon intensity. When off-resonant cavity mode, anti-bunching was not observed where g
C(0) 〜1. This absence of the non-classical correlation on the cavity mode is attributed to independently emitted photons from the background such as deep defect level in the GaAs layer. The off-resonant exciton exhibited partial anti-bunching with g X(0)=0.57, indicating that quantum mechanical coupling prevails. Interestingly, at zero detuning the autocorrelation of the overlapping exciton and cavity modes shows a better anti-bunching with g C+X (0)=0.35. As the exciton-cavity coupling is stronger, the relative weight of the deep states recombination contribution decrease, thereby the anti-bunching behavior is recovered to a better g (0), indicating that the photon statistics becomes more non-classical. These measurements are well explained using a medium-dependent master equation model.
This work was partially supported by Strategic Information and Communications R&D Promotion Programme (SCOPE) of Japan.
 For example, K. Hennessy et al., Nature 445 (2007) 896.
 T. Tawara et al., Opt. Express 17 (2009) 6643.
Fig. 1. PL intensity mapping with cavity mode detuning and 2nd order autocorrelation functions.
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