Role of Re-absorption Effect to Quality Factor in Quantum-Dot Photonic-Crystal Nanocavities

We have systematically evaluated quality (Q) factor in quantum-dot (QD) photonic-crystal nanocavities. The measured Q factor was very sensitive to the detuning energy of the cavity mode to QD inhomogeneous broadening due to the re-absorption effect of the uncoupled QDs within the nanocavity. We achieved a high Q factor of over 10,000 and an ultra-low threshold lasing by the detuning of the cavity mode and the suppression of this effect.