Ultra-low threshold photonic crystal nanocavity laser

We demonstrate that continuous-wave (CW) photonic crystal (PhC) nanocavity laser operates at room temperature with a very low effective threshold power of ∼375 nW. The CW lasing was achieved at 1.3 μm with InAs/GaAs self-assembled quantum dots (QDs) and high-quality PhC nanocavity with a quality factor of 87,000. The light-in versus light-out curve shows no sharp threshold unlike conventional lasers with pronounced kinks around the thresholds. This near-thresholdless behavior with smooth transition from thermal to coherent light region indicates that this nanocavity laser has a very high spontaneous emission coupling efficiency. We also discuss the characteristics of background noise of QD-based PhC nanocavity lasers compared with quantum well based PhC nanocavity lasers.