Low-threshold surface-passivated photonic crystal nanocavity laser

The efficiency and operating range of a photonic crystal laser are improved by passivating the In-GaAs quantum well gain medium and GaAs membrane using a (NH₄)S treatment. The passivated laser shows a fourfold reduction in nonradiative surface recombination rate, resulting in a fourfold reduction in lasing threshold. A three-level carrier dynamics model explains the results and shows that typical parameters of such lasers lead to a lasing threshold as much determined by surface recombination as by the overall impact of the cavity quality factor. Surface passivation therefore appears crucial in operating such lasers under practical conditions.