Characteristics of single-mode InGaAs submonolayer quantum-dot photonic-crystal vertical-cavity surface-emitting lasers

An InGaAs submonolayer (SML) quantum-dot photonic-crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (< 1 ML) and GaAs. A single-fundamental-mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. A side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over the entire current operation range. The beam profile and near-field image study of the PhC-VCSEL indicates that the laser beam,is well confined by the photonic crystal structure of the device.