High-power, 1-µm vertical-cavity surface-emitting laser exhibits low threshold current

High-power, 1-µm vertical-cavity surface-emitting laser exhibits low threshold current

A high-power oxide-defined vertical-cavity surface-emitting laser (VCSEL) is based on a lateral current-injection scheme for low resistance and lateral oxidation for carrier confinement. Workers from Lucent Technologies--Bell Labs (Murray Hill, NJ) and the Department of Physics and Photonics Research Center at the University of Connecticut (Storrs, CT) used low-pressure metal-organic chemical-vapor deposition to grow the laser structure layers on a <100> oriented gallium arsenide (GaAs) substrate. The multiple-quantum-well active region has a strain-compensated layer structure consisting of three indium gallium arsenide (InGaAs) quantum wells with gallium arsenide phosphide (GaAsP) barrier layers. A 50-nm-thick aluminum arsenide (AlAs) layer is placed between the active region and the two highly doped GaAs layers, then oxidized and converted to AlOX later in the fabrication process. The VCSEL structure is designed to form a 3l cavity with the quasi-nulls of the corresponding Fabry-Perot modes designed to overlay the two highly doped GaAs layers, reducing the free-carrier loss significantly. Devices were fabricated with diameters of 4 and 50 µm. The former exhibit threshold currents of about 1.5 mA and emit a few milliwatts of output power. The 50-µm devices produced about 250 mW of output power near 1 µm. Such high-power VCSELs are potentially important for applications such as cladding-pumped fiber lasers.