All-Epitaxial Single-Fused 1.55 µm Vertical Cavity Laser Based on an InP Bragg Reflector

We have realised an all-epitaxial 1.55 µm vertical cavity laser by employing a single wafer-fusion step. The laser structure is fabricated by fusing a 32-period p-doped (C) AlGaAs/GaAs top mirror onto a half-cavity structure consisting of a 50-period n-doped (Si) GaInAsP/InP bottom mirror and a 9 quantum well GaInAsP-active material. Laser mesas are fabricated using a wet etching procedure for the top mirror. The top mirror also contains an AlAs layer for oxidation for current confinement. The lasers operate pulsed at temperatures up to 40°C and at pulse lengths of 10 µs up to 5°C. The minimum threshold current density at room temperature is 1.8 kA/cm2 for a device diameter of 55 µm. Compared to nonoxidised laser diodes, the threshold current is markedly decreased in oxidised laser diodes.