Surface emitting InGaAsP/InP distributed feedback laser diode at 1.53 mu m with monolithic integrated microlens

Abstract
Monolithic integration of a distributed feedback (DFB) surface-emitting laser diode with a microlens is demonstrated. The transverse and longitudinal cross-sectional views of the laser diode are illustrated. The microlens and a DFB laser structure are located on opposite sides of an n-InP substrate. 11 mA minimum continuous wave (CW) threshold current and 5 mW CW emission perpendicular to the InP substrate are achieved at room temperature using a chemically etched 45 degrees mirror. Single mode emission at 1.53 mu m is obtained. The integrated microlens, etched by ion beam and coated with aluminum oxide, provides optical beam collimation and an ultralow laser mode reflectivity of <10/sup -4/.