Effects of microlens curvature on the operation of microlens-integrated extended cavity GaN VCSELs

摘要

We have fabricated and characterized an extended cavity GaN-VCSEL device integrated with a micro-lens. Laser performance varied depending on the curvature radius of the integrated microlens. At optimum curvature radius, threshold excitation energy was lowest while slope efficiency was largest. Furthermore, no mode hopping was observed and the laser was operated predominantly in single longitudinal mode. The existence of the optimum curvature radius is attributed to a combined effect of reduced light leak in the lateral direction and light feedback in the near-field regime of Gaussian mode.