Towards optically pumped GaN-based high-contrast grating V(E)CSELs

In this study we present the novel approach of GaN-based high-contrast grating (HCG) mirrors as highly reflective top mirrors in GaN vertical-(external)-cavity surface-emitting lasers [V(E)CSELs]. These mirrors can well be integrated into a conventional process flow for GaN-based VECSEL devices – in contrast to conventional Bragg mirrors. Results of thorough growth experiments performed to reliably fabricate high quality cavity structures with well-defined and fine-tuned optical properties will be reported. The properties of HCG mirrors have been calculated by extensive optical device simulations. Properties of HCG structures have been analyzed experimentally by reflection measurements and results will be discussed with a focus on HCG design, potential material combinations, compatibility with existing process steps in GaN technology and the various ways of integration into VECSEL structures.