GaN-based lasers on SiC: influence of mirror reflectivity on L-I characteristics

The influence of the mirror reflectivity on the L-I characteristics of GaN- based lasers has been studied. A cleaved, Al-coated fiber is used as an ext ernal micro-mirror to control the reflectance of the end facets allowing fo r a continuous adjustment of mirror losses of a particular laser. In contra st to other methods, this eliminates all ambiguities usually arising from t he comparison of different or differently coated devices. An increase in th e single facet external quantum efficiency by 45% is observed for uncoated lasers and simultaneously, the threshold current is reduced by 12%. Interna l losses of approximately 20-30 cm(-1) are derived from the differential qu antum efficiency variation depending on the particular device under investi gation. (C) 2001 Elsevier Science B.V. All rights reserved.