High Power Highly Efficient Vertical-Cavity Surface-Emitting Laser Diodes with a Au-Plated Heat Spreading Layer

Abstract

Vertical-cavity surface-emitting lasers (VCSELs) are gaining increasing attention due to their interesting properties. The ultimate device performance of VCSELs has exceeded in-plane laser data already regarding minimum threshold currents [1] and highest wall plug efficiency except for high output power pump lasers [2]. Whereas VCSELs are poised to prove their usefulness in short distance data link applications, high efficiency lasers are also attractive for high power applications like laser diode pumped solid state lasers. In general, the maximum output power of VCSELs is thermally limited. Improved heat sinking is therefore necessary to increase the maximum output power. A record high output power of 113 mW has been previously demonstrated with an up-side down mounting of a single VCSEL on a diamond heat sink [3]. Here we show how the thermal heat sinking in a 2D laser array can be improved by using a Au-plated heat spreading layer. The improved heat sinking results in an increase in maximum output power from 20 mW to 42 mW for a 64 µm diameter device. To our knowledge this is the highest output power for an unmounted VCSEL reported to date.