High-brightness pump sources using 2D VCSEL arrays

Abstract

Many applications require laser pump sources with high output power (tens to hundreds of Watts) in the smallest spot, with the smallest divergence. Such high-brightness pump sources typically use edge-emitting semiconductor lasers. However, it is also possible to use high-power two-dimensional vertical-cavity surfaceemitting laser (VCSEL) arrays for this purpose. Using a single 976nm 2D VCSEL array chip in an external cavity configuration, combined with a matching micro-lens array, we have demonstrated more than 30W output power from a 50μm/0.22NA fiber, corresponding to a brightness of 10MW/cm².sr. This represents a substantial reduction in module complexity compared to edge-emitter based modules with similar brightness. These novel high-brightness pump sources exhibit some well-known intrinsic VCSEL performance features such as wavelength stability and narrow spectrum. Power and brightness can be scaled up using polarization and spectral combining.