kW/cm2 VCSEL arrays for high-power applications

High beam qualities at high optical output powers make VCSELs attractive light sources for various applications like printing, engraving or pumping of solid state lasers. We report on mounted AlGaAs-GaAs two-dimensional VCSEL arrays of 0.123 mm2 size emitting 1.4 W cw optical output power at 10 degrees Celsius. The emitting wavelength of these bottom emitting VCSELs is 980 nm. Maximum power is achieved at a current of 3.3 A and an applied voltage of 2.8 V. The power density spatially averaged over the cleaved laser chip is as high as 1.1 kW/cm2. Narrow circular far-fields below 12 degrees FWHM allow easy focusing of the light to a spot size of less than 100 micrometer resulting in a power density of above 10 kW/cm2. Mounting of the VCSEL array is very convenient since there is no need to take care of precise facet alignment as required for conventional edge emitting laser arrays. Simple mounting on copper heat sinks or microchannel coolers leads to inexpensive laser modules with output powers in the Watt regime. Lifetime testing for more than 7000 hours at room temperature performed at 1 A current corresponding to an output power of about 440 mW has shown a degradation rate of about 1% per 1000 hours which is very promising for industrial applications. So far, we have successfully employed VCSEL arrays for foil marking and free space data transmission.