Researchers from the University of Illinois have developed a method for vertical-cavity surface-emitting laser (VCSEL) to provide high-power output with good beam quality. The method use Zn-diffusion to create disordering and filter out high order mode of the laser. As a result, VCSEL with larger aperture, which permits higher power, will still output single mode light with tight focus. This technology provides laser for energy-assisted magnetic recording, which could be used in next generation hard disk drive.