A new top-down method for fabricating gallium nitride (GaN) nanowires with precisely controlled geometries enables single-mode, rather than typically-observed multi-mode, lasing behavior. Single-mode lasing arises from strong mode competition induced by careful restriction of the nanowire dimensions. This research was published by Sandia National Laboratories and is featured in a BES EFRC newsletter that highlights the research done by each of the 46 EFRC centers to demonstrate the collective impact of the EFRC program. The article can be found here: Overcoming the First Grand Challenge