Sub-microwatt direct laser writing of fluorescent gold nanoclusters in polymer films

Abstract

<p>We report on the micro-pattering of fluorescent gold nanoclusters embedded in polyvinyl alcohol film using a low-cost continuous-wave laser. We show that the formation of gold nanoclusters requires low-level laser irradiation (<100 W/cm2), corresponding to a sub-microwatt focused beam. This low-intensity requirement enables substantially higher speed and cost-effective light patterning process. As a result of using only small intensities during gold nanoclusters production, no microscopic topological changes were observed in the polymer film. This class of gold nanoclusters potentially finds application in high-speed authenticity marking and similar labeling applications.</p>