Self-organized patterning on azo molecular glass film via optical near-field effect

Abstract

Self-organized surface patterning has attracted great research interest ranging from scientific understanding to various applications. Here, we report a unique patterning behavior observed on an azo molecular glass film with polystyrene microspheres on the surface upon irradiation with a circularly polarized laser beam. Photoinduced submicron hillocks are found to organize into concentric arrays around isolated polystyrene spheres, while more complex patterns are observed around two or more spheres close to each other. The irradiation first creates surface relief rings encircling the spheres and then the rings split into hillocks arranged in circular arrays with increasing exposure time. Pattern formation is shown to be controlled by synergy from the optical near-field of polystyrene spheres with the spontaneous hillock formation characteristics of the molecular glass film upon light irradiation. This work is beneficial to deepening the understanding of light–matter interactions and is expected to be applied in different areas.