Laser-Assisted Tailored Patterning of Au Nanoparticles over an Inch-Sized Area: Implications for Large Aperture Meta-optics

ABSTRACT: We investigate laser-induced dewetting of Au films to form nanoparticles with a controlled distribution and to alter these properties spatially with laser parameters for applications of large aperture meta-optics. By performing laser line scans under various parameter space conditions (power, speed, and beam size), we observe that laser power is an effective knob for adjusting the dewetting process while scan speed is not. Temperature numerical calculations show that the scan speeds used in this parameter space do not introduce a large temperature variation but the laser power does. By correlating calculated temperatures and associated experimental dewetting results, we confirm that local temperature is the driving factor in the laser-induced dewetting process. Furthermore, based on in situ thermal emission imaging, the thermal response time is estimated as similar to 2 ms and a self-terminating characteristic of the laser-induced dewetting process is observed. This self-terminating effect results in an insignificant change in subsequent laser scans, contributing to the robustness of this process for large area dewetting patterning by beam rastering. Based on these findings, we successfully demonstrate an inch round globe-shaped pattern consisting of Au nanoparticles.