Laser processing approaches for functional nano- and microstructures with photonic applications

Photonic materials with sub-wavelength features have enabled unique light-matter interactions; however, fabrication methods face challenges in achieving high-resolution features and tunable structures at scale. In this work, laser-processing of photonic materials is studied. First, multilayered gratings are fabricated using two-photon absorption lithography for polarization-sensitive structural colors. By varying the grating design and light polarization conditions, the transmitted structural color response is analyzed. Next, we investigate the laser focusing beyond Abbe’s diffraction limit using ultrasmooth plasmonic pyramidal arrays. The electric field enhancement due to nanoscale curvature at the apex is characterized, and pyramidal structures of different metals are integrated into a high-precision substrate patterning setup. Overall, this work showcases high-resolution feature size and structural control in laser-based techniques, offering insights into novel micro- and nanofabrication techniques.