Abstract

An increasing amount of research is being devoted to improving the spatial resolution of photo-polymerization in direct laser writing, a method used to microfabricate photonic circuits, ordering matrices for nanoemitters, and plasmonic-photonic transistors, just to name a few. Hyperbolic metamaterials and nanocavities enable a variety of uncommon optical effects such as extraordinary transmittance, zero reflectance, giant dephasing, and epsilon-near-zero permittivity [1]. We used a metal/insulator/metal/insulator planar multilayer to upgrade a standard two-photon direct laser writing process to hyper resolution [2]. The improved resolution opens new possibilities in the microfabrication of next-generation 2d/3d nanoscale devices, ordering matrices for nanoparticles, flexible substrate with tunable plasmonic resonance, and in thermoplasmonics [3]. Moreover, a high resolution is crucial for industrial applications in fields such as anti-counterfeiting and flat optics. Having reduced the voxel size by about 89% in height and 50% in width, we fabricated microlabel encoding physical unclonable functions [2], and apochromatic broadband metalenses with extended focal length and depth of focus, with a numerical aperture of 0.87 [2].

References:

[1] Lio G.E., Ferraro A., Giocondo M., Caputo R., and De Luca A., Advanced Optical Materials 8 (2020) 2000487.
[2] Lio G., Ferraro A., Ritacco T., Aceti D.M., De Luca A., Giocondo M., and Caputo R., Advanced Materials 33 (2021) 2008644.
[3] Lio G.E., De Luca A., Umeton C.P., and Caputo R., Journal of Applied Physics 128 (2020) 093107.