CC BY
0The 30th International Conference on Advanced Laser Technologies LD-I-7
ALT'23
Structural coloring and information encryption via ablation-free
femtosecond laser patterning
V. Lapidas1, A. Zhizhchenko1, A. Kuchmizhak1'2
1-Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Science, 5 Radio Str.,
Vladivostok 690041, Russia 2- Pacific Quantum Center, Far Eastern Federal University, Vladivostok, Russia
Structural colors coming from light interaction with resonant nanostructures hold promise for optical filtering, displaying, color marking and anti-counterfeiting of valuable goods. In sharp contrast to pigments, these colors are non-fading and stable against UV radiation and thermal treatment. At the same time, state-of-the-art applications require controlling over the color tones/saturation at submicron lateral scale, thus expensive and nonscalable lithography-based technologies are to be applied for fabrication of the pixelated nanostructures and their proper arrangement. Direct laser technologies were suggested for more cheap fabrication of nanostructures supporting structural color effects. In particular, tightly focused laser exposure was found to cause local dewetting of the thin Au films coated above the Fabry-Perot filter to form randomly arranged plasmonic nanoparticles that absorb specific wavelength range and modulate the reflectance spectra of the surface [1]. Despite simplicity of the suggested approach, color tone and saturation can not be precisely controlled once the nanostructures are formed through random self-organization process, while their average size depends on the initial thickness of the top Au film.
Fig . 1. Correlated scanning electron microscopy and optical images revealing the laser-printed nanostructures and their color appearance in the optical microscope (magnification 100x, numerical aperture of 0.95).
In our work, we suggested alternative approach providing control over the color tone and saturation at singlepixel level, expanded color gamut as well as fabrication resolution up to 50000 dpi. The approach is based on the femtosecond laser patterning of the metal-insulator-metal Fabry-Perot cavity with the layer thicknesses optimized to demonstrate pronounced reflectance dip in the visible spectral range. Variation of the applied pulse energy allowed to control geometry of the formed nanostructures spanning from 3D nanoprotrusions and volcano-like nanoholes to micro-holes and random nanotextured surfaces that modulate the local surface reflectivity at single-pixel length scale (Fig. 1).
This work was supported by Russian Science Foundation (grant. 21-72-20122)
[1] A.S. Roberts, S.M. Novikov, Y. Yang, Y. Chen, S. Boroviks, J. Beermann, S. I. Bozhevolnyi, Laser writing of bright colors on near-percolation
plasmonic reflector arrays, ACS nano vol. 13, 71-77 (2018).
