J. Eur. Opt. Society-Rapid Publ. 2026, 22, 45 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026041 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
Bayesian optimization of laser processes to maximize structural color gamut
Robin Mermillod-Blondin 1, 2, Nicolas Dalloz 2, Jessica Pellegrino 2, Nathalie Destouches 1, 3,*
, and Rémi Emonet 1, 3, 4,* 1 Univ Lyon, UJM-Saint-Etienne, CNRS, Institut d’ Optique Graduate School, Laboratoire Hubert Curien UMR 5516, F-42023 Saint- Etienne, France 2 TOPPAN Security SAS, 41 Avenue George V, 75008 Paris, France 3 Institut Universitaire de France 4 Inria, Domaine de Voluceau, 78150 Le Chesnay-Rocquencourt, France
Received 28 January 2026 / Accepted 19 April 2026
Abstract. Laser-induced printing is a fast, low-cost, and contactless method for producing high-resolution images on thin films containing metallic nanoparticles. While it enables visual effects and color rendering, its color gamut remains narrower than that of inkjet printing, mainly due to limited saturation and incomplete sRGB hue coverage. To address this, laser parameters, such as scan speed, power, repetition rate, and polarization must be precisely tuned. The color prediction being extremely complex and tedious, the preferred strategy is to build a parameter-to-color database by printing multiple samples under varying conditions and measuring outcomes. The manual tuning of parameters to obtain optimal colors is highly sensitive to sample variability. In this paper, we propose to replace an existing method with genetic algorithm by a novel Bayesian optimization approach to find the optimal laser parameters with the following advantages: simpler as reformulating the problem as multiobjective is not needed, less costly in laser inscription to reach the optimal gamut, and has a better gamut at fixed inscription number.
Keywords: Laser-induced, Color, Optimization, Bayesian.
1 Introduction
* Corresponding authors: nathalie. destouches @ univ-st-etienne. fr; remi. emonet @ univ-st-etienne. fr
Structural colors have emerged as a promising inkless approach for generating durable and versatile colors with high spatial resolution [ 1, 2 ]. They originate from the interaction of light with subwavelength architectures that shape the spectral response through well-identified physical mechanisms. Depending on the considered material and structure, coloration can arise from resonant absorption and scattering in plasmonic or dielectric metasurfaces [ 3 – 5 ], diffraction from periodic patterns [ 6 ], Bragg reflection in photonic crystals [ 7 ], or interference effects in multilayer and cavity-based systems [ 8 – 10 ]. Fabrication strategies for structural colors patterning typically rely on top-down approaches such as electron beam lithography or nanoimprinting, which provide precise control over the geometry. However, these approaches remain intrinsically limited in terms of throughput, scalability, and compatibility with large-area or non-planar substrates. In this context, laser processing offers an effective route toward structural coloration compatible with industrial-scale applications. By inducing localized and controlled material transformations, it enables the direct formation of nanostructures in a singlestep, non-contact process. This approach is compatible with a wide range of materials, large areas, complex geometries, and in-volume structuring, while maintaining high processing speeds and flexibility.
Laser-induced structural colors rely on several physical mechanisms depending on the initial material and structure. Exposing discontinuous metallic layers, or dielectric matrices containing metallic precursors, to a laser can induce the formation of metallic nanoparticle assemblies with controlled statistical properties. These random plasmonic metasurfaces exhibit optical responses governed by localized surface plasmon resonances and their collective interactions [ 11 – 18 ]. In parallel, laser-induced periodic surface structures can form through the interaction between the incident field and surface electromagnetic waves leading to diffractive effects on a wide range of materials [ 19, 20 ]. In thin film configurations, laser-induced changes in thickness or composition, for instance through oxidation or phase transformation, modify the optical path and generate interference-based coloration [ 21, 22 ]. More advanced
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