Tailoring metal-dielectric nanocomposite materials with ultrashort laser pulses for dichroic color control

Abstract

Hybrid nanostructure written by ultrafast laser pulses with horizontal polarization, featuring scan speed-dependent nanograting orientations and spectral transmission anisotropy.

Anti‐Counterfeiting White Light Printed Image Multiplexing by Fast Nanosecond Laser Processing

“…In last years, femtosecond laser processing of similar films was largely investigated, demonstrating the growth and reshaping of silver nanoparticles, their self-organization along embedded or surface gratings, as well as three dimensional self-organization. [40,41,45] However, for industrial applications, femtosecond lasers appear to be very expensive, and this led us to consider processing by nanosecond lasers already largely used for personalized grey level marking in the security market. The results reported below are the first ones demonstrating nanosecond-laser-induced self-organization of silver nanoparticles in TiO2 thin films.…”

“…As the period value is lower than the incident wavelengths (white light), the -1 st diffracted order only appears for an incidence angle larger than 10° for the blue (400 nm) part of the spectrum and is measured in the backscattering configuration described in Figure 2. When comparing these metasurfaces with the ones produced by femtosecond lasers, [37,40,41,45] the embedded nanoparticles can have higher sizes at low speed and the surface grating-like structures are parallel to the laser polarization while they were perpendicular to the laser polarization with the femtosecond laser processing. 2, obtained at various scan speeds and laser fluences.…”

“…Contrary to lithographic techniques, which remarkably control individual nanostructures, laser processing allows for tuning the statistical geometrical properties of nanoparticle assemblies, such as their size-distribution, shape anisotropy or spatial distribution through self-organization mechanisms. [40][41][42][43] Such a statistical control leads to what can be considered as random plasmonic metasurfaces, [44] consisting of randomly distributed metallic nanostructures with certain size, density, and orientation distributions, rather than well-ordered elements with an individually controlled size, position, and orientation. This makes the metasurface harder to replicate, but also requires new ways of selecting the metasurfaces, as the link between the design parameters of the metasurface and its colors is difficult to model.…”

Laser‐Empowered Random Metasurfaces for White Light Printed Image Multiplexing

“…Although not yet used for implementing white light image multiplexing, laser processing provides a powerful alternative fabrication technology compatible with low-cost, high versatility and large area processing capabilities, enabling customized large color image printing inside a material (embedded nanoparticles) and the tuning of dichroic plasmonic colors. [1,[38][39][40] The laser beam controls the statistical geometrical properties of nanoparticle assemblies and can induce self-organization processes with subwavelength features, related to the laser wavelength and polarization, yielding a strong dichroism. [38][39][41][42][43] Contrary to top-down techniques that form nanostructures one-by-one, laser processing triggers mechanisms that modify several parameters of the nanostructures simultaneously, forming what can be considered as a random metasurface.…”

Advances in ultrafast laser structuring of materials at the nanoscale

“…An example of the nanostructured Bragg grating area is given in Figure 11(c). Three-dimensional arrangements of nanoparticles and nanoscale-topographies can develop color properties to encrypt information [186]. Three-dimensional memories are demonstrated by 3D positioning of nanoparticle domains or nanogratings [175,187], where the latter couples positioning and orientational degrees of freedom to create high density storage in long-life supports (Figure 11(d)).…”