90 research outputs found
Dielectric geometric phase optical elements from femtosecond direct laser writing
We propose to use femtosecond direct laser writing technique to realize
dielectric optical elements from photo-resist materials for the generation of
structured light from purely geometrical phase transformations. This is
illustrated by the fabrication and characterization of spin-to-orbital optical
angular momentum couplers generating optical vortices of topological charge
from 1 to 20. In addition, the technique is scalable and allows obtaining
microscopic to macroscopic flat optics. These results thus demonstrate that
direct 3D photopolymerization technology qualifies for the realization of
spin-controlled geometric phase optical elements.Comment: 6 figure
Direct laser printing of high-resolution physically unclonable anti-counterfeit labels
Security labels combining facile structural color readout and physically
unclonable one-way function (PUF) approach provide promising strategy for
fighting against forgery of marketable products. Here, we justify direct
femtosecond-laser printing, a simple and scalable technology, for fabrication
of high-resolution (12500 dots per inch) and durable PUF labels with a
substantially large encoding capacity of 10 and a simple
spectroscopy-free optical signal readout. The proposed tags are comprised of
laser-printed plasmonic nanostructures exhibiting unique light scattering
behavior and unclonable 3D geometry. Uncontrollable stochastic variation of the
nanostructure geometry in the process of their spot-by-spot printing results in
random and broadband variation of the scattering color of each laser printed
"pixel", making laser-printed patterns unique and suitable for PUF labeling.Comment: 5 pages, 3 figure
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