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Michele Giocondo

Publications and source records attributed to Michele Giocondo.

3 recordsLinked to original sources

Microfluidic gratings for X-ray Phase Contrast Imaging

Fabrication of X-ray gratings has surged in the last two decades thanks to their vast employment in X-ray Phase Contrast Imaging, an imaging technique able to boost X-ray sensitivity to detect otherwise invisible details. These high aspect ratio devices are usually fabricated by complex, costly, multi-step processes that limit their size and volume scaling. These steps commonly involve UV or X-ray lithography, semiconductor selective etching and high-Z metal plating, usually Au, which require expensive tools and materials. Here we present a proof-of-concept fabrication via soft lithography and Hg infusion of microfluidic X-ray absorption gratings and their performance in biomedical imaging. Such fabrication technique requires fewer, less expensive, and more scalable processes using alternative and more sustainable materials, while showing comparable visibility with their conventional Au-based, solid equivalent. Our results constitute a promising shift in X-ray optics fabrication that could significantly lower barriers to commercialization and accelerate the practical deployment of X-ray Phase Contrast Imaging.

physics.optics

Hyper Resolution Two Photon Direct Laser Writing using ENZ Nano-Cavity

A novel technique is reported to improve the resolution of two-photon direct laser writing lithography. Thanks to the high collimation enabled by extraordinary $\varepsilon_{NZ}$ (near-zero) metamaterial features, ultra-thin dielectric hyper resolute nanostructures are within reach. With respect to the standard direct laser writing approach, a size reduction of $89\%$ and $50\%$ , in height and width respectively, is achieved with the height of the structures adjustable between 5nm and 50nm. The retrieved 2D fabrication parameters are exploited for fabricating hyper resolute 3D structures. In particular, a highly detailed dielectric bas-relief (500 nm of full height) of Da Vinci's \textit{"Lady with an Ermine"} has been realized. The proof-of-concept result shows intriguing cues for the current and trendsetting research scenario in anti-counterfeiting applications, flat optics and photonics.

physics.app-ph

Color Tuning by Spontaneous Propagation of Gap Surface Plasmons in Epsilon Near Zero Nano-Cavity

This work presents numerical and experimental results of plasmonic Metal-Insulator optical nano-cavities. The systems are composed of Silver as metal, polyvinylpyrrolidone or indium tin oxide or zinc oxide as insulator. The proposed nano-cavities exhibit extraordinary effects as colors changing in function of the incident/view angles, enhancement of the experimental real and imaginary parts of the pseudo dielectric constant, an extraordinary transmission of 50$\%$ and zero reflection for both polarizations at the resonant wavelengths. These results lead to the formation and propagation of surface plasmon polaritons and their hybridization in gap surface plasmons. The concurrence of these effects allow studying the Goos-Hänchen shift by exploiting the very narrow $Δ$ and $Ψ$ ellipsometer parameters. Thank to their optical properties, the proposed nano-cavities could be applied in several fields such tunable color filters, optics, photonics and sensing.

physics.optics