arXiv subjects

Noel Healy

Publications and source records attributed to Noel Healy.

3 recordsLinked to original sources

arXiv2026

Refractive index retrieval of 3D printed materials for photonic applications

The advent of additive manufacturing has opened opportunities to rapidly prototype devices and products ranging from automotive and aerospace applications to micro/nanoscale metastructures, as examples). Three-dimensional (3D) printing has become relevant for electromagnetic structures, integrated optics and photonics systems, however, the optical properties of commercially available 3D printed polymers at telecommunication wavelengths (wavelength 1550nm) is not always available. Provided the importance of 3D printing technologies, in this work, we evaluate both theoretically and experimentally the complex refractive index of four polymers including some recycled versions (namely Butenediol Vinyl Alcohol (BVOH), Polylactic Acid (PLA), Recycled Polyethylene Terephthalate (rPET), and recycled Polylactic Acid (rPLA)) as potential candidates for photonics applications. The 3D printed samples have thicknesses from ~100 to 400 nm (~64wavelengths to ~258wavelengths, respectively). The experimental reflectance and transmittance spectra are extracted and used to retrieve the complex refractive index of each printed material demonstrating extinction coefficients in the order of 10^-4 at wavelength=1550nm. The experimental results are validated using numerical simulations. Finally, as a proof-of-concept, a convex-planar lens and a Bragg mirror are designed and numerically evaluated, showing the potential of the proposed polymers for 3D printing photonic structures at telecommunication wavelengths.

physics.optics↗

arXiv2023

Plasmonic sensing using Babinet's principle

Developing methods to sense local variations in nearby materials, such as their refractive index and thickness, is important in different fields including chemistry and biomedical applications, among others. Localized surface plasmons (LSPs) excited in plasmonic nanostructures have demonstrated to be useful in this context due to the spectral location of their associated resonances being sensitive to changes near the plasmonic structures. In this manuscript, Babinet's principle is explored by exploiting LSP resonances excited in complementary metal-dielectric cylindrical plasmonic structures (plasmonic particle-dimers and aperture-dimers in our case). Both plasmonic structures are evaluated numerically and experimentally using Electron Energy Loss Spectroscopy (EELS), providing a full physical understanding of the complementary nature of the excited LSP resonances. The studied plasmonic structures are then exploited for dielectric sensing under two configurations: when a thin dielectric film is positioned atop the plasmonic structures and when the analyte surrounds/fills the plasmonic particles/apertures. The complementary sensing performance of both proposed structures is also evaluated, showing the approximate validity of the Babinet principle with sensitivities values of up to 700 nm/RIU for thin dielectric sensing.

physics.optics↗

arXiv2022

On-fiber high-resolution photonic nanojets via high refractive index dielectrics

In this manuscript, we present high spatial resolution focusing of electromagnetic waves at telecommunication wavelengths (λ0 = 1.55 μm) by using high-refractive index mesoscale dielectrics placed at the end of an optical fiber. Our approach exploits photonic nanojets (PNJs) to achieve high-intensity, spatially narrow focal spots. The response of the device is evaluated in detail considering 2-dimensional (2D) and 3-dimensional (3D) configurations using high-index mesoscale cylindrical and spherical dielectrics, respectively, placed on top of an optical fiber. It is shown how the PNJs can be shifted towards the output surface of the mesoscale high-index dielectric by simply truncating its 2D/3D cylindrical/spherical output profile. With this setup, a PNJ with a high transversal resolution is obtained using the 2D/3D engineered mesoscale dielectric particles achieving a Full-Width at Half-Maximum of FWHM = 0.28λ0 (2D truncated dielectric), and FWHMy = 0.17λ0 and FWHMx = 0.21λ0 (3D truncated dielectric). The proposed structure may have potential in applications where near-field high spatial resolution is required, such as in sensing and imaging systems.

physics.optics↗