arXiv subjects

Guillermo Serrera

Publications and source records attributed to Guillermo Serrera.

6 recordsLinked to original sources

arXiv2026

Enhanced Enantioselective Optical Trapping enabled by Longitudinal Mie Resonances in Silicon Nanodisks

Optical enantioseparation of nanoscale matter is fundamentally limited by the intrinsic weakness of chiroptical forces compared to the dominant achiral gradient forces and thermal fluctuations. Conventional plasmonic approaches typically enhance chirality at the cost of amplifying achiral attraction and heating. Here, we overcome this trade-off by exploiting longitudinal Mie resonances in silicon nanodisks. By employing an Azimuthally-Radially Polarized Beam (ARPB) illumination, we selectively excite longitudinal Mie resonances, with strong optical chirality gradients and comparatively uniform electric field intensities. Specifically, magnetic quadrupole (MQ) resonances, effectively decouple enantioselective forces from the achiral background, providing uniquely favorable conditions for enantioselective optical trapping. Combining full-wave simulations with Kramers' escape-rate theory, we demonstrate a robust trapping system that is both thermally stable and highly selective. We predict trapping selectivity ratios above 100 for particles with Pasteur parameters $|\kappa| \geq$ 0.03 and maintain selectivities above 2 even for weakly chiral analytes ($|\kappa| \approx$ 0.006). These results establish longitudinal Mie resonances in high-index dielectric nanostructures as a promising, non-invasive platform for all-optical chiral analysis and enantiomer separation.

physics.optics↗

arXiv2025

Color Routing and Beam Steering of Single-Molecule Emission with a Spherical Silicon Nanoantenna

Single-photon emitters radiate as electric dipoles, which limits light collection efficiency and complicates integration into flat photonic devices. Developing nanophotonic structures capable of directing photon emission with tunable angular distributions in the visible spectrum has been pursued for applications ranging from integrated optical systems to discrimination of molecular species. To date, such directional control has been achieved using components whose overall footprint is larger than the emission wavelength and often rely on lossy plasmonic components. Here, we employ the DNA origami technique for deterministic nanoscale assembly, positioning single fluorophores in nanometric proximity to a single silicon spherical nanoparticle and demonstrate unidirectional emission with forward-to-backward intensity ratios up to ~7 dB. Furthermore, we show that a single silicon nanosphere antenna can function as a color router or a beam steerer depending on its size, emitter spectral range and emitter-nanoparticle distance.

physics.optics↗

arXiv2025

3-dimensional plasmonic nanomotors enabled by independent integration of Optical Pulling and Lateral Forces

Light-matter interactions generally involve momentum exchange between incident photons and the target object giving rise to optical forces and torques. While typically weak, they become significant at the nanoscale, driving intense research interest in the exploitation of photon recoil to drive micro- and nanostructures. While great progress has been attained in controlling transversal degrees of freedom, three-dimensional movement remains challenging, particularly due to the impractical realization of pulling forces that oppose the direction of incident light. Here we theoretically present a novel nanomotor design that enables independent control over both transverse and longitudinal motion. This design exploits coupling between an azimuthally polarized Bessel beam and a dielectric glass cylinder to realistically achieve optical pulling forces. At the same time, asymmetric plasmonic dimers, embedded within the cylinder, provide lateral motion, through asymmetric scattering under plane wave illumination. We further demonstrate that unwanted displacements and rotations can be restrained, even at long illumination times. Our design unlocks a new degree of freedom in motion control, allowing for pulling, pushing, and lateral movement by simply tuning the polarization or switching between plane waves and Bessel beams.

physics.optics↗

arXiv2025

Distance dependent interaction between a single emitter and a single dielectric nanoparticle using DNA origami

Optical nanoantennas can manipulate light-matter interactions at the nanoscale, modifying the emission properties of nearby single photon emitters. To date, most optical antennas are based on metallic nanostructures that exhibit unmatched performance in terms of electric field enhancement but suffer from substantial ohmic losses that limit their applications. To circumvent these limitations, there is a growing interest in alternative materials. In particular, high-refractive-index dielectrics have emerged as promising candidates, offering negligible ohmic losses, and supporting both electric and magnetic resonances in the visible and near-infrared range that can unlock novel effects. Currently, the few available studies on dielectric nanoantennas focus on ensemble measurements. Here, we exploit the DNA origami technique to study the interaction between silicon nanoparticles and organic fluorophores at the single molecule level, in controlled geometries and at different spectral ranges within the visible spectrum. We characterize their distance-dependent interaction in terms of fluorescence intensity and lifetime, revealing a significant modification of the decay rate together with minimal quenching and a high fluorescence quantum yield even at short distances from the dielectric nanoparticle. This work demonstrates the advantages of dielectric nanoantennas over their metallic counterparts and paves the way for their applications in single-molecule spectroscopy and sensing.

physics.optics↗

arXiv2024

Amplified linear and nonlinear chiral sensing assisted by anapole modes in hybrid metasurfaces

The interaction between chiral molecules and circularly polarized light is largely influenced by the local optical chirality density. This interaction prompts substantial demand of the design of nanophotonic platforms capable of enhancing such effects across large and accessible volumes. Such a magnification requires nanostructures that provide strong electric and magnetic field enhancements while preserving the phase relation of circular light. Dielectric nanostructures, particularly those able to support resonances, are ideal candidates for this task due to their capacity for high electric and magnetic field enhancements. On the other hand, efficient third harmonic generation calls for strong electric field resonances within dielectric materials, a feature often boosted by incorporating plasmonic materials into hybrid systems. In this work, we numerically propose a coupled silicon disk-gold ring system that can exploit the anapole-induced field confinement to provide a broadband magnified circular dichroism under realistic conditions, reaching values up to a 230-fold enhancement. We also demonstrate that this structure can be employed as an efficient third harmonic generator which, when integrated with chiral media, enables an 800-fold enhancement in circular dichroism. Furthermore, we show that pulsed illumination at intensities up to 10 GW/cm2 does not induce temperature increments that could potentially damage the samples. These findings suggest that this system can be a promising and versatile approach towards ultrasensitive chiral sensing.

physics.optics↗

arXiv2021

Gold nanodoughnut as an outstanding nanoheater for photothermal applications

Photoinduced hyperthermia is a cancer therapy technique that induces death to cancerous cells via heat generated by plasmonic nanoparticles. While previous studies have shown that some nanoparticles can be effective at killing cancer cells under certain conditions, there is still a necessity (or the need) to improve its heating efficiency. In this work, we perform a detailed thermoplasmonic study comparing the most effective nanoparticle geometries up to now with a doughnut-shaped nanoparticle, demonstrating that the latter exhibits a superior tunable photothermal response in practical illumination conditions, i.e., unpolarized light. Furthermore, we show that nanoparticle heating in fluidic environments, i.e., nanoparticles undergoing Brownian rotations, strongly depends on the particle orientation with respect to the illumination source. We conclude that the heating performance of nanodoughnuts is outstanding, with a temperature increment 35% higher than the second best nanoheater (nanodisks). Furthermore, nanodoughnuts feature a weak dependence on orientation, being therefore, ideal candidates for photothermal therapy applications. Finally, we present a designing guide, covering a wide range of toroid designs, which can help on its experimental implementation.

physics.optics↗