3 research outputs found
Control of the Radiative Heat Transfer in a Pair of Rotating Nanostructures
The fluctuations of the electromagnetic field are at the origin of the
near-field radiative heat transfer between nanostructures, as well as the
Casimir forces and torques that they exert on each other. Here, working within
the formalism of fluctuational electrodynamics, we investigate the simultaneous
transfer of energy and angular momentum in a pair of rotating nanostructures.
We demonstrate that, due to the rotation of the nanostructures, the radiative
heat transfer between them can be increased, decreased, or even reversed with
respect to the transfer that occurs in absence of rotation, which is solely
determined by the difference in the temperature of the nanostructures. This
work unravels the unintuitive phenomena arising from the simultaneous transfer
of energy and angular momentum in pairs of rotating nanostructures.Comment: 9 pages, 4 figure
Spectral Vector Beams for High-Speed Spectroscopic Measurements
Structured light harnessing multiple degrees of freedom has become a powerful
approach to use complex states of light in fundamental studies and
applications. Here, we investigate the light field of an ultrafast laser beam
with a wavelength-depended polarization state, a beam we term spectral vector
beam. We demonstrate a simple technique to generate and tune such structured
beams and demonstrate their spectroscopic capabilities. By only measuring the
polarization state using fast photodetectors, it is possible to track
pulse-to-pulse changes in the frequency spectrum caused by, e.g. narrowband
transmission or absorption. In our experiments, we reach read-out rates of
around 6 MHz, which is limited by our technical ability to modulate the
spectrum and can in principle reach GHz read-out rates. In simulations we
extend the spectral range to more than 1000 nm by using a supercontinuum light
source, thereby paving the way to various applications requiring high-speed
spectroscopic measurements.Comment: 11 pages, 12 figure
Lattice Resonances Excited by Finite-Width Light Beams
ArtÃculo con 6 figurasPeriodic arrays of metallic nanostructures support collective lattice resonances, which give rise to optical responses that are, at the same time, stronger and more spectrally narrow than those of the localized plasmons of the individual nanostructures. Despite the extensive research effort devoted to investigating the optical properties of lattice resonances, the majority of theoretical studies have analyzed them under plane-wave excitation conditions. Such analysis not only constitutes an approximation to realistic experimental conditions, which require the use of finite-width light beams, but also misses a rich variety of interesting behaviors. Here, we provide a comprehensive study of the response of periodic arrays of metallic nanostructures when excited by finite-width light beams under both paraxial and nonparaxial conditions. We show how as the width of the light beam increases, the response of the array becomes more collective and converges to the plane-wave limit. Furthermore, we analyze the spatial extent of the lattice resonance and identify the optimum values of the light beam width to achieve the strongest optical responses. We also investigate the impact that the combination of finite-size effects in the array and the finite width of the light beam has on the response of the system. Our results provide a solid theoretical framework to understand the excitation of lattice resonances by finite-width light beams and uncover a set of behaviors that do not take place under plane-wave excitation.This work was sponsored by a Leonardo Grant for Researchers in Physics from the BBVA Foundation. The authors also acknowledge support from Grant Nos. PID2019-104268GB-C21 and PID2019-109502GA-I00 funded by MCIN/AEI/10.13039/501100011033 as well as the U.S. National Science Foundation (Grant No. DMR-1941680). L.Z. acknowledges support from the Department of Energy Computational Science Graduate Fellowship (Grant No. DE-SC0020347). J.R.D.-R. acknowledges a predoctoral fellowship from the MCIN/AEI assigned to Grant No. PID2019-109502GA-I00. We also thank the UNM Center for Advanced Research Computing, supported in part by the U.S. National Science Foundation, for providing some of the computational resources used in this work