21 research outputs found
Beyond Bounds on Light Scattering with Complex Frequency Excitations
Light scattering is one of the most established wave phenomena in optics,
lying at the heart of light-matter interactions and of crucial importance for
nanophotonic applications. Passivity, causality and energy conservation imply
strict bounds on the degree of control over scattering from small particles,
with implications on the performance of many optical devices. Here, we
demonstrate that these bounds can be surpassed by considering excitations at
complex frequencies, yielding extreme scattering responses as tailored
nanoparticles reach a quasi-steady-state regime. These mechanisms can be used
to engineer light scattering of nanostructures beyond conventional limits for
noninvasive sensing, imaging, and nanoscale light manipulation
Hybrid Nanophotonics
Advances in the field of plasmonics, that is, nanophotonics based on optical
properties of metal nanostructures, paved the way for the development of
ultrasensitive biological sensors and other devices whose operating principles
are based on localization of an electromagnetic field at the nanometer scale.
However, high dissipative losses of metal nanostructures limit their
performance in many modern areas, including metasurfaces, metamaterials, and
optical interconnections, which required the development of new devices that
combine them with high refractive index dielectric nanoparticles. Resulting
metal-dielectric (hybrid) nanostructures demonstrated many superior properties
from the point of view of practical application, including moderate dissipative
losses, resonant optical magnetic response, strong nonlinear optical
properties, which made the development in this field the vanguard of the modern
light science. This review is devoted to the current state of theoretical and
experimental studies of hybrid metal-dielectric nanoantennas and nanostructures
based on them, capable of selective scattering light waves, amplifying and
transmitting optical signals in the desired direction, controlling the
propagation of such signals, and generating optical harmonics.Comment: in russian, Accepted to Physics-Uspekhi (https://ufn.ru/en/). Will be
published in Englis
Boosting Terahertz Photoconductive Antenna Performance with Optimised Plasmonic Nanostructures
Advanced nanophotonics penetrates into other areas of science and technology, ranging from applied physics to biology, which results in many fascinating cross-disciplinary applications. It has been recently demonstrated that suitably engineered light-matter interactions at the nanoscale can overcome the limitations of today’s terahertz (THz) photoconductive antennas, making them one step closer to many practical implications. Here, we push forward this concept by comprehensive numerical optimization and experimental investigation of a log-periodic THz photoconductive antenna coupled to a silver nanoantenna array. We shed light on the operation principles of the resulting hybrid THz antenna, providing an approach to boost its performance. By tailoring the size of silver nanoantennas and their arrangement, we obtain an enhancement of optical-to-THz conversion efficiency 2-fold larger compared with previously reported results for similar structures, and the strongest enhancement is around 1 THz, a frequency range barely achievable by other compact THz sources. We also propose a cost-effective fabrication procedure to realize such hybrid THz antennas with optimized plasmonic nanostructures via thermal dewetting process, which does not require any post processing and makes the proposed solution very attractive for applications