Fano resonances and bound states in the continuum (BICs) exhibit a rich phenomenology stemming from, respectively, their asymmetric line shapes infinite quality factors. Here, we show experimentally theoretically that rod dimer metasurfaces narrow (high-Q) at THz frequencies. These evolve continuously into BIC as rods each become identical. We demonstrate analytically this is universal behavior occurring arrays of dimers consisting detuned resonant dipoles. arise result interference between...

Solid-state room-temperature lasing with tunability in a wide range of wavelengths is desirable for many applications. To achieve this, besides an efficient gain material tunable emission wavelength, high quality-factor optical cavity essential. Here, we combine film colloidal CdSe/CdZnS core-shell nanoplatelets square arrays nanocylinders made titanium dioxide to optically pumped at visible and room temperature. The all-dielectric support bound states the continuum (BICs), which result from...

Light absorption from finite semiconductor nanowires is investigated through a unified theoretical picture and numerical simulations. We first show theoretically the electromagnetic mode dispersion relation Mie extinction cross sections for infinite that formally equivalent (Janus) formulas yield both leaky/guided modes resonances as, respectively, complex wave vector or frequency solutions that, in turn, overlap only at grazing angles with respect to nanowire axis. For nanowires, angle of...

Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention optics and photonics, especially metasurfaces, is, planar arrays of sub‐wavelength meta‐atoms. One their most outstanding features is arbitrarily large Q‐factors they induce upon approaching BIC condition, which exploited here to achieve a narrow transparency band. It first shown how shift canonical an all‐dielectric...

Abstract Various optical phenomena can be induced in periodic arrays of nanoparticles by the radiative coupling local dipoles each particle. Probably most impressive example is bound states continuum (BICs), which are electromagnetic modes with a dispersion inside light cone but infinite lifetime, that is, cannot leak to continuum. Symmetry‐protected BICs appear at highly symmetric points systems. Although addition nonequivalent lattice unit cell an easy and straightforward way tuning...

We show the first experimental demonstration of room-temperature exciton-polariton (EP) condensation from a bound state in continuum (BIC). This is achieved by strongly coupling stable excitons an organic perylene dye with extremely long-lived BIC dielectric metasurface silicon nanoparticles. The long lifetime BIC, mainly due to suppression radiation leakage, allows for EP thermalization ground before decaying. property results threshold less than 5 μJ cm-2, 1 order magnitude lower lasing...

Abstract Understanding the interactions between small, submicrometer-sized colloidal particles is crucial for numerous scientific disciplines and technological applications. In this study, we employ optical tweezers as a powerful tool to investigate these interactions. We utilize full image reconstruction technique achieve high precision in characterizing particle pairs that enable nanometer-scale measurement of their positions. This approach captures intricate details provides comprehensive...

Lighting applications require directional and polarization control of the emitted light, which is currently achieved by bulky optical components such as lenses, parabolic mirrors, polarizers. Ideally, this would be without any external optics, but at nanoscale, during generation light. Semiconductor nanowires are promising candidates for lighting devices due to their efficient light outcoupling synthesis flexibility. In work, we demonstrate a precise both directionality nanowire array...

Bound states in the continuum (BICs) are electromagnetic modes with a dispersion inside light cone and infinite lifetimes. This exceptional property has led to intensive research demonstration of BICs gigahertz, teraherz, near-infrared, up visible region. In this study, we design experimentally demonstrate optical using subdiffraction lattice Si nanodisks. The out-of-plane magnetic dipole resonance dielectric nanodisks couples defines symmetry-protected BIC at normal incidence. mode becomes...

The directionality and polarization of light show peculiar properties when the scattering by a dielectric sphere can be described exclusively electric magnetic dipolar modes. Particularly, these modes oscillate in-phase with equal amplitude, at so-called first Kerker condition, zero optical backscattering condition emerges for non-dissipating spheres. However, role absorption gain in remains unexplored. In this work, we demonstrate that either or precludes and, hence, absence backscattered...

Bound states in the continuum (BICs) represent a new paradigm photonics due to full suppression of radiation losses. However, this has also hampered direct observation them. By using double terahertz (THz) near-field technique that allows local excitation and detection THz amplitude, we are able map for first time electromagnetic field amplitude phase BICs over extended areas, unveiling field-symmetry protection suppresses far-field radiation. This investigation, done metasurfaces dimer...

Abstract Bound states in the continuum (BICs) have been thoroughly investigated due to their formally divergent Q‐factor, especially those emerging all‐dielectric, nanostructured metasurfaces from symmetry protection at Γ point (in‐plane wavevector k || = 0). Less attention has paid accidental BICs that may appear any other band structure of supported modes, being turn difficult predict. Here, a coupled electric/magnetic dipole model is used determine analytical conditions for emergence...

Recently, many fascinating properties predicted for metamaterials (negative refraction, superlensing, electromagnetic cloaking,…) were experimentally demonstrated. Unfortunately, the best achievements have no direct translation to optical domain, without being burdened by technological and conceptual difficulties. Of particular importance within realm of negative-index (NIM), is issue simultaneously achieving strong electric magnetic responses low associated losses. Here, hybrid...

In recent years, extraordinary spin angular momenta have been investigated in a variety of structured electromagnetic waves, being especial interest sub-wavelength evanescent fields.Here we demonstrate analytically that, planar and cylindrical waveguides supporting transverse electric/magnetic modes, density arises inside the waveguide (different from induced region outside waveguide), carrying indeed longitudinal (so-called) Belinfante's momentum.Such contribution depends linearly on mode...

Fano resonances in plasmonics have received widespread attention for their distinctly narrow asymmetric line shapes. A variety of configurations been considered, either requiring complex metallic nanostructures or being extremely faint if originated simple single nanoparticles. Here we report on the emergence high-contrast, strongly shapes light scattered from semiconductor nanorods. Numerical calculations are carried out scattering cross sections finite semiconducting nanorods, with...

The interference between electric and magnetic dipolar fields is known to lead asymmetric angular distributions of the scattered intensity from small high refractive index (HRI) particles. Properly designed all-dielectric metasurfaces based on HRI spheres have been shown exhibit zero reflectivity, a generalized Brewster's effect, potentially for any angle, wavelength polarization choice. At normal incidence, effect related absence backscattering dielectric or disks at the, so-called, first...

The optical properties of infinite planar array scattering particles, metasurfaces and metagratings, are attracting special attention lately for their rich phenomenology, including both plasmonic high-refractive-index dielectric meta-atoms with a variety electric magnetic resonant responses. Herein we derive coupled dipole analytical formulation to describe the reflection transmission such periodic arrays, specular diffractive orders, valid in spectral regimes where only dipolar multipoles...

Increasing the sensitivity of chiral spectroscopic techniques such as circular dichroism (CD) spectroscopy is a current aspiration in research field nanophotonics. Enhancing CD depends on two complementary requirements: enhancement electromagnetic fields perceived by molecules under study and conservation helicity those fields, guaranteed duality symmetry. In this work, we introduce systematic method to design nanostructured dual periodic photonic systems capable enhancing molecular...

Bound states in the continuum (BICs) have attracted much attention Nanophotonics for their (formally) infinite Q factors, quasi-BICs (qBICs) being symmetry-broken version allowing in- and out-coupling at expense of finite (but large) factors. very all-dielectric metasurfaces Here we demonstrate that dark asymmetric qBICs arise optical domain Si tilted nanodisk metasurfaces, due to spectral overlap in-plane out-of-plane dipolar resonances these meta-atoms, similar so called Brewster microwave...

Bound states in the continuum (BICs) have attracted much attention Nanophotonics for their (formally) infinite Q factors, quasi-BICs (qBICs) being symmetry-broken version allowing in- and out-coupling at expense of finite (but large) factors. very all-dielectric metasurfaces Here we demonstrate that dark asymmetric qBICs arise optical domain Si tilted nanodisk metasurfaces, due to spectral overlap in-plane out-of-plane dipolar resonances these meta-atoms, similar so called Brewster microwave...

The nearly zero optical forward scattering and anti-dual conditions are usually associated to the so-called second Kerker condition, at which electric magnetic responses phase-shifted by {\pi}. However, as we show, this condition is insufficient both give rise anti-duality symmetry, in striking contrast actual view of problem. Interestingly, demonstrate that near dipolar resonances, energy radiation pattern far-field limit resembles one arising from first with nearly-zero backscattering.

Bound states in the continuum (BICs) are ubiquitous many areas of physics, attracting special interest for their ability to confine waves with infinite lifetimes. Metasurfaces provide a suitable platform realize them photonics; such BICs remarkably robust, being however complex tune frequency-wavevector space. Here we propose scheme engineer and quasi-BICs single magnetic-dipole resonance meta-atoms. Upon changing orientation resonances, show that resulting quasi-BICs, emerging from...

Resonant optical modes arising in all-dielectric metasurfaces have attracted much attention recent years, especially when so-called bound states the continuum (BICs) with diverging lifetimes are supported. With aim of studying theoretically emergence BICs, we extend a coupled electric and magnetic dipole analytical formulation to deal proper metasurface Green function for infinite lattice. Thereby, show how excite being able address their near-field pattern through point-source excitation...