scholarly journals Active angular tuning and switching of Brewster quasi bound states in the continuum in magneto-optic metasurfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Diego R. Abujetas ◽  
Nuno de Sousa ◽  
Antonio García-Martín ◽  
José M. Llorens ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Field ◽  
Magnetic Dipole ◽  
Bound States ◽  
Electromagnetic Spectrum ◽  
Resonant Modes ◽  
Out Of Plane ◽  
Q Factors ◽  
The Impact ◽  
The Continuum ◽  
Magneto Optic

Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in photonics, and especially in metasurfaces. One of their most outstanding features is their divergent Q-factors, indeed arbitrarily large upon approaching the BIC condition (quasi-BICs). Here, we investigate how to tune quasi-BICs in magneto-optic (MO) all-dielectric metasurfaces. The impact of the applied magnetic field in the BIC parameter space is revealed for a metasurface consisting of lossless semiconductor spheres with MO response. Through our coupled electric/magnetic dipole formulation, the MO activity is found to manifest itself through the interference of the out-of-plane electric/magnetic dipole resonances with the (MO-induced) in-plane magnetic/electric dipole, leading to a rich, magnetically tuned quasi-BIC phenomenology, resembling the behavior of Brewster quasi-BICs for tilted vertical-dipole resonant metasurfaces. Such resemblance underlies our proposed design for a fast MO switch of a Brewster quasi-BIC by simply reversing the driving magnetic field. This MO-active BIC behavior is further confirmed in the optical regime for a realistic Bi:YIG nanodisk metasurface through numerical calculations. Our results present various mechanisms to magneto-optically manipulate BICs and quasi-BICs, which could be exploited throughout the electromagnetic spectrum with applications in lasing, filtering, and sensing.

scholarly journals Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Diego R. Abujetas ◽  
Ángela Barreda ◽  
Fernando Moreno ◽  
Juan J. Sáenz ◽  
Amelie Litman ◽  
...  
Keyword(s):  
Plane Wave ◽  
Magnetic Dipole ◽  
Bound States ◽  
Normal Incidence ◽  
High Refractive Index ◽  
Electromagnetic Spectrum ◽  
Dipole Resonance ◽  
Microwave Regime ◽  
Q Factors ◽  
The Continuum

Abstract Bound states in the continuum (BICs) are ubiquitous in many areas of physics, attracting special interest for their ability to confine waves with infinite lifetimes. Metasurfaces provide a suitable platform to realize them in photonics; such BICs are remarkably robust, being however complex to tune in frequency-wavevector space. Here we propose a scheme to engineer BICs and quasi-BICs with single magnetic-dipole resonance meta-atoms. Upon changing the orientation of the magnetic-dipole resonances, we show that the resulting quasi-BICs, emerging from the symmetry-protected BIC at normal incidence, become transparent for plane-wave illumination exactly at the magnetic-dipole angle, due to a Brewster-like effect. While yielding infinite Q-factors at normal incidence (canonical BIC), these are termed Brewster quasi-BICs since a transmission channel is always allowed that slightly widens resonances at oblique incidences. This is demonstrated experimentally through reflectance measurements in the microwave regime with high-refractive-index mm-disk metasurfaces. Such Brewster-inspired configuration is a plausible scenario to achieve quasi-BICs throughout the electromagnetic spectrum inaccessible through plane-wave illumination at given angles, which could be extrapolated to other kind of waves.

scholarly journals Near-Field Excitation of Bound States in the Continuum in All-Dielectric Metasurfaces through a Coupled Electric/Magnetic Dipole Model

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 998
Author(s):  
Diego R. Abujetas ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Dipole ◽  
Density Of States ◽  
Bound States ◽  
Local Density ◽  
Near Field ◽  
Field Pattern ◽  
Local Density Of States ◽  
Optical Modes ◽  
Source Excitation ◽  
The Continuum

Resonant optical modes arising in all-dielectric metasurfaces have attracted much attention in recent years, especially when so-called bound states in the continuum (BICs) with diverging lifetimes are supported. With the aim of studying theoretically the emergence of BICs, we extend a coupled electric and magnetic dipole analytical formulation to deal with the proper metasurface Green function for the infinite lattice. Thereby, we show how to excite metasurface BICs, being able to address their near-field pattern through point-source excitation and their local density of states. We apply this formulation to fully characterize symmetry-protected BICs arising in all-dielectric metasurfaces made of Si nanospheres, revealing their near-field pattern and local density of states, and, thus, the mechanisms precluding their radiation into the continuum. This formulation provides, in turn, an insightful and fast tool to characterize BICs (and any other leaky/guided mode) near fields in all-dielectric (and also plasmonic) metasurfaces, which might be especially useful for the design of planar nanophotonic devices based on such resonant modes.

Quasi‐Bound States in the Continuum with Temperature‐Tunable Q Factors and Critical Coupling Point at Brewster's Angle

2021 ◽  
pp. 2000290
Author(s):  
Bing‐Ru Wu ◽  
Jhen‐Hong Yang ◽  
Pavel S. Pankin ◽  
Chih‐Hsiang Huang ◽  
Wei Lee ◽  
...  
Keyword(s):  
Bound States ◽  
Critical Coupling ◽  
Coupling Point ◽  
Q Factors ◽  
The Continuum

scholarly journals High Quality-Factor Dual-Band Fano Resonances Induced by Bound States in The Continuum Using A Planar Nanohole Slab

2021 ◽  
Author(s):  
Tian Sang ◽  
Qing Mi ◽  
Yao Pei ◽  
Chaoyu Yang ◽  
Shi Li ◽  
...  
Keyword(s):  
Bound States ◽  
Near Field ◽  
Dual Band ◽  
Q Factor ◽  
Fano Resonances ◽  
High Quality ◽  
Potential Applications ◽  
Q Factors ◽  
Symmetry Protected ◽  
The Continuum

Abstract In photonics, it is essential to achieve high quality (Q)-factor resonances to enhance light-mater interactions for improving performances of optical devices. Herein, we demonstrate that high Q-factor dual-band Fano resonances can be achieved by using a planar nanohole slab (PNS) based on the excitation of bound states in the continuum (BICs). By shrinking or expanding the tetramerized holes of the superlattice of the PNS, symmetry-protected BICs can be excited and the locations of Fano resonances as well as their Q-factors can be flexibly tuned. Physical mechanisms for the dual-band Fano resonances can be interpreted as the resonant couplings between the electric-toroidal dipoles or the magnetic-toroidal dipoles based on the far-field multiple decompositions and the near-field distributions of the superlattice. The dual-band Fano resonances of the PNS possess polarization independent feature, they can be survived even the geometric parameters of the PNS are significantly altered, making them more suitable for potential applications.

scholarly journals Bound States in the Continuum in the Visible Emerging from out-of-Plane Magnetic Dipoles

ACS Photonics ◽  
2020 ◽  
Vol 7 (8) ◽  
pp. 2204-2210 ◽  
Author(s):  
Shunsuke Murai ◽  
Diego R. Abujetas ◽  
Gabriel W. Castellanos ◽  
José A. Sánchez-Gil ◽  
Feifei Zhang ◽  
...  
Keyword(s):  
Bound States ◽  
Magnetic Dipoles ◽  
Out Of Plane ◽  
The Continuum

scholarly journals Controlling light absorption of graphene at critical coupling through magnetic dipole quasi-bound states in the continuum resonance

2020 ◽  
Vol 102 (15) ◽  
Author(s):  
Xing Wang ◽  
Junyi Duan ◽  
Wenya Chen ◽  
Chaobiao Zhou ◽  
Tingting Liu ◽  
...  
Keyword(s):  
Magnetic Dipole ◽  
Light Absorption ◽  
Bound States ◽  
Critical Coupling ◽  
The Continuum

scholarly journals Significantly enhanced second-harmonic generations with all-dielectric antenna array working in the quasi-bound states in the continuum and excited by linearly polarized plane waves

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhanghua Han ◽  
Fei Ding ◽  
Yangjian Cai ◽  
Uriel Levy
Keyword(s):  
Second Harmonic Generation ◽  
Magnetic Dipole ◽  
Harmonic Generation ◽  
Bound States ◽  
Second Harmonic ◽  
Generation Efficiency ◽  
Second Harmonic Generation Efficiency ◽  
Linearly Polarized ◽  
Magnetic Dipole Resonances ◽  
The Continuum

AbstractThe recently emerging all-dielectric optical nanoantennas based on high-index semiconductors have proven to be an effective and low-loss alternative to metal-based plasmonic structures for light control and manipulations of light–matter interactions. Nonlinear optical effects have been widely investigated to employ the enhanced interactions between incident light and the dielectrics at the Mie-type resonances, and in particular magnetic dipole resonances, which are supported by the semiconductor. In this paper, we explore the novel phenomenon of bound states in the continuum supported by high-index semiconductor nanostructures. By carefully designing an array of nanodisk structures with an inner air slot as the defect, we show that a novel high quality-factor resonance achieved based on the concept of bound state in the continuum can be easily excited by the simplest linearly polarized plane wave at normal incidence. This resonance further enhances the interactions between light and semiconductors and boosts the nonlinear effects. Using AlGaAs as the nonlinear material, we demonstrate a significant increase in the second-harmonic generation efficiency, up to six orders of magnitude higher than that achieved by magnetic dipole resonances. In particular, a second-harmonic generation efficiency around 10% can be numerically achieved at a moderate incident pump intensity of 5 MW/cm2.

scholarly journals High-quality-factor dual-band Fano resonances induced by dual bound states in the continuum using a planar nanohole slab

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Qing Mi ◽  
Tian Sang ◽  
Yao Pei ◽  
Chaoyu Yang ◽  
Shi Li ◽  
...  
Keyword(s):  
Bound States ◽  
Near Field ◽  
Dual Band ◽  
Q Factor ◽  
Fano Resonances ◽  
High Quality ◽  
Dual Bound ◽  
Potential Applications ◽  
Q Factors ◽  
The Continuum

AbstractIn photonics, it is essential to achieve high-quality (Q)-factor resonances to improve optical devices’ performances. Herein, we demonstrate that high-Q-factor dual-band Fano resonances can be achieved by using a planar nanohole slab (PNS) based on the excitation of dual bound states in the continuum (BICs). By shrinking or expanding the tetramerized holes of the superlattice of the PNS, two symmetry-protected BICs can be induced to dual-band Fano resonances and their locations as well as their Q-factors can be flexibly tuned. Physical mechanisms for the dual-band Fano resonances can be interpreted as the resonant couplings between the electric toroidal dipoles or the magnetic toroidal dipoles based on the far-field multiple decompositions and the near-field distributions of the superlattice. The dual-band Fano resonances of the PNS possess polarization-independent feature, and they can be survived even when the geometric parameters of the PNS are significantly altered, making them more suitable for potential applications.

scholarly journals Strong Coupling between Excitons and Magnetic Dipole Quasi-bound States in the Continuum in WS2–TiO2 Hybrid Metasurfaces

2021 ◽  
Author(s):  
Meibao Qin ◽  
Shuyuan Xiao ◽  
Wenxing Liu ◽  
Mingyu ouyang ◽  
Tian Yu ◽  
...  
Keyword(s):  
Strong Coupling ◽  
Magnetic Dipole ◽  
Bound States ◽  
The Continuum
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