scholarly journals Fabrication robustness in BIC metasurfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Julius Kühne ◽  
Juan Wang ◽  
Thomas Weber ◽  
Lucca Kühner ◽  
Stefan A. Maier ◽  
...  
Keyword(s):  
Bound States ◽  
Experimental Methodology ◽  
Sem Images ◽  
Biomolecular Sensing ◽  
Resonance Amplitude ◽  
Experimental Realization ◽  
Automated Processing ◽  
Geometrical Variation ◽  
Q Factors ◽  
Quality Factor Q

Abstract All-dielectric metasurfaces supporting photonic bound states in the continuum (BICs) are an exciting toolkit for achieving resonances with ultranarrow linewidths. However, the transition from theory to experimental realization can significantly reduce the optical performance of BIC-based nanophotonic systems, severely limiting their application potential. Here, we introduce a combined numerical/experimental methodology for predicting how unavoidable tolerances in nanofabrication such as random geometrical variations affect the performance of different BIC metasurface designs. We compare several established all-dielectric BIC unit cell geometries with broken in-plane inversion symmetry including tilted ellipses, asymmetric double rods, and split rings. Significantly, even for low fabrication-induced geometrical changes, both the BIC resonance amplitude and its quality factor (Q-factor) are significantly reduced. We find that the all-dielectric ellipses maintain the highest Q-factors throughout the geometrical variation range, whereas the rod and split ring geometries fall off more quickly. The same behavior is confirmed experimentally, where geometrical variation values are derived from automated processing of sets of scanning electron microscopy (SEM) images. Our methodology provides crucial insights into the performance degradation of BIC metasurfaces when moving from simulations to fabricated samples and will enable the development of robust, high-Q, and easy to manufacture nanophotonic platforms for applications ranging from biomolecular sensing to higher harmonic generation.

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 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 A Novel High Q Lamé-Mode Bulk Resonator with Low Bias Voltage

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 737
Author(s):  
Tianyun Wang ◽  
Zeji Chen ◽  
Qianqian Jia ◽  
Quan Yuan ◽  
Jinling Yang ◽  
...  
Keyword(s):  
Bias Voltage ◽  
Integrated Circuit ◽  
Nonlinear Behavior ◽  
Silicon On Insulator ◽  
Transduction Efficiency ◽  
Air Gaps ◽  
High Q ◽  
Bulk Mode ◽  
Q Factors ◽  
Quality Factor Q

This work reports a novel silicon on insulator (SOI)-based high quality factor (Q factor) Lamé-mode bulk resonator which can be driven into vibration by a bias voltage as low as 3 V. A SOI-based fabrication process was developed to produce the resonators with 70 nm air gaps, which have a high resonance frequency of 51.3 MHz and high Q factors over 8000 in air and over 30,000 in vacuum. The high Q values, nano-scale air gaps, and large electrode area greatly improve the capacitive transduction efficiency, which decreases the bias voltage for the high-stiffness bulk mode resonators with high Q. The resonator showed the nonlinear behavior. The proposed resonator can be applied to construct a wireless communication system with low power consumption and integrated circuit (IC) integration.

scholarly journals Quantum halo states in two-dimensional dipolar clusters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
G. Guijarro ◽  
G. E. Astrakharchik ◽  
J. Boronat
Keyword(s):  
Bound States ◽  
Pair Correlation ◽  
Bound State ◽  
Binding Energies ◽  
Ultracold Gases ◽  
Quantum Object ◽  
Experimental Realization ◽  
Halo Structure ◽  
Forbidden Region ◽  
Spatial Size

AbstractA halo is an intrinsically quantum object defined as a bound state of a spatial size which extends deeply into the classically forbidden region. Previously, halos have been observed in bound states of two and less frequently of three atoms. Here, we propose a realization of halo states containing as many as six atoms. We report the binding energies, pair correlation functions, spatial distributions, and sizes of few-body clusters composed by bosonic dipolar atoms in a bilayer geometry. We find two very distinct halo structures, for large interlayer separation the halo structure is roughly symmetric and we discover an unusual highly anisotropic shape of halo states close to the unbinding threshold. Our results open avenues of using ultracold gases for the experimental realization of halos composed by atoms with dipolar interactions and containing as many as six atoms.

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 resonant nanostructures: an overview of engineered materials for tailored applications

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shereena Joseph ◽  
Saurabh Pandey ◽  
Swagato Sarkar ◽  
Joby Joseph
Keyword(s):  
Bound States ◽  
Beam Steering ◽  
Functional Materials ◽  
Bound State ◽  
Dielectric Medium ◽  
Quality Factors ◽  
Theoretical Frameworks ◽  
Experimental Realization ◽  
Promising Tool ◽  
The Continuum

Abstract From theoretical model to experimental realization, the bound state in the continuum (BIC) is an emerging area of research interest in the last decade. In the initial years, well-established theoretical frameworks explained the underlying physics for optical BIC modes excited in various symmetrical configurations. Eventually, in the last couple of years, optical-BICs were exploited as a promising tool for experimental realization with advanced nanofabrication techniques for numerous breakthrough applications. Here, we present a review of the evolution of BIC modes in various symmetry and functioning mediums along with their application. More specifically, depending upon the nature of the interacting medium, the excitations of BIC modes are classified into the pure dielectric and lossy plasmonic BICs. The dielectric constituents are again classified as photonic crystal functioning in the subwavelength regime, influenced by the diffraction modes and metasurfaces for interactions far from the diffraction regime. More importantly, engineered functional materials evolved with the pure dielectric medium are explored for hybrid-quasi-BIC modes with huge-quality factors, exhibiting a promising approach to trigger the nanoscale phenomena more efficiently. Similarly, hybrid modes instigated by the photonic and plasmonic constituents can replace the high dissipative losses of metallic components, sustaining the high localization of field and high figure of merit. Further, the discussions are based on the applications of the localized BIC modes and high-quality quasi-BIC resonance traits in the nonlinear harmonic generation, refractometric sensing, imaging, lasing, nanocavities, low loss on-chip communication, and as a photodetector. The topology-controlled beam steering and, chiral sensing has also been briefly discussed.

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 Tunable Bound States in the Continuum in All-Dielectric Terahertz Metasurfaces

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 623 ◽  
Author(s):  
Xu Chen ◽  
Wenhui Fan
Keyword(s):  
Strontium Titanate ◽  
Fano Resonance ◽  
Bound States ◽  
Cell Structure ◽  
Unit Cell ◽  
Graphene Monolayer ◽  
Quality Factors ◽  
Resonance Amplitude ◽  
Potential Applications ◽  
The Continuum

In this paper, a tunable terahertz dielectric metasurfaces consisting of split gap bars in the unit cell is proposed and theoretically demonstrated, where the sharp high-quality Fano resonance can be achieved through excitation of quasi-bound states in the continuum (quasi-BIC) by breaking in-plane symmetry of the unit cell structure. With the structural asymmetry parameter decreasing and vanishing, the calculated eigenmodes spectra demonstrate the resonance changes from Fano to symmetry-protected BIC mode, and the radiative quality factors obey the inverse square law. Moreover, combining with graphene monolayer and strontium titanate materials, the quasi-BIC Fano resonance can be tuned independently, where the resonance amplitude can be tuned by adjusting the Fermi level of graphene and the resonance frequency can be tuned by controlling the temperature of strontium titanate materials. The proposed structure has numerous potential applications on tunable devices including modulators, switches, and sensors.

scholarly journals Sound Trapping in an Open Resonator

2021 ◽  
Author(s):  
Lujun Huang ◽  
Yan Kei Chiang ◽  
Sibo Huang ◽  
Chen Shen ◽  
Fu Deng ◽  
...  
Keyword(s):  
Quality Factor ◽  
Mirror Symmetry ◽  
Bound States ◽  
Open Resonator ◽  
Acoustic Resonator ◽  
Q Factor ◽  
Order Of Magnitude ◽  
Symmetry Protected ◽  
Quality Factor Q ◽  
Mode Interference

Abstract The ability of extreme sound energy confinement with high-quality factor (Q-factor) resonance is of vital importance for acoustic devices requiring high intensity and hypersensitivity in biological ultrasonics, enhanced collimated sound emission (i.e. sound laser) and high-resolution sensing. However, structures reported so far demonstrated a limited quality factor (Q-factor) of acoustic resonances, up to several tens in an open resonator. The emergence of bound states in the continuum (BIC) makes it possible to realize high-Q factor acoustic modes. Here, we report the theoretical design and experimental demonstration of acoustic BICs supported by a single open resonator. We predicted that such an open acoustic resonator could simultaneously support three types of BICs, including symmetry protected BIC, Friedrich-Wintgen BIC induced by mode interference, as well as a new kind of BIC: mirror-symmetry induced BIC. We also experimentally demonstrated the existence of all three types of BIC with Q-factor up to one order of magnitude greater than the highest Q-factor reported in an open resonator.

scholarly journals Stability of bound states in the continuum in low-contrast photonic structures

2021 ◽  
Vol 2015 (1) ◽  
pp. 012090
Author(s):  
E. E. Maslova ◽  
A.A. Bogdanov ◽  
M. V. Rybin ◽  
Z. F. Sadrieva
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Scattering Theory ◽  
Bound States ◽  
Q Factor ◽  
Low Contrast ◽  
Methods Analytical ◽  
Q Factors ◽  
Good Agreement ◽  
The Continuum

Abstract We consider quality (Q) factor of accidental bound states in the continuum in bilayer resonators consisting of low-index dielectric rods. The dependence of Q factor on the number of periods shows that Q factors increase with the increasing number of rods. We calculated the dependence of the resonator Q factor on the disorder by two methods: analytical (multiple scattering theory) and numerical (finite difference method) and showed that the results are in good agreement. Also, we investigated the dependence of the resonance frequency on disorder.

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