Embedded Photonic Eigenvalues in 3D Nanostructures

Monticone, Francesco; Alù, Andrea

doi:10.1103/physrevlett.112.213903

Cited by 296 publications

(252 citation statements)

References 17 publications

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“…For systems with continuous spectra, various PT -symmetric photonic crystals (PCs) have been considered by studying their complex band structures. For each Bloch * Corresponding author: phchan@ust.hk k, the coalescence of two eigenstates in a discrete spectrum is normally called an EP [28][29][30][31][32][33]. For example, in the PT -symmetric plasmonic waveguides, EPs can close the gap formed by two branches of surface plasmon polaritons [28].…”

Section: Introductionmentioning

confidence: 99%

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

2015

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Non-Hermitian systems with parity-time-(PT )-symmetric complex potentials can exhibit a phase transition when the degree of non-Hermiticity is increased. Two eigenstates coalesce at a transition point, which is known as the exceptional point (EP) for a discrete spectrum and spectral singularity for a continuous spectrum. The existence of an EP is known to give rise to a great variety of novel behaviors in various fields of physics. In this work, we study the complex band structures of one-dimensional photonic crystals with PT -symmetric complex potentials by setting up a Hamiltonian using the Bloch states of the photonic crystal without loss or gain as a basis. As a function of the degree of non-Hermiticity, two types of PT symmetry transitions are found. One is that a PT -broken phase can reenter into a PT -exact phase at a higher degree of non-Hermiticity. The other is that two EPs, one originating from the Brillouin zone center and the other from the Brillouin zone boundary, can coalesce at some k point in the interior of the Brillouin zone and create a singularity of higher order. Furthermore, we can induce a band inversion by tuning the filling ratio of the photonic crystal, and we find that the geometric phases of the bands before and after the inversion are independent of the amount of non-Hermiticity as long as the PT -exact phase is not broken. The standard concept of topological transition can hence be extended to non-Hermitian systems.

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Section: Introductionmentioning

confidence: 99%

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

2015

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“…It was demonstrated that under variation of some parameter such as, for example, the radius of the spheres the leaky modes dominating the spectrum can acquire an infinite life-time. In other words, the array can support bound states in the radiation continuum (BSCs) [33,35,37,48,71]. In this letter, we will address the ability of the BSCs to propagate light along the array primarily motivated by finding new opportunities for designing subwavelength waveguides.…”

Section: Light Guiding Above the Light Linementioning

confidence: 99%

Light Trapping above the Light Cone in One-Dimensional Arrays of Dielectric Spheres

2017

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Abstract:We demonstrate bound states in the radiation continuum (BSC) in a linear periodic array of dielectric spheres in air above the light cone. We classify the BSCs by orbital angular momentum m = 0, ±1, ±2 according to the rotational symmetry of the array, Bloch wave vector β directed along the array according to the translational symmetry, and polarization. The most simple symmetry protected BSCs have m = 0, β = 0 and occur in a wide range of the radius of the spheres and dielectric constant. More sophisticated BSCs with m = 0, β = 0 exist only for a selected radius of spheres at fixed dielectric constant. We also find robust Bloch BSCs with β = 0, m = 0. All BSCs reside within the first but below the other diffraction continua. We show that the BSCs can be easily detected by bright features in scattering of different plane waves by the array as dependent on type of the BSC. The symmetry protected TE/TM BSCs can be traced by collapsing Fano resonance in cross-sections of normally incident TE/TM plane waves. When plane wave with circular polarization with frequency tuned to the bound states with OAM illuminates the array the spin angular momentum of the incident wave transfers into the orbital angular momentum of the BSC. This, in turn, gives rise to giant vortical power currents rotating around the array. Incident wave with linear polarization with frequency tuned to the Bloch bound state in the continuum induces giant laminar power currents. At last, the plane wave with linear polarization incident under tilt relative to the axis of array excites Poynting currents spiralling around the array. It is demonstrated numerically that quasi-bound leaky modes of the array can propagate both stationary waves and light pulses to a distance of 60 wavelengths at the frequencies close to the bound states in the radiation continuum. A semi-analytical estimate for decay rates of the guided waves is found to match the numerical data to a good accuracy.

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“…The BICs are spatially bounded (localized in one, two or even three dimensions [2]) eigenstates of an optical system with quality factor that could, in principle, approach infinity despite lying within the light cone of the surrounding space, i.e. in the continuum spectrum of radiative modes [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of substrate on optical bound states in the continuum in 1D photonic structures

Sadrieva¹,

Sinev²,

Samusev³

et al. 2017

AIP Conference Proceedings

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In this work, we analyze properties of BIC in CMOS-compatible one-dimensional photonic structure based on siliconon-insulator wafer at telecommunication wavelengths, where the absorption of silicon is negligible. We reveal that a high-index substrate could destroy both off-Γ BIC and in-plane symmetry protected at-Γ BIC turning them into resonant states due to leakage into the diffraction channels opening in the substrate.

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Embedded Photonic Eigenvalues in 3D Nanostructures

Cited by 296 publications

References 17 publications

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

Coalescence of exceptional points and phase diagrams for one-dimensionalPT-symmetric photonic crystals

Light Trapping above the Light Cone in One-Dimensional Arrays of Dielectric Spheres

Effect of substrate on optical bound states in the continuum in 1D photonic structures

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