Critical field enhancement of asymptotic optical bound states in the continuum

Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert

doi:10.1038/srep18301

Cited by 144 publications

(114 citation statements)

References 30 publications

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“…Nowadays we witness a surge of interest to BICs in field of photonics, where BICs were observed in various set-ups with periodical dielectric permittivity [5][6][7][8][9][10] . In particular, the studies on BICs are motivated by applications to resonant light enhancement [11][12][13] and lasing 14,15 . Another remarkable property of BICs is the emergence of a collapsing Fano feature in its parametric vicinity [16][17][18][19] , that can be potentially employed to narrow-band filters 20,21 .…”

Section: Introductionmentioning

confidence: 99%

Optical defect mode with tunableQfactor in a one-dimensional anisotropic photonic crystal

2018

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We consider a one-dimensional photonic crystal composed of alternating layers of isotropic and anisotropic dielectric materials. Such a system has different band structures for different polarizations of light. We demonstrate that if an anisotropic defect layer is inserted into the structure, the crystal can support an optical bound state in the continuum. By tilting the principle dielectric axes of the defect layer relative to those of the photonic crystal we observe a long-lived resonance in the transmission spectrum. We derive an analytical expression for the decay rate of the resonance that agrees well with the numerical data by the Berreman anisotropic transfer matrix approach. An experimental set-up with a liquid crystal defect layer is proposed to tune the Q-factor of the resonance through applying an external electric field. We speculate that the set-up provides a simple and robust platform for observing optical bound states in the continuum in the form of resonances with tunable Q-factor.

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Section: Introductionmentioning

confidence: 99%

Optical defect mode with tunableQfactor in a one-dimensional anisotropic photonic crystal

2018

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“…We use the finite-element method16 in this calculation involving ε Si ( z ) profiles obtained by the method described in the previous section. The transmission spectra show an asymmetric Fano-resonance profile as a result of the configuration interference between resonant and non-resonant pathways17. The resonant pathway is created by coupling of the incident wave with a leaky TE 0 mode and its radiation decay toward the transmitted zero-order planewave channel through dominant first-order diffraction processes.…”

Section: Resultsmentioning

confidence: 99%

Multiple p-n junction subwavelength gratings for transmission-mode electro-optic modulators

Lee

Yoon

Song

et al. 2017

Sci Rep

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We propose a free-space electro-optic transmission modulator based on multiple p-n-junction semiconductor subwavelength gratings. The proposed device operates with a high-Q guided-mode resonance undergoing electro-optic resonance shift due to direct electrical control. Using rigorous electrical and optical modeling methods, we theoretically demonstrate a modulation depth of 84%, on-state efficiency 85%, and on-off extinction ratio of 19 dB at 1,550 nm wavelength under electrical control signals within a favorably low bias voltage range from −4 V to +1 V. This functionality operates in the transmission mode and sustainable in the high-speed operation regime up to a 10-GHz-scale modulation bandwidth in principle. The theoretical performance prediction is remarkably advantageous over plasmonic tunable metasurfaces in the power-efficiency and absolute modulation-depth aspects. Therefore, further experimental study is of great interest for creating practical-level metasurface components in various application areas.

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“…When the point is sufficiently close to the BSC point α can achieve enormous value however as dependent on the way of approaching [78]. That observation is important for applications [26,52,78,79]. According to above equation the BSC is a null eigenvector of matrix L with zero eigenvalue.…”

Section: Emergence Of the Bsc In Scatteringmentioning

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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Critical field enhancement of asymptotic optical bound states in the continuum

Cited by 144 publications

References 30 publications

Optical defect mode with tunableQfactor in a one-dimensional anisotropic photonic crystal

Optical defect mode with tunableQfactor in a one-dimensional anisotropic photonic crystal

Multiple p-n junction subwavelength gratings for transmission-mode electro-optic modulators

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

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