The Experts below are selected from a list of 7680 Experts worldwide ranked by ideXlab platform
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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transverse spin and surface Waves in acoustic metamaterials
Physical Review B, 2019Co-Authors: Konstantin Y Bliokh, Franco NoriAbstract:We consider spin angular momentum density in inhomogeneous acoustic fields: Evanescent Waves and surface Waves at interfaces with negative-density metamaterials. Despite being purely longitudinal (curl-free), acoustic Waves possess intrinsic vector properties described by the velocity field. Motivated by the recent description and observation of the spin properties in elastic and acoustic Waves, we compare these properties with their well-known electromagnetic counterparts. Surprisingly, both the transverse spin of Evanescent Waves and the parameters of surface Waves are very similar in electromagnetism and acoustics. We also briefly analyze the important role of dispersion in the description of the energy and spin densities in acoustic metamaterials.
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Parity-Time-Symmetric Optics, Extraordinary Momentum and Spin in Evanescent Waves, Optical Analog of Topological Insulators, and the Quantum Spin Hall Effect of Light
2019 IEEE Photonics Conference (IPC), 2019Co-Authors: Franco NoriAbstract:This talk provides a brief and pedagogical overview to some aspects of parity-time-symmetric optics, extraordinary momentum and spin in Evanescent Waves, an optical analog of topological insulators, and the quantum spin Hall effect of light.
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parity time symmetric optics extraordinary momentum and spin in Evanescent Waves and the quantum spin hall effect of light
Photonics Society Summer Topical Meeting Series, 2018Co-Authors: Franco NoriAbstract:This talk provides a brief and pedagogical overview to parity-time-symmetric optics, extraordinary momentum and spin in Evanescent Waves, and the quantum spin Hall effect of light.
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quantum spin hall effect of light
Science, 2015Co-Authors: Konstantin Y Bliokh, Daria A Smirnova, Franco NoriAbstract:Maxwell’s equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell Waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect—surface modes with strong spin-momentum locking. These modes are Evanescent Waves that form, for example, surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in Evanescent Waves and explain recent experiments that have demonstrated the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell’s theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.
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quantum spin hall effect of light
arXiv: Optics, 2015Co-Authors: Konstantin Y Bliokh, Daria A Smirnova, Franco NoriAbstract:Maxwell's equations, formulated 150 years ago, ultimately describe properties of light, from classical electromagnetism to quantum and relativistic aspects. The latter ones result in remarkable geometric and topological phenomena related to the spin-1 massless nature of photons. By analyzing fundamental spin properties of Maxwell Waves, we show that free-space light exhibits an intrinsic quantum spin Hall effect, i.e., surface modes with strong spin-momentum locking. These modes are Evanescent Waves that form, e.g., surface plasmon-polaritons at vacuum-metal interfaces. Our findings illuminate the unusual transverse spin in Evanescent Waves and explain recent experiments demonstrating the transverse spin-direction locking in the excitation of surface optical modes. This deepens our understanding of Maxwell's theory, reveals analogies with topological insulators for electrons, and offers applications for robust spin-directional optical interfaces.
Ping Sheng - One of the best experts on this subject based on the ideXlab platform.
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tuning fabry perot resonances via diffraction Evanescent Waves
Physical Review B, 2007Co-Authors: Bo Hou, Weijia Wen, Manzhu Ke, Zhengyou Liu, Jing Shi, Jun Mei, Ping ShengAbstract:By studying acoustic and electromagnetic wave transmission through a periodic array of subwavelength holes or slits with various channel lengths, we demonstrate both experimentally and theoretically that diffraction Evanescent Waves can play an important role in tuning the Fabry-Perot FP resonances. In particular, there can be total transmission peaks at wavelengths much below that of the Rayleigh-Wood limit, and FP resonances can occur for channel length 16% thinner than the half wavelength. In addition, the FP resonance condition can be tuned via both the periodicity and area fraction of holes. As a function of the ratio between the periodicity and plate thickness, the FP resonance is smoothly linked to the surface-wave-like mode induced by the periodic structure factor.
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tuning fabry perot resonances via diffraction Evanescent Waves
Physical Review B, 2007Co-Authors: Bo Hou, Weijia Wen, Zhengyou Liu, Jing Shi, Jun Mei, Ping ShengAbstract:By studying acoustic and electromagnetic wave transmission through a periodic array of subwavelength holes or slits with various channel lengths, we demonstrate both experimentally and theoretically that diffraction Evanescent Waves can play an important role in tuning the Fabry-Perot (FP) resonances. In particular, there can be total transmission peaks at wavelengths much below that of the Rayleigh-Wood limit, and FP resonances can occur for channel length $\ensuremath{\sim}16%$ thinner than the half wavelength. In addition, the FP resonance condition can be tuned via both the periodicity and area fraction of holes. As a function of the ratio between the periodicity and plate thickness, the FP resonance is smoothly linked to the surface-wave-like mode induced by the periodic structure factor.
Xiang Zhang - One of the best experts on this subject based on the ideXlab platform.
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far field optical superlens
Nano Letters, 2007Co-Authors: Zhaowei Liu, Cheng Sun, Yi Xiong, Stephane Durant, H J Lee, Yuri Pikus, Nicolas Fang, Xiang ZhangAbstract:Far-field optical lens resolution is fundamentally limited by diffraction, which typically is about half of the wavelength. This is due to the Evanescent Waves carrying small scale information from an object that fades away in the far field. A recently proposed superlens theory offers a new approach by surface excitation at the negative index medium. We introduce a far-field optical superlens (FSL) that is capable of imaging beyond the diffraction limit. The FSL significantly enhances the Evanescent Waves of an object and converts them into propagating Waves that are measured in the far field. We show that a FSL can image a subwavelength object consisting of two 50 nm wide lines separated by 70 nm working at 377 nm wavelength. The optical FSL promises new potential for nanoscale imaging and lithography.
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Far-field optical hyperlens magnifying sub-diffraction-limited objects
Science, 2007Co-Authors: Zhaowei Liu, Hyesog Lee, Cheng Sun, Yi Xiong, Xiang ZhangAbstract:The diffraction limit of light, which is causd by the loss of Evanescent Waves in the far field that carry high spatial frequency information, limits the resolution of optical lenses to the order of the wavelength of light. We report experimental demonstration of the optical hyperlens for sub-diffraction-limited imaging in the far field. The device magnifies subwavelength objects by transforming the scattered Evanescent Waves into propagating Waves in an anisotropic medium and projects the high-resolution image at far field. The optical hyperlens opens up possibilities in applications such as real-time biomolecular imaging and nanolithography.
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experimental study of transmission enhancement of Evanescent Waves through silver films assisted by surface plasmon excitation
Applied Physics A, 2005Co-Authors: N Fang, Zhaowei Liu, T J Yen, Xiang ZhangAbstract:In this paper, we investigated an essential precursor of superlensing: enhancing the transmission of Evanescent Waves assisted by excitation of surface plasmon. Using natural roughness as a well characterized grating, the transmission of Evanescent Waves is studied through silver thin films of increasing thickness. Measurements and calculations are performed in the wavelength range of 514.5 nm to 351.1 nm where the real part of the permittivity of silver is negative. Pronounced peaks due to surface-plasmon excitations are observed in the transmission spectra. We found the transmission of Evanescent Waves rapidly grows with the film thickness up to about 50 nm, after which it decays as loss becomes significant. As the permittivity of a silver slab approaches -1, we experimentally observed a broadening of surface plasmon bandwidth. Our study indicates a pathway to access the deep subwavelength features by metamaterial superlens.
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rapid growth of Evanescent wave by a silver superlens
Applied Physics Letters, 2003Co-Authors: Nicholas X Fang, Xiang ZhangAbstract:Recent theoretical work suggested the possibility of constructing a super-resolution diffraction-free lens by using a negative refractive index medium (NRIM). The key proposition is that Evanescent Waves can be greatly enhanced by increasing the thickness of the NRIM. We report here experimental evidence that confirms that the transmission of Evanescent Waves rapidly grows with the film thickness up to about 50 nm, after which it decays as loss becomes significant. These findings represent the first step toward the understanding and realization of a diffraction-free lens.
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regenerating Evanescent Waves from a silver superlens
Optics Express, 2003Co-Authors: Nicholas X Fang, Xiang ZhangAbstract:We investigated a precursor of superlensing: regenerating Evanescent Waves by excitation of a surface plasmon. Because the permittivity of a silver slab approaches -1, we experimentally observed a broadening of surface-plasmon bandwidth. Our study identifies a means to access deep subwavelength features by use of a metamaterial superlens.
A. S. Sergeev - One of the best experts on this subject based on the ideXlab platform.
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Evanescent Waves propagation along a periodically corrugated surface and their amplification by relativistic electron beam quasi optical theory
Physics of Plasmas, 2013Co-Authors: N S Ginzburg, I V Zheleznov, A M Malkin, A. S. SergeevAbstract:By using a quasi-optical approach, we study propagation of Evanescent Waves along a periodically corrugated surface and their excitation by relativistic electron beams. Under assumption of a shallow (in the scale of period) corrugation, the dispersion equation for normal Waves is derived and two particular cases are studied. In the first case, the wave frequency is far from the Bragg resonance; therefore, the Evanescent wave propagation can be described by using the impedance approximation with deceleration of the zeroth spatial harmonic. The second case takes place at the frequencies close to the Bragg resonance. There, the field can be represented as two counter-propagating quasi-optical wave beams, which are coupled on the corrugated surface and form an Evanescent normal wave. With regard to the interaction with an electron beam, the first case corresponds to the convective instability that can be used for amplification of radiation, while the second case corresponds to the absolute instability used in surface-wave oscillators. This paper is focused on studying main features of amplifier schemes, such as the increments, electron efficiency, and formation of a self-consistent spatial structure of the radiated field. For practical applications, the feasibility of realization of relativistic surface-wave amplifiers in the submillimeter wavelength range is estimated.By using a quasi-optical approach, we study propagation of Evanescent Waves along a periodically corrugated surface and their excitation by relativistic electron beams. Under assumption of a shallow (in the scale of period) corrugation, the dispersion equation for normal Waves is derived and two particular cases are studied. In the first case, the wave frequency is far from the Bragg resonance; therefore, the Evanescent wave propagation can be described by using the impedance approximation with deceleration of the zeroth spatial harmonic. The second case takes place at the frequencies close to the Bragg resonance. There, the field can be represented as two counter-propagating quasi-optical wave beams, which are coupled on the corrugated surface and form an Evanescent normal wave. With regard to the interaction with an electron beam, the first case corresponds to the convective instability that can be used for amplification of radiation, while the second case corresponds to the absolute instability used in...
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Evanescent Waves propagation along a periodically corrugated surface and their amplification by relativistic electron beam quasi optical theory
Physics of Plasmas, 2013Co-Authors: N S Ginzburg, I V Zheleznov, A M Malkin, A. S. SergeevAbstract:By using a quasi-optical approach, we study propagation of Evanescent Waves along a periodically corrugated surface and their excitation by relativistic electron beams. Under assumption of a shallow (in the scale of period) corrugation, the dispersion equation for normal Waves is derived and two particular cases are studied. In the first case, the wave frequency is far from the Bragg resonance; therefore, the Evanescent wave propagation can be described by using the impedance approximation with deceleration of the zeroth spatial harmonic. The second case takes place at the frequencies close to the Bragg resonance. There, the field can be represented as two counter-propagating quasi-optical wave beams, which are coupled on the corrugated surface and form an Evanescent normal wave. With regard to the interaction with an electron beam, the first case corresponds to the convective instability that can be used for amplification of radiation, while the second case corresponds to the absolute instability used in surface-wave oscillators. This paper is focused on studying main features of amplifier schemes, such as the increments, electron efficiency, and formation of a self-consistent spatial structure of the radiated field. For practical applications, the feasibility of realization of relativistic surface-wave amplifiers in the submillimeter wavelength range is estimated.
Motoichi Ohtsu - One of the best experts on this subject based on the ideXlab platform.
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laser spectroscopy of atoms guided by Evanescent Waves in micron sized hollow optical fibers
Physical Review Letters, 1996Co-Authors: Takeshi Nakata, Keiji Sakaki, Motoichi OhtsuAbstract:We report the first laser spectroscopic experiments on the Rb beam guided by blue-detuned Evanescent Waves in micron-sized hollow fibers. The two-step photoionization spectra show the long-range dispersive properties of dipole interaction between guided atoms and Evanescent Waves. A large enhancement factor of 20in in the transmitted atomic flux is obtained at optimal conditions and the total guidance efficiency is estimated to be above 40{percent}. The state- and species-selective guide with proper frequency detunings of the guide laser realizes in-line spatial separation of two stable Rb isotopes. {copyright} {ital 1996 The American Physical Society.}
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laser spectroscopy of atoms guided by Evanescent Waves in micron sized hollow optical fibers
Physical Review Letters, 1996Co-Authors: H Ito, Takeshi Nakata, Keiji Sakaki, Motoichi Ohtsu, Koochul Lee, Wonho JheAbstract:We report the first laser spectroscopic experiments on the Rb beam guided by blue-detuned Evanescent Waves in micron-sized hollow fibers. The two-step photoionization spectra show the long-range dispersive properties of dipole interaction between guided atoms and Evanescent Waves. A large enhancement factor of 20 in in the transmitted atomic flux is obtained at optimal conditions and the total guidance efficiency is estimated to be above 40%. The state- and species-selective guide with proper frequency detunings of the guide laser realizes in-line spatial separation of two stable Rb isotopes.
