Orbital-to-Spin Angular Momentum Conversion Employing Local Helicity

Spin-orbit interactions in optics traditionally describe an influence of the polarization degree of freedom of light on its spatial properties. The most prominent example is the generation of a spin-dependent optical vortex upon focusing or scattering of a circularly polarized plane-wave by a nanoparticle, converting spin to orbital angular momentum of light. Here, we present a mechanism of conversion of orbital-to-spin angular momentum of light upon scattering of a linearly polarized vortex beam by a spherical silicon nanoparticle. We show that focused linearly polarized Laguerre-Gaussian beams of first order ($\ell = \pm 1$) exhibit an $\ell$-dependent spatial distribution of helicity density in the focal volume. By using a dipolar scatterer the helicity density can be manipulated locally, while influencing globally the spin and orbital angular momentum of the beam. Specifically, the scattered light can be purely circularly polarized with the handedness depending on the orbital angular momentum of the incident beam. We corroborate our findings with theoretical calculations and an experimental demonstration. Our work sheds new light on the global and local properties of helicity conservation laws in electromagnetism.Comment: 8 pages, 6 figures, 1 tabl

Huygens' Dipole for Polarization-Controlled Nanoscale Light Routing

Structured illumination allows for satisfying the first Kerker condition of in-phase perpendicular electric and magnetic dipole moments in any isotropic scatterer that supports electric and magnetic dipolar resonances. The induced Huygens' dipole may be utilized for unidirectional coupling to waveguide modes that propagate transverse to the excitation beam. We study two configurations of a Huygens' dipole -- longitudinal electric and transverse magnetic dipole moments or vice versa. We experimentally show that only the radially polarized emission of the first and azimuthally polarized emission of the second configuration are directional in the far-field. This polarization selectivity implies that directional excitation of either TM or TE waveguide modes is possible. Applying this concept to a single nanoantenna excited with structured light, we are able to experimentally achieve scattering directivities of around 23 dB and 18 dB in TM and TE modes, respectively. This strong directivity paves the way for tunable polarization-controlled nanoscale light routing and applications in optical metrology, localization microscopy and on-chip optical devices.Comment: 5pages, 2 figure

Shaping Field Gradients for Nanolocalization

Deep sub-wavelength localization and displacement sensing of optical nanoantennas have emerged as extensively pursued objectives in nanometrology, where focused beams serve as high-precision optical rulers while the scattered light provides an optical readout. Here, we show that in these schemes using an optical excitation as a position gauge implies that the sensitivity to displacements of a nanoantenna depends on the spatial gradients of the excitation field. Specifically, we explore one of such novel localization schemes based on appearance of transversely spinning fields in strongly confined optical beams, resulting in far-field segmentation of left- and right-hand circular polarizations of the scattered light, an effect known as the giant spin-Hall effect of light. We construct vector beams with augmented transverse spin density gradient in the focal plane and experimentally confirm enhanced sensitivity of the far-field spin-segmentation to lateral displacements of an electric-dipole nanoantenna. We conclude that sculpturing of electromagnetic field gradients and intelligent design of scatterers pave the way towards future improvements in displacement sensitivity

ХАРАКТЕРИСТИКИ ИНТЕРФЕРОМЕТРИЧЕСКИХ БОРТОВЫХ РАДИОЛОКАЦИОННЫХ СТАНЦИЙ С СИНТЕЗИРОВАНИЕМ АПЕРТУРЫ АНТЕННЫ ПРИ СЕКТОРНОМ ОБЗОРЕ

One of the drawbacks of airborne interferometric synthetic aperture radar is a relatively narrow swath compared to analogous space based systems. Increasing the swath with side view of the interferometer can be possible by increasing the flight altitude and angle of sight. At the same time the height measurement accuracy decreases due to slant range distance increase. Another possible way of swath increasing is using sector scan. The efficiency of sector scan using in interferometric synthetic aperture radar is analyzed in this paper. The mathematical model and geometry of height measurement at a sector scan have been discussed. There was made an analysis of the effect of terrain height and observation angle on received signal phase changing. Observation angle changing is shown to contribute to the phase changing. Potential height accuracy measurement was calculated. The calculation results show that increasing the observation angle reduces height accuracy measurement. The maximum accuracy decrease is obtained at the observation angle of 90°. Despite height accuracy measurement decrease applying the sector scan allow to expand the swath. The accuracy decrease can be limited by selecting optimal parameters of scanning.Одним из недостатков интерферометрических бортовых радиолокационных станций с синтезированием апертуры антенны является относительно узкая, по сравнению с аналогичными системами космического базирования, полоса обзора. Увеличение полосы обзора при боковом обзоре интерферометра возможно за счет увеличения высоты полета и угла визирования, при этом снижается точность измерения высоты из-за увеличения наклонной дальности. Другим возможным вариантом увеличения полосы обзора является использование обзора отличного от бокового. В статье рассматривается эффективность применения секторного обзора в бортовых радиолокационных станциях с синтезированием апертуры антенны в режиме интерферометрии. Приводится математическая модель и описание геометрии процесса интерферометрического измерения высоты при секторном обзоре. Проведён анализ влияния высоты подстилающей поверхности и угла наблюдения на изменение фазы отраженного сигнала. Показано, что изменение угла наблюдения вносит дополнительный вклад в изменение фазы. Проведен расчет потенциальной точности измерения высоты. Результаты расчета показывают, что увеличение угла наблюдения снижает точность измерения высоты. Максимальное снижение точности наблюдается при угле наблюдения 90°. Несмотря на некоторое снижение точности измерения высоты, применение секторного обзора позволяет расширить полосу обзора. Снижение точности измерения высоты можно ограничить путем выбора оптимальных параметров сканирования

СОВРЕМЕННЫЕ БОРТОВЫЕ РАДИОЛОКАЦИОННЫЕ СТАНЦИИ И АНТЕННЫЕ РЕШЕТКИ МНОГОФУНКЦИОНАЛЬНЫХ АВИАЦИОННЫХ КОМПЛЕКСОВ ВОЕННОГО НАЗНАЧЕНИЯ

This article gives a brief description of the of modern and advanced aircraft systems and multi-functional on-board radar stations as part of their avionics, the characteristics of airborne radars and description of antenna arrays op-erationally available in Russia and abroad. It`s also shows possible ways of development of on-board radars in the near future.В данной статье дается краткое описание облика современных и перспективных многофункциональных авиационных комплексов и функции бортовых радиолокационных станций в составе их бортового радиоэлектронного оборудования. Приведены характеристики бортовых радиолокационных станций и описание антенных решеток, стоящих на вооружении в России и за рубежом. Приводятся возможные пути развития бортовых радио-локационных станций в ближайшем будущем

High frequency diffraction of an electromagnetic plane wave by an imperfectly conducting rectangular cylinder

Copyright @ 2011 IEEEWe shall consider the the problem of determining the scattered far wave field produced when a plane E-polarized wave is incident on an imperfectly conducting rectangular cylinder. By using the the uniform asymptotic solution for the problem of the diffraction of a plane wave by a right-angled impedance wedge, in conjunction with Keller's method, the a high frequency far field solution to the problem is given

Enhanced spin-orbit coupling in an epsilon-near-zero material

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