scholarly journals Topological funneling of light

Science ◽  
2020 ◽  
Vol 368 (6488) ◽  
pp. 311-314 ◽  
Author(s):  
Sebastian Weidemann ◽  
Mark Kremer ◽  
Tobias Helbig ◽  
Tobias Hofmann ◽  
Alexander Stegmaier ◽  
...  
Keyword(s):  
Optical Sensors ◽  
General Feature ◽  
Light Field ◽  
Nearest Neighbor ◽  
Skin Effect ◽  
Highly Efficient ◽  
Enhanced Sensitivity ◽  
Input Position ◽  
Exponential Localization ◽  
Complete Collapse

Dissipation is a general feature of non-Hermitian systems. But rather than being an unavoidable nuisance, non-Hermiticity can be precisely controlled and hence used for sophisticated applications, such as optical sensors with enhanced sensitivity. In our work, we implement a non-Hermitian photonic mesh lattice by tailoring the anisotropy of the nearest-neighbor coupling. The appearance of an interface results in a complete collapse of the entire eigenmode spectrum, leading to an exponential localization of all modes at the interface. As a consequence, any light field within the lattice travels toward this interface, irrespective of its shape and input position. On the basis of this topological phenomenon, called the “non-Hermitian skin effect,” we demonstrate a highly efficient funnel for light.

Highly efficient biocide silver-doped soda lime glass for application in water quality optical sensors

2020 ◽  
Vol 111 (10) ◽  
pp. 857-862
Author(s):  
Branimir Bajac ◽  
Jovana Stanojev ◽  
Slobodan Birgermajer ◽  
Milena Radojevic ◽  
Jovan Matovic
Keyword(s):  
Water Quality ◽  
Optical Sensors ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Highly Efficient

scholarly journals Determining Bottom Reflectance and Water Optical Properties Using Unmanned Underwater Vehicles under Clear or Cloudy Skies

2006 ◽  
Vol 23 (2) ◽  
pp. 314-324 ◽  
Author(s):  
David C. English ◽  
Kendall L. Carder
Keyword(s):  
Optical Properties ◽  
Water Column ◽  
Optical Sensors ◽  
Light Field ◽  
Field Measurements ◽  
Underwater Vehicles ◽  
Unmanned Underwater Vehicles ◽  
Cloudy Weather ◽  
Sea Grass ◽  
Ocean Color Imagery

Abstract An unmanned underwater vehicle (UUV) with hyperspectral optical sensors that measure downwelling irradiance and upwelling radiance was deployed over sandy bottoms, sea grass patches, and coral reefs near Lee Stocking Island, Bahamas, during the Coastal Benthic Optical Properties (CoBOP) program of 2000. These deployments occurred during both sunny and cloudy weather. If the rate of irradiance change due to cloud cover is slight, then the inclusion of a variable cloudy-irradiance factor will allow a reasonable estimation of water column absorption. Examination of data from a deployment in May 2000 under cloudy skies shows that the combination of hyperspectral light-field measurements, knowledge of the UUV's position in the water column, and a cloudy-irradiance factor permits consistent estimations of bottom reflectivity to be made from UUV measured reflectances. The spatial distribution of reflectance estimates obtained from a UUV may be useful for validation of airborne ocean color imagery.

scholarly journals Effect of Dispersion-Enhanced Sensitivity in a Two-Mode Optical Waveguide with an Asymmetric Diffraction Grating

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5492
Author(s):  
Andrei Tsarev
Keyword(s):  
Refractive Index ◽  
Optical Waveguide ◽  
Optical Sensors ◽  
High Efficiency ◽  
Single Mode ◽  
Bragg Diffraction ◽  
Mode Interaction ◽  
Enhanced Sensitivity ◽  
Better Than ◽  
Waveguide Surface

Analysis of trends in the development of silicon photonics shows the high efficiency regarding the creation of optical sensors. The concept of bimodal sensors, which suggests moving away from the usual paradigm based only on single-mode waveguides and using the inter-mode interaction of guided optical waves in a two-mode optical waveguide, is developed in the present paper. In this case, the interaction occurs in the presence of an asymmetric periodic perturbation of the refractive index above the waveguide surface. Such a system has unique dispersion properties that lead to the implementation of collinear Bragg diffraction with the mode number transformation, in which there is an extremely high dependence of the Bragg wavelength on the change in the refractive index of the environment. This is called the “effect of dispersion-enhanced sensitivity”. In this paper, it is shown by numerical calculation methods that the effect can be used to create optical sensors with the homogeneous sensitivity higher than 3000 nm/RIU, which is many times better than that of sensors in single-mode waveguide structures.

scholarly journals Image processing algorithms for a light-field camera and their application for optical flow diagnostics

2016 ◽  
pp. 224-233
Author(s):  
А.В. Серёдкин ◽  
М.П. Токарев
Keyword(s):  
Spatial Resolution ◽  
Optical Sensors ◽  
Light Field ◽  
Three Dimensional ◽  
Fluid Flows ◽  
Computational Photography ◽  
Gas Flows ◽  
Experimental Fluid Mechanics ◽  
Measurement Area ◽  
Experimental Fluid

Применение современных оптико-электронных приборов расширяет возможности исследований в области экспериментальной механики жидкостей. Методы вычислительной фотографии за счет использования основанных на ней устройств постепенно проникают в различные области науки и техники. Камера светового поля может использоваться для регистрации трехмерных распределений скорости в потоках жидкости и газа там, где расположение нескольких панорамных оптических сенсоров затруднено за счет ограничения оптического доступа и вибраций. В работе исследованы возможности пленоптической системы, состоящей из доступной на рынке промышленной камеры светового поля применительно для диагностики течений жидкости и газа. Предложен и протестирован новый программный алгоритм для вычисления карты глубины регистрируемой измерительной области. Согласно полученным результатам, пространственное разрешение метода по глубине при использовании 11 мегапиксельного сенсора достигает 1/40 от глубины резкости оптической системы. Указанный метод был использован для измерения 3D-полей скорости турбулентной струи внутри щелевого канала по всей его глубине. В будущем количество задач, в которых целесообразно использование пленоптических устройств с высоким пространственным разрешением, будет расти. Application of modern optoelectronic devices extends research in the field of experimental fluid mechanics. The methods of computational photography gradually penetrate into the various fields of science and technology due to using devices based on these methods. A light-field camera can be used to register a three-dimensional velocity distribution in fluid flows where the location of several panoramic optical sensors is difficult because of restrictions in an optical access and vibrations. in this paper we study the possibility of using a plenoptic system consisting of an industrial light-field camera to diagnose liquid and gas flows. A new software algorithm for computing a depth field of a measurement area is proposed. According to the obtained results, the spatial resolution of the method by depth reaches 1/40th of the depth of the field of the optical system when using 11 MP sensor. This method was used to measure 3D velocity fields of a turbulent jet inside a slot channel throughout its depth. In the future, the number of applications will grow for the cases where the use of plenoptic devices with high spatial resolution is appropriate.

Observation of Superlattice Dislocations on Cube Planes in Ni3Al

1973 ◽  
Vol 31 ◽  
pp. 174-175 ◽  
Author(s):  
J. M. Oblak ◽  
W. H. Rand
Keyword(s):  
Nearest Neighbor ◽  
Antiphase Boundary ◽  
Nearest Neighbors ◽  
High Energy ◽  
Cross Slip ◽  
Octahedral Plane ◽  
Trapping Mechanism ◽  
Slip Traces

The energy of an a/2 <110> shear antiphase. boundary in the Ll2 expected to be at a minimum on {100} cube planes because here strue ture is there is no violation of nearest-neighbor order. The latter however does involve the disruption of second nearest neighbors. It has been suggested that cross slip of paired a/2 <110> dislocations from octahedral onto cube planes is an important dislocation trapping mechanism in Ni3Al; furthermore, slip traces consistent with cube slip are observed above 920°K.Due to the high energy of the {111} antiphase boundary (> 200 mJ/m2), paired a/2 <110> dislocations are tightly constricted on the octahedral plane and cannot be individually resolved.

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