scholarly journals Polarization-dependent mode coupling in hyperbolic nanospheres

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Krzysztof M. Czajkowski ◽  
Maria Bancerek ◽  
Alexander Korneluk ◽  
Dominika Świtlik ◽  
Tomasz J. Antosiewicz
Keyword(s):  
Optical Properties ◽  
Mode Coupling ◽  
Numerical Study ◽  
Incident Light ◽  
Unusual Behavior ◽  
Modal Response ◽  
Hyperbolic Dispersion ◽  
Light Matter Interaction ◽  
Strong Scattering ◽  
Insight Into

Abstract Hyperbolic materials offer much wider freedom in designing optical properties of nanostructures than ones with isotropic and elliptical dispersion, both metallic or dielectric. Here, we present a detailed theoretical and numerical study on the unique optical properties of spherical nanoantennas composed of such materials. Hyperbolic nanospheres exhibit a rich modal structure that, depending on the polarization and direction of incident light, can exhibit either a full plasmonic-like response with multiple electric resonances, a single, dominant electric dipole or one with mixed magnetic and electric modes with an atypical reversed modal order. We derive conditions for observing these resonances in the dipolar approximation and offer insight into how the modal response evolves with the size, material composition, and illumination. Specifically, the origin of the magnetic dipole mode lies in the hyperbolic dispersion and its existence is determined by two diagonal permittivity components of different sign. Our analysis shows that the origin of this unusual behavior stems from complex coupling between electric and magnetic multipoles, which leads to very strong scattering or absorbing modes. These observations assert that hyperbolic nanoantennas offer a promising route towards novel light–matter interaction regimes.

scholarly journals Improved optical performance of multi-layer MoS2 phototransistor with see-through metal electrode

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Junghak Park ◽  
Dipjyoti Das ◽  
Minho Ahn ◽  
Sungho Park ◽  
Jihyun Hur ◽  
...  
Keyword(s):  
Optical Properties ◽  
Incident Light ◽  
Single Layer ◽  
Metal Electrode ◽  
Narrow Bandgap ◽  
Photocurrent Measurement ◽  
Contact Electrodes ◽  
532 Nm ◽  
Insight Into ◽  
Bottom Gate

Abstract In recent years, MoS2 has emerged as a prime material for photodetector as well as phototransistor applications. Usually, the higher density of state and relatively narrow bandgap of multi-layer MoS2 give it an edge over monolayer MoS2 for phototransistor applications. However, MoS2 demonstrates thickness-dependent energy bandgap properties, with multi-layer MoS2 having indirect bandgap characteristics and therefore possess inferior optical properties. Herein, we investigate the electrical as well as optical properties of single-layer and multi-layer MoS2-based phototransistors and demonstrate improved optical properties of multi-layer MoS2 phototransistor through the use of see-through metal electrode instead of the traditional global bottom gate or patterned local bottom gate structures. The see-through metal electrode utilized in this study shows transmittance of more than 70% under 532 nm visible light, thereby allowing the incident light to reach the entire active area below the source and drain electrodes. The effect of contact electrodes on the MoS2 phototransistors was investigated further by comparing the proposed electrode with conventional opaque electrodes and transparent IZO electrodes. A position-dependent photocurrent measurement was also carried out by locally illuminating the MoS2 channel at different positions in order to gain better insight into the behavior of the photocurrent mechanism of the multi-layer MoS2 phototransistor with the transparent metal. It was observed that more electrons are injected from the source when the beam is placed on the source side due to the reduced barrier height, giving rise to a significant enhancement of the photocurrent.

scholarly journals Numerical Study on the Surface Plasmon Resonance Tunability of Spherical and Non-Spherical Core-Shell Dimer Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1728
Author(s):  
Joshua Fernandes ◽  
Sangmo Kang
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Surface Plasmon Resonance ◽  
Aspect Ratio ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Shell Thickness ◽  
Numerical Study ◽  
Field Enhancement ◽  
Core Shell

The near-field enhancement and localized surface plasmon resonance (LSPR) on the core-shell noble metal nanostructure surfaces are widely studied for various biomedical applications. However, the study of the optical properties of new plasmonic non-spherical nanostructures is less explored. This numerical study quantifies the optical properties of spherical and non-spherical (prolate and oblate) dimer nanostructures by introducing finite element modelling in COMSOL Multiphysics. The surface plasmon resonance peaks of gold nanostructures should be understood and controlled for use in biological applications such as photothermal therapy and drug delivery. In this study, we find that non-spherical prolate and oblate gold dimers give excellent tunability in a wide range of biological windows. The electromagnetic field enhancement and surface plasmon resonance peak can be tuned by varying the aspect ratio of non-spherical nanostructures, the refractive index of the surrounding medium, shell thickness, and the distance of separation between nanostructures. The absorption spectra exhibit considerably greater dependency on the aspect ratio and refractive index than the shell thickness and separation distance. These results may be essential for applying the spherical and non-spherical nanostructures to various absorption-based applications.

scholarly journals NEGATIVE REFRACTION AND SUBWAVELENGTH FOCUSING USING PHOTONIC CRYSTALS

2004 ◽  
Vol 18 (25) ◽  
pp. 1275-1291 ◽  
Author(s):  
EKMEL OZBAY ◽  
KAAN GUVEN ◽  
ERTUGRUL CUBUKCU ◽  
KORAY AYDIN ◽  
B. KAMIL ALICI
Keyword(s):  
Optical Properties ◽  
Photonic Crystals ◽  
Negative Refraction ◽  
Numerical Study ◽  
Effective Index ◽  
Index Of Refraction ◽  
Far Field ◽  
Two Dimensional ◽  
Flat Lens ◽  
Effective Index Of Refraction

In this article, we present an experimental and numerical study of novel optical properties of two-dimensional dielectric photonic crystals (PCs) which exhibit negative refraction. We investigate two mechanisms which utilize the band structure of the PC to generate a negative effective index of refraction (n eff <0) and demonstrate the negative refraction experimentally. To the isotropic extend of n eff , different PC slab structures are employed to focus the radiation of a point source. It is shown experimentally that the PC can generate an image of the source with subwavelength resolution in the vicinity of the PC interface. Using a different PC, one can also obtain a far field focusing. In the latter case, we explicitly show the flat lens behavior of the structure. These examples indicate that PC-based lenses can surpass limitations of conventional lenses and lead to novel optics applications.

scholarly journals Magneto-Optical Properties of In-Plane Bi-YIG Films with Oblique-Incident Light.

1993 ◽  
Vol 17 (2) ◽  
pp. 157-160
Author(s):  
N. Kawai ◽  
Z. Hirano ◽  
E. Komuro ◽  
T. Namikawa ◽  
Y. Yamazaki
Keyword(s):  
Optical Properties ◽  
Incident Light

scholarly journals Orientation dependence of optical activity in light scattering by nanoparticle clusters

2022 ◽  
Author(s):  
Atefeh Fazel Najafabadi ◽  
Baptiste Auguié
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Optical Activity ◽  
Incident Light ◽  
Spatial Arrangement ◽  
Orientation Dependence ◽  
Nanoparticle Clusters

The optical properties of nanoparticle clusters vary with the spatial arrangement of the constituent particles, but also the overall orientation of the cluster with respect to the incident light. This...

scholarly journals Dental calculus: Nano-characterization

2012 ◽  
Vol 59 (3) ◽  
pp. 154-159
Author(s):  
Djurica Grga ◽  
Marina Marjanovic ◽  
Igor Hut ◽  
Bojan Dzeletovic ◽  
Djuro Koruga
Keyword(s):  
Magnetic Field Gradient ◽  
Dental Calculus ◽  
Oral Diseases ◽  
Force Microscopy ◽  
Atomic Force ◽  
Light Matter Interaction ◽  
The Magnetic Field ◽  
Very High ◽  
Insight Into

Emerging technologies and new nanoscale information have potential to transform dental practice by improving all aspects of diagnostics and therapy. Nanocharacterization allows understanding of oral diseases at molecular and cellular levels which eventually can increase the success of prevention and treatment. Opto-magnetic spectroscopy (OMS) is a promising new technique based on light-matter interaction which allows insight into the quantum state of matter. Since biomolecules and tissues are usually paramagnetic or diamagnetic materials it is possible to determine the dynamics of para-and diamagnetism at different teeth structures using that method. The topography of the surface of a sample can be obtained with a very high resolution using atomic force microscopy (AFM), which allows observation of minimal changes up to 10 nm, while magnetic force microscopy (MFM) is used to record the magnetic field gradient and its distribution over the surface of a sample. The aim of this study was to determine the possibility of AFM and MFM for the characterization of dental calculus, and a potential application of OMS for the detection of subgingival dental calculus.

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