scholarly journals Analysis of Scattering by Plasmonic Gratings of Circular Nanorods Using Lattice Sums Technique

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3923
Author(s):  
Jandieri ◽  
Yasumoto ◽  
Pistora ◽  
Erni
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Electromagnetic Scattering ◽  
Near Field ◽  
Planar Geometry ◽  
Refractive Index Sensor ◽  
Infinite Length ◽  
Absorption Bands ◽  
Lattice Sums ◽  
Plasmonic Gratings

A self-contained formulation for analyzing electromagnetic scattering by a significant class of planar gratings composed of plasmonic nanorods, which were infinite length along their axes, is presented. The procedure for the lattice sums technique was implemented in a cylindrical harmonic expansion method based on the generalized reflection matrix approach for full-wave scattering analysis of plasmonic gratings. The method provided a high computational efficiency and can be considered as one of the best-suited numerical tools for the optimization of plasmonic sensors and plasmonic guiding devices both having a planar geometry. Although the proposed formalism can be applied to analyze a wide class of plasmonic gratings, three configurations were studied in the manuscript. Firstly, a multilayered grating of silver nanocylinders formed analogously to photonic crystals was considered. In the region far from the resonances of a single plasmonic nanocylinder, the structure showed similar properties compared to conventional photonic crystals. When one or a few nanorods were periodically removed from the original crystal, thus forming a crystal with defects, a new band was formed in the spectral responses because of the resonant tunneling through the defect layers. The rigorous formulation of plasmonic gratings with defects was proposed for the first time. Finally, a plasmonic planar grating of metal-coated dielectric nanorods coupled to the dielectric slab was investigated from the viewpoint of design of a refractive index sensor. Dual-absorption bands attributable to the excitation of the localized surface plasmons were studied, and the near field distributions were given in both absorption bands associated with the resonances on the upper and inner surfaces of a single metal-coated nanocylinder. Resonance in the second absorption band was sensitive to the refractive index of the background medium and could be useful for the design of refractive index sensors. Also analyzed was a phase-matching condition between the evanescent space-harmonics of the plasmonic grating and the guided modes inside the slab, leading to a strong coupling.

Single-Frequency Refractive Index Sensor Based on a Finite One-Dimensional Photonic Crystals with Two Defects

2006 ◽  
Vol 45 (8B) ◽  
pp. 6754-6758 ◽  
Author(s):  
H. Alatas ◽  
H. Mayditia ◽  
H. Hardhienata ◽  
A. A. Iskandar ◽  
M. O. Tjia
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Single Frequency ◽  
Refractive Index Sensor ◽  
One Dimensional

scholarly journals A Generalized case of Electromagnetic Scattering from a finite number of Ferromagnetic cylinders

2015 ◽  
Vol 4 (3) ◽  
pp. 8 ◽  
Author(s):  
T. Kumar ◽  
N. Kalyanasundaram ◽  
B. K. Lande
Keyword(s):  
Finite Number ◽  
Electromagnetic Scattering ◽  
Scattered Field ◽  
Near Field ◽  
Scattering Problem ◽  
Normal Incidence ◽  
Generalized Solution ◽  
Numerical Results ◽  
Infinite Length ◽  
Angle Of Incidence

A generalized solution of the scattering problem from an array containing a finite number of axially magnetized ferromagnetic cylinders of infinite length placed in free space is presented in this paper. The analysis is carried out by matching the tangential boundary conditions at the surface of each cylinder to find the unknown expansion coefficients of the scattered field. Planar arrays consist of a finite number of ferromagnetic microwires are considered to obtain the numerical results for TMz and TEz polarizations in terms of the variation in scattered field components of the near field and scattering cross section (SCS) with respect to angle of incidence, radius of microwires, spacing among the microwires and operating frequency. For validation purpose, numerical results of the proposed analysis specialized for the case of single microwire and normal incidence for TMz polarization are compared with the results available in the literature for the specialized case and both are found to be matched completely.

Efficient analysis method of light scattering by a grating of plasmonic nanorods

2018 ◽  
Vol 37 (4) ◽  
pp. 1436-1448 ◽  
Author(s):  
Vakhtang Jandieri ◽  
Lana Okropiridze ◽  
Kiyotoshi Yasumoto ◽  
Daniel Erni ◽  
Jaromir Pistora
Keyword(s):  
Refractive Index ◽  
Recursive Algorithm ◽  
Surrounding Medium ◽  
Separate Analysis ◽  
Dielectric Slab ◽  
Absorption Bands ◽  
Reflection And Transmission ◽  
Content Type ◽  
Lattice Sums ◽  
Computation Efficiency

Purpose The purpose of this paper is to develop a rigorous self-contained formulation for analyzing electromagnetic scattering by grating of plasmonic nanorods. The authors investigate this structure from the viewpoint of the practical application as a refractive index plasmonic sensor. The presented rigorous formulation is accompanied with a neat implementation providing a high computation efficiency and could be considered as an important tool for designing and optimizing compact sensors. Design/methodology/approach Scattering of an incident plane wave by grating made of a periodic arrangement of metal-coated dielectric nanocylinders on a dielectric slab is rigorously investigated using the recursive algorithm combined with the lattice sums technique. As a dielectric slab, the authors consider glass material, which is widely used in experiments, whereas silver (Ag) is used as a low loss metal suitable to excite plasmon resonances. The main advantage of the developed self-contained formulation is that first the authors extract the reflection and transmission matrices of a single planar array from a separate analysis of the grating and the slab and then obtain the scattering characteristics of the whole structure by using a recursive formula. The method is computationally fast. Findings Dependence of the surface plasmon resonance wavelength on the refractive index of the surrounding medium is carefully investigated. The resonance peaks are red-shifted with respect to an increasing refractive index of surrounding medium showing an almost linear behavior. Near field distributions are analyzed at the resonance wavelengths of the spectral responses. Special attention is paid to the formation of the dual-absorption bands because of the excitation of the localized surface plasmons. The authors give physical insight to the coupling between grating and the glass slab. The authors found that a strong enhancement of the field inside the slab occurs when the scattered wave of the grating is phase-matched to the guided modes supported by the slab. Originality/value In the authors’ formulation, they do not use any approximation and it is rigorous and accurate. The authors use their original method. The method is based on the lattice sums technique and uses the recursive algorithm to calculate the generalized reflection and transmission characteristics by grating. Such fast and accurate method is an effective tool apt for designing and optimizing tailored sensors, for e.g. advanced biomedical applications.

scholarly journals Dimerized high contrast gratings

Nanophotonics ◽  
2018 ◽  
Vol 7 (6) ◽  
pp. 1157-1168 ◽  
Author(s):  
Adam C. Overvig ◽  
Sajan Shrestha ◽  
Nanfang Yu
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Period Doubling ◽  
Building Blocks ◽  
Optical Modulator ◽  
Refractive Index Sensor ◽  
Spectral Features ◽  
High Contrast ◽  
Index Contrast ◽  
Lateral Localization

AbstractMetasurfaces and planar photonic crystals are two classes of subwavelength diffractive optical devices offering novel functionalities. The former employ independently operating subwavelength “meta-units” as their building blocks, while the latter exploit the collective response of many periodic building blocks. High contrast gratings (HCGs) are an example of one-dimensional (1D) planar photonic crystals with large refractive index contrast, exhibiting large in-plane scattering even with a limited number of grating periods. They are best known for their broadband features. Low contrast gratings (LCGs) are known for their control over sharp spectral features but require many periods due to small in-plane scattering. We explore a class of symmetry-broken HCGs called dimerized high contrast gratings (DHCGs), which have a period-doubling perturbation applied. DHCGs support modes accessible by free-space illumination with a long, controllable photon lifetime (inversely proportional to the magnitude of the perturbation) and reduced lateral energy divergence (confined by the high index contrast of the grating). We catalogue and clarify the resonant modes introduced by the dimerizing perturbation in 1D DHCGs and briefly explore the increased in-plane scattering present in two-dimensional (2D) DHCGs. We introduce an approach maximizing lateral localization by band structure engineering in the unperturbed HCG and using the dimerizing perturbation to generate sharp spectral features in devices with small footprint. We confirm the simultaneous control of photon lifetime and lateral localization with full-wave simulations of finite-sized DHCGs. We conclude by numerically demonstrating two compact devices (an optical modulator and a refractive index sensor) benefitting from the unique design freedoms of DHCGs.

scholarly journals Cryptic iridescence in a fossil weevil generated by single diamond photonic crystals

2014 ◽  
Vol 11 (100) ◽  
pp. 20140736 ◽  
Author(s):  
Maria E. McNamara ◽  
Vinod Saranathan ◽  
Emma R. Locatelli ◽  
Heeso Noh ◽  
Derek E. G. Briggs ◽  
...  
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Structural Properties ◽  
Fossil Record ◽  
Near Field ◽  
Three Dimensional ◽  
Biological Functions ◽  
Scatter Light

Nature's most spectacular colours originate in integumentary tissue architectures that scatter light via nanoscale modulations of the refractive index. The most intricate biophotonic nanostructures are three-dimensional crystals with opal, single diamond or single gyroid lattices. Despite intense interest in their optical and structural properties, the evolution of such nanostructures is poorly understood, due in part to a lack of data from the fossil record. Here, we report preservation of single diamond ( Fd -3 m ) three-dimensional photonic crystals in scales of a 735 000 year old specimen of the brown Nearctic weevil Hypera diversipunctata from Gold Run, Canada, and in extant conspecifics. The preserved red to green structural colours exhibit near-field brilliancy yet are inconspicuous from afar; they most likely had cryptic functions in substrate matching. The discovery of pristine fossil examples indicates that the fossil record is likely to yield further data on the evolution of three-dimensional photonic nanostructures and their biological functions.

First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers

2018 ◽  
Author(s):  
Adrian Cernescu ◽  
Michał Szuwarzyński ◽  
Urszula Kwolek ◽  
Karol Wolski ◽  
Paweł Wydro ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Absorption Band ◽  
Spectral Region ◽  
Near Field ◽  
Phospholipid Bilayers ◽  
Model Systems ◽  
Absorption Bands ◽  
Protein Complement ◽  
20 Nm

<div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div>

scholarly journals Refractive Index Sensor for Salty and Sugary Solution Based on Optical Fiber Technical

2021 ◽  
Vol 1879 (3) ◽  
pp. 032077
Author(s):  
Maher Khaleel Ibrahim ◽  
Shehab A Kadhim ◽  
Nabeil Ibrahim Fawaz
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Refractive Index Sensor
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