scholarly journals Tuning Plasmon Induced Reflectance with Hybrid Metasurfaces

Photonics ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 29 ◽  
Author(s):  
Mohsin Habib ◽  
Ekmel Ozbay ◽  
Humeyra Caglayan
Keyword(s):  
Modulation Depth ◽  
Contrast Ratio ◽  
Fdtd Method ◽  
Spectral Contrast ◽  
Design Flexibility ◽  
Different Dimensions ◽  
Control Light ◽  
And Control ◽  
Difference Time ◽  
Total Shift

Electrically tunable metasurfaces with graphene offer design flexibility to efficiently manipulate and control light. These metasurfaces can be used to generate plasmon-induced reflectance (PIR), which can be tuned by electrostatic doping of the graphene layer. We numerically investigated two designs for tunable PIR devices using the finite difference time-domain (FDTD) method. The first design is based on two rectangular antennas of the same size and a disk; in the second design, two parallel rectangular antennas with different dimensions are used. The PIR-effect was achieved by weak hybridization of two bright modes in both devices and tuned by changing the Fermi level of graphene. A total shift of ∼362 nm was observed in the design with the modulation depth of 53% and a spectral contrast ratio of 76%. These tunable PIR devices can be used for tunable enhanced biosensing and switchable systems.

All-optical simultaneous XOR-AND operation using 1-D periodic nonlinear material

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tanay Chattopadhyay
Keyword(s):  
Contrast Ratio ◽  
Fdtd Method ◽  
Optical Computing ◽  
Material Model ◽  
Nonlinear Material ◽  
Gate Operation ◽  
Nonlinear Materials ◽  
One Dimensional ◽  
All Optical ◽  
Difference Time

Abstract In this paper, an all-optical XOR-AND gate operation has been proposed using one-dimensional periodic nonlinear material model. This structure consists of alternating layers of different nonlinear materials. In this design, we can obtain XOR and AND logical operation simultaneously at the reflected and transmitted port of the periodic structure. Numerical simulation has also been done using the finite-difference-time-domain (FDTD) method. The response time of this switching operation is picoseconds (ps) range order. We find low insertion loss (−3.01 dB), high contrast ratio (14.13 dB) and high extension ratio (10.93 dB) of this device. This design will be useful in future all-optical computing.

The Theoretical Study of TM Transmittance and Contrast Ratio for Sub-Wavelength Metallic Gratings

2014 ◽  
Vol 575 ◽  
pp. 138-141
Author(s):  
Ren Cheng Jin ◽  
Yang Rui ◽  
Jin Kui Chu ◽  
Ying Jie Zhang
Keyword(s):  
Performance Indicators ◽  
Theoretical Study ◽  
Structural Parameters ◽  
Contrast Ratio ◽  
Fdtd Method ◽  
Slit Width ◽  
Wave Band ◽  
Metallic Gratings ◽  
Difference Time ◽  
Sub Wavelength

According to the requirement of the bionic navigation sensitive wave band of 380nm~520nm for sub-wavelength metallic gratings, in order to achieve performance indicators under the basic structural parameters. Analyzing TM transmittance and contrast ratio is carried out by employing finite-difference time-domain (FDTD) method. The result reveals that height, slit width and dielectric of grating impact TM transmittance and contrast ratio in various extents, and the greatest influence on the TM transmittance and contrast ratio is slit dielectric and slit width respectively.

scholarly journals 2D Anisotropic Photonic Crystals of Hollow Semiconductor Nanorod with Liquid Crystals

2013 ◽  
Vol 394 ◽  
pp. 38-44
Author(s):  
Filiz Karaomerlioglu ◽  
Sevket Simsek ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay
Keyword(s):  
Optical Properties ◽  
Photonic Crystals ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Light Wave ◽  
Fdtd Method ◽  
Two Dimensional ◽  
Plane Wave Expansion ◽  
Control Light ◽  
Difference Time

Photonic crystals (PCs) have many applications in order to control light-wave propagation. A novel type of two-dimensional anisotropic PC is investigated band gap and optical properties as a hollow semiconductor nanorod with nematicliquid crystals (LC). The PC structure composed of an anisotropic nematicLC in semiconductor square hollow nanorod is designed using the plane wave expansion (PWE) method and finite-difference time-domain (FDTD) method. It has been used 5CB (4-pentyl-4`-cyanobiphenyl) as LC core, and Tellurium (Te) as square hollow nanorod material.The PC with hollow Tenanorod with nematicLC is compared with the PC with solid Tenanorodand the PC with hollow Tenanorod.

scholarly journals Identification of analytical singularity in non-plasmonic nano-sensing system

2021 ◽  
Author(s):  
Yanyan Zhou ◽  
Haixi Zhang
Keyword(s):  
Fdtd Method ◽  
High Sensitivity ◽  
Distinct Advantage ◽  
Complex Frequency ◽  
Material Loss ◽  
Fundamental Physics ◽  
Design Flexibility ◽  
Dielectric Nanoparticle ◽  
Sensor Configuration ◽  
Difference Time

Abstract Nanosensors based on small particles are essential in the advancement of countless areas involving biomedical and fundamental physics. While the Clausius-Mossoti relation reveals the natural advantage of plasmonic nanoparticles as a singularity-generating device with the possibility of achieving ultra-high sensitivity, practical issues such as metallic losses and sensor configuration often preclude them from being considered as the ideal nanosensor. Non-plasmonic, or dielectric nanoparticles, though have distinct advantage in small material loss and design flexibility, cannot have a pole in the Clausius-Mossoti relation. Here, we demonstrate how such limitation on dipolar resonance of a dielectric nanoparticle can be fundamentally overturned if the nanoparticle is placed in an assisting dielectric cavity. Using the pseudo-orthonormal eigenmode method (POEM), we pinpoint the singularity of such non-plasmonic system in the complex frequency plane. The framework of the study provides not only analysis of the underlying physics, but also generates a set of guidelines to facilitate the device optimization in the real world. For numerical simulation, we use finite-difference time-domain (FDTD) method to demonstrate giant sensitivity of the structure when it operates around the pole.

Compact and ultrafast all optical 1-bit comparator based on wave interference and threshold switching methods

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Asghar Askarian
Keyword(s):  
Finite Difference Time Domain ◽  
Contrast Ratio ◽  
Logical Structure ◽  
Ring Resonators ◽  
Plane Wave Expansion ◽  
Threshold Switching ◽  
Wave Interference ◽  
All Optical ◽  
Fdtd Methods ◽  
Difference Time

Abstract In this study, we are going to design all optical 1-bit comparator by combining wave interference and threshold switching methods. The final structure composed of two nonlinear ring resonators and seven waveguides. The functionality of the suggested logical structure is analyzed and simulated by using plane wave expansion (PWE) and finite difference time domain (FDTD) methods. According to results, the proposed all optical 1-bit comparator has faster response and smaller footprint than all previous works. The maximum ON-OFF contrast ratio, delay time and area of the suggested optical comparator are about 16.67 dB, 1.8 ps, and 513 µm2, respectively.

scholarly journals Tuning flavin environment to detect and control light-induced conformational switching in Drosophila cryptochrome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siddarth Chandrasekaran ◽  
Connor M. Schneps ◽  
Robert Dunleavy ◽  
Changfan Lin ◽  
Cristina C. DeOliveira ◽  
...  
Keyword(s):  
Side Reactions ◽  
Resonance Spectroscopy ◽  
Conformational Switching ◽  
Spin Resonance ◽  
Degradation Activity ◽  
Recognition Motifs ◽  
Cellular Turnover ◽  
Control Light ◽  
Dynamics Simulations ◽  
And Control

AbstractLight-induction of an anionic semiquinone (SQ) flavin radical in Drosophila cryptochrome (dCRY) alters the dCRY conformation to promote binding and degradation of the circadian clock protein Timeless (TIM). Specific peptide ligation with sortase A attaches a nitroxide spin-probe to the dCRY C-terminal tail (CTT) while avoiding deleterious side reactions. Pulse dipolar electron-spin resonance spectroscopy from the CTT nitroxide to the SQ shows that flavin photoreduction shifts the CTT ~1 nm and increases its motion, without causing full displacement from the protein. dCRY engineered to form the neutral SQ serves as a dark-state proxy to reveal that the CTT remains docked when the flavin ring is reduced but uncharged. Substitutions of flavin-proximal His378 promote CTT undocking in the dark or diminish undocking in the light, consistent with molecular dynamics simulations and TIM degradation activity. The His378 variants inform on recognition motifs for dCRY cellular turnover and strategies for developing optogenetic tools.

scholarly journals Designing the Hotspots Distribution by Anisotropic Growth

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 187
Author(s):  
Tianshun Li ◽  
Renxian Gao ◽  
Xiaolong Zhang ◽  
Yongjun Zhang
Keyword(s):  
Au Nanoparticles ◽  
Fdtd Method ◽  
Polarization Dependence ◽  
Noble Metal Nanoparticles ◽  
Oblique Angle Deposition ◽  
Matlab Simulation ◽  
Different Shapes ◽  
Plasma Enhancement ◽  
Difference Time ◽  
Good Agreement

Changing the morphology of noble metal nanoparticles and polarization dependence of nanoparticles with different morphologies is an important part of further research on surface plasma enhancement. Therefore, we used the method based on Matlab simulation to provide a simple and effective method for preparing the morphologies of Au nanoparticles with different morphologies, and prepared the structure of Au nanoparticles with good uniformity and different morphologies by oblique angle deposition (OAD) technology. The change of the surface morphology of nanoparticles from spherical to square to diamond can be effectively controlled by changing the deposition angle. The finite difference time domain (FDTD) method was used to simulate the electromagnetic fields of Au nanoparticles with different morphologies to explore the polarization dependence of nanoparticles with different shapes, which was in good agreement with Raman spectrum.

scholarly journals Full-frame and high-contrast smart windows from halide-exchanged perovskites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
You Liu ◽  
Jungan Wang ◽  
Fangfang Wang ◽  
Zhengchun Cheng ◽  
Yinyu Fang ◽  
...  
Keyword(s):  
Contrast Ratio ◽  
High Contrast ◽  
Smart Window ◽  
Frame Size ◽  
Smart Windows ◽  
Ideal Solutions ◽  
Ion Gel ◽  
And Control ◽  
Colour Rendering ◽  
Perovskite Photovoltaic

AbstractWindow glazing plays an essential role to modulate indoor light and heat transmission, which is a prospect to save the energy cost in buildings. The latest photovoltachromic technology has been regarded as one of the most ideal solutions, however, to achieve full-frame size (100% active area) and high-contrast ratio (>30% variable in visible wavelength) for smart window applicability is still a challenge. Here we report a photovoltachromic device combining full-transparent perovskite photovoltaic and ion-gel based electrochromic components in a vertical tandem architecture without any intermediated electrode. Most importantly, by accurately adjusting the halide-exchanging period, this photovoltachromic module can realize a high pristine transmittance up to 76%. Moreover, it possesses excellent colour-rendering index to 96, wide contrast ratio (>30%) on average visible transmittance (400-780 nm), and a self-adaptable transmittance adjustment and control indoor brightness and temperature automatically depending on different solar irradiances.

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Xue Jiao ◽  
Bo Yang
Keyword(s):  
Electromagnetic Pulse ◽  
Coupling Effect ◽  
Fdtd Method ◽  
Current Source ◽  
Low Frequency ◽  
Frequency Component ◽  
Lightning Current ◽  
Proper Size ◽  
Practical Engineering ◽  
Difference Time

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.

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