Influence of the Nano-mesh Metal Electrode to Light Excitation of Carriers in Semiconductor

2012 ◽  
Vol 1391 ◽  
Author(s):  
Kumi Masunaga ◽  
Kenji Nakamura ◽  
Ryota Kitagawa ◽  
Eishi Tsutsumi ◽  
Tsutomu Nakanishi ◽  
...  
Keyword(s):  
Near Field ◽  
Fdtd Method ◽  
Surface Region ◽  
Metal Electrode ◽  
Infrared Region ◽  
Thin Metal Film ◽  
Infrared Light ◽  
Light Excitation ◽  
Theoretical Simulations ◽  
Difference Time

ABSTRACTA thin metal film with nano-apertures, called “nano-mesh electrode,” generates near-field lights near the electrode. We investigated carrier excitations in semiconductors by the near-field light. Finite-difference time-domain (FDTD) method revealed that when the infrared light irradiates the Au nano-mesh electrode on Ge, near-field lights are generated and absorbed in the surface region of the Ge. In order to measure the photocurrent involved by near-filed lights, we fabricated a Schottky cell and applied a Au nano-mesh electrode on the n-type Ge. The efficiency of the Schottky cell with the Au nano-mesh electrode improved in infrared region compared to plain the Au-film Schottky cell. The agreement between theoretical simulations and experiments indicates that near-field lights enhance the carrier excitation in the semiconductor.

Trapping of Nano-Particles Using a Near-Field Optical Fiber Probe

2012 ◽  
Vol 516 ◽  
pp. 90-95
Author(s):  
Bing Hui Liu ◽  
Li Jun Yang ◽  
Yang Wang
Keyword(s):  
Near Field ◽  
Fdtd Method ◽  
Laser Wavelength ◽  
Nano Particles ◽  
Minimum Size ◽  
Fiber Probe ◽  
Circular Shape ◽  
Optical Fiber Probe ◽  
Fibre Probe ◽  
Difference Time

By employing a generalization of the conservation law for momentum using the finite difference time domain (FDTD) method, the feasibility of using a near-field optical fibre probe to create near-field optical trapping is investigated. Numerical results indicate that the scheme is able to trap nanoparticles with diameters of tens of nanometres in a circular shape with lower laser intensity. Using the built system with a tapered metal-coated fibre probe, 120 nm polystyrene particles are trapped in a multi-circular shape with a minimum size of 400 nm. They are at a resolution of λ/7 (λ: laser wavelength) and d (d: tip diameter of fiber probe), respectively.

scholarly journals Near-Field Vortex Beams Diffraction on Surface Micro-Defects and Diffractive Axicons for Polarization State Recognition

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1973
Author(s):  
Dmitry Savelyev ◽  
Nikolay Kazanskiy
Keyword(s):  
Light Propagation ◽  
Near Field ◽  
Polarization State ◽  
Fdtd Method ◽  
Minimum Size ◽  
Size Change ◽  
State Recognition ◽  
Input Radiation ◽  
Height Change ◽  
Difference Time

The diffraction of vortex Gaussian laser beams by elementary objects of micro-optics (surface micro-defects) to recognize the type of polarization (linear, circular, radial, azimuthal) of the input radiation was investigated in this paper. We considered two main types of defects (protrusion and depression in the form of a circle and a square) with different sizes (the radius and height were varied). Light propagation (3D) through the proposed micro-defects was modeled using the finite difference time domain (FDTD) method. The possibility of recognizing (including size change) of surface micro-defects (protrusions and depressions) and all the above types of polarization are shown. Thus, micro-defects act as sensors for the polarization state of the illuminating beam. The focusing properties of micro-defects are compared with diffractive axicons with different numerical apertures (NAs). The possibility of sub-wavelength focusing with element height change is demonstrated. In particular, it is numerically shown that a silicon cylinder (protrusion) forms a light spot with a minimum size of the all intensity FWHM of 0.28λ.

Efficiency of Implicit Symplectic Finite-Difference Time-Domain Method for Near-Field Optics

2012 ◽  
Author(s):  
Ikuo Saitoh ◽  
Makoto Naruse
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Conservation Of Energy ◽  
Near Field Optics ◽  
Polarization Control ◽  
Metal Nanostructure ◽  
Difference Time

We proposed a new method, implicit symplectic finite difference time domain (FDTD) method) which inherits the good properties from the conventional FDTD method, simplecticity and the conservation of energy. The proposed method is free from the Courant-Friedrics-Lewy condition at the same time. In this paper, we show our method is more efficient than the conventional FDTD method using a typical problem, a polarization control in optical near and far fields of the designing the shape of a metal nanostructure.

CHERENKOV RADIATION INDUCED BY COSMOGENIC NEUTRINOS IN NEAR-FIELD

2013 ◽  
Vol 28 (02) ◽  
pp. 1340006
Author(s):  
CHIA-YU HU ◽  
CHIH-CHING CHEN ◽  
PISIN CHEN
Keyword(s):  
Near Field ◽  
Fdtd Method ◽  
Field Approximation ◽  
High Energy ◽  
Dense Medium ◽  
Numerical Code ◽  
Peak Structure ◽  
Alternative Approach ◽  
Radiation Induced ◽  
Difference Time

The radio technique of cosmogenic neutrino detection, which relies on the Cherenkov signals coherently emitted from the particle showers in dense medium, has now become a mature field. We present an alternative approach to calculate such Cherenkov pulse by a numerical code based on the finite difference time-domain (FDTD) method that does not rely on the far-field approximation. We show that for a shower elongated by the LPM (Landau-Pomeranchuk-Migdal) effect and thus with a multi-peak structure, the generated Cherenkov signal will always be a bipolar and asymmetric waveform in the near-field regime regardless of the specific variations of the multi-peak structure, which makes it a generic and distinctive feature. This should provide an important characteristic signature for the identification of ultra-high energy cosmogenic neutrinos.

FDTD Study of the Surface Waves Detection in Apertureless Scanning Near-Field Microscopy

2008 ◽  
Author(s):  
G. Parent ◽  
S. Fumeron ◽  
D. Lacroix
Keyword(s):  
Surface Waves ◽  
Near Field ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Far Field ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Experimental Tool ◽  
Field Transformation ◽  
Difference Time

Recent studies have shown the importance of surface waves in heat transfer near interfaces. The scanning near field optical microscopy (SNOM) provides an experimental tool to investigate the thermal electromagnetic field near surfaces. In this work, we present a three dimensional model of SNOM devices. This model is based on the finite-difference-time domain (FDTD) method associated to a near to far field transformation. Near field and far field scattered by a silicon tetrahedral tip and by a pecfectly conducting one are presented and discussed.

scholarly journals Modified Finite-Difference Time-Domain Method for Hertzian Dipole Source under Low-Frequency Band

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2733
Author(s):  
Minhyuk Kim ◽  
SangWook Park
Keyword(s):  
Finite Difference ◽  
Frequency Band ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Low Frequency ◽  
Dipole Source ◽  
Static Approximation ◽  
Difference Time

In this paper, a modified finite-difference time-domain (FDTD) method is proposed for the rapid analysis of a Hertzian dipole source in the low-frequency band. The FDTD technique is one of the most widely used methods for interpreting high-resolution problems such as those associated with the human body. However, this method has been difficult to use in the low-frequency band as the required number of iterations has increased significantly in such cases. To avoid this problem, FDTD techniques using quasi-static assumptions in low-frequency bands were used. However, this method was applied only to plane wave excitation, making it difficult to apply to near-field problems. Therefore, a modified approach is proposed, involving the application of the FDTD technique with a quasi-static approximation to an electric and magnetic dipole problem. The results when using the proposed method are in good agreement with those from a theoretical solution. An example of comparison with the standard FDTD method is shown for illustrating the proposed method’s performance.

scholarly journals Numerical Analysis of Ridged-Circular Nanoaperture for Near-Field Optical Disk

ISRN Optics ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Toshiaki Kitamura
Keyword(s):  
Phase Change ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Near Field ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Free Electrons ◽  
Metallic Material ◽  
Motion Equations ◽  
Difference Time

A ridged-circular nanoaperture is investigated through three-dimensional (finite-difference time-domain) FDTD method. The motion equations of free electrons are inserted to analyze a metallic material. The electromagnetic field distributions of optical near-field around the aperture are investigated. The phase change disk illuminated by a near-field optical light through a ridged-circular nanoaperture is also analyzed. The far-field scattering patterns from the phase change disk and the crosstalk characteristics between plural marks are studied.

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 Fabrication and Application of SERS-Active Cellulose Fibers Regenerated from Waste Resource

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2142
Author(s):  
Shengjun Wang ◽  
Jiaqi Guo ◽  
Yibo Ma ◽  
Alan X. Wang ◽  
Xianming Kong ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Cellulose Fiber ◽  
Cellulose Fibers ◽  
Regenerated Cellulose ◽  
Sers Substrate ◽  
Au Nps ◽  
Convenient Approach ◽  
Theoretical Simulations ◽  
Difference Time ◽  
Raman Probe

The flexible SERS substrate were prepared base on regenerated cellulose fibers, in which the Au nanoparticles were controllably assembled on fiber through electrostatic interaction. The cellulose fiber was regenerated from waste paper through the dry-jet wet spinning method, an eco-friendly and convenient approach by using ionic liquid. The Au NPs could be controllably distributed on the surface of fiber by adjusting the conditions during the process of assembling. Finite-difference time-domain theoretical simulations verified the intense local electromagnetic fields of plasmonic composites. The flexible SERS fibers show excellent SERS sensitivity and adsorption capability. A typical Raman probe molecule, 4-Mercaptobenzoicacid (4-MBA), was used to verify the SERS cellulose fibers, the sensitivity could achieve to 10−9 M. The flexible SERS fibers were successfully used for identifying dimetridazole (DMZ) from aqueous solution. Furthermore, the flexible SERS fibers were used for detecting DMZ from the surface of fish by simply swabbing process. It is clear that the fabricated plasmonic composite can be applied for the identifying toxins and chemicals.

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