scholarly journals Sub-Wavelength Focusing in Inhomogeneous Media with a Metasurface Near Field Plate

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4534 ◽  
Author(s):  
Andrew C. Strikwerda ◽  
Timothy Sleasman ◽  
William Anderson ◽  
Ra’id Awadallah
Keyword(s):  
Finite Element Method ◽  
Layered Medium ◽  
Near Field ◽  
Skin Surface ◽  
Diffraction Limit ◽  
The Finite Element Method ◽  
Field Plate ◽  
Hyperthermic Treatment ◽  
Reactive Coupling ◽  
Sub Wavelength

Overcoming the diffraction limit, which enables focusing much less than the wavelength, requires tailoring the evanescent spectrum of an aperture’s field distribution. We model and simulate a corrugated near field plate, which can generate a sub-wavelength focus in inhomogeneous background media. All reactive coupling, between the metasurface near field plate and the focusing domain and among the corrugations in the metasurface, is taken into consideration with the finite element method, which we solve in combination with a constraint to generate a desired focus. Various geometries for the near field plate are considered and we demonstrate that the proposed method can effectively create a deeply sub-wavelength focus within a layered medium having properties resembling brain tissue. Such a device could find use as a detector of biological signals or for hyperthermic treatment near the skin surface.

Plasmonic Lithography

2004 ◽  
Author(s):  
W. Srituravanich ◽  
N. Fang ◽  
C. Sun ◽  
S. Durant ◽  
M. Ambati ◽  
...  
Keyword(s):  
Surface Plasmons ◽  
Ion Beam ◽  
Near Field ◽  
Diffraction Limit ◽  
Fdtd Simulation ◽  
Hole Array ◽  
Exposure Test ◽  
Spacer Layer ◽  
Bull's Eye ◽  
Sub Wavelength

As the next-generation technology moves below 100 nm mark, the need arises for a capability of manipulation and positioning of light on the scale of tens of nanometers. Plasmonic optics opens the door to operate beyond the diffraction limit by placing a sub-wavelength aperture in an opaque metal sheet. Recent experimental works [1] demonstrated that a giant transmission efficiency (>15%) can be achieved by exciting the surface plasmons with artificially displaced arrays of sub-wavelength holes. Moreover the effectively short modal wavelength of surface plasmons opens up the possibility to overcome the diffraction limit in the near-field lithography. This shows promise in a revolutionary high throughput and high density optical lithography. In this paper, we demonstrate the feasibility of near-field nanolithography by exciting surface plasmon on nanostructures perforated on metal film. Plasmonic masks of hole arrays and “bull’s eye” structures (single hole surrounded by concentric ring grating) [2] are fabricated using Focused Ion Beam (FIB). A special index matching spacer layer is then deposited onto the masks to ensure high transmissivity. Consequently, an I-line negative photoresist is spun on the top of spacer layer in order to obtain the exposure results. A FDTD simulation study has been conducted to predict the near field profile [3] of the designed plasmonic masks. Our preliminary exposure test using these hole-array masks demonstrated 170 nm period dot array patterns, well beyond the resolution limit of conventional lithography using near-UV wavelength. Furthermore, the exposure result obtained from the bull’s eye structures indicated the characteristics of periodicity and polarization dependence, which confirmed the contribution of surface plasmons.

Simulation of Interfacial Corner Cracks in Bimaterial Systems

2012 ◽  
Author(s):  
Badrinath Veluri ◽  
Henrik Myhre Jensen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Front ◽  
Near Field ◽  
Three Dimensional ◽  
Strain Energy Release ◽  
Numerical Approach ◽  
The Finite Element Method ◽  
Corner Cracks ◽  
Element Method

A phenomenological model focused on modeling the shape of such interface cracks and calculating the critical stress for steady-state propagation has been developed. The crack propagation is investigated by estimating the fracture mechanics parameters that include the strain energy release rate, crack front profiles and the three-dimensional mode-mixity along the crack front. A numerical approach is then applied for coupling the far field solutions utilizing the capability of the Finite Element Method to the near field (crack tip) solutions based on the J-integral. The developed two-dimensional numerical approach for the calculation of fracture mechanical properties has been validated with three-dimensional models for varying crack front shapes. In this study, a custom quantitative approach was formulated based on the finite element method with iterative adjustment of the crack front to estimate the critical delamination stress as a function of the fracture criterion and corner angles. The implication of the results on the delamination is discussed in terms of crack front profiles and the critical stresses, which can then be used as the framework for modeling reliability of advanced interconnects system.

Modeling of Welding Distortion in Stiffened Rings

1991 ◽  
Vol 35 (02) ◽  
pp. 162-171
Author(s):  
Amiram Moshaiov ◽  
Haoshi Song
Keyword(s):  
Finite Element Method ◽  
Near Field ◽  
Three Dimensional ◽  
Welding Distortion ◽  
Far Field ◽  
The Finite Element Method ◽  
Temperature Changes ◽  
Welding Arc ◽  
Local Asymmetric ◽  
Ring Stiffener

A simple model is developed to describe the deformation of a ring stiffener under welding, with applications to submarine hulls. The model is based on the realization that only a small part of the structure near the welding arc (near field) undergoes high temperature changes, and thus behaves thermo-elastic-plastically, while the rest of the structure (far field) is elastic in nature. The model is used to predict the overall axisymmetric residual shrinkage of different rings and the results are shown to be in excellent agreement with the finite-element method (FEM). This concept of near and far field could also be used to simplify three-dimensional FE models when predicting local, asymmetric welding distortions of various geometry.

Optically Induced Sub-Wavelength Transient Apertures in Sb-Te Based Films

2011 ◽  
Vol 1338 ◽  
Author(s):  
Robert E. Simpson ◽  
Paul J. Fons ◽  
Alexander V. Kolobov ◽  
Xiomin Wang ◽  
Junji Tominaga
Keyword(s):  
Thin Films ◽  
Density Functional ◽  
Near Field ◽  
Diffraction Limit ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Thermally Induced ◽  
Melting Temperatures ◽  
Sub Wavelength

ABSTRACTThe origin of sub-diffraction-limit apertures in Sb-based thin films is discussed. Electromagnetic energy can be channeled by these apertures thus allowing near-field focussing- the Super-RENS effect. The aperture formation within Sb, Sb2Te3, Sb2Te, SbTe and Ge2Sb2Te5 is investigated by time resolved optical pump-probe techniques and found to occur without melting. Density functional calculations have shown that these materials exhibit a thresholdlike change in their optical properties below their melting temperatures. The threshold is shown to be a consequence of thermally induced misalignment of p-orbital bonds. It is the non-linearity of this process that leads to the formation of the sub-diffraction-limit apertures.

scholarly journals Sub-Wavelength Probing and Modification of Complex Photonic Structures

2010 ◽  
Author(s):  
Silvia Vignolini
Keyword(s):  
Light Propagation ◽  
High Spatial Resolution ◽  
Near Field ◽  
Optical Microscope ◽  
Diffraction Limit ◽  
Nano Structures ◽  
Propagation Of Light ◽  
Technological Impact ◽  
Coupling Phenomena ◽  
Sub Wavelength

The aim of this thesis consists in the study and modification of complex photonic nano-structures. Nowadays, propagation of light in such materials is a rich and fascinating area of research, both for its fundamental implications and for its practical technological impact. To deeply investigate light propagation inside these structures a high spatial resolution technique is required, especially because intriguing effects often occur on length scales comparable with the diffraction-limit or involve coupling phenomena on this length scale. For this reason in this thesis a Scanning Near-Field Optical Microscope represents one the most straightforward tool both to study and locally modify complex photonic nano-structures from perfect periodic to completely random ones.

Sub-wavelength Imaging through Metallic Nanorod Array

2006 ◽  
Vol 919 ◽  
Author(s):  
Atsushi Ono ◽  
Jun-ichi Kato ◽  
Satoshi Kawata
Keyword(s):  
Imaging System ◽  
Near Field ◽  
Nanorod Array ◽  
Diffraction Limit ◽  
Localized Surface Plasmon ◽  
Negative Index ◽  
Negative Index Material ◽  
Frequency Regime ◽  
Dipole Sources ◽  
Sub Wavelength

AbstractNegative index material is expected to exhibit interesting optical properties. Especially, superlens effect, which is predicted by John B. Pendry in 2000, is very attractive to overcome the diffraction limit in optical imaging [1]. Although there is no negative index material in nature, Pendry numerically suggested that several metals, only dielectric constant is negative at optical frequencies, behave like a superlens under the electrostatic limit and for the p-polarized fields. X. Zhang experimentally demonstrated this superlens effect by constructing nanolithography system with silver thin film in 2005 [2].In this presentation, we newly propose a sub-wavelength imaging system at optical frequency regime in an array of metallic nanorods [3]. The near-field components of dipole sources were plasmonically transferred through the rod array to reproduce the image of the dipoles in the other side.We calculated the field distribution at the different planes of imaging process using the finite-difference time-domain (FDTD) algorithm and found that the spatial resolution was 40 nm, which was much beyond the diffraction-limit and was limited by the array pitch. The typical configuration is a hexagonal arrangement with 40 nm periodicity of silver rods of 50 nm height and 20 nm diameter. The image formation highly depends on the coherence and the polarization of the dipole sources, array pitch, and the source-array distance. The principle of our near-field imaging is based on the longitudinal resonance of the localized surface plasmon along a metallic nanorod. The spectral responses of the device are also investigated.

Simulation of tuning graphene plasmonic behaviors by ferroelectric domains for self-driven infrared photodetector applications

Nanoscale ◽  
2019 ◽  
Vol 11 (43) ◽  
pp. 20868-20875 ◽  
Author(s):  
Junxiong Guo ◽  
Yu Liu ◽  
Yuan Lin ◽  
Yu Tian ◽  
Jinxing Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Interfacial Effect ◽  
Infrared Photodetector ◽  
The Finite Element Method ◽  
Ferroelectric Domains ◽  
Element Method

We propose a graphene plasmonic infrared photodetector tuned by ferroelectric domains and investigate the interfacial effect using the finite element method.

Sign in / Sign up

Export Citation Format

Share Document