Dielectric Pillars Research Articles

Mechanism and optimal design of a high-k dielectric conduction enhancement SOI LDMOS

A high-k dielectric conduction enhancement SOI LDMOS is proposed and investigated by simulation. The high-k dielectric pillars are located at sidewalls of the drift region. The high-k dielectric assists the self-adapted depletion in the drift region, reshapes the electric field distribution, and makes the three-dimensional RESURF effect realized in a high-voltage blocking state. Dependences of the breakdown voltage (VB) and the specific on-resistance (Ron,sp) on device parameters are exhibited using three-dimensional simulation. Simulation results show that the proposed structure increases VB by 16%–18% and decreases Ron.sp by 13%–20%, compared with the conventional super-junction SOI LDMOS. Furthermore, the charge-imbalance caused by the substrate-assisted depletion effect is alleviated.

Two-Dimensional Analytical Drain Current Model for Double-Gate MOSFET Incorporating Dielectric Pocket

In this paper, a dielectric-pocket double-gate MOSFET is described for low-voltage low-power applications. A complete drain current model has been developed including the channel length modulation effect. The analytical results have been validated by comparing them with the simulation results using the ATLAS 3-D device simulator. This paper analyzes the impact of dielectric pillars on large-signal performance metrics in terms of linearity and digital performance. Due to high <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> ratio, device gain, and extremely low value of intrinsic delay and power dissipation, the proposed design is a suitable candidate for low-voltage low-power digital and analog applications.

Local Field Enhancement of Pillar Nanosurfaces for SERS

We present studies on the analysis and characterization of a unique nanosurface used for Surface-Enhanced Raman Spectroscopy. The optical properties of a nanostructure composed of dielectric pillars that support plasmonic nanoparticles have been investigated. A theoretical analysis has been performed to determine the structural properties that localize the electric field around the silver disk. We define an enhancement factor in terms of the local field integrated over the nanoparticle surface and find that this figure of merit varies considerably depending upon the pillar attributes. An analytic model is presented and validated via full wave analysis, which elucidates the optical effects occurring in the nanostructure. Starting from the basic phenomenology associated with a single pillar structure, we show that several different effects combine to create a global resonance.

Simulation and fabrication of THz waveguides with silicon wafer by using eye-shaped pillars as building blocks

Silicon-based photonic crystal is a promising material for terahertz (THz) waveguide due to its high refractive index contrast. In this work, we introduce eye-shaped pillars as the feature building blocks for two-dimensional (2D) photonic crystals. The simulation study shows that larger TE mode band gaps (PBGs) can be created by the arrangement of dielectric eye-shaped pillars in air. The reflective spectra demonstrate that there are complex PBGs, where the peak position and intensity can be changed by varying the parameter e. Moreover, the peak of reflective spectra exhibits an obvious blue shift with the increase of incidence angle of light. When the vacant space in the structure is filled by polystyrene (PS) microspheres of 2 μm in diameter, the peak intensity of reflective spectra reduces significantly compared with that without PS microspheres, which suggests that this design can act as a sensor in the fields of biology, agriculture or medicine.

Flat Band Slow Light in Symmetric Line Defect Photonic Crystal Waveguides

Flat band slow light in symmetric line defect photonic crystal waveguides formed by adding dielectric pillars in the air holes nearest to the waveguide core is investigated. By adjusting the radii of the new dielectric pillars, a linear band in the photonic band structure appears which denotes low group velocity dispersion. High average group index of 74.4 with 2.3-nm bandwidth is demonstrated in an optimized waveguide by finite-difference time-domain simulation.

Effect of scatterer shape variations between different channels on coupling characteristics of photonic crystal couplers

In the present paper, a two-dimensional photonic crystal (PC) waveguide coupler is mainly studied. The PC coupler containing a single row of dielectric rods in the interaction region is composed of square-arrayed dielectric pillars in air. The effects of the geometrical parameters of the scatterers (including elliptical, rectangular and triangular scatterers) between two different channels on the coupling characteristics of the PC couplers are analyzed by using the finite-difference time-domain (FDTD) method. The simulation results indicate that the coupling property is sensitive to the shape variations of scatterers. The coupling length strongly depends on shape variations of scatterers between the two coupling channels, which is beneficial in fabricating compact integrated optical components.

Electromagnetic Bandgap Structure Containing High‐K Dielectric Ceramics

A square lattice two‐dimensional (2D) electromagnetic bandgap (EBG) structure containing high permittivity (high‐K) dielectric ceramics was investigated. A finite element method‐based band structure calculation technique was used. The calculation results for 2D EBG structures were presented. To verify the validity of the modeling results, an EBG structure prototype containing a series of high‐K dielectric ceramic pillars surrounded by polymethyl methacrylate polymer was fabricated by the dice‐and‐fill technique. The modeled EBG structure shows two transverse‐magnetic gaps spanning 11.06–17.29 and 21.5–24.7 Ghz, respectively. Using a transmission/reflection method, the transmission parameter of the prototype sample from 7 to 19 GHz was measured, and a gap width up to 44% has been demonstrated. The measured propagation characteristics agree well with the calculated results.

Lightwave splitting in two dimensional photonic crystal analogue of coupler

Two bent channels are created in an otherwise periodically arrayed photonic crystal structure by removing some dielectric pillars. If lightwave is introduced into one channel, a part of it would couple into the second channel and propagate down the guide. Factors deciding the amount of light couple from the first channel into the second channel are discussed thoroughly. This coupling scheme could be an important part for photonic integrated devices.

Enhanced coupling of plasmons in hole arrays with periodic dielectric antennas

We compare the angle-dependent transmission spectra of a metal hole array with dielectric pillars in each hole with that of a conventional metal hole array. The pillars enhance the optical transmission as well as the interaction between surface plasmon modes. This results in an observed splitting Delta omega/omega as large as 6%, at normal incidence, for the modes on the pillar side of the array.

Photonic Crystal Polarizing and Non-Polarizing Beam Splitters

A polarizing beam splitter (PBS) and a non-polarizing beam splitter (NPBS) based on a photonic crystal (PC) directional coupler are demonstrated. The photonic crystal directional coupler consists of a hexagonal lattice of dielectric pillars in air and has a complete photonic band gap. The photonic band structure and the band gap map are calculated using the plane wave expansion (PWE) method. The splitting properties of the splitter are investigated numerically using the finite difference time domain (FDTD) method.

Magnetron photonic switching circuit in photonic crystal

We proposed a theoretical model of magnetron photonic switching circuit (MPSC) in photonic crystal (PC) and investigated the properties of MPSC using the plane wave expansion method in combination with supercell method. This model is a PC composed of dielectric pillars set in air, in which one row of dielectric pillars is replaced by ferrite material with the dielectric constant same as that of the original dielectric pillars. When external static magnetic field is applied, the permeability of the ferrite pillars will not be equal to one and guide modes along the row of ferrite pillars may be generated in band gap. When the external field is removed, this system reverts to a perfect PC. Thus, this system forms a photonic switching circuit controlled by the external field. In calculation, we take square pillars set in square lattice. The calculation results show that this MPSC is reasonable and realizable, and some valuable results are obtained.

Investigation on Seasonal Water Area Change in Lake Sakata Based on POLSAR Image Analysis

This paper examines seasonal change of the true water area of Lake Sakata by using Polarimetric Synthetic Aperture Radar area of Lake Sakata by using Polarimetric Synthetic Aperture Radar (POLSAR) image analysis. The true water area includes not only the body of water but also the water area under emerged-plants and/or floating-leave plants in the lake. Statistical POLSAR image analysis is carried out for both X- and L-band data, based on the three-component scattering power decomposition method, where the decomposed components are surface scattering, double-bounce scattering and volume scattering components. From the results of the image analysis for the L-band POLSAR data acquired by Pi-SAR system, it is found that strong double-bounce scattering can be observed at the vicinity of the boundary region between water area and the surrounding emerged-plants area in early and middle summer. This phenomenon is an important factor for environmental monitoring. To verify the generating mechanism of the double-bounce scattering, the Finite-Difference Time-Domain (FDTD) polarimetric scattering analysis is also executed for a simplified boundary model, which simulates the local boundary region around the lake and consists of lots of vertical thin dielectric pillars on a perfect electric conductor (PEC) plate or on a PEC and dielectric hybrid plate. Taking into account the polarimetric feature of the double-bounce scattering obtained by both the FDTD and POLSAR image analyses, one can distinguish the actual water area from the bush of the emerged-plants around the lake, even when the water area is concealed by emerged-plants and/or floating-leave plants. Consequently, it is found that by using the proposed approach, one can estimate the true water area seasonal change for the lake and the surrounding wetland.

Apodized photonic crystal waveguide gratings

Apodized photonic crystal (PC) waveguide gratings are proposed to suppress sidelobes which appear in reflection spectra of usual PC waveguide gratings. By using specific functions (Gauss and Gauss-cosine functions) for the longitudinal refractive index distribution, it is possible to suppress sidelobes in the reflection spectra of PC waveguide gratings efficiently. The apodization is realized by simply changing diameters of dielectric pillars adjacent to the PC waveguide core. It is shown that by using Gauss-cosine functions for the apodization, Bragg frequency of the waveguide grating becomes insensitive to the magnitude of perturbation leading to the possibility of designing waveguide gratings with arbitrarily Bragg frequency and bandwidth by modulating geometrical parameters only.

Modeling of two-dimensional photonic crystal resonant cavities incorporating elliptically shaped dielectric cylinders

Modeling of photonic crystal structures is an ongoing challenge. This letter is devoted to the theoretical modeling of photonic crystal resonant cavities, composed of elliptically shaped dielectric pillars. Through this rigorous study, we can examine the impact of the elliptical-shape deformations to important quantities related to the photonic crystal cavity performance, such as the quality factor and the resonance frequency.

Finite-element mode-solver for nonlinear periodic optical waveguides and its application to photonic crystal circuits

A finite-element method (FEM) is newly formulated for the modal analysis of nonlinear periodic optical waveguides. In order to treat periodicity in the propagation direction, periodic boundary conditions are imposed on the envelope of electromagnetic fields. The validity of this method is verified by way of numerical examples of a PC waveguide composed of nonlinear dielectric pillars placed on square array in the cladding region. Furthermore, the present method is applied to various nonlinear photonic crystal waveguide structures for exploring appropriate structures to enhance the nonlinearity and their nonlinear modal properties are presented, including coupled-resonator optical waveguides.

Near-field optical probing of two-dimensional photonic crystals: theory and experiment.

We report new experimental results, and their theoretical analysis, on the mechanisms that control light transfer between two integrated waveguides connected by two-dimensional matrices of dielectric pillars. The optical properties of the system are analysed from the well-established formalism of classical field susceptibilities (Green dyadic functions). We apply this scheme to investigate the optical properties of two-dimensional arrays connected to two integrated waveguides. Comparisons with current experimental work based on near-field optical probing are provided together with a spectral analysis of the phenomenon.