Vector Finite Element Research Articles

Ultrashort hybrid plasmonic transverse electric pass polarizer for silicon-on-insulator platform

A design of a transverse electric (TE)-pass polarizer based on hybrid plasmonic silicon-on-insulator (SOI) platform is reported and analyzed using full vectorial finite element method. The proposed design has gold nanorods that are injected into the silicon dioxide substrate to tolerate the function of the device, and hence the required polarizing state can be obtained. Detailed design principle is presented, taking advantage of the distinct confinements of the TE and transverse magnetic modes in the core region and their coupling with the surface plasmon modes around the metallic nanorods. According to the positions of the gold nanorods, the suggested plasmonic SOI can be used as a TE-pass polarizer with a compact device length of 1.85 μm with 0.1639 dB insertion losses and extinction ratio of 14.58 dB at wavelength of 1.55 μm. The optimized geometrical parameters offer 3 orders of magnitude smaller than similar devices previously demonstrated on the SOI platform. The proposed design has advantages in terms of simplicity and compactness, which makes it a good candidate to be used in integrated silicon photonics. Further, the compact device size and good performance could provide a simple yet satisfactory solution to the polarization-dependent performance drawback of the silicon photonics devices on the SOI platform.

Design of a porous cored hexagonal photonic crystal fiber based optical sensor with high relative sensitivity for lower operating wavelength

In this article, highly sensitive and low confinement loss enriching micro structured photonic crystal fiber (PCF) has been suggested as an optical sensor. The proposed PCF is porous cored hexagonal (P-HPCF) where cladding contains five layers with circular air holes and core vicinity is formed by two layered elliptical air holes. Two fundamental propagation characteristics such as the relative sensitivity and confinement loss of the proposed P-HPCF have been numerically scrutinized by the full vectorial finite element method (FEM) simulation procedure. The optimized values are modified with different geometrical parameters like diameters of circular or elliptical air holes, pitches of the core, and cladding region over a spacious assortment of wavelength from 0.8 µm to 1.8 µm. All pretending results exhibit that the relative sensitivity is enlarged according to decrement of wavelength of the transmission band (O+E+S+C+L+U). In addition, all useable liquids reveal the maximum sensitivity of 57.00%, 57.18%, and 57.27% for n=1.33, 1.354, and 1.366 respectively by lower band. Moreover, effective area, nonlinear coefficient, frequency, propagation constant, total electric energy, total magnetic energy, and wave number in free space of the proposed P-HPCF have been reported recently.

3D vector finite-element electromagnetic forward modeling for large loop sources using a total-field algorithm and unstructured tetrahedral grids

Unstructured tetrahedral grids with local refinement facilitate the use of total-field solution approaches to geophysical electromagnetic (EM) forward problems. These approaches, when combined with the vector finite-element (FE) method and with refinement near transmitters and receivers, can give accurate solutions and can easily handle realistic models with complex geometry and topography. We have applied this approach to 3D forward modeling for fixed- and moving-loop configurations. MUMPS, a direct solver, was used to solve the linear system of equations generated by FE analysis. A direct solver is particularly suited to the moving-loop configuration for which the right side is different for every transmitter loop, but for which the coefficient matrix is unchanged. Therefore, the coefficient matrix need only be factorized once, and then the system can be solved efficiently for all different right sides. We compared our results with several typical scenarios from the literature: a conductive brick in a homogeneous half-space and a complex conductor at a vertical contact both for fixed-loop configurations, and a homogeneous half-space for a moving-loop configuration. We also evaluated results for the massive sulfide ore deposit of the Ovoid Zone at Voisey’s Bay, Labrador, Canada, for which we considered fixed- and moving-loop configurations. This model also provides an illustration of the complex vortex current systems that are generated by time-domain EM methods within highly conductive ore bodies in a resistive host.

Photonic Crystal Fiber Based Sensor for Detecting Binary Liquid Mixture

Detection of liquid mixture of different volume ratio is very important in industrial purposes. The paper reports a sensing mechanism of binary liquid mixture for different volume fraction, based on the measurement of refractive index of the mixture. Here, a highly sensitive liquid filled core Photonic Crystal Fiber structure has been proposed to detect liquid mixture solution. Numerical investigation of the proposed structure is carried out by employing full vectorial Finite Element Method (FEM).

Seven-core photonic liquid crystal fibers for simultaneous mode shaping and temperature sensing

Through doping liquid crystals into the core region, we propose a kind of seven-core photonic crystal fiber (PCF) which can achieve mode shaping and temperature sensing simultaneously in the communication window of 1.1–1.7 μm. To the best of our knowledge, this is the first time that the function of seven-core PCFs as temperature sensors is investigated. By using the full vectorial finite element method, the characteristics of the fiber with the temperature, such as the effective mode area, the waveguide dispersion, and the confinement loss, are analyzed. This kind of PCF can be competitive in providing temperature sensing in multi-core PCF lasers.

Dual-core terahertz polarization splitter based on porous fibers with near-tie units

Terahertz (THz) radiation, which is defined as the electromagnetic wave with a frequency ranging from 0.1 THz to 10 THz, has attracted widespread attention in recent years because of its unique possibilities in many fields. High-performance THz polarization splitter, a key device in THz manipulation, is of great significance for studying the THz devices. In the present paper, a novel dual-core THz polarization splitter is proposed, which is based on porous fiber with near-tie units. The introduction of near-tie units into the fiber core can enhance asymmetry to realize high mode birefringence. And the results show that the porous THz fiber exhibits high birefringence at a level of 10-2 over a wide frequency range. An index converse matching coupling (ICMC) method, which exhibits several advantages (such as short splitting length, high extinction ratio, low loss, and broad operation bandwidth), is used to allow for the coupling of one polarization mode within a broad operation band, while the coupling of the other polarization component is effectively inhibited. The splitting length is equal to one coupling length of x- or y-polarization component for which inter-core coupling occurs, and short splitting length means low transmission loss. Unlike the reported filling method, an adjusting structure method is proposed in the paper to satisfy the condition of index converse matching coupling. The full vector finite element method (FEM), which is based on the variational principle and the subdivision interpolation, is used to analyze the guiding properties of the proposed THz polarization splitter. The FEM is a widely used numerical method in physical modeling and simulation. Simulation results show that the THz polarization splitter operates within a wide frequency range of 0.5-2.5 THz. The splitting length does not exceed 2.5 cm in the whole frequency range and the minimum is only 0.428 cm. At 2.3 THz, the material absorption losses of x- and y-polarization are both less than 0.35 dB, and the extinction ratios for x- and y-polarization are 2.9 and 19.2 dB, respectively. Moreover, by comparing with a THz polarization splitter with filling method, the proposed THz polarization with adjusting structure method is easier to realize, the operating frequency range is wider, the splitting length is shorter, and the material absorption loss is lower. Finally, we note that the fabrication of such THz porous fiber designs could be realized by several methods, such as a capillary stacking technique, a polymer casting technique, a hole drilling technique, etc.

ベクトル有限要素法を用いた交流磁場下における3次元電磁流体解析

ベクトル有限要素法を用いた交流磁場下における3次元電磁流体解析

Highly birefringent large mode area photonic crystal fiber-based sensor for interferometry applications

In this work, highly birefringent large mode area (LMA) photonic crystal fiber (PCF) structure for interferometric sensor applications is proposed. The effective mode area, birefringence and the sensitivity coefficient of the proposed PCF structure by employing the full vectorial finite element method (FV-FEM) have been thoroughly investigated. The numerical results have shown that proposed structure simultaneously offers high birefringence of order 10[Formula: see text], adequately LMA and high sensitivity for various liquid analytes by employing the elliptical liquid core holes.

Extremely low material loss and dispersion flattened TOPAS based circular porous fiber for long distance terahertz wave transmission

Abstract In this paper, we present a porous-core circular photonic crystal fiber (PC-CPCF) with ultra-low material loss for efficient terahertz wave transmission. The full vector finite element method with an ideally matched layer boundary condition is used to characterize the wave guiding properties of the proposed fiber. At an operating frequency of 1 THz, simulated results exhibit an extremely low effective material loss of 0.043 cm −1 , higher core power fraction of 47% and ultra-flattened dispersion variation of 0.09 ps/THz/cm. The effects of important design properties such as single mode operation, confinement loss and effective area of the fiber are investigated in the terahertz regime. Moreover, the proposed fiber can be fabricated using the capillary stacking or sol-gel technique and be useful for long distance transmission of terahertz waves.

Highly sensitive face-shaped label-free photonic crystal refractometer for glucose concentration monitoring

In this paper, a novel highly sensitive photonic crystal (PhC) refractometer for glucose concentration monitoring is reported and studied. The proposed design is based on two dimensional PhC platform with face-shaped defect filled with the analyzed analyte. Through this study, the effect of the structure geometrical parameters on the biosensor performance is investigated in order to maximize its sensitivity. The suggested biosensor proved to surpass the recent sensors with high linear sensitivity of 359 nm/RIU and an average quality factor of 477. The results are calculated using full-vectorial finite difference time domain method with perfectly matched layer boundary conditions. Also, the modal analysis of the PhC biosensor is made using full vectorial finite element method. Further, the reported biosensor has high quality promising applications for glucose monitoring.

Optimization and enhancement of liquid analyte sensing performance based on square-cored octagonal photonic crystal fiber

This paper presents an optimum design for highly sensitive square-cored octagonal photonic crystal fiber (S-OPCF) based liquid sensor. Full vectorial finite element method (FEM) with perfectly matched layer (PML) circular boundary has been applied to investigate propagation characteristics of proposed structure, in which both core and cladding are microstructured. Ring numbers, air filling ratios both in core and cladding area and structural shapes in core region are varied to examine sensitivity and confinement loss. According to simulation, five-ring S-OPCF structure is designed and optimized different parameters. The proposed S-OPCF significantly enhances sensitivity and reduces confinement loss for the optimized parameters. Finally the S-OPCF structure improves the sensitivity 1.16, 1.21 and 1.24 times for water, Ethanol and Benzyne analytes respectively compare to prior structure. In addition to this, the proposed structure operates for a wide range of wavelength from 0.6μm to 2.2μm with larger effective area and also suitable for nonlinear applications.

Enhancement of relative sensitivity of photonic crystal fiber with high birefringence and low confinement loss

In this article, we demonstrate a unique hexagonal lattice structure of Photonic Crystal Fiber for liquid sensing applications. Relative sensitivity, confinement loss and birefringence of the structure have been investigated theoretically. The numerical inquiry has been taken place using the full vectorial Finite Element Method (FEM). We have shown a comparative performance analysis between two lattice structures of the proposed Photonic Crystal Fiber. It is found that the presence of elliptic air holes instead of circular air holes in the core region and the innermost ring of the cladding bring higher birefringence with high sensitivity and low confinement loss. According to the simulated results, at 1.33μm operating wavelength, the birefringence, confinement loss, and relative sensitivity of the suggested PCF are 2.825×10−3, 2.07×10−6dB/m and 43.84% respectively for Ethanol filled core.

Directional light scattering from individual Au nanocup

We investigate the optical scattering properties of gold nanocup with different orientation and fractional height by full vector finite element method. All of the scattering cross section, the distribution of electric field intensity, and the ability of directional light scattering are simulated, respectively. It is demonstrated that the scattering cross section of Au nanocup is a superposition of scattering spectrum of a transverse mode and an axial mode. The wavelength and the intensity of the maximum value of the scattering cross section increase initially then reduce with the fractional height increasing for transverse mode, while they increase monotonously with the fractional height increasing for axial mode. Furthermore, the calculation results show that the ability of redirecting incident light of Au nanocup mainly depends on the transverse mode. And the deflected angle of scattering increases with the fractional height of Au nanocup decreasing. These results indicate that Au nanocup has a promising application in the planar plasmon devices.

A new structure of photonic crystal fiber with high sensitivity, high nonlinearity, high birefringence and low confinement loss for liquid analyte sensing applications

This paper proposes the design and optimization of microstructure optical fiber for liquid sensing applications. A number of propagation characteristics have been compared between two formations of hexagonal cladding of our proposed PCF structure. The core of the proposed PCF structure is designed with two rows of supplementary elliptical air holes. We investigate the performance of the designed PCFs for Ethanol as a liquid sample to be sensed. Numerical analysis is carried out by employing the full vectorial Finite Element Method (FEM) to examine the modal birefringence, confinement loss, relative sensitivity and nonlinear coefficient of the proposed PCF structure.

Numerical analysis of photonic crystal fiber based hemoglobin sensor

Optical fiber sensor for measuring hemoglobin (Hb) concentrations of human peripheral blood based on photonic crystal fiber (PCF) is numerically proposed in this work. It presents a simple and accurate method to measure Hb concentration. In this paper, we have numerically analyzed a solid-core PCF being infiltrated with Hb by using full vectorial finite element method (FEM) based solver. From the imaginary part of the fundamental mode effective index we obtain the confinement loss of the fiber for different Hb concentrations. As Hb concentration increases, confinement loss increases indicating the amount of Hb present. By tailoring the pitch constant and diameter of the holes, we have also deduced the dependence of sensor performance on these parameters.

THE 3D TRANSIENT ELECTROMAGNETIC FORWARD MODELING OF VOLCANOGENIC MASSIVE SULFIDE ORE DEPOSITS

AbstractThe transient electromagnetic forward modeling of volcanogenic massive sulfide (VMS) ore deposits is to calculate the eddy currents electromagnetic response of a three dimensional body in the full space of deep‐sea environment. We simulated the three dimensional transient electromagnetic response of the VMS deposits using full‐domain vector finite element method. The ore body was discretized with brick rectangular elements. The finite element equation was deduced in frequency domain by employing Galerkin procedure, and the conversion to time domain was by inverse Fourier transform. We confirmed the validity of the full‐domain vector finite element algorithm by comparing simulated results with analytical solutions of double half‐space model. The results have a good agreement with each other, which indicates that the vector finite element method is capable of solving whole space problem. In order to demonstrate the ability of the numerical method in calculating the response of VMS deposits containing complex boundary conditions, we compared vector finite element solution of a three dimensional electrical model with physical experiment results according to electromagnetic physical scale modeling rules. The comparison suggests that for the complex electromagnetic boundary of seawater, ore body and country rocks, the transient electromagnetic response of VMS deposits calculated by full‐domain vector finite element method has same features with the physical scale modeling result. The vector finite element method is simple and its results are precise with obvious and clear anomaly response.

Ultrabroadband Supercontinuum Generation Through Photonic Crystal Fiber With As2S3 Chalcogenide Core

In this paper, a novel design of silica photonic crystal fiber is proposed and analyzed for supercontinuum generation (SCG). The suggested design has an As2S3 chalcogenide core region with large nonlinear coefficient and low anomalous dispersion. The modal analysis of the reported design is performed using a full vectorial finite element method while the SCG is simulated by solving the nonlinear Schrodinger equation using the split-step Fourier method. The effects of the fiber length, pump peak power, and pump wavelength on the SCG performance are studied thoroughly. It has been shown that the reported design has a very low zero dispersion wavelength, which facilitates the pumping at wavelength of 1.55 μm. Furthermore, the investigated design has ultrabroadband super continuum spectra of 2656 and 1788 nm around wavelengths of 1.55 and 1.3 μm, respectively, with a short device length of 10 mm. To the best of the authors' knowledge, the achieved ultrabroadband spectra are the maximum bandwidths with the shortest length for the two operating wavelengths 1.55 and 1.3 μm, simultaneously.

Study of highly birefringence dispersion shifted photonic crystal fiber with asymmetrical cladding

In this article we compared two models of the highly birefringent photonic crystal fiber using a full vectorial finite element method with anisotropic perfectly matched boundary layers. High birefringence and low confinement loss are successfully achieved in both fibers. The zero dispersion wavelengths are achieved for both structures in the near infrared region. The simulation results revealed that it is possible to obtain the zero dispersion at the near infrared wavelength with low confinement loss and high birefringence by changing the structural parameters of the photonic crystal fiber. Such fibers are very useful for polarization maintaining devices, dispersion compensating devices, sensing applications and nonlinear application.

A novel three dimensional vector finite element method for periodic photonic devices

ABSTRACTThis article presents a novel Three‐Dimensional (3D) Vector Finite Element Method to solve eigenvalue problems for periodic structures. With the formulation, numerical investigations of photonic crystals and subwavelength grating waveguide in a silicon‐on‐insulator platform have been performed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2665–2668, 2016

Comparison of finite element and transfer matrix methods for numerical investigation of surface plasmon waveguides

In this paper, we investigate Surface Plasmon Polaritons (SPPs) in the visible regime at a metal/dielectric interface within two different waveguide structures, the first is a Photonic Crystal Fiber where the Full Vector Finite Element Method (FVFEM) is used and the second is a slab waveguide where the transfer matrix method (TMM) is used. Knowing the diversities between the two methods in terms of speed, simplicity, and scope of application, computation is implemented with respect to wavelength and metal layer thickness in order to analyze and compare the performances of the two methods. Simulation results show that the TMM can be a good approximation for the FVFEM and that SPPs behave more like modes propagating in a semi infinite metal/dielectric structure as metal thickness increases from about 150nm.