A comparison of the performance of THz photoconductive antennas

This letter explores the influence of the geometry of bias electrodes in the performance of terahertz (THz) photoconductive antennas (PCAs). To this end, a methodology is presented to calculate numerically the operational bandwidth and radiation efficiency of the PCAs. The procedure is validated through a comparison to experimental measurements. Also, results are depicted from numerical simulations of different PCAs under varying conditions of bias voltage, doping factor, and incident optical power. It is concluded that an appropriate con figuration of the electrodes may double the efficiency of the antennas, with a penalty in the bandwidth of the radiated pulse usually smaller than 10%.This work was supported in part by the Spanish Ministry of Education under Project CSD2008-00068, the Junta de Andalucia Project P09-TIC-5327, the EU FP7/2007-2013 under Grant 205294 (HIRF-SE project), and the Spanish National Project TEC2010-20841-C04-0

Time-domain numerical modeling of THz photoconductive antennas

This paper presents a computational procedure to simulate the time-domain behavior of photoconductive antennas made of semiconductor and metal materials. Physical modeling of semiconductor devices at terahertz regime can be achieved by applying joint electronic and electromagnetic procedures, e.g., solving a coupled system of equations inferred from Poisson’s drift-diffusion and Maxwell’s equations. A set of discrete equations are derived by applying a combined finite-difference methodology for the previous steady-state and the finite-difference time-domain procedure for the transient regime. The results for the radiated electric field at broadside direction show good agreement with the experimental results previously reported in the literatureThis work was supported in part by the Spanish Ministry of Education under Project CSD2008-00068, the Junta de Andalucia Project P09-TIC-5327, the EU FP7/2007-2013, under grant 205294 (HIRF-SE project), and the Spanish National Project TEC2010-20841-C04-0

An analysis of the Leap-Frog Discontinuous Galerkin method for Maxwell equations

In this paper, we explore the accuracy limits of a Finite-Element Time-Domain method applied to the Maxwell equations, based on a Discontinuous Galerkin scheme in space, and a Leap-Frog temporal integration. The dispersion and dissipation properties of the method are investigated, as well as the anisotropy of the errors. The results of this novel analysis are represented in a practical and comprehensible manner, useful for the application of the method, and for the understanding of the behavior of the errors in Discontinuous Gelerkin Time-Domain methods. A comparison with the Finite-Difference Time-Domain method, in terms of computational cost, is also includedThe work described in this paper and the research leading to these results has received funding from the European Community’s Seventh Framework Programme FP7/2007-2013, under grant agreement no 205294 (HIRF SE project), and from the Spanish National Projects TEC2010-20841-C04-04, CSD2008-00068, and the Junta de Andalucia Project P09-TIC-

A Computationally Efficient Method for Simulating Metal-Nanowire Dipole Antennas at Infrared and Longer Visible Wavelengths

This paper presents a numerically efficient approach for simulating nanowires at infrared and long optical wavelengths. A computationally efficient circuit-equivalent modeling approach based on the electric-field integral-equation (EFIE) formulation is employed to simulate the highly dispersive behavior of nanowires at short wavelengths. The proposed approach can be used both for frequency-domain and for time-domain EFIE formulations. In comparison with widely used full-wave solutions achieved through the finite-difference time-domain method, the circuit-based EFIE formulation results in a sharp reduction of the computational resources while retaining high accuracy.This work was supported in part by the Spanish Ministry of Education under Project PR2009-0443, in part by the Penn State MRSEC under NSF Grant 0213623, in part by the EU FP7/2007-2013 under Grant GA 205294 (HIRF SE project), in part by the Spanish National Projects TEC2010-20841- C04-04, CSD200800068, and DEX-5300002008105, and in part by the Junta de Andalucia Project P09-TIC5327

Efficient antenna modeling by DGTD

The work described in this article is partially funded by the Spanish National Projects TEC2013-48414-C3-01, CSD2008-00068, P09-TIC-5327, and P12-TIC-1442 and by the GENIL Excellence Network

A New efficient and stable 3D Conformal FDTD

A novel conformal technique for the FDTD method, here referred to as Conformal Relaxed Dey-Mittra method, is proposed and assessed in this letter. This technique helps avoid local time-step restrictions caused by irregular cells, thereby im- proving the global stability criterion of the original Dey-Mittra method. The approach retains a second-order spatial convergence. A numerical experiment based on the NASA almond has been chosen to show the improvement in accuracy and computational performance of the proposed method.The work described in this letter and the research leading to these results has received support from the Projects TEC2013- 48414-C3-01 and TEC2015-68766-REDC (MINECO, Spain), P12-TIC-1442 (Junta de Andalucia, Spain), Alhambra-UGRFDTD (AIRBUS DS), and by the CSIRC alhambra.ugr.es supercomputing center

Implementation of Open Boundary Problems in Photo-Conductive Antennas by Using Convolutional Perfectly Matched Layers

A method to simulate an open boundary problem within the Finite Differences Time Domain (FDTD) approach for the emission of photo-conductive antennas is presented here. For this purpose we use convolutional perfectly matched layers (CPML). In these devices, the semiconductor region, where transient currents are present in simulation time, is considered to be an ”active” medium. This medium is extended virtually beyond its boundaries or the computational domain limits. We explain in this paper how to simulate the transient state of a semiconductor in a CPML region as well as the potential of the method developed to solve conventional practical applications

Dotig1 :un programa para el estudio en el dominio del tiempo de la interacción de ondas electromagnéticas con estructuras de hilo

Universidad de Granada. Departamento de Física Aplicada. Leída el 30 de mayo de 198