Showing 8 results for Simulation
Tahereh Nemati Aram, Saeed Batebi, Massoud Mohebbi,
Volume 6, Issue 1 (10-2012)
Abstract
We investigate theoretically the high-order harmonic spectrum extension and numerical generation of an intense isolated attosecond pulse from He+ ion irradiated by a two-color laser field. Our simulation results show that the chirp of the fundamental field can control HHG cutoff position. Also, these results show that the envelope forms of two fields are important factors for controlling the resultant attosecond pulses. Besides, the effects of relative intensity are investigated. As a result, by using the optimized conditions an intense isolated 126-as (attosecond) pulse can be observed
Hamed Amin Pour, Alireza Hojabri,
Volume 6, Issue 1 (10-2012)
Abstract
We present a novel slanted faces of thin-disk composite Yb:YAG YAG laser which is side-pumped by four non-symmetric hollow- ducts. The pump light distribution in the disk is modeled by using Monte-Carlo ray tracing method. The temperature distribution inside the crystal is calculated by taking into account either the concentration of Yb+3 ion or the different transmission of laser output coupler. By using Finite Element Analysis (FEA) method, we calculated the absorption efficiency through the disk. The resonator is simulated by self consistently method. The resulting of optical efficiency and the output power of our laser have been modeled.
Mohammad Sadegh Soltani Gishini, Alireza Ganjovi, Majid Taraz, Masoud Saeed,
Volume 12, Issue 1 (1-2018)
Abstract
In this work, applicability of Particle in Cell-Monte Carlo Collisions (PIC-MCC) simulation method for better understanding of the plasma physical mechanisms and real important aspects of a plasma column driven by surface wave plasma discharges that is used in plasma antennas is examined. Via the implementation of geometry and physical parameters of the plasma column to an Object Oriented PIC-MCC code, the plasma density, electrical conductivity, plasma kinetic energy and electric field inside the plasma column as its essential properties are obtained. The gas within the plasma column is taken to be argon which is kept at the low operational background pressures. The radial increasing and axial decreasing of the electric field in the plasma column is observed. Moreover, the plasma density reduces radially, while it is maximized along the axial positions. It is seen that, the density of charged particles and their corresponding current densities are maximized at the positions closer to the surface wave launcher.
Zahra Danesh Kaftroudi, Abolfazl Mzandarani,
Volume 13, Issue 1 (1-2019)
Abstract
In this paper, a numerical study of barrier characterization effects on the high-temperature internal performance of an InGaAsP multi-quantum well laser is presented. The softwareused for this purpose self-consistently combines the three-dimensional simulation of carrier transports, self-heating, and optical waveguiding. The laser model calculates all relevant physical mechanisms, including their dependence on temperature and local carrier density. The results have shown that the proposed laser, which operates at 1325 nm, suffers from electron leakage. The electron leakage current decreases by reducing the barrier thickness. Although tensile strain barriers lead to improved laser optical behavior, it increases leakage current because of electron non-uniformity.
Samaneh Biabani, Gholamreza Foroutan,
Volume 13, Issue 2 (12-2019)
Abstract
The dynamics of fast gas heating in a high power microwave discharge in air, is investigated in the framework of FDTD simulations of the Maxwell equations coupled with the fluid simulations of the plasma. It is shown that, an ultra-fast gas heating of the order of several 100 Kelvins occurs in less than 100 ns. The main role in the heating is played by the electron impact dissociation of , dissociation via quenching of metastable states of , as well as, quenching by nitrogen molecules. Among the electronically excited metastable states, are the most important species. Slow heating of the gas above 1 is attributed to the vibrational relaxation processes of , among them vibrational-translational relaxation of demonstrates the highest heating rate. The heating rate and thus the gas temperature are significantly increased with increasing of the microwave pulse amplitude, pulse width, and the gas pressure. In all cases, enhanced dissociation is the main factor behind the enhanced gas heating. The same effects are observed for increasing of the initial gas temperature, and percentage in a mixture.
Elham Karimi, Seyed Mohamad Bagher Ghorashi, Maryam Hashemi,
Volume 14, Issue 1 (1-2020)
Abstract
Recently, organo–metal halide perovskites have attracted much attention of the scientific community relating to their successful application in the absorber layer of low-cost solar cells. However, enough is known about the material and device properties, to realize that much remains to be learned.
In this paper, the electrical and optical properties of perovskite solar cells are investigated
using the COMSOL Multiphysics simulation program. It is a study of the influences
of carrier diffusion length (L), dielectric constant (ε
r), the valence band offset (VBO) of absorber/hole transport materials (HTM) and illumination intensity on fill factor (FF), short-circuit current density(J
SC), performance (PCE), and open-circuit voltage(V
OC). Also, J-V characteristics are calculated for diff
erent ε
r values. The simulation results point to the great dependence of efficiency on the carrier diffusion length of absorber layers. It is shown that, to obtain a high rate of efficiency, the relative permittivity should not be higher than 45.
Zahra Danesh Kaftroudi,
Volume 15, Issue 1 (1-2021)
Abstract
In this work, for the first time, the improved lasing performance of a blue GaN-based laser diode is demonstrated by the introduction and vertical optimization of a new quadruple asymmetric waveguide structure. In the new proposed waveguide structure, in the first step, p-waveguide and electron blocking layers have been omitted. Then a triple asymmetry was considered for the design of an AlGaNp-cladding layer inside the waveguide structure. The performances of the conventional and proposed laser structures were theoretically studied using the photonic integrated circuit simulator in 3D simulation software. The 3deminsional simulations of carrier transport, optical wave- guiding and self-heating were combined self-consistently in the software. A good agreement was achieved between simulations and experiments by careful choice of different material parameters in the physical models. The effects of the AlGaN p-cladding layer properties on the performance of the new quadruple asymmetric waveguide GaN-based laser were theoretically studied. Threshold current, output power, and operation voltage were compared for different composition of Al, doping, and thickness of the AlGaN p-cladding layer. According to the simulation results, the optimized values of Al composition, doping, and thickness of the AlGaN p-cladding layer obtained for high-power performance.
Tarek Al-Saeed,
Volume 17, Issue 1 (1-2023)
Abstract
In this work we applied a Bessel beam (BB) to a layer of turbid medium. We applied the Monte Carlo simulation. This work emulates a tissue under surgery by a Bessel beam. Actually, the BB introduces less divergence. Thus it will be good for surgery. On the other part this is done by Monte Carlo simulation. Upon simulation we got family of curves to characterize absorption, reflection and scattering of this layer. Where we got numerical values of absorption, transmission and reflection of this layer. The curves are for layer thickness that varies along with varying scattering coefficient, absorption coefficient and anisotropy factor.
