Modeling and Implementing Nonlinear Equations in Solid-State Lasers for Studying their Performance

In this paper, the effect of radius variation of beam light on output efficacy of SFD Yttrium aluminium borate laser doped with Neodymium ion, which is simultaneously a non-linear and active laser crystal, is investigated in a double-pass cavity. This is done with a concave lens that concentrates (Reduction of optical radius within nonlinear material) as much optical laser as possible, resulting in increasing the laser efficiency, second harmonic and the population inversion difference. In this study, we first developed five discrete differential equations describing the interactions of 807 nm pump beam, 1060nm laser beam and 530nm second harmonic beam. Output efficiencies of laser and second harmonic beams at pumping power of Pp =20W and beam radius of 5μm have been presented. Meanwhile, in this paper, the first experiment for creating second harmonic in solid state lasers was fully described with a figure and its procedure was investigated and then the equations (second harmonic and laser and population inversion) were studied. Radius variation of beam light aims at increasing laser output efficacy and improving second harmonic and population inversion. The analytic methods which have been solved the discrete differential equations via Matlab

High Ion/Ioff current ratio graphene field effect transistor: the role of line defect

The present paper casts light upon the performance of an armchair graphene nanoribbon (AGNR) field effect transistor in the presence of one-dimensional topological defects. The defects containing 5–8–5 sp2-hybridized carbon rings were placed in a perfect graphene sheet. The atomic scale behavior of the transistor was investigated in the non-equilibrium Green's function (NEGF) and tight-binding Hamiltonian frameworks. AGNRFET basic terms such as the on/off current, transconductance and subthreshold swing were investigated along with the extended line defect (ELD). The results indicated that the presence of ELDs had a significant effect on the parameters of the GNRFET. Compared to conventional transistors, the increase of the Ion/Ioff ratio in graphene transistors with ELDs enhances their applicability in digital devices

Enhancing Efficiency of Two-bond Solar Cells Based on GaAs/InGaP

Multi-junction solar cells play a crucial role in the ConcentratedPhotovoltaic (CPV) Systems. Recent developments in CPV concerning high powerproduction and cost effective-ness along with better efficiency are due to theadvancements in multi-junction cells. This paper presents a simulation model of thegeneralized Multi-junction solar cell and introduces a two-bond solar cell based onInGaP/GaAs with an AlGaAs/GaAs tunnel layer.For enhancing the efficiency of theproposed solar cell, the model adopts absorption enhancement techniques as well asreducing loss of recombination by manipulating number of junctions and varying thematerial properties of the multi-junctions and the tunneling layer. The proposed Multijunctionsolar cell model employing tunnel junctions can improve efficiency up to by35.6%. The primary results of the simulation for the proposed structure indicate that it ispossible to reduce the loss of recombination by developing appropriate lattice matchamong the layers; it is also likely to have suitable absorption level of the phonons.Simulation results presented in this paper are in agreement with experimental results