Population inversion of G14 excited state of Tm3+ investigated by means of numerical solutions of the rate equations system in Yb:Tm:Nd:LiYF4 crystal

2009 ◽  
Vol 105 (11) ◽  
pp. 113503 ◽  
Author(s):  
André Felipe Henriques Librantz ◽  
Laércio Gomes ◽  
Lilia Coronato Courrol ◽  
Izilda Marcia Ranieri ◽  
Sonia Lícia Baldochi
Keyword(s):  
Excited State ◽  
Population Inversion ◽  
Numerical Solutions ◽  
Rate Equations

Energy transfer rates and population inversion of I411/2 excited state of Er3+ investigated by means of numerical solutions of the rate equations system in Er:LiYF4 crystal

2009 ◽  
Vol 106 (10) ◽  
pp. 103508 ◽  
Author(s):  
Laércio Gomes ◽  
André Felipe Henriques Librantz ◽  
Fabio Henrique Jagosich ◽  
Wonder Alexandre Luz Alves ◽  
Izilda Marcia Ranieri ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Population Inversion ◽  
Numerical Solutions ◽  
Rate Equations ◽  
Transfer Rates

scholarly journals Увеличение эффективности тандема полупроводниковый лазер-оптический усилитель на основе самоорганизующихся 8s квантовых точек

2021 ◽  
Vol 55 (12) ◽  
pp. 1223
Author(s):  
А.Е. Жуков ◽  
Н.В. Крыжановская ◽  
Э.И. Моисеев ◽  
А.С. Драгунова ◽  
А.М. Надточий ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited State ◽  
Laser Diode ◽  
Ground State ◽  
Semiconductor Optical Amplifier ◽  
Optical Transition ◽  
Optical Amplifier ◽  
Rate Equations ◽  
Resonator Length ◽  
Optimal Value

The rate equations are used to analyze the characteristics of a tandem consisting of a laser diode and a semiconductor optical amplifier made of a single heterostructure with quantum dots. The optimal value of the current distribution coefficient the amplifier and the laser, as well as the optimal resonator length that provides the highest output power of the tandem were determined. It is shown that the use of the tandem allows, at the same total consumed current, to significantly (more than 4 times for 1 A) increase the power emitted through the ground-state optical transition in comparison with that achievable with a laser diode solely being limited by the onset of lasing through an excited-state optical transition.

scholarly journals Mathematical Modeling and Analysis of Multirobot Cooperative Hunting Behaviors

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yong Song ◽  
Yibin Li ◽  
Caihong Li ◽  
Xin Ma
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Numerical Solutions ◽  
Rate Equations ◽  
Ratio Analysis ◽  
Hunting Behavior ◽  
Modeling And Analysis ◽  
Cooperative Hunting ◽  
Model Equations ◽  
The Mathematical Model

This paper presents a mathematical model of multirobot cooperative hunting behavior. Multiple robots try to search for and surround a prey. When a robot detects a prey it forms a following team. When another “searching” robot detects the same prey, the robots form a new following team. Until four robots have detected the same prey, the prey disappears from the simulation and the robots return to searching for other prey. If a following team fails to be joined by another robot within a certain time limit the team is disbanded and the robots return to searching state. The mathematical model is formulated by a set of rate equations. The evolution of robot collective hunting behaviors represents the transition between different states of robots. The complex collective hunting behavior emerges through local interaction. The paper presents numerical solutions to normalized versions of the model equations and provides both a steady state and a collaboration ratio analysis. The value of the delay time is shown through mathematical modeling to be a strong factor in the performance of the system as well as the relative numbers of the searching robots and the prey.

EXCITED STATE PHOTOLUMINESCENCE IN STEPPED InGaAs/AlGaAs QUANTUM WELLS UNDER PICOSECOND EXCITATION

2003 ◽  
Vol 02 (06) ◽  
pp. 427-435
Author(s):  
V. A. SHALYGIN ◽  
L. E. VOROBJEV ◽  
V. Yu. PANEVIN ◽  
D. A. FIRSOV ◽  
S. HANNA ◽  
...  
Keyword(s):  
Excited State ◽  
Quantum Wells ◽  
Special Interest ◽  
Population Inversion ◽  
Auger Recombination ◽  
Stimulated Emission ◽  
Energy Structure ◽  
Electron Hole ◽  
Picosecond Excitation ◽  
Electron Energy Structure

The technique of photoluminescence (PL) studies based on intense picosecond excitation of electron–hole pairs is applied to investigate the electron energy structure including the positions of high-lying excited levels in stepped quantum wells (QWs). The spectra of PL in regimes of spontaneous and stimulated emission are studied under different excitation levels and light polarizations. Of special interest are intense photoluminescence signals from excited subbands. The feasibility of a e3–e2 intersubband population inversion in stepped QWs is demonstrated and the influence of Auger recombination was examined.

scholarly journals Dynamics of positrons during relativistic electron runaway

2018 ◽  
Vol 84 (5) ◽  
Author(s):  
O. Embréus ◽  
L. Hesslow ◽  
M. Hoppe ◽  
G. Papp ◽  
K. Richards ◽  
...  
Keyword(s):  
Pair Production ◽  
Electric Fields ◽  
Numerical Solutions ◽  
Production Cross ◽  
Analytical Formula ◽  
Rate Equations ◽  
Annihilation Radiation ◽  
Operational Parameters ◽  
Pair Production Cross Section ◽  
Strong Electric Fields

Sufficiently strong electric fields in plasmas can accelerate charged particles to relativistic energies. In this paper we describe the dynamics of positrons accelerated in such electric fields, and calculate the fraction of created positrons that become runaway accelerated, along with the amount of radiation that they emit. We derive an analytical formula that shows the relative importance of the different positron production processes, and show that, above a certain threshold electric field, the pair production by photons is lower than that by collisions. We furthermore present analytical and numerical solutions to the positron kinetic equation; these are applied to calculate the fraction of positrons that become accelerated or thermalized, which enters into rate equations that describe the evolution of the density of the slow and fast positron populations. Finally, to indicate operational parameters required for positron detection during runaway in tokamak discharges, we give expressions for the parameter dependencies of detected annihilation radiation compared to bremsstrahlung detected at an angle perpendicular to the direction of runaway acceleration. Using the full leading-order pair-production cross-section, we demonstrate that previous related work has overestimated the collisional pair production by at least a factor of four.

A rate equation method for the sequential double ionisation, including autoionising state excitation, of a noble gas

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
Damien Middleton ◽  
Katravulapally Tejaswi ◽  
Lampros Nikolopoulos
Keyword(s):  
External Field ◽  
Numerical Solutions ◽  
Noble Gas ◽  
Time Dependent ◽  
Rate Equations ◽  
Stochastic Field ◽  
Pulse Characteristics ◽  
Ion Species ◽  
Double Ionisation ◽  
Strong External Field

AbstractA set of rate equations have been tested against a more robust set of Time-Dependent Density Matrix (TDDM) equations [D. P. W. Middleton, L. A. A. Nikolopoulos, J. Mod. Opti. 59, 1650 (2012)] by using them to determine the populations of ion species and autoionising states (AIS) in noble gas atoms when interacting with a strong external field. Two field shapes were tested here — sinusoidal and square — and a variety of pulse characteristics were examined, i.e. intensity, duration and photon energy, for the neon atomic system. It was found that the rate equations were sufficiently accurate only when the external field is way off-resonant with the AIS. Moreover, analytical solutions of the rate equations in the square pulse case agree with the numerical solutions for a time-dependent pulse containing many cycles. An attempt to model a stochastic field was also made and it was found that the use of such a field diminished and broadened the ion yield ratio due to the presence of an added bandwidth.

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