scholarly journals An investigation on the temperature dependence of the relative population inversion and the gain in EDFAs by the modified rate equations

2005 ◽  
Vol 254 (4-6) ◽  
pp. 248-255 ◽  
Author(s):  
Cüneyt Berkdemir ◽  
Sedat Özsoy
Keyword(s):  
Temperature Dependence ◽  
Population Inversion ◽  
Rate Equations ◽  
Relative Population

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

TEMPERATURE DEPENDENCE OF TERAHERTZ EMISSION FROM SILICON DEVICES DOPED WITH BORON

2004 ◽  
Vol 14 (03) ◽  
pp. 670-675
Author(s):  
R. T. TROEGER ◽  
T. N. ADAM ◽  
S. K. RAY ◽  
P.-C. LV ◽  
S. KIM ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Temperature Dependence ◽  
Theoretical Calculations ◽  
Rate Equations ◽  
Line Center ◽  
Spectral Emission ◽  
Terahertz Emission ◽  
Time Resolved ◽  
Silicon Devices ◽  
Terahertz Emitters

In this paper, we report on electrically pumped terahertz emitters based on silicon doped with boron acceptors. At cryogenic temperatures, three narrow spectral emission lines attributed to radiative transitions from p-like excited hydrogenic states to the s-like Γ8 ground state associated with the boron dopants were observed centered around 8 THz. The spectral emission line center frequencies were in remarkable agreement with values reported from absorption measurements and theoretical calculations. The total time-resolved terahertz emission power was found to be up to 31 μW per device facet. We have solved the rate equations describing the populations in the hydrogenic dopant states involved in the emission mechanism and derived expressions for the current pumping and temperature dependence of the emitted terahertz power, yielding excellent agreement with the experimental data. These results suggest that silicon-based terahertz emitters may be fabricated without epitaxial quantum wells. The observed temperature dependence suggests that electric field assisted thermal escape of carriers from upper hydrogenic states may be responsible for lower output powers at higher temperatures.

Kinetic theory for a short-wavelength lasing plasma

1982 ◽  
Vol 27 (3) ◽  
pp. 473-489 ◽  
Author(s):  
Daniel M. Heffernan ◽  
Richard L. Liboff
Keyword(s):  
Kinetic Theory ◽  
Absorption Coefficient ◽  
Population Inversion ◽  
Unit Length ◽  
Rate Coefficients ◽  
Radiation Absorption ◽  
Rate Equations ◽  
Algebraic Solution ◽  
Electron Densities ◽  
Spatial Homogeneity

A kinetic analysis is made of a reacting plasma dominated by three-body recombination and ionization, together with collisional and radiative excitation and de-excitation of atomic states. The plasma includes excited atoms, ions, electrons and photons. The kinetic theory yields rate equations for these species, together with explicit expressions for relevant rate coefficients. In the limit of spatial homogeneity and assuming atom and electron densities are close to equilibrium, an explicit form is obtained for the radiation absorption coefficient per unit length. A criterion is then constructed for population inversion. Application to a helium-like active medium (e.g. Al+11) and hydrogen-like passive medium (e.g. A1+12), at electron temperature of 300 eV, reveals that population inversion ensues at electron densities in excess of 1020 cm−3. Algebraic solution of atomic state rate equations demonstrates that the absorption coefficient grows insensitive to photon-atom interactions with increasing electron density.

The water relations of hemlock (Tsuga canadensis). III. The temperature dependence of water exchange in a pressure bomb

1973 ◽  
Vol 51 (8) ◽  
pp. 1537-1543 ◽  
Author(s):  
M. T. Tyree ◽  
M. Benis ◽  
J. Dainty
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Water Exchange ◽  
Membrane Resistance ◽  
Tsuga Canadensis ◽  
Rate Equations ◽  
Rate Theory ◽  
Water Permeation ◽  
Pressure Bomb ◽  
Extracellular Resistance

The pressure-bomb technique has been used to measure the temperature dependence of water exchange between the apoplast and symplast of hemlock (Tsuga canadensis) shoots. By applying the Arrhenius rate theory, the activation energy for water exchange in the whole shoot equals 25.9 + 0.6 × 103 J per mole. A theory is proposed on the basis of the Arrhenius rate equations which allows us to predict the relative magnitudes of the membrane resistance, Rm, and the extracellular resistance, Rx, to water permeation. On the basis of our calculations, we believe Rm is at least one-quarter of Rx and may even exceed Rx, but more work needs to be done to be sure.

THE MONTE-CARLO SIMULATION OF TRANSPORT IN QUANTUM WELL GaAs/AlGaAs HETEROSTRUCTURE DOPED WITH SHALLOW DONORS UNDER IMPURITY BREAKDOWN

2007 ◽  
Vol 06 (03n04) ◽  
pp. 253-256
Author(s):  
L. V. GAVRILENKO ◽  
V. YA. ALESHKIN ◽  
A. A. DUBINOV
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Distribution Function ◽  
Monte Carlo Method ◽  
Electric Field ◽  
Electron Concentration ◽  
Ground State ◽  
Population Inversion ◽  
Rate Equations ◽  
The Monte Carlo Method

The impurity breakdown was simulated in numerical calculations. The distribution function for an electron in the electric field was calculated using the Monte-Carlo method. The electron concentration in the impurity ground state and in the first subband was determined by solving the rate equations. It was found out that a population inversion between the 1s-level and the bottom of the first subband is likely to arise. The requirements for the population inversion to occur were determined.

scholarly journals The role of Nd3+ in the population inversion between 1G4 and 3H6 states of Tm3+ in Yb:Nd:Tm:YLF crystal

Exacta ◽  
2008 ◽  
Vol 5 (1) ◽  
Author(s):  
André Felipe Henriques Librantz ◽  
Lilia Coronato Courrol ◽  
Laércio Gomes ◽  
Sonia Lícia Baldochi ◽  
Izilda Marcia Ranieri
Keyword(s):  
Energy Transfer ◽  
Population Inversion ◽  
Upconversion Emission ◽  
Rate Equations ◽  
Kutta Method ◽  
Pumping Rate ◽  
Transfer Rates ◽  
Runge Kutta Method ◽  
Rate Threshold

In this paper, we present the energy transfer rates of YLF:Yb:Tm:Nd system, identifying the most important processes that lead to the thulium blue upconversion emission under excitation around 792 nm. The calculation of the rate equations system based on numerical method using Runge-Kutta method was employed for analyzing the population inversion between 1G4 and 3H4 states of Tm3+. Population inversion was achieved only in Yb:Nd:Tm doped YLF crystal, which exhibits a pumping rate threshold of 620 s-1. The Nd3+ absorption near 792 nm is very important because the excitation is rapidly transferred to Yb3+, that also interacts with Tm3+.

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

scholarly journals The role of Nd3+ in the population inversion between 1G4 and 3H6 states of Tm3+ in Yb:Nd:Tm:YLF crystal 1 DOI: 10.5585/exacta.v5i1.1035

Exacta ◽  
2008 ◽  
Vol 5 (1) ◽  
Author(s):  
André Felipe Henriques Librantz ◽  
Lilia Coronato Courrol ◽  
Laércio Gomes ◽  
Sonia Lícia Baldochi ◽  
Izilda Marcia Ranieri
Keyword(s):  
Energy Transfer ◽  
Population Inversion ◽  
Upconversion Emission ◽  
Rate Equations ◽  
Kutta Method ◽  
Pumping Rate ◽  
Transfer Rates ◽  
Runge Kutta Method ◽  
Rate Threshold

In this paper, we present the energy transfer rates of YLF:Yb:Tm:Nd system, identifying the most important processes that lead to the thulium blue upconversion emission under excitation around 792 nm. The calculation of the rate equations system based on numerical method using Runge-Kutta method was employed for analyzing the population inversion between 1G4 and 3H4 states of Tm3+. Population inversion was achieved only in Yb:Nd:Tm doped YLF crystal, which exhibits a pumping rate threshold of 620 s-1. The Nd3+ absorption near 792 nm is very important because the excitation is rapidly transferred to Yb3+, that also interacts with Tm3+.

The Behaviour of Population in a Plasma Interacting with an Atomic Gas

1984 ◽  
Vol 39 (2) ◽  
pp. 132-141
Author(s):  
Utaro Furukane ◽  
Toshiatsu Oda
Keyword(s):  
Steady State ◽  
Population Inversion ◽  
Initial Conditions ◽  
Hydrogen Plasma ◽  
Excited Level ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
Rate Equations ◽  
Quasi Steady State ◽  
Energy Equations

The processes leading to the population inversion are investigated in a recombining hydrogen plasma which is interacting with a cool and dense neutral hydrogen gas by using the rate equations on the basis of a collisional-radiative (CR) model and the energy equations for electrons, ions and neutral particles. The quasi-steady state (QSS) approximation is used only for the levels i lying above a certain level i* which is not the first excited level. The calculations have shown that the quasi-steady state cannot be realized while intense energy-flows due to the collisional processes exist between different kinds of the particles such as the electrons and the ions in the plasma, and that the population inversion is realized only in the quasi-steady state following the transient phase. The effects of the initial conditions of the hydrogen plasma and of the introduced neutral hydrogen gas on the overpopulation density are also discussed.

Spin–lattice relaxation of Fe3+ in rutile for X- and F-band transitions

1969 ◽  
Vol 47 (15) ◽  
pp. 1573-1583 ◽  
Author(s):  
G. J. Lichtenberger
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Transition Probabilities ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Rate Equations ◽  
Relaxation Rates ◽  
Time Resolved ◽  
Spin Lattice

Detailed measurements of the angular and temperature dependence (1.6 °K to 4.2 °K) of the dominant spin–lattice relaxation rates of Fe3+ in rutile have been carried out for a number of strong transitions at 9.4 Gc and 121 Gc using the pulse saturation method. At 9.4 Gc, two relaxation time components were observed, ranging from 0.5 to 1.2 ms and 1.6 to 4.0 ms, respectively, at 4.2 °K. Assuming a relationship of the form log(relaxation time) = −n∙log(temperature), the temperature dependence factor n was found to be between 0.4 and 1.0. The single relaxation time resolved at F band had values from 0.7 to 1.0 ms at 4.2 °K, and n between 0.1 and 0.6. The corresponding relative relaxation rates were calculated from the direct process spin–phonon transition probabilities, assuming Debye elastic isotropy for rutile. Using a cubic spin–lattice coupling tensor, [Formula: see text] was found to be 0.5 and the rate equations for the six-level system were solved. The calculated effective relaxation times were successfully identified with the slower dominant relaxation component of the experimental data.

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