Theory of lasing without population inversion

2021 ◽  
Author(s):  
Heide Maria Doss
Keyword(s):  
Population Inversion

Supradegeneracy and the Second Law of Thermodynamics

2020 ◽  
Vol 45 (2) ◽  
pp. 121-132
Author(s):  
Daniel P. Sheehan
Keyword(s):  
Steady State ◽  
Statistical Mechanics ◽  
Population Inversion ◽  
Laboratory Experiments ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Boltzmann Factor ◽  
Energy Currents ◽  
Non Equilibrium

AbstractCanonical statistical mechanics hinges on two quantities, i. e., state degeneracy and the Boltzmann factor, the latter of which usually dominates thermodynamic behaviors. A recently identified phenomenon (supradegeneracy) reverses this order of dominance and predicts effects for equilibrium that are normally associated with non-equilibrium, including population inversion and steady-state particle and energy currents. This study examines two thermodynamic paradoxes that arise from supradegeneracy and proposes laboratory experiments by which they might be resolved.

scholarly journals Population inversion in hyperfine states of Rb with a single nanosecond chirped pulse in the framework of a four-level system

2014 ◽  
Vol 89 (4) ◽  
Author(s):  
G. Liu ◽  
V. Zakharov ◽  
T. Collins ◽  
P. Gould ◽  
S. A. Malinovskaya
Keyword(s):  
Population Inversion ◽  
Level System ◽  
Chirped Pulse

Feasibility Of Novel Si-Based Interminiband Lasers

1998 ◽  
Vol 533 ◽  
Author(s):  
Gregory Sun ◽  
Lionel Friedman ◽  
Richard A. Soref
Keyword(s):  
Quantum Wells ◽  
Current Density ◽  
Population Inversion ◽  
Heavy Hole ◽  
Optical Gain ◽  
Laser Structure ◽  
Strained Si ◽  
Superlattice Structures ◽  
A Current

AbstractWe have designed a parallel interminiband lasing in superlattice structures of coherently strained Si0.5Ge0.5/Si quantum wells (QWs). Population inversion is achieved between the non-parabolic heavy-hole valence minibands locally in-k-space. Lasing transition is at 5.4μm. Our analysis indicates that an optical gain of 134/cm can be obtained when the laser structure is pumped with a current density of 5kA/cm2.

Observation of population inversion in recombining Al plasma by time‐ and space‐resolved x‐ray spectroscopy

1996 ◽  
Vol 68 (11) ◽  
pp. 1479-1481 ◽  
Author(s):  
M. Katsuragawa ◽  
J. Itatani ◽  
S. Orimo ◽  
T. Ozaki ◽  
H. Kuroda ◽  
...  
Keyword(s):  
Population Inversion ◽  
Time And Space ◽  
X Ray

Research Progress and Prospect of Fiber Gas Laser Sources (II): Based on Population Inversion

2021 ◽  
Vol 48 (4) ◽  
pp. 0401009
Author(s):  
王泽锋 Wang Zefeng ◽  
周智越 Zhou Zhiyue ◽  
崔宇龙 Cui Yulong ◽  
黄威 Huang Wei ◽  
李智贤 Li Zhixian ◽  
...  
Keyword(s):  
Population Inversion ◽  
Research Progress ◽  
Gas Laser ◽  
Laser Sources

Dynamics of entanglement and population inversion of two qubits in a hybrid nonlinear system

2021 ◽  
pp. 2150037
Author(s):  
E. M. Khalil ◽  
A.-B. A. Mohamed
Keyword(s):  
Electromagnetic Field ◽  
Nonlinear System ◽  
Analytical Solution ◽  
Nonlinear Interaction ◽  
Population Inversion ◽  
Stark Shift ◽  
Parametric Amplifier ◽  
Kerr Medium ◽  
Interaction Terms

An analytical solution is obtained when the Kerr medium and Stark shift are considered as nonlinear interaction terms to the system containing two-qubit and two-mode electromagnetic field from the parametric amplifier. Dynamics of the population inversion, cavity–qubit and qubit–qubit entanglements are analyzed under the unitary cavity–qubit interaction, the Kerr medium and the Stark shift. The population inversion of a qubit presents periodic revivals and collapses. The results show that the entanglement and the population inversion as well as the inversion have the same stable intervals, that is, the collapse intervals. It is found that the Kerr medium and the Stark shift may lead to reduction of the periods and the amplitudes of the population inversion and the cavity–qubit/qubit–qubit entanglement. The deteriorated qubit–qubit/cavity–qubit entanglement and the population inversion, due to the Kerr medium, may be increased by increasing the Stark shift and vice versa.

Design and Simulation of an Electrically Pumped SPASER

2021 ◽  
Author(s):  
Ali Fattah ◽  
Abdolber Mallah Livani ◽  
Eliye Norouzi
Keyword(s):  
Surface Plasmons ◽  
Power Efficiency ◽  
Population Inversion ◽  
Cavity Length ◽  
Optical Gain ◽  
Photonic Devices ◽  
Forward Voltage ◽  
Pn Junction ◽  
Inversion Condition ◽  
Resonance Cavity

Abstract In this investigation, a novel SPASER is designed and simulated which uses a forward biased pn junction to induce population inversion condition. Simulations are performed by means of SILVACO software. In the proposed structure, the active region is considered as a direct bandgap material (InGaAs) and a larger bandgap material (InP) is used for p and n regions to form heterojunctions. This pn junction is in contact with gold and surface plasmons propagate along their interface. Free space wavelength of the oscillations of surface plasmons is 1550nm that is used in photonic devices, frequently. To form the resonance cavity of the SPASER, two high reflective mirrors are placed at the ends of the plasmonic waveguide. Applied forward voltage and absorption coefficient of the SPASER are 1.2V and − 0.33cm− 1, respectively. Thus, the optical gain for a 50 microns cavity length is 1cm− 1. Moreover, the power consumption of the proposed device at these conditions is 1.2mW. The output plasmonic power is 0.6mW which yields 50% power efficiency.

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