Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Gain due to level-dependent collisions

Jing-Yong Ye, Mingsheng Zhan, Shikang Zhou

Published Sep 1, 1993• 0 citations
Publisher

Abstract

Based on the level dependence of collision cross sections, a mechanism of light amplification without inversion in a Doppler-broadened three-level system is further studied. In the rate equations, we use a collision-kernel model and consider all of the decay and pumping rates. The emission and absorption profiles are derived by solving the coupled mass-velocity equations numerically. Then, the possibility of obtaining positive gain with noninversion for an ensemble of particles is shown.

DOI
10.1103/physreva.48.2256

Related papers

Light gain without the population inversion due to the level dependence of collision cross sections

Jing-Yong Ye, Ming-Shing Zhan, Shikang Zhou

Based on the different changes of the velocity distributions of the ground and excited levels due to the level dependence of collision cross sections in a flowing system, a new mechanism for the light amplification without population inversion is presented.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Oct 28, 1992•0 citations

Control of group velocity by phase-changing collisions

Chana Goren, A. D. Wilson‐Gordon, M. Rosenbluh +1 more

We discuss the influence of phase-changing collisions on the group velocities in Doppler-broadened, cycling, degenerate two-level systems where ${F}_{e}={F}_{g}+1$ and ${F}_{g}>0$, interacting with pump and probe lasers, that exhibit electromagnetically induced absorption (EIA). Two model systems are considered: the $N$ system where the pump and probe are polarized perpendicularly, and EIA is due to transfer of coherence (TOC), and the double two-level system (TLS) where both lasers have the same polarization, and EIA is due to transfer of population (TOP). For the case of Doppler-broadened EIA TOC, which occurs at low pump intensity, there is a switch from positive to negative dispersion and group velocity, as the rate of phase-changing collisions is increased. For the case of EIA TOP at low pump intensity, the dispersion and group velocity remain negative even when the collision rate is increased. Pressure-induced narrowing, accompanied by an increase in the magnitude of the negative dispersion and a decrease in the magnitude of the negative group velocity, occurs in both EIA TOC and EIA TOP, at low pump intensity. When the pump intensity is increased, a switch from negative to positive dispersion and group velocity, with increasing collision rate, also occurs in the double TLS system. However, the effect is far smaller than in the case of the $N$ system at low pump intensity.

Physical Review A•Aug 29, 2005•1 citation

Light amplification by the effect of velocity redistributions of particles due to the level dependence of collision cross sections

Jing-Yong Ye, Mingsheng Zhan, Shi-Kang Zhou

Physics Letters A•Jun 1, 1992•1 citation

Effect of Doppler broadening on optical gain without inversion in a four-level model

Dezhong Wang, Jin-Yue Gao

We discuss the effect of Doppler broadening on the gain and refractive index experienced by an optical probe when passing through a collection of atoms in the absence of a population inversion. We calculate the gain-absorption spectrum of the medium when the atoms have a Maxwell velocity distribution and compare the atomic response when the pump and probe beams are arranged in copropagating and counterpropagating configurations. The results in these two cases can be qualitatively very different from each other, as we show with the help of numerical calculations. A physical interpretation and the conditions for the validity of the results are provided.

Physical Review A•Oct 1, 1995•15 citations

Nonlinear theory of noninversion lasers of an open three-level system

Shi-Yao Zhu, De-Zhong Wang, Jin-Yue Gao

A nonlinear theory of a noninversion laser of an open three-level system based on electromagnetically induced transparency is given. In this noninversion laser model, a nonselective pumping mechanism is used for obtaining lasing gain such that the population in the lower lasing level is always larger than a half of the total population no matter whether the driving field is on or off. In the lasing region, there is no direct pumping to the upper level. The conditions for the existence of a nontrivial and stable laser field are obtained. The dependence of the laser intensity on the intensity of the driving field and the ratio of the two decay rates from the upper level has been obtained, and the ways to obtain a large laser field have been studied.

Physical Review A•Feb 1, 1997•28 citations

Gain without inversion in a V-type system with low coherence decay rate for the upper levels

Dipankar Bhattacharyya, Biswajit Ray, Pradip Narayan Ghosh

Inversionless gain is observed in a V-type inhomogeneously broadened system without introducing any incoherent pumping and only by changing the collisional dephasing decay rate. In this system sub-Doppler linewidth is achieved with off-resonance pump detuning.

arXiv:physics/0405079•May 15, 2004•0 citations
Based on the level dependence of collision cross sections, a mechanism of light amplification without inversion in a Doppler-broadened three-level system is further studied. In the rate equations, we use a collision-kernel model and consider all of the decay and pumping rates. The emission and absorption profiles are derived by solving the coupled mass-velocity equations numerically. Then, the possibility of obtaining positive gain with noninversion for an ensemble of particles is shown.
We discuss the influence of phase-changing collisions on the group velocities in Doppler-broadened, cycling, degenerate two-level systems where Fe=Fg+1{F}_{e}={F}_{g}+1Fe​=Fg​+1 and Fg>0{F}_{g}>0Fg​>0, interacting with pump and probe lasers, that exhibit electromagnetically induced absorption (EIA). Two model systems are considered: the NNN system where the pump and probe are polarized perpendicularly, and EIA is due to transfer of coherence (TOC), and the double two-level system (TLS) where both lasers have the same polarization, and EIA is due to transfer of population (TOP). For the case of Doppler-broadened EIA TOC, which occurs at low pump intensity, there is a switch from positive to negative dispersion and group velocity, as the rate of phase-changing collisions is increased. For the case of EIA TOP at low pump intensity, the dispersion and group velocity remain negative even when the collision rate is increased. Pressure-induced narrowing, accompanied by an increase in the magnitude of the negative dispersion and a decrease in the magnitude of the negative group velocity, occurs in both EIA TOC and EIA TOP, at low pump intensity. When the pump intensity is increased, a switch from negative to positive dispersion and group velocity, with increasing collision rate, also occurs in the double TLS system. However, the effect is far smaller than in the case of the NNN system at low pump intensity.
We discuss the effect of Doppler broadening on the gain and refractive index experienced by an optical probe when passing through a collection of atoms in the absence of a population inversion. We calculate the gain-absorption spectrum of the medium when the atoms have a Maxwell velocity distribution and compare the atomic response when the pump and probe beams are arranged in copropagating and counterpropagating configurations. The results in these two cases can be qualitatively very different from each other, as we show with the help of numerical calculations. A physical interpretation and the conditions for the validity of the results are provided.
A nonlinear theory of a noninversion laser of an open three-level system based on electromagnetically induced transparency is given. In this noninversion laser model, a nonselective pumping mechanism is used for obtaining lasing gain such that the population in the lower lasing level is always larger than a half of the total population no matter whether the driving field is on or off. In the lasing region, there is no direct pumping to the upper level. The conditions for the existence of a nontrivial and stable laser field are obtained. The dependence of the laser intensity on the intensity of the driving field and the ratio of the two decay rates from the upper level has been obtained, and the ways to obtain a large laser field have been studied.