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

Acta Physica Sinica

Role of selective excitation of dressed populations in lasing without inversion

Wang Zhen-hua, Xiangming Hu, (1)华中师范大学物理系，武汉 430079; (2)华中师范大学物理系，武汉 430079;南华大学数理学院，衡阳 421001

Published Jan 1, 2004• 2 citations
Publisher

Abstract

Exemplifying the three-level systems in the V configuration, we investigate the role of selective excitation of dressed populations in lasing without inversion. Incoherent driving field transfers population from either of the dressed states to excited state when the level spacing between dressed states produced by the coherent field is much larger than the spectral width of the incoherent driving field. With atomic decay pathways，unidirectional channel of population transfer is formed and selective excitation of dressed populations is established. Employing selective excitation of dressed populations，three severe limits are relaxed. First，it is no longer required that the decay rate of the low-frequency driving transition is larger than that of high-frequency laser transition. Second，the threshold for incoherent driving rate is remarkably lowered. Third，linear gain of the laser without inversion is no longer inversely proportional to the coherent driving field intensity, and the gain is significantly enhanced.

DOI
10.7498/aps.53.2569

Related papers

Coherently driven three-level atoms: unexpected inversions, pump bandwidth effects and observation of continuous lasing

Krishna K. Meduri, Peter B. Sellin, Geoffrey A. Wilson +1 more

We show that continuous-wave, two colour excitation of three-level atoms opens new channels of irreversible population transfer between atomic levels. This process, which we describe as dynamically induced irreversibility, leads to unanticipated phenomena including the inversion of atomic transitions whose upper atomic level has no conventional source of irreversible population pumping. We also study the effect of excitation-field bandwidth on the gain exhibited by driven, three-level, V-type atomic systems. Gain, which may or may not be inversionless in the atomic-state basis, is produced through strong monochromatic driving of one atomic transition and weaker pumping of a coupled transition. It is found that monochromatic pumping frequently yields greater optical gain than incoherent (wide bandwidth) pumping. This is particularly true when system gain can be attributed to hidden inversions among the eigenstates (semi-classical dressed states) of the coupled atom+driving field quantum system. Last, we report the observation of continuous-wave lasing in a strongly driven barium cascade system and interpret its properties in terms of the models presented.

Quantum Optics Journal of the European Optical Society Part B•Aug 1, 1994•6 citations

Dressed states analysis of lasing without inversion in a three-level ladder system: the steady-state regime

Doron Braunstein, R. Shuker

A dressed-state study of lasing without population inversion from a three-level atom interacting with a bi-chromatic laser field in the ladder configuration is presented. In our model we allow the atom to be dressed by both of the coupling and probe fields. The system under consideration is explored both analytically and numerically within the steady-state regime. A parameter study is performed in which we explore the influence of the change of control parameters (Rabi frequencies and incoherent pump rates, etc) on the system behaviour. The parameter study also applies to situations where both coherent fields have comparable intensities. Expressions for steady-state populations and coherences are derived, from which the constraints on the system control parameters allowing gain or absorption of various types, are calculated. The system is demonstrated to possess gain without inversion (GWI), as well as regular gain with inversion, for the appropriate choice of system control parameters. Inversion without lasing (IWL) is also found. The dressed-state approach offers a different insight into the system dynamics in which Rabi oscillations and spectral features appear natural. We believe that the dressed-state approach provides a more adequate description of the system dynamics than that provided by the bare state basis.

Journal of Physics B Atomic Molecular and Optical Physics•May 26, 2009•12 citations

Realization of lasing without inversion in the system with lower-level coherence

Zhenfei Luo, Zhizhan Xu

It is shown that the ladder system with lower-level coherence may be used to obtain lasing without inversion. The present model system has several important features. (1) No requirement is placed on atomic decay rates. (2) The Rabi frequency of coherence-driving field must exceed a lower threshold. (3) An unidirectional pumping is indispensable. (4) A dressed-state-coherence origin of gain is proved without strong coherence-driving field approximation.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 10, 1993•0 citations

Lasing without inversion in dressed-state lasers

Ning Lü, P. R. Berman

We study the operational properties of the lasing field generated from strongly driven two-level atoms in a ring cavity by including the field saturation to all orders. Lasing without inversion between bare atomic states can occur for both off-resonant-- and resonant-pump fields. In the case of an off-resonant--pump field, lasing occurs at one of the Rabi sidebands, for which there exists population inversion between the relevant dressed-atom--field states. In the case of a resonant-pump field, lasing can occur near either of two Rabi sidebands, for which there is no population inversion between the dressed states; here the gain is due to the atomic coherence between the dressed states. While the operation of the off-resonantly--pumped dressed-state laser is similar to that of an ordinary laser, the operation of the resonantly pumped dressed-state laser exhibits some interesting features, such as (1) mode pushing and (2) larger laser intensity coming from smaller linear gain as the detuning is changed. In order to show such features, the calculations have to go beyond the secular approximation.

Physical Review A•Nov 1, 1991•27 citations

Time-dependent dressed-states analysis of lasing without population inversion in a three-level ladder scheme

Doron Braunstein, R. Shuker

A dressed-state study of lasing without population inversion from a three-level atom interacting with a bichromatic laser field in the ladder configuration is being formulated. The system is allowed to be dressed by both laser-field photons (double dressing). The temporal behavior of the system under consideration is being explored numerically. Although the use of dressed-basis density matrix equations introduces major complexity into the equations, this procedure has crucial importance to the understanding of the atomic spectrum and the underlying physics of the processes involved. The system is found to possess a gain without population inversion, as well as a regular gain with inversion for various transitions, both in the transient and steady-state regimes. Enhancement of the refractive index accompanied by vanishingly small absorption was also found. The frequency response of various transitions is explored via numerical Fourier analysis. Some transitions are found to exhibit a dispersion-like line shape, clear evidence of a quantum-coherent interference effect. The spectrum consists of two distinct quintets centered about the coupling and probe-laser frequencies. The spectral features consisting of each quintet are located symmetrically (at resonance conditions only) around the line center at positions shifted from the center by the generalized Rabi and double Rabi frequencies.

Laser Physics•Mar 1, 2008•4 citations

Strong-field index enhancement via incoherent excitation

Xiangming Hu, Ling-bo Kong, Jun Xu

We show that it is possible, in principle, to employ an incoherent field as a control field to achieve maximal atomic coherence for a probe field, which characterizes ultralarge index of refraction and vanishing absorption. For this purpose we consider a three-level V system in which there are two dipole transitions, of which one is weak and the other is strong. The strong probe field is applied to the weak transition and the incoherent field drives the strong transition. For such an arrangement, selective dressed-population trapping, which corresponds to maximal atomic coherence, is established by relying on the incoherent field and the spontaneous relaxation to transfer population from one dressed state to the other. This scheme as an extreme example explains that strong-field index enhancement based on selective dressed-population trapping is resistant to the control field fluctuations.

Journal of Physics B Atomic Molecular and Optical Physics•Oct 24, 2002•1 citation
Exemplifying the three-level systems in the V configuration, we investigate the role of selective excitation of dressed populations in lasing without inversion. Incoherent driving field transfers population from either of the dressed states to excited state when the level spacing between dressed states produced by the coherent field is much larger than the spectral width of the incoherent driving field. With atomic decay pathways，unidirectional channel of population transfer is formed and selective excitation of dressed populations is established. Employing selective excitation of dressed populations，three severe limits are relaxed. First，it is no longer required that the decay rate of the low-frequency driving transition is larger than that of high-frequency laser transition. Second，the threshold for incoherent driving rate is remarkably lowered. Third，linear gain of the laser without inversion is no longer inversely proportional to the coherent driving field intensity, and the gain is significantly enhanced.
We show that continuous-wave, two colour excitation of three-level atoms opens new channels of irreversible population transfer between atomic levels. This process, which we describe as dynamically induced irreversibility, leads to unanticipated phenomena including the inversion of atomic transitions whose upper atomic level has no conventional source of irreversible population pumping. We also study the effect of excitation-field bandwidth on the gain exhibited by driven, three-level, V-type atomic systems. Gain, which may or may not be inversionless in the atomic-state basis, is produced through strong monochromatic driving of one atomic transition and weaker pumping of a coupled transition. It is found that monochromatic pumping frequently yields greater optical gain than incoherent (wide bandwidth) pumping. This is particularly true when system gain can be attributed to hidden inversions among the eigenstates (semi-classical dressed states) of the coupled atom+driving field quantum system. Last, we report the observation of continuous-wave lasing in a strongly driven barium cascade system and interpret its properties in terms of the models presented.
A dressed-state study of lasing without population inversion from a three-level atom interacting with a bi-chromatic laser field in the ladder configuration is presented. In our model we allow the atom to be dressed by both of the coupling and probe fields. The system under consideration is explored both analytically and numerically within the steady-state regime. A parameter study is performed in which we explore the influence of the change of control parameters (Rabi frequencies and incoherent pump rates, etc) on the system behaviour. The parameter study also applies to situations where both coherent fields have comparable intensities. Expressions for steady-state populations and coherences are derived, from which the constraints on the system control parameters allowing gain or absorption of various types, are calculated. The system is demonstrated to possess gain without inversion (GWI), as well as regular gain with inversion, for the appropriate choice of system control parameters. Inversion without lasing (IWL) is also found. The dressed-state approach offers a different insight into the system dynamics in which Rabi oscillations and spectral features appear natural. We believe that the dressed-state approach provides a more adequate description of the system dynamics than that provided by the bare state basis.
We study the operational properties of the lasing field generated from strongly driven two-level atoms in a ring cavity by including the field saturation to all orders. Lasing without inversion between bare atomic states can occur for both off-resonant-- and resonant-pump fields. In the case of an off-resonant--pump field, lasing occurs at one of the Rabi sidebands, for which there exists population inversion between the relevant dressed-atom--field states. In the case of a resonant-pump field, lasing can occur near either of two Rabi sidebands, for which there is no population inversion between the dressed states; here the gain is due to the atomic coherence between the dressed states. While the operation of the off-resonantly--pumped dressed-state laser is similar to that of an ordinary laser, the operation of the resonantly pumped dressed-state laser exhibits some interesting features, such as (1) mode pushing and (2) larger laser intensity coming from smaller linear gain as the detuning is changed. In order to show such features, the calculations have to go beyond the secular approximation.
A dressed-state study of lasing without population inversion from a three-level atom interacting with a bichromatic laser field in the ladder configuration is being formulated. The system is allowed to be dressed by both laser-field photons (double dressing). The temporal behavior of the system under consideration is being explored numerically. Although the use of dressed-basis density matrix equations introduces major complexity into the equations, this procedure has crucial importance to the understanding of the atomic spectrum and the underlying physics of the processes involved. The system is found to possess a gain without population inversion, as well as a regular gain with inversion for various transitions, both in the transient and steady-state regimes. Enhancement of the refractive index accompanied by vanishingly small absorption was also found. The frequency response of various transitions is explored via numerical Fourier analysis. Some transitions are found to exhibit a dispersion-like line shape, clear evidence of a quantum-coherent interference effect. The spectrum consists of two distinct quintets centered about the coupling and probe-laser frequencies. The spectral features consisting of each quintet are located symmetrically (at resonance conditions only) around the line center at positions shifted from the center by the generalized Rabi and double Rabi frequencies.
We show that it is possible, in principle, to employ an incoherent field as a control field to achieve maximal atomic coherence for a probe field, which characterizes ultralarge index of refraction and vanishing absorption. For this purpose we consider a three-level V system in which there are two dipole transitions, of which one is weak and the other is strong. The strong probe field is applied to the weak transition and the incoherent field drives the strong transition. For such an arrangement, selective dressed-population trapping, which corresponds to maximal atomic coherence, is established by relying on the incoherent field and the spontaneous relaxation to transfer population from one dressed state to the other. This scheme as an extreme example explains that strong-field index enhancement based on selective dressed-population trapping is resistant to the control field fluctuations.