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Soviet Journal of Quantum Electronics

Four-wave stimulated emission in a resonantly absorbing gas with amplification in a feedback loop

I. M. Bel'Diugin, Anatoli P. Sukhorukov, В. Н. Титов, Vyacheslav A. Trofimov

Published Aug 1, 1991• 0 citations
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A numerical study is made of the dynamics of lasing in a resonantly absorbing gas within a system where amplification is provided by a feedback loop. The mechanism of self-limitation of the emitted pulse, associated with saturation of the transition, is identified. The possibility of optimization of the lasing process is considered.

Soviet Journal of Quantum Electronics•Aug 31, 1991•1 citation

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Lasers without inversion (LWI) in Space: A possible explanation for intense, narrow-band, emissions that dominate the visible and/or far-UV (FUV) spectra of certain astronomical objects

P. P. Sorokin, J. H. Glownia

The optical or far-UV (FUV) spectra of certain objects in Space are completely dominated by one or two spectrally narrow emission lines, strongly suggesting that laser action of some kind occurs in these objects. However, the electronic level structures of the atoms/ions producing these emissions preclude the possibility of maintaining population inversions on the electronic transitions involved. In lasers, gain is normally produced on an optical transition that is inverted, i.e. one that has more atoms maintained in the upper than in the lower state, so that stimulated emission can exceed stimulated absorption. However, as a result of discoveries made in quantum electronics over the past 30 years or so, one now knows that there are several ways to make stimulated emission occur on a transition that is not inverted, i.e. to realize a “laser without inversion (LWI)”. This requires first making the atoms non-absorbing at the lasing frequency, i.e. setting up a condition of “electromagnetically induced transparency (EIT)”. Some recently developed EIT techniques for three-level atoms are first reviewed. A simple model for a space LWI based upon a gas of two-level atoms is then proposed. In this model, transparency results from a form of EIT induced by the presence of an intense, monochromatic, continuous-wave, laser beam tuned to the frequency of the two-level-atom transition. Amplification of light at this same frequency occurs via resonant stimulated hyper-Raman scattering (SHRS) and four-wave mixing (FWM), with pumping energy provided by continuum starlight spectrally overlapping the two outer absorption sidebands (“Mollow bands”) induced by the presence of the beam at . Two specific examples of superintense line emission from Space are here considered. These are (a) the H(α) emission line appearing as a dominant singularity in certain reddened, early-type stars, and (b) the powerful O VI (1032 Å, 1038 Å) emission doublet that dominates the FUV emission spectra of symbiotic stars such as RR Tel.

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Amplification in a three-level gas excited by two unidirectional waves

V. A. Efremov, Stanislav F. Dyubko

Radiophysics and Quantum Electronics•Jul 1, 1981•0 citations

Stimulated emission of gamma-radiation: A proposed experiment

Gilbert R. Hoy

The purpose of this paper is to describe a method for observing stimulated emission of gamma radiation. Stimulated emission of gamma radiation has never been observed. Stimulated emission of gamma radiation will be essential for developing gamma-ray lasers. The method uses the ‘π phase-shift induced transparency’ of gamma radiation, previously called the ‘gamma echo’. The gamma-echo technique is based on a modification of the time-differential Mössbauer spectroscopic method, i.e. the source is moved ‘instantaneously’ during the lifetime of the excited state. Then a resonant absorber becomes transparent to the resonant gamma radiation. There is a type of ‘self-stimulated’ emission in which the radiation ‘absorbed’, before the phase shift, is stimulated to emit after the phase shift. To observe stimulated emission of the resonant gamma radiation, one performs the same gamma-echo experiment except the resonant absorber is replaced by another source. This secondary source is chosen to be in resonance with the original source. Under these conditions there will be no stimulated emission, in the secondary source, before the π phase shift because the incident radiation is absorbed. However, after the phase shift, the secondary source becomes transparent to the incident radiation. If one uses a matched pair of Co57 sources and the secondary source is 2mCi, there will be about 3 nuclei in the secondary source, in the first excited state of Fe57, that are available to be stimulated during the 97.8ns lifetime of the primary source radiation.

Journal of Modern Optics•Nov 1, 2004•3 citations
The optical or far-UV (FUV) spectra of certain objects in Space are completely dominated by one or two spectrally narrow emission lines, strongly suggesting that laser action of some kind occurs in these objects. However, the electronic level structures of the atoms/ions producing these emissions preclude the possibility of maintaining population inversions on the electronic transitions involved. In lasers, gain is normally produced on an optical transition that is inverted, i.e. one that has more atoms maintained in the upper than in the lower state, so that stimulated emission can exceed stimulated absorption. However, as a result of discoveries made in quantum electronics over the past 30 years or so, one now knows that there are several ways to make stimulated emission occur on a transition that is not inverted, i.e. to realize a “laser without inversion (LWI)”. This requires first making the atoms non-absorbing at the lasing frequency, i.e. setting up a condition of “electromagnetically induced transparency (EIT)”. Some recently developed EIT techniques for three-level atoms are first reviewed. A simple model for a space LWI based upon a gas of two-level atoms is then proposed. In this model, transparency results from a form of EIT induced by the presence of an intense, monochromatic, continuous-wave, laser beam tuned to the frequency of the two-level-atom transition. Amplification of light at this same frequency occurs via resonant stimulated hyper-Raman scattering (SHRS) and four-wave mixing (FWM), with pumping energy provided by continuum starlight spectrally overlapping the two outer absorption sidebands (“Mollow bands”) induced by the presence of the beam at . Two specific examples of superintense line emission from Space are here considered. These are (a) the H(α) emission line appearing as a dominant singularity in certain reddened, early-type stars, and (b) the powerful O VI (1032 Å, 1038 Å) emission doublet that dominates the FUV emission spectra of symbiotic stars such as RR Tel.
The purpose of this paper is to describe a method for observing stimulated emission of gamma radiation. Stimulated emission of gamma radiation has never been observed. Stimulated emission of gamma radiation will be essential for developing gamma-ray lasers. The method uses the ‘π phase-shift induced transparency’ of gamma radiation, previously called the ‘gamma echo’. The gamma-echo technique is based on a modification of the time-differential Mössbauer spectroscopic method, i.e. the source is moved ‘instantaneously’ during the lifetime of the excited state. Then a resonant absorber becomes transparent to the resonant gamma radiation. There is a type of ‘self-stimulated’ emission in which the radiation ‘absorbed’, before the phase shift, is stimulated to emit after the phase shift. To observe stimulated emission of the resonant gamma radiation, one performs the same gamma-echo experiment except the resonant absorber is replaced by another source. This secondary source is chosen to be in resonance with the original source. Under these conditions there will be no stimulated emission, in the secondary source, before the π phase shift because the incident radiation is absorbed. However, after the phase shift, the secondary source becomes transparent to the incident radiation. If one uses a matched pair of Co57 sources and the secondary source is 2mCi, there will be about 3 nuclei in the secondary source, in the first excited state of Fe57, that are available to be stimulated during the 97.8ns lifetime of the primary source radiation.