Soviet Journal of Quantum Electronics

Amplification of light in a linear chain of freely expanding plasma spheres

А. В. Боровский, Владлен Васильевич Коробкин, V. B. Mokrov, Ch. K. Mukhtarov

Published Dec 31, 1989• 2 citations

Abstract

An analysis is made of the amplification of light in a linear chain of freely expanding plasma spheres. It is shown that an optimal distribution of these spheres on a straight line ensures more effective amplification of light due to transitions in hydrogen-like ions in the case of recombination pumping of such a system than the amplification that can be expected of a freely expanding plasma filament.

DOI: 10.1070/qe1989v019n12abeh009823

Related papers

Laser cooling of an expanding ultracold plasma

N. Ya. Shaparev, Nikolai Shaparev

We analyze the resonance absorption spectrum of ions in an expanding ultracold spherical plasma. It is shown that the spectrum width is controlled by the highest expansion velocity at the sphere boundary. As the expansion velocity grows, the initial optical thickness of the medium decreases and the medium becomes transparent. We suggest a broadband laser radiation in the red absorption spectrum of ions be used to decelerate ions in an expanding plasma in order to achieve crystallization.

International Conference on Optoelectronics and MicroelectronicsJul 1, 20150 citations

Gain effects on microsphere resonant emission structures

Vitaly V. Datsyuk

The effects of light absorption and amplification on the transition rates of the electric-dipole emission of atoms or molecules embedded in micrometer-sized dielectric spheres are investigated in the framework of classical electrodynamics. The expression for the form factor of a resonant emission line is derived. Its dependence on the imaginary part of the light’s refractive index is investigated. It is discovered that the active sphere does not act as an optical resonator if light amplification is strong.

Journal of the Optical Society of America BJan 1, 200210 citations

Resonator-free amplification of spontaneous radiation under recombination pumping conditions

A. L. Belov, F. V. Bunkin, Sergei I Yakovlenko

A one-dimensional radiative transfer model is used in a study of the amplification of spontaneous radiation as a result of a population-inverted ionic transition pumped by recombination. The problem of such transfer is solved analytically in the steady-state case and it is shown that the intensities of the radiation emitted in both directions are the same irrespective of the distribution of the unsaturated gain over the length of the active medium. Numerical calculations are reported of the stage of establishment of light fluxes. It is shown that during this transient stage a nonlinear interaction between opposite light fluxes is responsible for nonmonotonic behavior of the output radiation intensity. The problem of amplification in a traveling pump wave is treated analytically.

Soviet Journal of Quantum ElectronicsJan 31, 19870 citations

Stimulated emission due to Doppler-free transitions in optically pumped lasers

A. K. Popov, Vladimir M. Shalaev

An analysis is made of conditions for achieving amplification due to transitions whose Doppler broadening is eliminated (under optical pumping) by light shifts which depend on the atomic velocity. An investigation is made of the spectral characteristics of this amplification process and of the features of lasing due to these transitions. The advantages of lasing due to this type of pumping are shown and possibilities for achieving unidirectional lasing in ring resonators are indicated.

Soviet Journal of Quantum ElectronicsMar 31, 19822 citations

Change in the shape of frequency-modulated light pulses during amplification

E G Lariontsev, V. N. Serkin

An analysis is made of the propagation of a frequency-modulated light pulse in a linearly amplifying medium with an inhomogeneously broadened gain profile. It is shown that a pulse can be compressed considerably during amplification. Conditions are established under which strong distortions of the pulse shape may result in its splitting. An analysis is made of the influence of the phase self-modulation of radiation on the shape of ultrashort light pulses in oscillators and amplifiers.

Soviet Journal of Quantum ElectronicsJun 30, 19761 citation

Flashlamp Pumped Dye Amplifiers

Thomas Efthimiopoulos

The major purpose of the work described in this thesis is the experimental and theoretical study of the amplification of the spontaneous emission in dye amplifiers. This work falls into three distinct sections: (a) the study of high-current short-pulse flashtubes operating in (or near) the ablation regime; (b) the study of the amplification process of the spontaneous emission in a homogeneously broadened medium, such as a dye material, in the thin cell case, where there is no variation of the pumping across the cell; and, (c) the study of the amplification of the spontaneous emission in the thick cell case, where gain and index of refraction inhomogeneities exist across the cell thickness. In each case, we have developed theoretical models and compared their predictions with the experimental results. In particular, for the ablation-type flashlamps, it is shown that their behaviour is well represented by an analysis in which the discharge plasma is supposed to radiate as a blackbody at the temperature of the plasma. This model accounts for the fact that the light output from a flashlamp saturates whereas the current does not, provides a more accurate value for the plasma resistivity as a function of temperatures and gives a useful design criterion for determining the physical dimensions of an ablation-type flashlamp. With respect to the amplification of the spontaneous emission in a thin cell, it is mainly shown that (i) the spontaneous emission propagating along the gain medium is subject to narrowing along with shifting of its peak wavelength; (ii) even at moderate pumping the population of the excited singlet state, which determines the gain of the system, is non-uniform along the cell; (iii) it is possible to calculate the unsaturated gain by calculating the intensity of a particular wave-length and its spectral narrowing both as a function of the exciation and compare them with the same quantities measured experimentally; (iv) it is also possible to develop a semianalytic system independent method to measure the gain approximately. The theory developed to account for the propagation of the amplified spontaneous emission (ASE) has been partly extended to cover the case of the propagation and spectral narrowing of the ASE in a thick cell, where non-uniformities of the index of refraction and the gain are important along with the diffraction losses. In this particular case, it is shown that a model, which assumes an index step variation across the cell, and solves the Maxwell's equation for the field propagation along the cell, can account for the spatial distribution of the field across the cell and its manifestation at the far field. Most of the predictions of the model are verified experimentally. In particular, it is shown that (i) in a thick cell, part of the ASE propagates outside the gain medium, because of the lensing effect caused by heating of the lasing material; (ii) the field across the cell can exhibit stable spatial modes, which can produce a far field far from the amplifying cell axis; (iii) it is possible to improve the spectral narrowing of the ASE since saturation can be delayed to higher pumping than before and most of the narrowing occurs below saturation of the gain; (iv) it is also possible to measure the temperature and the index of refraction change due to heating by measuring the far field angle, and estimate the diffraction losses involved in the propagation of the ASE in a thick cell. Finally, a number of suggestions on further research are proposed.

Oct 1, 19780 citations