arXiv subjects

A. K. Popov

Publications and source records attributed to A. K. Popov.

24 records · Page 2Linked to original sources

arXiv2000

Atomic coherence and interference phenomena in resonant nonlinear optical interactions

Interference effects in quantum transitions, giving rise to amplification without inversion, optical transparency and to enhancements in nonlinear optical frequency conversions are considered. Review of the relevant early theoretical and experimental results is given. The role of relaxation processes, spontaneous cascade of polarizations, local field effects, Doppler-broadening, as well as specific features of the interference in the spectral continuum are discussed.

quant-ph↗

arXiv2000

Inversionless amplification and laser-induced transparency at the discrete transitions and the transitions to continuum

The effects of coherence of quantum transitions and the interference of resonant nonlinear optical processes on the spectra of absorption, amplification, and nonlinear-optical generation are considered. The most favorable conditions are discussed for the inversionless amplification, resonant refraction in the absence of absorption and for resonant enhancement of nonlinear-optical generation at the discrete transitions and the transitions to continuum.

quant-ph↗

arXiv2000

Nonlinear interference effects in emission, absorption, and generation spectra

Nonlinear effects in emission and absorption spectra of gaseous systems are considered. It is shown that level splitting can be detected spectroscopically even if it is below the Doppler width. Conditions for distinguishing interference effects from those due to nonequilibrium velocity distribution are determined. In the case of large Doppler broadening the correction for atomic motion is equivalent to the substitution of an "effective immobile atom" for the moving atom ensemble. The spectral manifestation of nonlinear effects is analyzed in detail. The influence of nonlinear interference effects on the generation characteristics in the presence of external field is investigated.

quant-ph↗

arXiv2000

Resonant radiative processes

The frequency correlation properties of the radiation from an atom in a strong field in resonance with neighboring transitions are considered. It is shown that the difference in frequency correlation in two-photon and stepwise processes decreases with increase of the external field. The spectral compositions of the Doppler-broadened resonance scattering and fluorescence are analyzed. It is shown that in these cases the Doppler line width is anisotropic.

quant-ph↗

arXiv2000

Effect of resonance radiative processes on the amplification factor

Optimal conditions to acomplish amplification without inversion in three-level schemes based on quantum nonlinear interference effects are analyzed. Specific features of relaxation processes in optical transitions seting these conditions apart from those in microwave schemes are outlined. Numerical evaluations related to neon 2s_2-2p_4-3s_2 transitions are given.

quant-ph↗

arXiv2000

Shape of the amplification line corresponding to an adjacent transition in a strong field

An analysis is made of the effect of a strong field on the shape of the amplification spectral line for mono-velocity V-type three-level atoms. There are three strong-field contributions, differing in their dependence on the set of relaxation parameters of the medium and on the differences among the populations corresponding to the Raman transitions. An analysis is made of the conditions under which each of the contributions is predominant. The change in the line shape by an intensified external field is found for each case. Neon atoms are discussed as an example. The results are compared with those corresponding to a Maxwellian velocity distribution.

quant-ph↗