Nonresonance multipulse inversion and energy absorption by an atom

S. A. Moiseev

A. M. Bonch-Bruevich, V. A. Khodovoǐ, N. A. Chigir

Masataka Mizushima

When a radiation field of frequency ω1 interacts with atoms, etch of which has a transition frequency ω b a =(E b -E a )/\hbar, with ω1-ω b a =Δ≠0, nonresonant absorption can take place with probability P 1 inversely proportional to Δ 2 (a pressure broadening). When another radiation field of frequency ω2, such that ω1+ω2=2 ω b a , interacts simultaneously with the gas a resonant two-photon absorption can take place in addition to the nonresonant absorption. The probability of this two-photon absorption process, P 2, is found to be inversely proportional to Δ 4. If \varOmega=| <n-1|E|n ><b| µ|a >| is the Rabi frequency of the transition, it is found that P 2/(P 1(Δ)+P 1(-Δ)) is given by 12{ \varOmega(-Δ)\varOmega(-Δ)}2/{Δ 2(\varOmega(-Δ)2+\varOmega(Δ)2)}.

Roman V. Markov, Alexander Ivanovich Plekhanov, Anatolii M. Shalagin

Lasing at the resonance transitions ( D 1− and D 2− lines) of sodium was observed in the superradiance mode upon nonresonance optical excitation in the presence of a buffer gas. The dependences of the lasing intensity on the exciting radiation intensity and on the detuning of its frequency from the frequencies of resonance transitions were studied. It is found that, under specific conditions of the experiment (high pressure of a buffer gas and a rather high radiation intensity), in the case of a large positive detuning of the exciting radiation frequency from the resonance (“working”) transition frequency, the population inversion is produced at the “ working” transition, which results in lasing.

E. B. Treacy

Fedor F. Baryshnikov, Valerii S. Lisitsa, S. A. Sukhin