Double-resonance and relaxation in a three-level system

L. A. Budkin, M. N. Penenkov, A. I. Pikhtelev

N. M. Lawandy

It is well known that the presence of a real atomic level which is nearly resonant with the pump field can greatly enhance the Raman emission cross section. In order to accurately calculate the Raman gain in systems where resonance enhancement plays a dominant role, expressions for the pump and signal susceptibilities must be derived. These expressions should be valid for arbitrary field strengths in order to allow for pump and signal saturation. In addition, the theory should allow for arbitrary longitudinal and transverse relaxation rates. This latter point is extremely vital for three level atomic systems such as the alkali earth metals since they do not have population reservoirs and can have widely varying spontaneous lifetimes on the three pertinent transitions. Moreover, the dephasing rates are strong functions of electron states and are therefore also different for the three coupled pairs of levels. These considerations are not as important when molecular systems are concerned since the large reservoir of rotational states serve to produce essentially equal longitudinal recovery rates for the population of the three levels. The three level system with three arbitrary longitudinal and transverse relaxation rates was solved. There is no need for setting either pair of rates equal and the expressions are valid for arbitrarily strong fields.

Munir Hasan Nayfeh, Ali Hasan Nayfeh

An analytical semiclassical expression is derived for the two-photon transition in a three-level system under the influence of two pulsed fields. We study the Autler-Townes doublet as a function of the time dependence of the field amplitudes and the relaxation widths of the levels. The time variations of the field amplitudes cause shifts in the doublet and modify the radiative decay widths of the levels. The validity of the treatment extends into the intermediate-intensity regime.

Ya. D. Klubis

J. Łuczka

Yu. A. Vdovin, V. M. Ermachenko, I P Konovalov +1 more

An analysis is made of the method for measuring the relaxation constants of a common level in resonance interaction of two opposite traveling waves with a three-level system, based on the modulation of the polarization of one of the waves. The results for the 3 s 2 level of neon, obtained experimentally for the 3 s 2 –3 p 2 and 3 s 2 –3 p 4 transitions, were in agreement with the values obtained earlier by other methods.