THEORETICAL INVESTIGATION OF PHENOMENA IN THE CLOSED RAMAN-DRIVEN 4-LEVEL SYMMETRICAL MODEL

We construct a solution to the linear complex absorption coefficient f or the closed Raman-driven four-level symmetrical model. We derive, fr om this solution, asymptotic expressions for the spectra around and aw ay from the two-photon resonance in the absence as well as in the pres ence of the Doppler broadening. They are used for the derivations of a nalytical conditions and the discussion of the physical origins of var ious phenomena that do not appear in the traditional two-level system.