  An inversionless gain of anti-Stokes radiation above the oscillation
threshold in an optically-dense far-from-degenerate double-Lambda
Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes
are illustrated with numerical simulations applied to sodium dimer vapor.
Optical switching from absorption to gain via transparency controlled by a
small variation of the medium and of the driving radiation parameters which are
at a level less than one photon per molecule is shown. Related video/audio
clips see in: A.K. Popov, S.A. Myslivets, and T.F. George, Optics Express Vol.
7, No 3, 148 (2000)(http://epubs.osa.org/oearchive/source/22947.htm) or
download: http://kirensky.krasn.ru/popov/opa/opa.htm
