INTERACTION OF LASER-RADIATION WITH DOPPLER-BROADENED MEDIA IN COHERENT POPULATION TRAPPING REGIME - LAW OF LIGHT-PROPAGATION

The influence of thermal motion of atoms on laser light propagation th rough a coherent optically dense medium is investigated theoretically. If the laser light intensity does not exceed a certain threshold valu e (intensity of coherent population trapping switching on multiplied b y square of ratio of Doppler broadening to natural linewidth), the pro pagation law is strongly influenced by atomic motion: the laser intens ity decreases neither exponentially, nor linearily, but as second-orde r polynomial of the optical depth. Above this threshold the propagatio n law is linear.