INVERSIONLESS LIGHT AMPLIFICATION IN SODIUM

Light amplification without population inversion in sodium vapor is re ported. The result of this work is the amplification of a weak probe b eam at a wavelength of 589.0 nm when the atoms are driven coherently b y a long pulse at 589.6 nm, and the amplification of a weak probe beam at 589.6 nm when the atoms are driven coherently at 589.0 nm. The pop ulation contributions in the upper and lower lasing levels are calcula ted through the absorption spectra.