Experimental Demonstration of Laser Oscillation without Population Inversion via Quantum Interference in Rb

Laser oscillation without population inversion is demonstrated experimentally in a V-type atomic configuration within the $D_1\mathrm{and}{D}_2$ lines of Rb vapor. It is shown that the effect is due to the atomic interference. The experimental results, as first predicted by careful theoretical analysis, are in a good agreement with detailed calculations.