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.