QUASI-CW LASER ACTION THROUGH PULSED LASER PUMPING OF METASTABLE STATES IN DENSE VAPORS

A new scheme is proposed for exciting laser action employing resonant pumping of metastable states together with collisional energy transfer in hot and dense vapors. The specific case of Ca is presented here as an example. Large population inversions and gain on Ca 4s5s 3S1-4s4p 3P2,1,0 transitions at 6162.17 angstrom, 6122.22 angstrom and 6102.72 angstrom are reported. A unique feature here is that these population inversions are maintained over long periods of time after the exciting laser pulse, extending from 90-mu-s in the case of J = 0 state up to 250-mu-s in the case of J = 1 state. This offers an unusual possibility of making quasi-continuous laser sources from short pulse excitation.