Measurements of the upper and lower level lifetime in He-Se lasers

Abstract

The lifetimes τ 2 and τ 1 of the upper and lower levels of the 5227 Å (5p 4D 7 2 →5s 4P 5/2) laser transition in He-Se were measured. The obtained values are: τ 2=(18.5±1.85) × 10 -9 sec; τ 1=(2±0.4) × 10 -9 sec. The value of τ 2 was determined by measuring the time constant of the transient in the fluorescent emission consecutive to a sudden interruption of the laser oscillation inside the cavity. The value of τ 1 was determined by measuring the change induced by one laser transition on the unsaturated gain of another laser transition sharing the same lower level. Finally the “radiation trapping” factor is evaluated, thus ruling out the possibility that radiation trapping might be responsible for saturation in the laser output versus discharge current.