High gain 4.3-4.5 µm optically pumped CO2laser

Three different isotopic species of CO
2
were excited by the output of a line-tunable pulsed HF laser providing about 1 mJ per pulse pump energy. Excited CO
2
gases then lased, in a mirrorless system, on six lines in the
4.3-4.5\mu
m range. Gains in excess of 2 cm
^-1
and quantum efficiencies close to 50 percent were measured. Two lines, 4.473 and 4.528 μm, were found to have less than 5 dB/km atmospheric attenuation.