Radiation trapping effects in Cu, Mn, Ca, Sr, and Ba vapor lasers

The radiation trapping effect was investigated in Cu, Mn, Ca, Sr, and Ba vapor lasers with a cylinder discharge tube. Compared with the negligible impact induced by the gas temperature, the lower level population density of radiation trapping was found to dominate the effective spontaneous emission probability. Meanwhile a tube radius scanning from 1 mm to 20 mm revealed that the threshold parameters of radiation trapping effect were affected little by the tube radius when the radius changed from 20 mm to 5 mm, but they varied visibly when the tube radius decreased from 5 mm to 1 mm. Furthermore, the threshold temperature and the lower level population density of the radiation trapping effect in six resonant lines in Cu, Mn, Ca, Sr and Ba vapor lasers were calculated, and the threshold temperature was found to be close to the initial lasing temperature of the corresponding resonance level to metastable level transition.