Linewidth measurement and population calculation of a He‐Cd laser

摘要

The radiative linewidth and pressure broadening of Cdii 4416‐Å transition have been found to be 56±6 MHz and 8.7±2.9 MHz/Torr from the Lamb dip in a single‐mode He‐Cd laser. The population densities of the He metastables and Cd upper laser levels and the small‐signal gains of the Cdii 4416‐ and 3250‐Å transitions are calculated under the various conditoins of a positive column He‐Cd laser through the rate diagram involving most of the important collisional and radiative processes. The calculated results are in trhe fair agreement with the experiments reported by other authors. The saturation of the laser output with an increasing discharge current can be explained by the rapid increase of stepwise excitation from the He metastable and the comparatively slow decrease of the electron temperature. Based on the measured linewidth and$rate diagram, the possibility of high‐power pulsed He‐Cd laser in a high‐pressure region is proposed.