THE PERFORMANCE OF THE HOLLOW-CATHODE DISCHARGE CONTINUOUS-WAVE MULTICOLOR HE-CD+ LASER

We report on the performance of a hollow-cathode discharge continuous wave He-Cd+ laser module, which is capable of simultaneously deliverin g stable, milliwatt output power at the three primary spectral lines: blue (lambda = 441.6 nm), green (lambda = 533.7 and 537.8 nm), and red (lambda = 635.5 and 636.0 nm). In particular, the laser output charac teristics for single- and multi-line operation and the power interacti on between the laser lines are presented. The results show that the mo st efficient simultaneous laser oscillations at the red, green and blu e lines occur for the He pressure (8 mbar at an inner diameter of the hollow cathode of 4 mm) at which the hollow-cathode effect is stronges t. We find strong power interaction between the green and red lines, s howing experimentally that, apart from the already known increase in t he He-Cd+ laser output power in the green owing to the radiative casca de transitions in the red, also the red lines gain in their output pow er under simultaneous operation with the green lines, which de-populat e the lower laser levels of the red transitions. Under some conditions the de-population of the lower laser levels of the red transitions by the green lines' oscillations can be the dominant mechanism for the b uild-up of the population inversion between the upper and lower levels of the red transitions.