Abstract
We report on the performance of a hollow-cathode discharge continuous wave He-Cd+ laser module, which is capable of simultaneously delivering 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 characteristics for single- and multi-line operation and the power interaction between the laser lines are presented. The results show that the most efficient simultaneous laser oscillations at the red, green and blue 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 strongest. We find strong power interaction between the green and red lines, showing experimentally that, apart from the already known increase in the He-Cd+ laser output power in the green owing to the radiative cascade transitions in the red, also the red lines gain in their output power under simultaneous operation with the green lines, which de-populate 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 build-up of the population inversion between the upper and lower levels of the red transitions.
Published Version
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