Optogalvanic effect on a hollow cathode He—Cd+ laser

A hollow cathode He—Cd+ laser simultaneously emits three primary colors. Therefore, a white color laser beam is emitted from this laser. This paper describes the optogalvanic effect and the results of our measurements under the study of stabilization of the white light laser. In the measurement, the colors red, green or blue were monochromatically emitted and the change of the anode voltage was measured in accordance with laser optical power by turning the optical path in the resonator on and off. The optogalvanic signal was noticeable when the color red or blue was emitted. However, almost no effect was observed during emission of the color green. The optogalvanic signal during emission of the color blue depends not only on the optical intensity, but the beam diameter. This indicates that the optogalvanic signal during emission of the color blue is dependent on the change of the cathodic effect. On the other hand, the gain distribution of blue in the bore is presumed to reach the neighborhood of the cathode surface. During emission of red, the optogalvanic signal is proportional to the light intensity, regardless of the beam diameter. It is understood that the optogalvanic effect during red color emission is caused by the change of the He+ population which is distributed at the center of the bore and is the origin of the red color emission.