Self-selection of longitudinal modes at the 632.8 nm line in a helium-neon laser in a copper hollow cathode

The paper reports single-mode lasing in an He-Ne laser in a copper hollow cathode at a wavelength of 632.8 nm; optimum discharge characteristics were achieved without the use of selecting elements in the cavity. Lasing conditions are considered in relation to increases in the mixture pressure and changes in the concentrations of the components. The single-mode intensity is shown to be the maximum intensity that the laser can attain.