Distribution of the gain in an He–Ne laser over the cross section of the discharge tube with a transverse microwave discharge

An experimental investigation was made of the unsaturated gain and its distribution over the cross section of the active medium of an He–Ne laser with a transverse microwave discharge at high pressures (in the range corresponding to single-frequency lasing) and over a wide range of ratios of the He–Ne mixture components and pump powers. It was found that at mixture pressures of 2–11 Torr, the gain for a transverse microwave discharge was 1.5–2 times higher than that for a dc discharge. The distribution of the gain over the cross section of the microwave discharge was Gaussian, planar, or had a dip at the center of the discharge tube, its form depending on the pressure and microwave pump power.