Optically dense active media for solid-state lasers

The author has examined the potential of optically dense active media in solid-state lasers using, as an example, YSGG:Cr³⁺,Nd³⁺ active elements with a chromium concentration=1×10²⁰ cm^-3, and a neodymium concentration=3×10²⁰ cm^-3. One element had a square cross section (dimensions were 0.5×0.5×8 cm³ ) and the other was cylindrical (0.4-cm-diameter, 7-cm-long). The optical density and geometrical size were chosen so that the limiting pump regime would be encountered at a relatively low average power. The solid-state laser pump cavity was cylindrical. This made it possible to compare the square (zig-zag) and cylindrical active elements under identical conditions. The results are presented. An effect, called the static STON-effect (smoothing of thermo-optical inhomogeneities), is discussed