Clarification on Laser Dye Concentrations

In Physics Update for the February 2002 issue of Physics Today ( Physics Today 0031-9228 55 2 2002 9  https://doi.org/10.1063/1.2408449 page 9 ), one item states, “In most dye lasers, the dye concentration cannot go above a millimole/liter without quenching the fluorescence.” Subsequently, lasing at a concentration of 9 mmol/L is highlighted as an achievement by the authors. ¹ It should be noted that dye concentrations of several mmol/L, sometimes up to 10 mmol/L, have been known for a long time in the field of laser-pumped dye lasers. ²