Excited singlet-state absorption in dyes and their effect on dye lasers

The performance of dye lasers with excited singlet-state absorption (ESA) at the pump and the lasing wavelengths is analyzed for short pulse pumped systems in the medium range of pumping intensities. Analytical and numerical solutions are presented for a wide range of the variable parameters such as ESA cross sections, the cavity reflectivity, and the pumping intensity. An experiment is described for measuring ESA cross sections in the pumping as well as the lasing regions, and the results for rhodamine 6G and rhodamine B are given, showing that due to ESA, the effective gain of the laser will be much lower than that expected from previously published data on the stimulated emission cross sections.