Induced absorption of pump radiation in solutions of organic dyes used as active media in ultraviolet lasers

The dependence of the quantum efficiency of fluorescence on the intensity of pumping with the fourth harmonic of neodymium laser radiation (265 nm) was determined for solutions of several organic compounds (paraterphenyl, PPD, α–NPD, α–NPO, etc.). The reduction in the quantum efficiency with rising pump intensity was attributed to an induced absorption at the pump wavelength. A qualitative comparison was made of the intensity of the induced absorption and laser characteristics of the investigated compounds.