Induced pump absorption, lasing threshold, and efficiency of organic compound lasers

Induced pump absorption was measured at the wavelength of 353 nm (the third harmonic of a neodymium laser), and the singlet and triplet excited levels in which the pump absorption mainly occurred were determined for solutions of a number of active molecules (POPOP, BBO, α-NPO, rhodamine 6G). The efficiency and lasing threshold (in the longitudinal arrangement) were measured for the same compounds. Calculations showed that allowance for induced absorption at the pump wavelength in certain compounds (POPOP, BBO, uranine) completely explains their lasing characteristics, while for others (perylene, rhodamine 6G) the explanation is only partial.