Upconverted lasing based on many-photon absorption: an all dynamic description

A theory is developed for the propagation through a nonlinear medium of strong pump and amplifiedspontaneous-emission pulses. The theory is based on a solution of the density matrix equations that aims at providing an adequate treatment of the nonlinear polarization of the material without addressing the Taylor expansion over the powers of intensity. The theory has been applied for modeling of three-photon absorption induced upconverted stimulated emission of organic molecules in solvents. Numerical results are presented for the organic chromophore 4-[N-(2-hydroxyethyl)-N-(methyl)amino phenyl]-4'-(6-hydroxyhexyl sulfonyl) stilbene dissolved in dimethyl sulfoxide. The results are in good agreement with available experimental results.