HIGHLY-ACTIVE 2-PHOTON DYES - DESIGN, SYNTHESIS, AND CHARACTERIZATIONTOWARD APPLICATION

A series of compounds with systematically varied molecular structures which exhibit very large effective two-photon cross sections has been synthesized and characterized in solution using a nonlinear transmissi on technique. The general structure of these compounds can be categori zed into two basic structural families: acceptor/donor/donor/acceptor and donor/ bridge/acceptor. This study attempts to determine certain m olecular structure/effective two-photon absorption relationships by ca reful characterization and as a function of systematically varied chan ges in the organic structure of the dye molecules. Such information ca n be useful in the design of more efficient two-photon dyes for imagin g and power-limiting applications. The results of the study indicate t hat with the incorporation of certain combinations of structural eleme nts, dyes can be synthesized which have greatly increased effective cr oss sections as high as 152.5 x 10(-48) cm(4) s/photon molecule in ben zene solution at 800 nm using 8 ns pulses. This value is orders of mag nitude higher than commercially available organic dyes measured at the same wavelength. Although the process is thought to involve a combina tion of two-photon absorption and excited state absorption phenomena, the information gathered from these new families of dyes has provided an important first step in producing improved materials for use in man y different two-photon technology application.