Functionalized tetrafluorenylethylene-type chromophores: Synthesis, two-photon absorption and effective optical power-limiting properties in the visible-to-near IR region

A series of novel multipolar fluorophores based on tetra-substituted olefinic scaffold using functionalized fluorenyl and indenofluorenyl units as the aryl substituents has been synthesized and investigated for their two-photon-related properties in the femtosecond and nanosecond time domains. When probed by the femtosecond pulses, these chromophores are found to possess appreciable intrinsic two-photon absorptivities with their local maxima very close to the short-wavelength end of the dynamic tuning range of a Ti: sapphire laser. While under the irradiation of nanosecond pulses, these dye molecules exhibit promising nonlinear optical-power-attenuation properties across the visible-to-near infrared region. Combining with their medium-high fluorescence quantum efficiencies, such archetype represents a new class of structures that could be utilized as effective broadband optical power-limiters and frequency up-converters especially with great potentiality to work in the visible regime.