Third order nonlinear optical susceptibility of fluorescein-containing polymers determined by electro-absorption spectroscopy

► Two new polymers with high fluorescein concentrations were prepared. ► Their χ(3) were found to be in the order of 10−12 esu by electroabsorption. ► The χ(3) values by EAS are less by 2 order than those found by Z-scan and DFWM. ► Dye concentration significantly influence the χ(3) of materials.