The dispersion of the refractive index of poly(9,9-dioctylfluorene) has bee
n determined in the spectral region immediately below its absorption edge.
Both the Cauchy and Sellmeier models for the functional form of the refract
ive index dispersion were used to analyse transmittance interference fringe
s. The refractive index increases from 1.614 at 900 nm to 1.781 at 450 nm.