Optical properties of organic-chromophore doped sol–gel coatings: poling-induced birefringence

Forming and measuring the departure from centrosymmetry in the structure of materials are critical for optical devices based on second-order effects. In this work, we consider guest–host systems consisting of a corona-poled, sol–gel, porous silicate film matrix doped with disperse red 1 (DR1) or p-nitroaniline (PNA) chromophores, and application of the in situ poling optical polarimetry (POP) method. Refractive indices and physical thicknesses are consistently determined by ex situ null ellipsometry, atomic force microscopy and polarimetric measurements. From this procedure and associated modeling, at largest POP sensitivity with s-polarized light in this case, we find that the resulting poling-induced birefringence achieved at its peak (0.45±0.07, at 670 nm) has a magnitude comparable to the film refractive indices (nF=1.419±0.005, before poling).