Holographic Performance of Azo-Carbazole Dye-Doped UP Resin Films Using a Dyeing Process

For the practical application of dynamic holography using updatable dyed materials, optical transparency and an enlarged sample size with a uniform dispersion of the dye and no air bubbles are crucial. The holographic films were prepared by applying a dyeing method comprising application, curing, dyeing, and washing to an unsaturated polyester (UP) resin film. The unsaturated polyester (UP) resin film with high optical transparency was dyed with a 3-[(4-cyanophenyl)azo]-9H-carbazole-9-ethanol (CACzE) (azo-carbazole) dye via the surfactant, polyoxyethylene (5) docosyl ether, in an aqueous solution. The amount of dye uptake obtained via the dyeing process ranged from 0.49 to 6.75 wt.%. The dye concentration in the UP resin was proportional to the dye concentration in the aqueous solution and the immersion time. The UP resin film with 3.65 wt.% dye exhibited the optical diffraction property η₁ of 0.23% with a response time τ of 5.9 s and a decay time of 3.6 s. The spectroscopic evaluation of the UP resin film crosslinking reaction and the dyeing state in the UP resin film are discussed. Furthermore, as an example of its functionality, the dynamic holographic properties of the dye-doped UP resin film are discussed.