Heat resistant polymer matrix containing acrylo-polyhedral silsesquioxane for erbium-doped waveguide amplifier applications

We report on the fabrication of fluorinated polymer film as host material for erbium ions (Er³⁺) with a goal of achieving sufficient thermal stability, optical clarity and a chemical resistance to withstand typical fabrication processing. Precursor solutions were prepared using 2,2,3,3,4,4,5,5-octafluoropentyl acrylate as a fluoromonomer, tetrahydrofurfuryl acrylate as a solubility enhancer, Ebecryl 220 as a cross-linking agent, acrylo-polyhedral oligomeric silsesquioxane as a heat-resistance improver and Darocur 4265 as a radical photoinitiator with various weight ratios. Fluoropolymer films prepared from the precursor solution had excellent transmission properties (low transmission losses less than 2% over the visible and near-infrared regions) and high thermal decomposition temperatures (greater than 350 °C). Er³⁺-doped precursor solution was also prepared by adding of erbium(III) trifluoromethane sulfonate as an erbium source. The crosslinked, patterned and Er³⁺-doped fluoropolymer films were successfully fabricated using the Er³⁺-doped precursor solution by both micromolding in capillaries and soft-imprint lithography on glass substrates for Er³⁺-doped waveguide amplifier applications.