Two-stage holographic photopolymers with high dynamic range

Two-stage holographic photopolymers capable of high refractive index modulation (Δn) on the order of 10–2 enable the fabrication of a myriad of optical elements. While there are commercial products available that meet these requirements, researchers often want the flexibility to customize both the form factor of the samples as well as the mechanical and chemical properties for their specific applications. We present a novel high refractive index acrylate writing monomer in a low refractive index urethane matrix as a model material for customization for optical applications. We discuss the achievable Δn of this custom monomer, 1,3-bis(phenylthio)-2-propyl acrylate (BPTPA) in the urethane matrix as a function of solubility, along with a comparison to a commercially available high refractive index monomer, 2,4,6- tribromophenyl acrylate. Formulations with BPTPA exhibit a peak-to-mean Δn ≈ 0.029 in transmission holograms without any obvious deficiencies in transparency, color, or scatter. This writing monomer and the synthetic processes present a promising platform for the fabrication of high-performance holographic photopolymers for a wide range of research applications.