Diffraction efficiency in reflection holograms stored in photopolymers doped with metallic nanoparticles

The storing of volume holographic reflection gratings in eco-friendly photopolymers represents a challenge at present since they can be used in many important applications such as sensors and holographic optical elements. The main goal of this work was record unslanted volume holographic reflection gratings in a low toxicity poly(vinyl alcohol)-based photopolymer called Biophotopol. The composition of the photopolymer layers was optimized in a first stage. Subsequently, the holographic material was doped with high refractive index Platinum nanoparticles in order to increase the refractive index modulation during the recording stage. Results obtained were analysed as a function of the Platinum nanoparticles concentration used. Maximum diffraction efficiencies of 28% was reached when a concentration of 0.58 nanomoles of Platinum nanoparticles per gram of poly(vinyl alcohol) was employed.