Reflection Holograms Stored In An Environment-Friendly Photopolymer

The recording 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 holographic optical elements and biosensors. In this sense, the aim of this work has been fabricated reflection gratings in the symmetrical experimental in "Biophotopol" and to study the dependence of diffraction efficiency on physical thickness, recording intensity and exposure energy. An increase in diffraction efficiency was observed when the photopolymer films were cured with a LED lamp to improve the stability of the reflection holograms. The maximums diffraction efficiencies around 30 % were obtained for reflection gratings with a spatial frequency of 4888 lines/mm. The index modulation and optical thickness were obtained by fitting procedure through Kogelnik's coupled wave theory. Experimental and theoretical results have been interpreted to modify the photopolymer formulation and exposure conditions in order to increase the diffraction efficiencies.