Holographic transmission gratings stored in a hydrogel matrix

Abstract

The development and optimization of photopolymers in which time-stable holographic grating can be stored when the material is immersed in an aqueous medium represent a challenge at present. In this sense, the aim of this work was the fabrication of unslanted transmission gratings in a hydrogel matrix which incorporates in its molecular structure a monomer (2-Methacryloyloxyethyl phosphorylcholine) that can act as an anti-fouling agent. The dependence of the diffraction efficiency on the thickness of the hydrogel matrix and the stability of the transmission gratings immersed in water were also studied. An increment in the diffraction efficiency up to 47 % was observed after a washing stage. After two days immersed in water, the holograms showed high stability even though the diffraction efficiency decreased to 37%. The optical parameters were obtained by fitting procedure through Kogelnik’s coupled wave theory.