Ultraviolet holographic recording in photopolymers



Norland Optical Adhesive (NOA) acrylate based photopolymers were studied as a medium for Bragg grating fabrication. NOA photopolymers have absorption maximum in near UV region, but they are transparent in visible light region. Photopolymers were irradiated by He-Cd laser 325 nm line interference patterns during holographic recording. In light irradiated regions photopolymerization takes place and volume grating can be recorded. Diffraction efficiency in dependence on sample thickness, recording beams polarization state and intensity was investigated on transmission mode. Enlargement of sample thickness allows to achieve better angular selectivity of diffracted beam, therefore thickness of prepared samples were up to 2.4 mm. In this work diffraction efficiency over 80% was achieved. The best angular selectivity of diffracted beam was several minutes. Gratings with high diffraction efficiency and good angular selectivity successfully can be used in telecommunications and data storage devices. Advantages of this grating are long term mechanical stability, low dependence on temperature changes, simple and cheap preparation (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)