Stability of holographic gratings recorded on photopolymer films using acrylamide as monomer andN,N'-methylenebisacrylamide

Abstract

The stability of holographic gratings recorded on photopolymer films containing acrylamide as a monomer and N,N'- methylenebisacrylamide as a crosslinker was investigated experimentally. The photopolymer films contained acrylamide, N,N'-methylenebisacrylamide, eosin Y, and triethanolamine in polyvinyl alcohol matrices. Four sets of films with different N,N'-methylenebisacrylamide concentrations were fabricated. The concentration of N,N'- methylenebisacrylamide was determined from the relative molar ratio of the crosslinker and the monomer. The relative molar ratio of N,N’-methylenebisacrylamide and acrylamide was set to 0.1, 0.02, 0.004, or 0. The photopolymer films were exposed to two intersecting 532 nm laser beams produced by a YVO laser for 100 s to form a holographic grating with a spatial frequency of 653 lines/mm. Each impinging beam had an intensity of 1.0 mW and a diameter of 2.25 mm. The diffracted intensity was measured during recording using a He-Ne laser at 633 nm and after one, two, and three days of dark storage using a YVO laser. Among the studied photopolymer films, that with a relative molar ratio of 0.1 showed high diffraction efficiency immediately after recording (91%) and the best stability after three days (80%).