High-performance transmission holographic gratings via different polymerization rates of dipentaerythritol acrylates and siloxane-containing epoxides

Well-defined transmission holographic gratings with high diffraction efficiency were fabricated by irradiating a mixture of photopolymerizable materials with different reaction rates consisting of penta-/hexafunctional acrylates and siloxane-containing glycidyl ether (88%) or cyclohexene oxide (85%) as radically and cationically polymerizable monomers, respectively, with Nd:YAG laser (lambda = 532 nm). The ratio between the acrylate and epoxide was important to obtain gratings with high diffraction efficiency. They had smooth surface morphologies of well-regulated spacing (0.9 mu m). Performance of holographic gratings was optimized by varying the chemical structures of epoxide under various experimental conditions. Introduction of siloxane component into epoxide induced easy diffusion and distinct separation of the epoxide from the polymerized matrix formed by the acrylate, by their low viscosity and incompatible property during the fabrication of the gratings. These gratings were actually used to store a real image.