The Formation of Volume Transmission Gratings in Acrylamide-Based Photopolymers Using Curcumin as a Long-Wavelength Photosensitizer

Curcumin, a natural dye found in the Curcuma longa rhizome, commonly called turmeric, is used as a photosensitizer in acrylamide-based photopolymers for holographic data storage. We studied the absorbance of photopolymer films that show two absorption bands due to curcumin, acrylamide monomer (AA), and the crosslinking agent N,N ' -methylenebisacrylamide (MBA). Analysis of the real-time diffraction efficiency of these films shows a maximum of 16% for the sample with the highest curcumin concentration. Moreover, increasing the curcumin load enhanced the refractive index contrast from 7.8 x 10(-4) for the photopolymer with the lowest curcumin load to 1.1 x 10(-3) for the photopolymer with the largest load. The sensitivity and diffraction efficiency of the recorded gratings also increased from 7.0 to 9.8 cm center dot J(-1) and from 7.9 to 16% with the increase in curcumin load, respectively. Finally, the influence of NaOH on the photopolymerization of the AA-curcumin-based sample shows a diffraction efficiency increase with the NaOH content, revealing that the curcumin enol form is more efficient as a photosensitizer.

Automated summary

Curcumin, a natural dye found in turmeric, can be used as a photosensitizer in acrylamide-based photopolymers for holographic data storage. Increasing the concentration of curcumin enhances the absorbance, refractive index contrast, sensitivity, and diffraction efficiency of the photopolymer films. Furthermore, the addition of NaOH promotes the efficiency of photopolymerization in the AA-curcumin-based sample.