Natural dye-doped poly(methyl methacrylate) microparticles for nonlinear optics

Poly(methyl methacrylate) (PMMA) microparticles doped with natural dyes such as paprika and chlorophyll have been prepared by the solvent evaporation technique. A mixture of paprika and chlorophyll in different ratios was also doped with microparticles. The distribution of the diameter of particles spreads in the range of 3-7 μm. UV-visible spectroscopic studies have shown that the absorption wavelength is shifted to a longer wavelength region when the paprika content increases in the dopant mixture. The nonlinear optical properties of the samples were investigated. It is found that the coloured particles have remarkable optical nonlinearities in the nanosecond regime because of the interaction of double bonds in PMMA with the delocalised π-electron system of dyes.