The geometric structures, energy and optical properties of intrinsic and Cu, Ti, Zr-doped graphenes were investigated using first-principles method. The results indicate that the doped graphenes can be prepared by experiment under certain conditions and stable. The absorption spectrums show that the absorption rates of doped systems are larger, and the amplitude ratios of them are smaller than that of intrinsic graphene in the range of visible light. The real parts of conductivity are larger and the fluctuations become smaller. Thus, it can be predicted that Cu, Ti, Zr-doped graphene can be used as visible light sensitive materials in sensors.
Experimental studies of holographic thermal stability in phenanthrenequinone (PQ)-doped poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MAA)] photopolymers are presented. A possibility to improve the thermal stability of holograms is demonstrated by doping methacrylic acid (MAA) into the poly(methyl methacrylate) (PMMA) polymer matrix. MAA as a copolymerization monomer can form a more stable polymer matrix with methyl methacrylate (MMA) monomer and increase average molecular weight of photoproducts, which finally depress the diffusion of photoproduct. The optimized MAA concentration copolymerized into P(MMA-co-MAA) polymer matrix can bring nearly a month's lifetime of gratings, which is obviously an improvement over the usual PQ-PMMA material under thermal treatment.
This paper presented an experimental study of holographic scattering caused by noise gratings recorded in the
PQ-PMMA photopolymers. Dependence of the thickness and temperature on the holographic scattering losses was
evaluated. It is found that the scattering losses increased as the thickness and temperature. According to the relationship
between the polymerization rate and exposure, the optimal material parameters thickness 2mm and the temperature
20-30°C were obtained for avoiding the buildup of strong noise gratings.