Hybrid materials based on combination of polymers and inorganic nanoparticles (NP) attracted considerable attention in the last decade due to their advantageous electrical, optical, or mechanical properties. Recently, we reported a significant improvement of the photoresponse by doping azopolymers with ZnO NP. To study the influence of the composition of the dopant, in our present work we have synthesized anisotropic organic/inorganic nanocomposite materials by incorporating 5-15 nm sized SiO2 NP in a side-chain azopolymer. As a result we observe an enhancement of the photoinduced birefringence in these composite materials with about 20% compared to the nondoped sample. Additionally, we discuss possible mechanisms leading to this enhancement related with the scattering caused by the NP and the increased mobility of the azochromophores in the vicinity of NP.
We have studied one-dimensional (1D) relief metalized subwavelength gratings, which support resonant optical transmission. We have used pregrooved DVD stampers, metalized with a thin Al layer. The sensitivity of resonant transmission of the gratings to the cladding environment was investigated by the help of matching fluids. We have shown that the shift of the spectral position of the resonance peak can be used for sensor applications, e.g., for determination of very low concentrations of nanosized dielectric particles in distilled water.
We describe an experimental set up that measures material optical anisotropy and its eventual evolution in real time. The setup is based on a new photopolarimeter that measures the four Stokes parameters of quasi-monochromatic light quickly and simultaneously. The photoinduced anisotropy in the material optical constants is determined from the measured Stokes parameters. The features of the experimental setup are demonstrated by simultaneous measurement of the photoinduced changes in dichroism and birefringence of layers of rigid solutions of azodyes in polymethyl methacrylate, for which it is known that linearly polarized light orients the dye molecules.
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