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Yayın Electrochromic switching of WO3 nanostructures and thin films(Springer-Verlag, 2006-04) Karakurt, İsmail; Boneberg, Johannes; Leiderer, PaulWe present transmission measurements through tungsten tri-oxide nanostructures and thin films prepared by sol-gel process on micro-contact printed substrates. Identical electrochromic switching times are found for both the nanostructures and the bulk films with equal thicknesses upon intercalation of H+ ions. We attribute the large change in the transmission through nanostructures at 632 nm, which can not be solely explained by absorption, to diffraction effects.Yayın Nonreciprocal switching of VO2 thin films on microstructured surfaces(Optical Soc Amer, 2010-05-15) Karakurt, İsmail; Adams, Charles H; Leiderer, Paul; Boneberg, Johannes; Haglund, Richard F.We demonstrate that the combination of near-field focusing and a switchable oxide layer permits construction of a modulator with different optical switching thresholds in two opposing directions. For that purpose VO2 layers are deposited onto spherical micrometer-sized particles. The phase transition in VO2 is induced by a nanosecond-pulsed Nd:YAG laser from two different directions. The measured thresholds differ by a factor of 2.4, consistent with calculated differences in the intensities in the two directions.Yayın Size-dependent self-organization of colloidal particles on chemically patterned surfaces(SP Zhejiang University Press, 2006-04-14) Karakurt, İsmail; Leiderer, Paul; Boneberg, JohannesA study of the self-organization of colloidal particles during the evaporation of particle solutions on chemically patterned surfaces is presented. On a surface with hydrophilic and hydrophobic regions, colloidal particles form compact structures on the hydrophilic sites. When a colloidal solution containing a mixture of particles with a variation in size is used, the number density of each type of particle deposited on the hydrophilic islands after evaporation decreases with increasing particle size. This makes it possible to produce a concentration gradient of the particles on islands of different sizes. It is shown that this technique could allow for particle separation.Yayın Transmission increase upon switching of VO2 thin films on microstructured surfaces(American Institute of Physics, 2007-08-27) Karakurt, İsmail; Boneberg, Johannes; Leiderer, Paul; Lopez, Rene; Halabica, Andrej; Haglund, Richard F.The authors compare transmission measurements of near-infrared light through VO2 thin films on smooth substrates and on ordered arrays of silica microspheres. When the samples are heated above the critical temperature for the semiconductor-metallic phase transition, smooth thin films show reduced transmission independent of thickness; however, the VO2 film deposited on the microspheres may show either reduced or enhanced transmission, depending on VO2 film thickness. They show that this at a first glance, unexpected behavior is directly related to the change of scattering efficiency upon the phase transition. This suggests that optical transmission through thin-film microstructures could be tuned by an appropriate combination of microsphere ordering and VO2 film thickness.