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Lee, Sang-Ho;Jahng, Woong-Sang;Park, Ki-Hong;Kim, Nakjoong;Joo, Won-Jae;Park, Dong-Hoon
- Macromolecular Research
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- v.11 no.6
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- pp.431-436
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- 2003
A new photoconducting polymer, diphenyl hydrazone-substituted polysiloxane, was successfully synthesized by the hydrosilylation method and characterized by FT-IR, $^1$H-NMR, and $^{29}$ Si-NMR spectroscopy. The glass transition temperature (T$_{g}$) of the polysiloxane having pendant diphenyl hydrazone was ca. 62 $^{\circ}C$, which enabled a component of a low-T$_{g}$ photorefractive material to be prepared without the addition of any plasticizers. This polysiloxane, with 1 wt% of $C_{60}$ dopant, showed a high photoconductivity (2.8 ${\times}$ 10$^{-12}$ S/cm at 70 V/${\mu}{\textrm}{m}$) at 633 nm, which is necessary for fast build-up of the space-charge field. A photorefractive composite was prepared by adding a nonlinear optical chromophore, 2-{3-[2-(dibutylamino)-1-ethenyl]-5,5-dimethyl-2-cyclohexenylidene} malononitrile, into the photoconducting polysiloxane together with $C_{60}$ . This composite shows a large orientation birefringence ($\Delta$n = 2.6 ${\times}$ 10$^{-3}$ at 50 V/${\mu}{\textrm}{m}$) and a high diffraction efficiency of 81 % at an electric field of 40 V /${\mu}{\textrm}{m}$.textrm}{m}$.EX>.
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김기현;심광보;오근호
- Journal of the Korean Crystal Growth and Crystal Technology
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- v.8 no.1
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- pp.10-17
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- 1998
The characteristics of the lithium niobate single ($LiNbO_3$) crystals grown doped with $Mg^{2+}$ or $Zn^{2+}$ ions, which are well-known as the ions improving the photorefractive resistance of $LiNbO_3$, have been analysed in comparision with those of undoped $LiNbO_3$ crystal. In particular, $Zn^{2+}$ doping was estimated to increase the photorefractive resistance indirectly from the optical and electrical properties. Therefore, the $LiNbO_3$ crystals doped with ZnO could be used for high intensive laser device application.
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이재철;장지웅;김준태;신승호
- Korean Journal of Optics and Photonics
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- v.10 no.5
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- pp.391-395
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- 1999
We present the measurement of the diffraction efficiency and response time of the photorefractive grating recorded in $LiNbO_3$ photorefractive crystal doped with 4%-mole MgO. Two laser sources were used in the experiments; frequency-doubled Q-switched Nd:YAG laser ($\lambda$=532 nm) and cw Ar-ion laser ($\lambda$=514.5 nm). The same optical geometry was also used in both experiments in order to maintain the experimental consistency. Using the two-wave mixing scheme in both experiments we measured the maximum diffraction efficiency in the range of beam intensity of 1.6~100 W/ $\textrm{cm}^2$, and the response times for both cases of recording and erasing. Two sets of results obtained from the experiments are compared and analyzed.
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Choi, Dong-Hoon;Jun, Woong-Gi;Oh, Kwang-Yong;Yoon, Han-Na;Kim, Jae-Hong
- Macromolecular Research
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- v.11 no.4
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- pp.250-255
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- 2003
We prepared the photorefractive sol-gel glass based on organic-inorganic hybrid materials containing a charge transporting molecule, second-order nonlinear optical (NLO) chromophore, photosensitizer, and plasticizer. Carbazole and 2-{ 4-[(2-hydroxy-ethyl)-methyl-amino]-benzylidene}-malononitrile were reacted with isocyanato-triethoxy silane and the functionalized silanes were employed to fabricate the efficient photorefractive media induding 2,4,7-trinitrot1uorenone (TNF) to form a charge transfer complex. The prepared sol-gel glass samples showed a large net gain coefficient and high diffraction efficiency at a certain composition. As the concentration of photosensitizer increased, the photorefractive properties were enhanced due to an increment of charge carrier density. Dynamic behavior of the diffraction efficiency was also investigated with the concentration of the photosensitizer.
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