• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.226-227
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• 1998

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.52-56
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• 2010

In this paper, we investigate the polarization multiplexing for micro holographic storage. The proposed multiplexing method is performed by using crystal media that use photorefractive materials such as Fe-doped $LiNbO_3$. We discuss the feasibility of fast recording, high capacity and transfer rate for polarization multiplexing method. Finally, we experimentally verify the proposed method using polarization selectivity.

• 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.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.73-83
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• 1993

The temporal differential equation describing the build-up of the space-charge field in the presence of square and sinusoidal alternating field in photorefractive materials is solved analytically. We also measured the average two-wave mixing gain and the full temopral gain variations in a B$i_{12}$Si$O_{20}$ crystal with applied fields of up to 7 KV/cm amplitude and 1 KHz repetition rate. It has been found that the experimental measurements agree well with the theoretical results.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.430-432
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• 2010

We verified through a noncritical phase-matched second-harmonic generation experiment that the periodically-poled $LiNbO_3$ (PPLN) had a large effective nonlinear optical coefficient, demonstrating that the QPM grating was uniform throughout the entire length of PPLN. The quasi-phase matching temperature was $193.4^{\circ}C$. The maximum SHG output power at the fundamental power of 2.0 W was found to be 18.0 mW; generated second-harmonic beam was found to have no photorefractive effect.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.6
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• pp.246-251
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• 2003

We report the theory of thin-sample Z -scan for materials, viz. diffusion-dominated photorefractives, having a nonlinearly induced phase that may be proportional to the spatial derivative of the intensity profile. The on-axis far-field intensity is approximately an even function of the scan distance on different positive and negative values for phase shift $\Delta$$\Phi$$_{o}$. In case of positive phase shift, the Z -scan graph shows a minimum and two maxima, while for the negative value, only one minimum is observed. The fact is that far-field beam profiles display beam distortion and shift of the peak as compared with Kerr-type or photovoltaic nonlinearities.s.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.223-239
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• 1990

This paper presents an overview on the present status and future trends of photonic physics and engineering as applicable to optical materials and devices that would enable optical information processing and optical commmication technologies of the future. Covered subjects include semiconductor quantum devices, organic materials, photorefractive physics, quantum effect, non-linear processing optical amplification, memory, integrated optics, and applications in all-optical communications and processing, including photonic switching.

• Broadcasting and Media Magazine
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• v.6 no.1
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• pp.78-87
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• 2001

Seven kinds of most representative photorefractive crystals expected to contribute to the realization of the volume holographic storage were reviewed The growth conditions and problems for highly homogeneous optical qualities of the following crystals depending on the growth methods were discussed;(1) $LiNbO_3$ and $Bi_2SiO_{20}$ by Czochralski method (2) $Bi_{12}TiO_{20}$, $KNbO_3$ and $BaTiO_3$ by top seeded solution growth and (3) $(Sr_{1-x}Ba_{x})Nb_{2}O_{6}$ and $(K_{1-y}Na_y)_{2A-2}(Sr_{1-x}Ba_x)_{2-A}Nb_2O_6$ by Stepanov method, And then the figure of merits for the estimation of phororefractive materials on performances, such as $Q_1$, $Q_2$ and sensitivity, were discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.230-231
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• 2003

$KNbO_3$is one of the best materials for efficient nonlinear frequency conversion, due to its large nonlinear optical coefficient ($d_{33}$ ＝ 20.6 pm／V), wide transparency range (0.4 ~ 5 $\mu$m) and freedom from photorefractive effects. Quasi-phase-matched second harmonic generation using periodically poled $KNbO_3$ (PPKN) crystals has been reported. Here we report on fabrication of PPKN and demonstration of a pulsed optical param etric oscillator (QPM OPO) pumped by an Nd：YAG laser. (omitted)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.6
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• pp.235-239
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• 2006

ZnO-doped near-stoichiometric $LiNbO_3$ single crystals of $0.8{\sim}1.0mm$ diameter and $30{\sim}35mm$ length were grown by the micro-pulling down (U-PD) method. The structure of the grown crystals was confirmed by powder x-ray diffraction (XRD) patterns. Electron probe micro analysis (EPMA) showed that Zn ions were homogeneously incorporated In grown crystals. The threshold in ZnO doping level was confirmed that an abrupt change in the features of $OH^-$ absorption band as doping level reaching about 2 mol%.