• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.314-321
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• 1996

In this paper, the chemical process of each step in fabricating the holographic phase diffraction grating with silver salt sensitive materials has been studied in detail. A new analysis of the bleaching methods have been made through the study. The result shows that among the types of bleaching methods, the reversal bleach can not be reacted chemically. And the experiments about the chemical reactions, the characteristics of the reaction products and the refractive modulation types by the bleaching methods have been done to prove the theory. It is investigated that the exposure acts as the catalyst of developing reaction and affects the developing reaction time conspicuously. At the optimum developing reaction times, which could be taken from the experiments, the holographic diffraction gratings with high diffraction efficiency over 70% could be obtained in the range of the exposure quantity 50~350 [$\mu$J/ $\textrm{cm}^2$]. From the experiments about the correlation of the chemical processing conditions of the composition of developers, the exposure, and the developing reaction time, it has proved that the enhancement of the diffraction efficiency is impossible in the limited exposure energy and conventional constant chemical reaction time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.127-130
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• 2003

We have carried out two-beam interference experiment to form holographic grating on amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver, $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ muliti-layer. In this study holographic grating formed using He-Ne laser(632.8nm) under different polarization state(intensity, phase polarization holography). The diffraction efficiency was obtained by first order intensity. The maximum diffraction efficiency of $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver was 0.8% and The maximum diffraction efficiency of $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer(multi-layer I, multi-layer II) were 1.4% and 3.1%.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.197-201
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• 2003

We investigated recording dynamics of a holographic grating in the photorefractive LiNbO$_3$ crystal under the low-intensity condition of recording beams. New expressions for the space-charge field and the recording time constant were obtained by solving the Kukhtarev equations under the global space -charge field, which is induced in the previous process of recording and erasing. Their validity can be confirmed by considering the limit that the period of the grating goes to infinity both theoretically and experimentally. It was found that the new expression for the recording time constant allows us to determine acceptor concentration to be $1.2${\times}$10^{21}m^{-3}$ for pure LiNbO$_3$ crystal and 2.5${\times}$$10^{21}m^{-3}$ for the 0.1 mol% iron doped LiNbO$_3$ crystal from the measured ratio of the recording time constant under the extremely large grating condition, in which the diffusion effect can be neglected, to that under the small grating condition.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.48-56
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• 2000

Effects of the correlated random fluctuation in each grating half-period have been studied by an effective index transfer matrix method in quarter wavelength shifted DFB lasers. As the correlation coefficient changes from 0 to -1, single mode stability and wavelength accuracy are less degraded by the reduced error in the grating period. This fact shows that holographic grating fabrication is better than electron-beam lithography in discrete device fabrication provided that the magnitude of the random fluctuation is the same.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.55-56
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• 2006

We investigated the diffraction grating efficiency by the DPSS laser beam wavelength to improve the diffraction efficiency on AsGeSeS & Ag/ AsGeSeS thin film. Diffraction efficiency was obtained from DPSS(532nm)(P:P)polarized laser beam on AsGeSeS, Ag/ AsGeSeS and AsGeSeS/Ag/AsGeSeS thin films. As a result, for the laser beam intensity, 0.24 mW, single AsGeSeS thin film shows the highest value of 0.161% diffraction efficiency at 300 s and for 2.4 mW, it was recorded with the fastest speed of 50 s, which the diffraction grating forming speed is faster than that of 0.24 mW beam. Ag/ AsGeSeS and AsGeSeS/ Ag/ AsGeSeS multi-layered thin film also show the faster grating forming speed at 2.4 mW and higher value of diffraction efficiency at 0.24 mW.

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.77-85
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• 1992

The design of a flat-field XUV spectrograph is optimized for a high throughput, aberration-corrected spectral image in the wavelength region of 50-300 $\AA$ The varied-line spacing (VLS) concave grating theory for an XUV spectrograph with a toroidal mirror in front of an entrance slit is derived. Since the derived theory includes the arbitrary shaped source, it is able to correct the limit of the simple optimization theory which considers only a point source at the center of the entrance slit. The reflection matrix at the toroidal mirror and the diffraction matrix at VLS grating are derived and compared with those of a holographic grating. The absolute energy efficiency of a flat-field spectrograph is calculated by considering the reflectivities of the toroidal mirror and the Au coated concave grating and the grating efficiency. The alignment sensitivity of the toroidal mirror and the concave grating is investigated, and the method to achieve the best imaging of XUV spectrum is discussed. The calculated resolving power of the flat-field XUV spectrograph is more than 4000 in the aberration-corrected wavelength range. The focused spot size at the dispersion plane is less than $20\mu \textrm m\times \mu \textrm m$at the wavelength 100$\AA$ It is shown that a high throughput characteristic can also be achieved through a careful adjustment of alignment parameters.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.403-407
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• 2010

This paper shows that the diffraction efficiency is influenced by superadditivity for the combination of the different developing agent and concentrations in the reversal bleach applied to the Slavich PFG-01 plate to be used for recording transmission holograms. The four developers based on ascorbic acid in combination with metol, phenidone, hydroquinone respectively, were studied. In diffraction efficiency aspect, the superadditivity effect of mixture of two developing agents is lower than one developing agent developer, AAC in the reversal bleach.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.437-440
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• 2002

Characteristics of holographic polymer dispersed liquid crystal(HPDLC) were studied according to various matrix materials to improve the electro-optic properties. Various types of polyurethane acrylates (PUAs) have been designed and synthesized. The morphologies of these gratings were measured by atomic force microscopy(AFM) and electro-optic properties were obtained with UV-visible spectroscopy. Real time measurements of grating fabrication have been obtained according to PUA structures. High reflection efficiency was obtained by modifying the molecular structure.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.63-69
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• 2001

Holographic transmission gratings were performed by an Ar-laser( ${\lambda}$=514nm) intensity, the ratio fo LC contents to the surfactant. The addition of the surfactant to the LC and pre-polymer systems causes the droplet to maintain the ideal size at the high fraction(over 40wt%) of the LC contents that induce the films to be fabricated with high diffraction efficiency than that of no surfactant series. The image of these films was examined using a charge coupled device (CCD). We also studied the angular selectivity plots which support the important role in the multiplexer channel (MUX). Eventually, we showed the reconstructive optical image recorded in this transmission mode of HPDLCs.

• Macromolecular Research
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• v.11 no.1
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• pp.36-41
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• 2003

Holographic gratings in two kinds of photopolymers (PPs) were fabricated by optical interference method. Polyvinylalcohol (PVA) and polyvinylacetate (PVAc) were employed as polymer binders and photopolymerization of acrylamide (AA) was confirmed using infrared spectroscopy. Dynamic behavior of the diffraction efficiency was monitored and its temporal stability at room temperature was also observed. Additionally, the temperature dependence of these gratings was investigated in two PPs. The surface topographical change of the photopolymer layer was observed by atomic force microscope (AFM).