• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.112-117
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• 2008

Single-mode propagation conditions of X-ray waveguides are investigated by numerical calculations in order to understand the importance of waveguide design parameters, such as core thickness and the optical constants of waveguide materials, on the transmission and coherence properties of the waveguide. The simulation code for mode analyzing is developed based on a numerical solution of the parabolic wave equation. The initial boundary value problem is solved numerically using a finite-difference scheme based on the Crank-Nicolson scheme. The E-field intensities in a core layer are calculated at an X-ray energy of 8.0 keV for air and beryllium(Be) core waveguides with different cladding layers such as Pt, Au, W, Ni and Si to determine the dependence on waveguide materials. The highest E-field intensity radiated at the exit of the waveguide is obtained from the Pt cladded beryllium core with a thickness of 20 nm. However, the intensity from the air core waveguide with Pt cladding reaches 64% of the Be-Pt waveguide. The dependence on the core thickness, which is the major parameter used to generate a single mode in the waveguide, is investigated for the air-Pt, and Be-Pt waveguides at an X-ray energy of 8.0 keV. The mode profiles at the exit are shown for the single mode at a thickness of up to 20 nm for the air-Pt and the Be-Pt waveguides.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.333-336
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• 2010

The generation of coherent x-ray beams by using a multi-slit diffraction phenomenon is presented. The mode-confinement conditions in the x-ray waveguide (XWG) needed to obtain single-mode beams are determined. The XWGs are stacked to form an XWG array. The core of the XWG array is used as a slit in an opaque screen, similar to those used for visible light. Diffraction patterns that interfered constructively in the XWG array are investigated based on multi-slit diffraction theory. The irradiance distributions are studied at on observation screen. The FWHM of diffracted x-ray spectra were between $1.67{\times}10^{-4}$ to $3.30{\times}10^{-5}$ radians which lead to a spot-size of a few tens of micrometers on the screen at distance of 1 m. The intensities decrease with increase in the period of the XWG array, i.e. a thicker cladding, due to growth of the higher-order diffraction peaks.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.997-1006
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• 2003

LICA technique evolved as a basic fabrication process fur micro-structure. The present report deals with the basic technological features in the sequence of the LIGA technique such as deep x-ray lithography(DXRL), electroplating, and moulding processes at Pohang Light Source (PLS). We designed 3-D structured master for fabrication of polymeric optical wavegude and manufactured polymeric optical wavegude with the same using hot embossing process. Polymeric optical waveguide could be produced with ${\pm}$ 1 $\mu\textrm{m}$ accuracy and good surface roughness.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.60-61
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• 2005

Polycapillary optics are fabricated for hard X-ray waveguide. The Calculation of propagation conditions in polycapillary are conducted to obtain the focal length and spot size as well as the demension of the polycapillary optic devices. X-ray energy of 8 KeV is propagated in the polycapillary optics which the exit diameter of 2.3 mm. and 17 mm in length.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.594-597
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• 2002

Silicon Oxynitride(SiON) thick films on p-type silicon(100) wafers have obtained by using plasma-enhanced chemical vapor deposition from SiH$_4$ , N$_2$O and N$_2$. Prism coupler measurements show that the refractive indices of SiON layers range from 1.4620 to 1.5312. A high deposition power of 180 W leads to deposition rates of up to 5.92${\mu}$m/h. The influence of the deposition condition on the chemical composition was investigated using X-ray photoelectron spectroscopy. After deposition of the SiON thick films, the films were annealed at 1050$^{\circ}C$ in a nitrogen atmosphere for 2 h to remove absorption band near 1.5${\mu}$m.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.472-476
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• 1998

The surface reactions of silica film($SiO_2-P_2O_5-B_2O_3-GeO_2$) with fluorocarbon plasma has been studied by using angle -resolved x-ray photoelectron spectroscopy(XPS). It has been confirmed that residual carbon consists of C-C and C-CFx bonds and fluorine mainly binds silicon in the case of etched silica by using $CF_4$ gas plasma. The surface reaction of silica with various fluorocarbon gases, such as $CF_4,C_2F_6 and CHF_3$ were investigated. XPS results showed that though the etching gases were changed, the elements and binding states of the residual layers on the etched silica by using various fluorocarbon gas plasma were nearly the same . This seems to be due to the high volatility of byproducts, that is, $SiF_4 and CO_2$ etc..

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.479-483
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• 2002

Silicon dioxide thick film using silica optical waveguide cladding was fabricated by Plasma Enhanced Chemical Vapor Deposition(PECVD) method, at a low temperature ($320^{\circ}$C) and from $(SiH_4+N_2O)$ gas mixtures. The effects of deposition parameters on properties of $SiO_2$ thick films were investigated by variation of $N_2O/SiH_4$ flow ratio and RF power. After the deposition process, the samples were annealed in a furnace at $1150^{\circ}$C, in N2 atmosphere, for 2h. As the $N_2O/SiH_4$ flow ratio increased, deposition rate decreased from 9.4 to 2.9 ${\mu}m/h$. As the RF power increased, deposition rate increased from 4.7 to 6.9 ${\mu}m/h$. The thickness and the refractive index measurements were measured by prism coupler. X-ray Photoelectron Spectroscopy(XPS) and Fourier Transform-infrared Spectroscopy(FT-IR) were used to determine the chemical states. The cross-section of films was observed by Scanning Electron Microscopy(SEM).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.5
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• pp.205-209
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• 2011

Zinc oxide has semi-conductivity and super conductivity characteristics. It can be used optically and is applied on many areas such as gas sensor, solar cell and optical waveguide. In this paper, to improve optical characteristics of ZnO, aluminum was added on zinc oxide. Zinc oxide and aluminum zinc oxide was fabricated as nano fiber form. ZnO solution was created by mixing poly vinyl pyrrolidone, ethyl alcohol, and zinc acetate. An Al doped ZnO was created by adding aluminum solution to ZnO sol. By applying these sols on electro spinning method, nano fibers were fabricated. These fibers are heat treated at 300, 500, and $700^{\circ}C$ degrees and were analyzed with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to examine the nano structures. TGA and DSC measurement was also used to measure the change of mass and calorie upon temperature change. The absorbance of ZnO and Al-doped ZnO was carried out by UV-vis measurement.

• Korean Journal of Materials Research
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• v.25 no.12
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• pp.703-707
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• 2015

In this study, we investigated the effect of annealing conditions on the ferromagnetic resonance(FMR) of yttrium iron garnet ($Y_3Fe_5O_{12}$, YIG) thin film prepared on gadolinium gallium garnet ($Gd_3Ga_5O_{12}$, GGG) substrate. The YIG thin films were grown by rf magnetron sputtering at room temperature and were annealed at various temperatures from 700 to $1000^{\circ}C$. FMR characteristics of the YIG thin films were investigated with a coplanar waveguide FMR measurement system in a frequency range from 5 to 20 GHz. X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to characterize the phase formation, crystal structure and composition of the YIG thin films. Field dependent magnetization curves at room temperature were obtained by using a vibrating sample magnetometer(VSM). The FMR measurements revealed that the resonance magnetic field was highly dependent on the annealing condition: the lowest FMR linewidth can be observed for the $800^{\circ}C$ annealed sample, which agrees with the VSM results. We also found that the Fe and O composition changes during the annealing process play important roles in the observed magnetic properties.

• The Korean Journal of Ceramics
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• v.1 no.4
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• pp.191-196
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• 1995

Using sol-gel processing method, thin films of lathanum modified lead titanate(PLT) on Corning 7059 glass were prepared. A differential thermal analysis (DTA/TG) curve of gel powder and infrared spectra (FT-IR) of the films were measured to estimate residual organices in them. The heat-treated films were characterized by X-ray diffraction(XRD). Microstructures of the films were observed by a scanning electron microscope (SEM). Optical properties of the films were determined by a UV-VIS spectrophotometer. The waveguiding properties and optical attenuation were measured with the end coupling method and the cut back method. Effects of the drying conditions on the transmittance and the propagation loss of the films were investigated. Experimemtal results showed that the content of residual organics in the film decreased as the drying temperature of the film increased. As the La content of the film increased, the grain size decreased and the transmittance increased. The transmittances of the films increased with the increasing of the drying temperature. The propagation losses in the film decreased as the drying temperature increased.