• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.545-554
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• 2003

Design of the optical modulator composed of a three-waveguide coupler and CPW traveling-wave electrodes was carried out. Switching phenomena of three-waveguide couplers were analyzed by using the coupled mode theory, and the coupling-lengths of the devices were calculated by means of the FDM. CPW traveling-wave electrodes were analysed by the CMM and SOR simulation technique in order to find the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on z-cut LiNbO$_3$ substrate. Ti was in-diffused in LiNbO$_3$ to make waveguides and Au electrodes were built on the waveguides by the electrolyte technique. The fabricated modulator chip was end-polished, pig-tailed and packaged in a brass mount with K-connector. The insertion loss and the switching voltage of the optical modulator were about 4㏈ and 19V, respectively. Network analyzer was used to obtain the S parameter and the corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted to be Z$_{c}$= 45 Ω, N$_{eff}$=2.20, and $\alpha$$_{0}$=0.055/cm√GHZ. The measured optical response R($\omega$) was compared with the theoretically estimated one, showing both responses agree well. The measurement results revealed that 3㏈ bandwidth turned out to be about 13 GHz.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.375-384
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• 2004

Switching phenomenon of a three-waveguide optical coupler was analyzed by using the coupled mode theory, and the coupling-length of the device was calculated by means of the FDM. CPW traveling-wave electrodes were designed by the CMM and SOR simulation techniques so as to satisfy the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on a z-cut LiNbO$_3$ substrate. Ti was in-diffused in LiNbO$_3$ to make waveguides and Au electrodes were built on the waveguides by the electroplating technique. Insertion loss and switching voltage of the optical modulator were about 4 ㏈ and 15.6V. Network analyzer was used to obtain S parameters and corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted as such Z$_{c}$=39.2 $\Omega$, Neff=2.48, and a0=0.0665/cm((GHz) (1/2)). The measured optical response R(w) was compared with the theoretically estimated and both responses were shown to agree well. The measurement results revealed that the ㏈ bandwidth turned out to be about 13 GHz.

• Korean Journal of Optics and Photonics
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• v.9 no.5
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• pp.321-325
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• 1998

We explain that a holographic filter of the generalized Hough transform can be easily obtained by use of rotational multiplexing in hologram recording. To show the feasibility of our approach experimentally, we recorded the Hough transform filter of both line and circle parameterization by combined use of rotational and angle multiplexing. Experimental results on the Hough transform for a few input patterns are presented.

• Journal of the Korean Chemical Society
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• v.22 no.6
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• pp.365-369
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• 1978

Ellipsometric and reflectance measurements were made on an iron surface in a cathodically reduced state and in an anodically passivated state. From the differences in the optical parameters (${\Delta},\;{\psi}$, and reflectance) between the reduced (film-free) and passivated (film-covered) states the thickness and optical constants of the surface film were determined. In the passive state at -400 mV vs. SCE in borate-boric acid buffer solution the anodic film had a thickness of about 11${\AA}$ and optical constants of ${\tilde{n}}$= 2.8 - 0.8 i. This value indicates a substantial electronic conductivity of the anodic film.

• Journal of the Korean Vacuum Society
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• v.11 no.1
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• pp.28-34
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• 2002

Thin films of $Sb_{2-x}Bi_xTe_3$ (x = 0.0, 0.5, and 1.0) are grown by vacuum evaporation. XRD analysis shows the amorphous nature of the films, and the composition studies confirm the stoichiometry of the films. Microstructural parameters of the films have been calculated and used to explain the electrical and optical properties of the films. It is observed that the carrier type has changed from p- to n-type at higher concentration (x = 1.0) of Bi. The resistivity of the films decreases rapidly with the increase of Bi concentration. However, the refractive index and optical band gap of the films increase with the Bi concentration.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.287-292
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• 2004

This paper presents the effect of scratches on an optical connector interface surface on the insertion loss of optical connectors. We propose a model for calculating the insertion loss of optical connectors. The model is expressed in terms of geometrical parameters of scratches assuming that the transmission coefficient of a light wave on the scratch surfaces is linearly varied as a function of scratch depth. Geometrical parameters of scratches such as location, width, and depth of scratches are measured using 3D optical interferometry surface profiler. We obtain the equation of the transmission coefficient in terms of scratch depth comparing the experimental insertion loss data to the insertion loss data using the model presented in this paper. Using the model and the equation of the transmission coefficient presented in this paper, we present the results of the insertion loss of optical connectors for various geometrical parameters of scratches. Scratches which are located at longer than two times the core radius from the center of the core show negligible effect on the insertion loss of optical connectors.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.151-156
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• 1995

The influences of fluorophor, scatterer, absorber in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by laser induced fluorescence spectroscopy. It has been found that the effects of optical properties in scattering media by the optical parameters(${\mu}_{s}$, ${\mu}_{a}$, ${\mu}_{t}$). The value of scattering coefficient ${\mu}_{s}$ is large by means of the increasing particles of scatterer, it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.105-106
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• 2012

일반적으로 CG 합성이라 하면 '자연스러운' 것을 잘된 CG영상이라고 한다. 이 때 촬영된 영상이 정지화면 일 수 만은 없다. 카메라가 움직이는 영상에서는 CG합성도 실사카메라 무빙에 맞게 정확한 정합이 되어야 자연스러운 영상이 된다. 이를 위해 합성단계에서 작업할 때 3D 카메라 트래킹 기술이 필요하다. 카메라트래킹은 촬영된 실사영상만으로 카메라의 3차원 이동정보와 광학적 파라미터 등 촬영시의 3차원 공간을 복원하는 과정을 포함하고 있다. 이 과정에서 카메라 트래킹에 대한 오류의 발생으로 실사와 CG의 합성에 대한 생산성에 많은 문제점을 가지고 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 소프트웨어에서 트래킹데이터를 보정하는 방법을 제안한다.

• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.373-376
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• 2002

An asymmetrical directional coupler with two nonidentical fibers has, for the first time, been proposed and analyzed for an EDFA gain flattening filter (GFF). The characteristics of the transmission spectra of the GFFs have been theoretically investigated for the core spacings, the coupling lengths and the fiber parameters of the asymmetrical directional coupler. The analytical results show that an EDFA gain spectrum with flatness of ~7 ㏈ can be flattened to within $\pm$0.75 ㏈ over a bandwidth of 30 nm by using the asymmetrical directional coupler-based GFF.

• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.108-113
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• 2000

This paper presents a simple but novel gain deviation detector scheme which can be used for general gain-clamping systems. By using the difference of ASEJprobe powers extracted from the edges of gain-flattened bandwidth, gain deviation of EDFA can be exactly detected regardless of the operating condition of a constructed EDFA. To prove the vahd1ty of the suggested scheme, we Implemented gain clamping systems on a single EDFA and cascaded EDFA's link and achieved sufficient gam-clamping performance without the elaborate measurement for tlIe determination of control parameters. eters.