• ETRI Journal
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• 제31권5호
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• pp.593-597
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• 2009

In this paper, we present a spatial perturbation method to control the optical patterns in semiconductor microresonators in the far-field configuration. We propose a fast all-optical switch which operates at a low light level. The switching beam controls the behavior of output beams with strong intensities. The method has been applied successfully to different optical patterns such as rolls, squares, and hexagons.

• 대한치과보철학회지
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• 제40권5호
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• pp.493-506
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• 2002

Recently as the esthetic concerns about dental prosthesis have been increased, the nonmetallic post and core systems have been introduced clinically to improve the color and the low optical transmittance of conventional casting metal post and core systems. The purpose of this study was to compare and analyze the optical transmittance and the shade changes of all-ceramic crowns with two nonmetallic post and core systems. The experimental groups were classified as follows : Total 27 specimens(9 samples in each group) were evaluated. Group I : Natural teeth as a control group Group II : CosmoPost and $Empress^{(R)}$ core (Ivoclar-Vivadent, Liechtenstein) Group III : $LIGHT-POST^{TM}$ and $LIGHT-CORE^{TM}$ (Bisco, U.S.A.) In all group, all-ceramic crowns were fabricated with the same shade of IPS $Empress^{(R)}$ II (Ivoclar-Vivadent, Liechtenstein) after abutment preparation, and then two kinds of spectrophotometers, UV 3101 PC (Shimadzu, Japan) and CM 503i (Minolta Co. Ltd. Japan), were used to measure the optical transmittance and the color value. The following results were obtained : 1. The optical transmittance of each group without all-ceramic crowns, was siginificantly decreased in order of Group III, I and II (p<0.05). 2. The optical transmittance of each group with all-ceramic crowns cemented, were siginificantly decreased in order of Group I, II and III (p<0.05). 3. In comparison with the shade of all-ceramic crowns, there were no significant differences between groups regardless of the cementation. 4. In comparison with the shade changes in each group after the cementation of all-ceramic crowns, there were no significant differences between groups. From the above results, it is thought that the selection among materials used in this study doesn't influence greatly the esthetic restoration, because the differences of optical transmittance were so small that those were clinically insignificant.

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.65-70
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• 2014

This paper presents the simulation and design of an all-optical subtractor using a quantum-dot semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA MZI) structure consisting of two cascaded switches, the first of which produces the differential bit. Then the second switch produces the borrow bit by using the output of the first switch and the subtrahend data stream. Simulation results were obtained by solving the rate equations of the QD-SOA. The effects of QD-SOA length, peak power and current density have been investigated. The designed gate can operate at speeds of over 250 Gb/s. The simulation results demonstrate a high extinction ratio and a clear and wide-opening eye diagram.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.109-111
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• 2002

We have demonstrated all-opticalflip-flop based on optical bistability in a SOA/DFB-SOA with broadband gain. Input signal with the wavelength of 1340.23 nm or 1680.93 nm and the current of about 98% of the lasing threshold is injected into theDFB-SOA. Current injected into SOA is 80 mA All-optical flip-flop has various applications such as all-optical memory, demultiplexing, packet-header buffering, and retiming.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.17-20
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• 1999

In these days, wavelength division multiplexing(WDM) all-optical network are being deployed to support various multimedia communication services. In this paper, various WDM all-optical network are discussed, and a design of an all-optical backbone network has been proposed by using multiple self-healing ring technology. The proposed multiple self-healing ring network improves network expandability and efficiency of bandwidth, while it retains simplicity and ease of network control, which are from the nature self-healing ring. Using PDI traffic modeling technique, a well-balanced all-optical backbone network using multiple self-healing ring is designed for the 2010s in Korea.

• Journal of Photoscience
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• 제9권2호
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• pp.317-319
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• 2002

All-optical switching has been demonstrated in bacteriorhodopsin (bR) based on nonlinear intensity induced excited state absorption. The transmission of a cw probe laser beam at 410 nm corresponding to the peak absorption of M state through a bR film is switched by a pulsed pump laser beam at 570 nm that corresponds to the maximum initial 8 state absorption. The switching characteristics have been analyzed using the rate equation approach considering all the six intermediate states (B, K, L, M, N and 0) in the bR photocycle. The switching characteristics are shown to be sensitive to life time of the M state, absorption cross-section of the 8 state at probe wavelength ($\sigma$ $\_$Bp/) and peak pump intensity. It has been shown that the probe laser beam can be completely switched off (100 % modulation) by the pump laser beam at relatively low pump powers, for $\sigma$$\_$Bp/ = O. The switching characteristics have been used to design all-optical NOT, OR, AND and the universal NOR and NAND logic gates for optical computing with two pulsed pump laser beams.

• 한국광학회지
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• 제13권3호
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• pp.245-250
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• 2002

전광위상천이스위치(All-optical phase-shift switch)에서 백 펨토초이하의 펄스폭을 가지는 두 극초단 직교펄스의 전파특성을 수치적으로 연구하였다. 이러한 전광스위치에서 자기라만산란 및 상호라만산란과 walk-off 효과를 고려하여, 솔리톤펄스와 고차솔리톤펄스간의 복잡한 비선형상호작용이 펄스의 형태변화, 펄스의 위상천이분포, 그리고 대조비등의 스위칭특성에 끼치는 영향들을 분석하였다. 특히 스위칭을 위해 필요한 walk-of f효과를 라만 walk-off효과에서 얻을 수 있기 때문에, 이러한 전광스위치에 전형적인 복굴절률(Δn = 2.4$\times$$10^{-5}$)을 가지는 광섬유를 사용해도 좋은 스위칭특성을 가짐을 보였다.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.766-771
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• 2014

Single-ring all-pass filters with various coupling ratios are designed, fabricated, and characterized to assess the validity of the split-step time-domain modeling approach, which is considered for direct simulation of time-domain characteristics, such as optical delay, of various ring resonator devices. When the coupling ratio of the single-ring all-pass filter is 0.4 and 0.8, the delay time is measured to be about 145 and 42 ps respectively, which is comparable to the time-domain modeling results of 151 and 47 ps respectively. The measurements for two- and three-ring all-pass filters are also found to agree quite well with the simulation results. With these results it is confirmed that the split-step time-domain model could be efficiently incorporated into an optical-communication simulation module for ring resonator delay components in an all-optical packet switching system.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.116-117
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• 2000

전광 네트워크(All-optical Network)에서 중요한 기능을 담당하는 전광 교환기는 전광 교환 소자 (All-optical Switching Element)로 이루어져 있는데, 각 교환 소자들은 스위칭 모듈(SM), 라우팅 제어 처리기(RCP), 헤더 처리 모듈(HPM), 그리고 입/출력 인터페이스 모듈(IIM, OIM)로 이루어져 있다. 스위칭 시스템 내에 도착하는 패킷은 원하는 스위치의 출력단에 도착하기 전에 많은 교환 소자(SE)들을 지나가게 되는데, 이 때 수많은 패킷들이 서로 충돌하게 되며, 이 과정에서 패킷이 손실된다. (중략)

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.864-867
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• 2005

All-optical networks are emerging as a promising technology for per second class communication. However, they are intrinsically different from electro-optical networks, particularly because they do not regenerate signals in the networks. The characteristics of all-optical network components and architectures manifest and still unstudied security vulnerabilities but also offer a new array of possible countermeasures. In this paper, we have analysed the security issue to protect against intrusion.