• Current Optics and Photonics
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• v.1 no.3
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• pp.239-246
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• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.674-681
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• 2000

We proposed polymer based vertical asymmetric optical coupler. And we optimized the proposed device by coupling characteristic analysis In 1.33um wavelength, TE mode, we obtained very short coupling length(L=277.6um), high coupling efficiency(94%). The merits of proposed device are low propagation loss due to very short full device, low production cost and time, and high integrated fabrication. We will use this to fabricate optical switch, modulator and tunable WDM devices, etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1108-1116
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• 1993

Y-branch directional coupler optica1 switches with two different coupling lengths are fabricated on z-cut LiNbO3 and tested at r = 1.3 rm. The normal mode and coupled mode theories are utilized to calculate device coupling length and switching voltage. Simulation of the beam propagation method (BPM) is also performed to confirm the device coupling lengths. For dc operation, experimental results are in good agreement with the modee theories expectation.

• Electrical & Electronic Materials
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• v.4 no.3
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• pp.249-258
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• 1991

He-Ne레이저(.lambda.=0.6328[.mu.m])를 광원으로 사용하는 y-cut LiNbO$_{3}$기판의 광 도파로 형성 과정을 빔 전송방식 메카니즘을 이용하여 광 도파로에서 광파의 전계 변화 및 전계 분포에 대하여 시뮬레이션 하였다. 그리고 Xl(55[.mu.m])* Zl(5000[.mu.m])인 LiNbO$_{3}$기판의 광 도파로 폭을 4[.mu.m], 버퍼층을 0.02[.mu.m]로 하였을때 도파로 층의 깊이가 0.2[.mu.m]인 지점에서 인가전압에 대한 x방향의 전계(E$_{x}$)와 y방향의 전계(E$_{y}$ )분포를 관찰하였다. 또한 단일 도파로의 파라미터 조건을 적용하여 X-스위치를 구성하였을때 전계를 인가하지 않은 상태에서 굴절율 변화(dn) 0.002, 도파로 폭(w) 3[.mu.m]로 하여 도파로의 교차각(.alpha.)을 0.4.deg.~0.6.deg.로 변화시킨 경우, .alpha.=0.5.deg.와 0.6.deg.일 때는 광빔이 bar측으로 출력되었고 .alpha.=0.4에서는 광빔이 cross측으로 출력 됨을 확인하였다. 따라서 위에서 확인된 도파로의 교차각 .alpha.=0.4.deg.인 경우, 전극간격(gap)이 2[.mu.m]인 조건에서 스위칭 전압을 인가하였을 때 25[V]에서 전기광학 효과에 의하여 광빔이 cross측에서 bar측으로 변조됨을 확인함으로써 X-스위치 광변조기의 기본적인 설계조건을 구현하였다.