• E2M - 전기 전자와 첨단 소재
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• 제9권3호
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• pp.298-303
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• 1996

A double diffusion technique is developed to enhance the effective mode index of optical waveguides in $LiTaO_3$. It consists of Zn diffusion from the vapor phase at relatively low temperatures (750->$800^{\circ}C$), into waveguides initially produced by Ti indiffusion at higher temperature (1150->$1200^{\circ}C$). Both X- and Z-cut substrates are investigated. A model that combines profiles of both diffusion is formulated to calculate the expected effective index values for planar waveguides. Good agreement is found between experimental results and model predictions which assume that the initial Ti profile is not affected by the lower temperature Zn diffusion. Effective index enhancements as high as 0.005 and 0.003 are obtained by this method for the fundamental extraordinary and ordinary modes, respectively.

• 대한전자공학회논문지
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• 제26권10호
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• pp.1584-1590
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• 1989

In this study, a planar waveguide has been fabricated on a Y-cut LiNbO3 substrate by the Ti indiffusion technique and its guiding characteristics are measured by bright M-line spectroscopy. Using the photolithography method, an electro-optic grating modulator with interdigital electrodes has been fabricated by depositing Al on the Ti:LiNbO3 planar waveguide. And the beam intensity diffracted by the grating is measured as the applied voltage is increased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.282-285
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• 1999

Fabrication and pakaging method for low delve voltage and 10Gbps Ti diffused waveguide LiNbO$_3$ optical intensity modulator are described. Optical waveguides were prepared by conventionaly electron-beam evaporation and Ti-indiffusion into Z-cut plate LiNbO$_3$. Traveling-wave electrodes were used for obtaining the wideband frequency response and impedance matching. Microwave effective index and characteristic impedance measured by time domain reflectometry and compared with the calculated value by conformal mapping. The characteristics of 10Gbps modulator at the 1550nm wavelength are as follows : perfect modulation voltage Is about 5V, optical insertion loss Is about 5dB, 3-dB bandwidth is 10GHz, and characteristic impedance is about 50$\Omega$.

• 대한전자공학회논문지
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• 제25권3호
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• pp.343-351
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• 1988

Planar optical waveguides are fabricated on a Y-cut LiNbO3 single crystal substrate by Ti indiffusion method. From data measured by the bright M-line spectroscopy, refractive index profiles are reconstructed by WKB approximation method. Then, single strip, X-crossing strip, and Y-brinch strip optical waveguides are fabricated on X-cut LiNbO3 single crystal substrate, with waveguide patterns made by the laser beam direct writing method. And their near-field intensity profiles are observed after coupling the light to the waveguide edges.

• 한국재료학회지
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• 제12권4호
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• pp.254-258
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• 2002

To realize channel cross-connecting in optical communications systems, a high speed optical matrix switch was fabricated using z-cut $LiNbO_3$. For switch fabrication was design bending structure and coupling length and four $2{\times}2$ directional couplers were integrated on one substrate far construction of a $4{\times}4$ switch. Single-mode optical waveguides were formed by Ti-diffusion at a wet $O_2$ atmosphere. Ti-diffusion profile, refractive index variation and waveguide morphology were analyzed by Prism coupler and optical microscopy, respectively.

• 한국통신학회논문지
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• 제17권4호
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• pp.371-378
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• 1992

본 논문에서는 Y-cut $LiNbO_3$ 기판 위에 TIPE 방식을 이용하여 평면 광도파로 렌즈를 제작하고 그 특성을 측정하였다. Ti 내부확산 평면광도파로 및 TIPE 평면 광도파로 제작하고, 프리즘 결합으로 굴절율을 측정하였다. 측정한 기본파 유효굴절율로부터 평면 광도파로 렌즈의 궤적을 구하여, 사진식각법과 lift-off기법을 이용하여 TIPE 평면 광도파로 렌즈를 제작하였다. 도파로를 따라 도파되던 광이 평면 광도파로 렌즈에 의하여 접속되는 현상을 관측하였고 측정한 결과와 컴퓨터 시뮬레이션의 결과가 잘 일치함을 알 수 있었다. 관측한 초점의 위치 및 크기가 설계한 값과 잘 일치하였다.

• 한국광학회지
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• 제7권1호
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• pp.51-59
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• 1996

평면 광도파로 렌즈는 집적광학회로에 널리 사용된다. 본 논문에서는 새로운 형태의 평면 광도파로 렌즈를 제안하고 제작하여 기존의 볼록-평면렌즈와 그 특성을 비교하였다. 제안한 볼록-오목형 렌즈는 원형의 경계를 가지며 선형경계를 가지는 볼록-평면 렌즈에서 발생하는 구면 수차를 제거할 수 있다. Y-cut LiNbO$_{3}$ 기판 위에 Ti-내부확산 양자교환방식을 이용하여 제안한 볼록-오목 렌즈와 기존의 볼록-평면 렌즈에 비해 초점에서의 spot의 크기를 약 59% 정도 줄일 수 있었다.