• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.140-140
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• 2003

Ti:LiNbO$_3$ 광 도파로를 이용한 광 변조기의 마이크로파 손실을 감소시키고 RF와 광파의 속도정합의 조건하에서 초고속 광변조의 제작을 위해서는 두꺼운 TW(travelling wave) 전극이 필수적이다 또한, 두꺼운 Au 전극이 우수한 RF 특성을 갖기 위해서는 도금된 Au 전극이 고순도의 작은 grain size를 갖는 도금 층을 제조하여야 하며, 도금 후 Au 층의 뒤틀림 현상이 작아야 한다. 따라서, 본 연구에서는 LiNbO$_3$ 기판 위에 30nm Ni-Cr과 50nm의 Au의 기저 막을 올렸으며 감광제를 이용한 photo-lithography 공정으로 CPW(coplanar waveguide) 구조의 패턴을 약 13$\mu\textrm{m}$의 두께로 형성 한 후 non-cyanidic 액을 이용하여 전류밀도 0.02 - 0.06 mA, bubble 및 non-bubble flow를 조건으로 하여 도금된 Au 전극의 특성을 관찰하였다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.110-117
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• 1998

An optical modulator with CPW(coplanar waveguide) electode on Ti:LiNbO$_{3}$ optical waveguide wasfabricated and characterized. The electrical-optical bandwidth measurement showed an optical response of -3dBat 10 GHzand S$_{11}$ lessthan -10dB upto 20GHz. The typeical specifications are : 5.6V of driving voltage, 4.2dB of insertion loss and 30dB of on/off extinction. The eye pattern proved that the optical meduator, fabricated in this work, has properties good enough for application.

• Korean Journal of Optics and Photonics
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• v.19 no.6
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• pp.408-415
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• 2008

The characteristics of a ferroelectric-domain inverted grating fabricated by applying a high-voltage pulse at room temperature in Ti-diffused channel waveguides in z-cut $LiNbO_3$ (Ti:PPLN) were examined for channel waveguide quasi phase-matched secondharmonic generation devices. The fabrication conditions of uniform periodic domain-inversion were examined. Ti:PPLN with period ${\Lambda}=16.6{\mu}m$ for SHG were fabricated and the performances were measured. A normalized SHG efficiency as high as 473 (%/W) was obtained with 49 mm interaction length.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.287-291
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• 2009

In this paper, an optical switch/modulator is designed and its light propagating characteristics analyzed using a simplified BPM. The distinctive feature of this switch/modulator is that all its waveguide branches are designed as single-mode. The principle of the device is based on the coupled mode theory in the Y-junction interconnecting waveguide. In spite of the fact all waveguides are designed as single-mode, by adjusting the interconnecting waveguide length'of the device the same characteristics as existing up to date devices are obtainable. Numerical results show that the switching characteristics periodically depend upon an interconnecting waveguide length with a spatial of about $150^{{\mu}m}$ in the $Ti:LiNbO_3$ step index waveguide. The design concept would therefore be utilized effectively in fabricating a monolithic high density optical integrated circuit.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1829-1834
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• 2008

An optical switch/modulator is designed and the light propagating characteristics is analyzed by the simplified BPM. The distinctive feature of the switch/modulator is that all the waveguide branches are designed to be single-mode. Principle of the device is based on the coupled mode theory in the Y-junction interconnecting waveguide. In spite of all the waveguides are designed to be single-mode, adjusting the interconnecting waveguide length of the device, the same characteristics as existing device up to date is obtainable. Numerical results show that the switching characteristics periodically depends on the interconnecting waveguide length with a spatial of about 150${\mu}m$ in the Ti:LiNbO3 step index waveguide. The concept of design would be utilized effectively in fabricating the monolithic high density of optical integrated circuit.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.76-82
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• 1997

The characteristics of optical waeguides and IDT electrodes fabricated for acousto-optic tunable filters (AOTE) used for optical communications were analyzed. A $Ti:LiNbO_3$ in-diffusion method was employed for the formation of the optical waveguide with a dimension of width $8\mu\textrm{m}$, length $30000\mu\textrm{m}$, and thickness $1150{\AA}$. The diffusion was carried at $1050^{\circ}C$ for 8 houss to pattern the optical waveguide with Ti. The resulted waveguide exhibited a single mode at a 1550nm wavelength range and its propagation loss was less than 0.5dB/cm. The width of IDT, with 10 SAW periods, was $5000\mu\textrm{m}$, S11 reflection characteristics and impedances of th eelectrodes deposited with Au were analyzed using a network analyzer; $48.1\Omega$ at th ecenter frquency of 193MHz for Au deposition thickness of $1500{\AA}$ and $50.7\Omega$ at the center frequency of 192MHz for au deposition thickness of $1600{\AA}$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.471-476
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• 2005

We proposed an optical modulator of reflective type to compose the electric field sensor, and theoretically analyzed the performance and characteristics. For the high sensitivity of the sensor, a method to improve the modulation index of the modulator was presented. The electric field sensor using Ti:LiNbO$_{3}$ waveguide was fabricated and qualitatively investigated the characteristics by measuring the low frequency electric field. Even though the sensor showed relatively low modulation index, the electric filed strength of 10$^{-2}$V/m was measured. The experimental results revealed the utilities of this type electric field sensor.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.423-428
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• 2000

We have demonstrated a -8 dB additional reduction in the intensity sidelobe of an apodized-interaction-strength guide-wave acousto-optic filter with a center passband of 1551.6 nm. Acoustic-intensity weighting was achieved by launching a surface acoustic wave (SAW) beam in a straight acoustic waveguide, and gradually transferring this SAW intensity to the active device, and back out, by evanescent-wave coupling across a 50 !lm barrier over a 19 rom interaction length. The intensity sidelobe was -4.27 dB for an unapodized filter with abmpt onset and cutoff of the interaction, but sidelobes were reduced to at most -12.68 dB for a SAW intensity with raised-cosine weighting. The RF driving power was 17.78 mW. A linear tuning rate of 8.86 nmIMHz and a spectral width of -1.7 nm were demonstrated. rated.