• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.147-148
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• 1997

• 센서학회지
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• 제31권4호
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• pp.194-213
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• 2022

This study comprehensively reviewed four types of integrated-optic electric-field sensors based on titanium diffused lithium-niobate waveguides: symmetric and asymmetric Mach-Zehnder interferometers, 1×2 directional couplers, and Y-fed balanced-bridge Mach-Zehnder interferometers. First, we briefly explain the crystal properties and electro-optic effect of lithium niobate and the waveguide fabrication process. We theoretically analyzed the key parameters and operating principles of each sensor and antennas. We also describe and compare the design, simulation, implementation, and performance tests: dc and ac characteristics, frequency response, dynamic range, and sensitivity. The experimental results revealed that the sensitivity of the sensor based on the Y-fed balanced bridge Mach-Zehnder interferometer (YBB-MZI) was higher than that of the other types of sensors.

• 대한기계학회논문집A
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• 제33권3호
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• pp.196-200
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• 2009

Lithium niobate ($LN:LiNbO_3$) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN devices, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult b traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters such as down force and relative velocity, were investigated for the LN CMP process To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.102-103
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• 2005

• 한국결정성장학회지
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• 제8권1호
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• pp.10-17
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• 1998

Lithium Niobate($LiNbO_3$) 단결정 소재의 광손상에 대한 저항성을 향상시키는 첨가이온으로 잘 알려져 있는 $Mg^{2+}$ 및 $Zn^{2+}$ 이온을 첨가하여 육성한 단결정들의 특성을 비교 분석하였다. 특히 고강도 laser 광의 조사시에 더욱 우수한 특성을 보이는 것으로 알려진 $Zn^{2+}$이온의 첨가량에 따른 광학적 특성 및 전기적 특성의 변화를 측정하여 광손상 저항성을 평가하였으며, 고강도 laser 기기에의 응용 가능성을 고찰하였다.

• Current Optics and Photonics
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• 제6권3호
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• pp.323-331
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• 2022

Electro-optic modulator (EOM) takes a vital role in connecting the electric and optical fields. Here, we present a heterogeneously integrated EOM based on the lithium niobate-on-insulator (LNOI) platform. The key modulation waveguide structure is a field-enhanced slot waveguide formed by embedding silicon nanowires in a thin-film lithium niobate (LN), which is different from the previously reported LN ridge or etchless LN waveguides. Based on such slot structure, optical mode field area is reduced and enhanced electric field in the slot region can interact well with LN material with high Electro-optic (EO) coefficient. Therefore, the improvements in both aspects have positive effects on enhancing the modulation performance. From results, the corresponding EOM by adding such modulation waveguide structure achieves better performance, where the key half-wave-voltage-length product (V_𝜋L) and 3 dB EO bandwidth are 1.78 V·cm and 40 GHz under the electrode gap width of only 6 ㎛, respectively. Moreover, Lower V_𝜋L can also be achieved. With these characteristics, such field-enhanced waveguide structure could further promote the development of LNOI-based EOM.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.420-423
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• 2010

We fabricated 1 mm-thick periodically-poled lithium niobate (PPLN) crystals by using a high-voltage amplifier for standard electric field poling combined with a voltage multiplier. Furthermore, two 1 mm-thick PPLNs were directly bonded to make a 2 mm-thick PPLN. The large aperture allowed broad angular tuning, and a broad spectral range of quasi-phase matched second-harmonic generation can be achieved in a single channel. High-power applications are also expected.

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.205-209
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• 2008

We demonstrated a simple way of evaluating the duty cycle error in periodically polled lithium niobate(PPLN) based on the method of binary phase diffraction grating. To demonstrate this method, -Z face etched PPLN of desired periods were fabricated by the standard electric field poling technique. The etched PPLN was considered as a surface-relief binary phase grating. The diffraction patterns were recorded for different spatial locations along the length of the sample. The experimentally observed efficiencies of the diffracted orders were compared with the theoretically calculated values to estimate the duty cycle error.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.121-122
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• 2008

Lithium Niobate (LN:LiNbO3) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN device, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult by traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters scuh as pressure and relative velocity, were investigated for the LN CMP process. To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance and non-linear characteristic.

• 한국결정성장학회지
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• 제7권3호
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• pp.384-392
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• 1997

레이저의 파장을 변환시키는 비선형광학 재료인 potassium lithium niobate(KLN) 단결정은 상온에서 정방형 tungsten-bronze 구조를 갖는 강유전체이다. 결정성장이 매우 어렵고 성장된 결정을 냉각하는 과정에 생기는 균열에 의해 고품질의 단결정을 얻기가 쉽지 않았다. 결정성장 도중에 생기는 용액의 증발에 의한 조성의 변화를 알아보고자 열중량 분석을 행하였는데 결정성장 온도보다 약 1$0^{\circ}C$ 정도 높은 $1000^{\circ}C$에서 휘발은 $1.46{\times}10^{-5}$g/ ($\textrm{cm}^2$hr)로 미량이었다. 백금판을 핵생성의 자리로 사용하고 온도에 요동을 주며 서냉을 하여 결정을 성장시키는 방법을 사용하여 좋은 품질의 비교적 대형인 1 cm 정도의 KLN 단결정을 성장시킬 수 있었다. 상전이 온도는 $490^{\circ}C$로 앞서 보고된 것보다 고온이었다. OH- 밴드에 의한 광학적 이방성이 IR 영역에서 존재하였다.