• Journal of the Optical Society of Korea
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• 제10권4호
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• pp.188-195
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• 2006

Third harmonic generation microscopy is described in the frame work of the theory of harmonic generation with Gaussian focused beams inside a bulk material as well as at the vicinity of an interface. This model is then applied to characterize different types of materials in terms of electronic third-order susceptibility. Examples of bulk glasses, poled glasses, laser-induced modifications in glasses and nanoparticles in solution are given in order to give a survey of the broad application field of THG microscopy in material characterization.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.224-225
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• 2003

Since group velocity (GV) mismatch significantly limits the efficiency of nonlinear interactions such as second harmonic generation (SHG), several techniques have been developed to compensate GV mismatch. The simplest way to avoid the GV mismatch problem is to reduce the device length. However, it results in a poor trade-off between the SHG spectral bandwidth and the conversion efficiency. (omitted)

• 한국진공학회:학술대회논문집
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• 한국진공학회 2003년도 제24회 학술발표회 초록집
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• pp.47-48
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• 2003

• 한국광학회지
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• 제2권3호
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• pp.133-138
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• 1991

Eosin을 첨가한 boric acid 유리질 포화흡수체의 포화세기는 비교적 낮은 것으로(약 700 mW/$\textrm{cm}^2$) 측정되었고, 세기가 낮은 경우에서도 축퇴4광파혼합에 의해 광학적 위상공액파를 발생시킬 수 있었다. 파장이 488nm인 Ar-ion laser를 사용하여 이 매질에서 DFWM에 의한 위상공액파의 편광특성을 보였고, 위상공액 반사율의 빛의 세기와 파장에 대한 의존성을 측정하였다. 이 매질에서 비축퇴2광파혼합에 의한 에너지 교환은 두 광속의 주파수차가 약 100 Hz 정도인 경우에 최대가 되었다.

• 한국결정성장학회지
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• 제5권4호
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• pp.318-331
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• 1995

Hologen lamp를 열원으로 한 적외선 집중가열 방식의 Floating zone법을 이용하여 조화융해조성(48.6 mol% $Li_2O : 51.4 mol% LiNbO_3$)의 $LiNbO_3$ 단결정과 여기에 5 mol%의 MgO를 첨가한 $LiNbO_3$:5mod%MgO 단결정을 c-축으로 성장시켰다. 고품질의 광학용 $LiNbO_3$ 결정을 성장시키기 위해 원료봉의 최적 소결조건 및 성장 분위이게 따른 원료봉/융액 계면에 대한 고찰을 하였고, 이를 바탕으로 하여 ga s flow rate, pulling rate, 원료봉과 종자정의 회전속도 등에 대한 최적의 결정성장 조건을 확립하였다. 성장된 결정에 대해서 chemical etching을 통한 etch pattern과 ICP(Inductively Coupled Plasma) 분석을 통한 조성 변동 및 불순물 Fe 함량을 조사하였고, 5 mol% MgO의 첨가에 따른 투과율과 굴절율의 변화를 관찰하였다. 또한 $LiNbO_3$의 비선형 광학특성에 대해서는 측정한 굴절율 값을 data로 하여 비선형 광학 굴절율 $n_2$를 계산하여 다른 광학물질과 비교하였고, 이와 관련하여 비선형 광학특성에 대한 전반적인 고찰을 하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.132-132
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• 2003

Second-order nonlinear optical(NLO) materials have been extensively studied for applications in photonic devices, such as frequency doubling and electro-optical(EO) modulation, because of their large optical nonlinearity, excellent processibility, low dielectric constant, and high laser damage thresholds. The poling behaviour of NLO chromophore in organic/inorganic matrixes showed the randomization of poled NLO chromophore in the absence of poling Held. The liquid crystal molecules in a droplet showed a long-range orientational order along a director. Therefore, liquid crystal effects on poling behaviour of NLO chromophore dispersed in organically modified inorganic sol-gel materials were investigated. Using sol-gel process for the development of NLO material has received increasing attention, Organically modifked inorganic NLO sol-Eel materials are obtained via incorporation of the organic NLO active chromophore into an alkoxysilane based inorganic network. One of the most important thing in this works was that tetraethoxysilane(TEOS) and methyltrimathoxysilane(HTMS) were used as precursor followed by hydrolysis and condensation without using any acidic catalyst during the process. The NLO chromophores in the liquid crystal nanodomains were well mixed with I/O hybrid matrix, deposited on transparent ITO-coated glasses. The poling behaviour of liquid crystal effects of NLO chromophore dispersed in I/O hybrid matrix were investigated by UV-vis spectroscopy. Size distribution and morphology of the NLO chromophores doped in the liquid crystal nanodomains dispersed in I/O hybrid matrix were investigated by SEM.

• Current Optics and Photonics
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• 제7권6호
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• pp.708-713
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• 2023

A robust all-fiber nonlinear amplifying loop-mirror-based mode-locked femtosecond laser is demonstrated. Power-dependent nonlinear phase shift in a Sagnac loop enables stable and power-efficient mode-locking working as an artificial saturable absorber. The pump power is adjusted to achieve the lowest intensity noise for stable long-term operation. The minimum pump power for mode-locking is 180 mW, and the optimal pump power is 300 mW. The lowest integrated root-mean-square relative intensity noise of a free-running mode-locked laser is 0.009% [integration bandwidth: 1 Hz-10 MHz]. The long-term repetition-rate instability of a free-running mode-locked laser is 10^-7 over 1,000 s averaging time. The repetition-rate phase noise scaled at 10-GHz carrier is -122 dBc/Hz at 10 kHz Fourier frequency. The demonstrated method can be applied as a seed source in high-precision real-time mid-infrared molecular spectroscopy.

• 한국결정성장학회지
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• 제4권1호
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• pp.105-110
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• 1994

L-arginine phosphate monohydrate (LAP)와 tris(hydroxymethyl)aminomethane sulfate(THAMS)는 레이저의 파장변환소자등과 같은 소자응용에 있어서 새로운 유기 비선형광학재료이다. 본 연구에서는 온도강하법과 온도차법을 이용하여 LAP와 THAMS 단결정의 육성을 시도하였으며 이들 방벙에 따른 육성조건을 확립하였다. 그리고 육성결정의 특성을 광학현미경, XPD, FTIR 등을 통하여 평가하였다.

• 전기학회논문지P
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• 제51권3호
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• pp.142-148
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• 2002

Considerable progress has been made in organic photorefractive materials, since the first observation of photorefractive phenomena from organic materials. Within recent years, a large number of organic photorefractive materials, especially amorphous materials, have been developed based on polymeric composites, fully functional polymers and the multi-functional chromophore approach. Among these organic photorefractive materials, some of them containing carbazole components as a charge transporting function have been demonstrated to exhibit high performance photorefractive effects. The carbazole building blocks with charge transporting function or multifunctions play a very important role in photorefraction. In this paper, it confirmed that acceptor-substituted carbazoles show the multifunctionality both of photoconductivity and electro-optic(EO) activity and photorefractive materials newly can be developed with acceptor-substituted carbazoles.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.173-173
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• 2010

$Bi_4Ti_3O_{12}$ ($B_4T_3$) is a unique ferroelectric material that has a relatively high dielectric constant, high Curie temperature, high breakdown strength, and large spontaneous polarization. As a result this material has been widely studied for many applications, including nonvolatile ferroelectric random memories, microelectronic mechanical systems, and nonlinear-optical devices. Several reports have appeared on the use of Mn dopants to improve the electrical properties of $B_4T_3$ thin films. Mn ions have frequently been used for this purpose in thin films and multilayer capacitors in situations where intrinsic oxygen vacancies are the major defects. However, no systematic study of the optical properties of $B_4T_3$ films has appeared to date. Here, we report optical data for these films, determined by spectroscopic ellipsometry (SE). We also report the effects of thermal annealing and Mn doping on the optical properties. The SE data were analyzed using a multilayer model that is consistent with the original sample structure, specifically surface roughness/$B_4T_3$ film/Pt/Ti/$SiO_2$/c-Si). The data are well described by the Tauc-Lorentz dispersion function, which can therefore be used to model the optical properties of these materials. Parameters for reconstructing the dielectric functions of these films are also reported. The SE data show that thermal annealing crystallizes $B_4T_3$ films, as confirmed by the appearance of $B_4T_3$ peaks in X-ray diffraction patterns. The bandgap of $B_4T_3$ red-shifts with increasing Mn concentration. We interpret this as evidence of the existence deep levels generated by the Mn transition-metal d states. These results will be useful in a number of contexts, including more detailed studies of the optical properties of these materials for engineering high-speed devices.