• Current Optics and Photonics
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• v.3 no.4
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• pp.342-349
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• 2019

We present a theoretical research concerning terahertz (THz) wave generation with $KTiOPO_4$ (KTP) by collinear phase matching (CPM) stimulated polariton scattering (SPS). Both CPM and corresponding nonzero nonlinear coefficients can be simultaneously realized with $s{\rightarrow}f+f$ in yz plane, $s{\rightarrow}f+s$ with ${\theta}$ < ${\Omega}$ in xz plane and $s{\rightarrow}f+f$ with ${\theta}$ < ${\Omega}$ in xz plane. The effective nonlinear coefficients including electronic nonlinearities and ionic nonlinearities are calculated. Based on the parameter values of refractive indices, absorption coefficients and effective nonlinear coefficients, we simulate THz wave intensities generated with CPM SPS by solving coupled wave equations and give the relationship among the maximum THz wave intensity, optimal crystal length and the angle ${\theta}$. The calculation results demonstrate that CPM SPS with KTP can generate THz waves with high intensities and quantum conversion efficiencies.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.1-11
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• 1997

The soot and OH radical distributions have been experimentally studied in ethylene and propane laminar diffusion flames. The integrated soot volume fraction was measured along the centerline of a flame using a laser light extinction method. Planar laser light scattering and PLIF techniques are employed for the soot and OH radical distribution measurements utilizing Nd:YAG laser and OPO, FDO system. The concentration of OH radical is rapidly decreased at the edge of sooting region, which implies the importance of OH radical species on the soot oxidation process. For ethylene flames, the addition of air in fuel moves the OH radical distribution towards the center line of a flame at the soot oxidation region, while the concentration of OH radical remains relatively high at the soot formation region. The interaction between soot particles and OH radicals becomes more active with fuel-air at the soot oxidation region. For propane flames, however, any indication of the increased interaction between soot particles and OH radicals with fuel-air was not noticed.

• Journal of Species Research
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• v.5 no.3
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• pp.309-312
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• 2016

Cleantioides rotundata (Kussakin, 1982) is reported for the first time in South Korea. Specimens of C. rotundata were collected with a small hand net from the intertidal zone of Opo-ri, Yeongdeok-gun in South Korea. This species makes tubes using seagrass debris at our sampling location and distinguished by the following characteristics: pleotelson long, length almost 1.6 times as long as width; dorsum of distal one third with deeply bilobed depression on plane. In this paper, we provide descriptions of diagnostic characteristics and illustrations of morphology of C. rotundata. Additionally, a key to the Korean species of the genus Cleantioides is provided and the partial sequences of the mitochondrial cytochrome c oxidase subunit 1 (CO1) are provided as molecular characteristics.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.95-98
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• 1999

This paper describes preliminary discussions on spatial distribution of NO density, which is mostly contained in simulated NOX exhaust, between a wire-cylinder geometry discharge gaps by using Laser Induced Fluorescence(LIF) Spectroscopy. Spatial distribution of NO density will be measured with varying NO concentrations from 166 to 644[ppm] and diameters of central electrode from 6 to 10mm. Pulsed Nd:YAG laser, Optical Parametric Oscillator(OPO), and Frequency Doubler are used to excite NO molecules to their excited state.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.938-940
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• 2003

고출력 반도체 레이저(500mW)의 출력광 파장 809nm과 반도체 레이저로 여기되는 Nd:YVO4레이저의 출력광 파장 1064nm를 공진기 내부에서 비선형 광학 소자인 KTP(Potassium titanyl posphate : KTPiOPO$_4$)를 사용하여 합주파 발생 실험을 행하여 459nm의 청색레이저를 얻었다. 제2의 위상 정합 정합조건($\psi$=90$^{\circ}$, $\theta$=90$^{\circ}$)에서 반도체 레이저의 입력광 세기가 400mW일 때 청색레이저의 최대 출력 0.95mW를 얻었으며, 청색레이저의 발진문턱입력 세기는 120mW이었다.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2256-2258
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• 1999

This paper describes preliminary discussions on spatial distribution of NO density, which is mostly contained in simulated NOx exhaust, between a wire-cylinder geometry discharge gaps by using Laser Induced Fluorescence(LIF) Spectroscopy, Spatial distribution of NO density will be measured with varying NO concentrations from 166 to 644 [ppm] and diameters of central electrode from 6 to 10mm. Pulsed Nd:YAG laser. Optical Parametric Oscillator(OPO), and Frequency Doubler are used to excite NO molecules to their excited state.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.230-231
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• 2003

$KNbO_3$is one of the best materials for efficient nonlinear frequency conversion, due to its large nonlinear optical coefficient ($d_{33}$ ＝ 20.6 pm／V), wide transparency range (0.4 ~ 5 $\mu$m) and freedom from photorefractive effects. Quasi-phase-matched second harmonic generation using periodically poled $KNbO_3$ (PPKN) crystals has been reported. Here we report on fabrication of PPKN and demonstration of a pulsed optical param etric oscillator (QPM OPO) pumped by an Nd：YAG laser. (omitted)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.224-227
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• 2006

We have chained 459nm blue laser radiation generated by intracavity sum frequency generation( SFG ) due to the mixing of the 1064 nm laser output of a Nd:YVO4 pumped by diode and the 809nm radiation from higg-power semiconductor laser(500mW). The maximum blue output power of 0.95 mW was obtained using 400 mW input power of semiconductor laser at the type II phase matching condition (${\psi}=90^{\circ}\;{\theta}=90^{\circ}$). The threshold input power of blue laser generation was 120 mW.

• Medical Lasers
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• v.9 no.2
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• pp.126-133
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• 2020

Recurrent respiratory papillomatosis (RRP) is a benign tumor that occurs in the respiratory tract, especially in the larynx. The etiology of RRP is human papillomavirus (HPV). According to the age of occurrence, RRP is divided into childhood-onset and adult-onset types. Generally, childhood-onset RRP shows a high recurrence rate and diffuse involvement in the respiratory tract. Adult-onset RRP is more localized and appears more frequently as a solitary lesion. It may be the result of sexual transmission or the proliferation of latent HPV infections. At present, the treatment of choice for RRP is CO₂ laser ablation. In addition, pulse dye laser or KTP (KTiOPO: potassium-titanyl-phosphate) lasers are also used. Non-surgical adjuvant therapies can be applied in cases requiring repetitive surgery or with diffuse extensions. This review will introduce the clinical features of RRP and various treatment options including lasers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.12-17
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• 1993

Growth runs of KTP single crystals were carried out by the hydrothermal method. KTP powders used for the crystal growth were prepared as a single phase by the solid state reaction of a stoichiometric mixture of $KH_2PO_4 and TiO_2$ at TEX>$800^{\circ}C$ and subsequently by the hydrothermal treatment at $250^{\circ}C$ 4m KF solution. The most effective solvents for the crystal growth of KTP were KF and K $K_2HPO_4$ solutions. Solubilities of KTP in these solutions were positive over the range $350~450^{\circ}C$.Seed crystals of good quality could be obtained by the horizontal temperature gradient method at temperatures over the range 380~430^{\circ}C$ in these solutions. The hydrothermal conditions for the high growth rates of seed crystals are as follows: growth method; vertical temperature gradient method, solvent; 4m KF or $K_2HPO_4$ solution, temperature region; $400~450^{\circ}C$, pressure region; $1000~1500kg/cm^2$, where solubility of KTP was large enough to proceed the growth. Under such conditions, seed crystals of KTP are grown at a rate of approximately 0.06-0.08mm/day in the direction of the c-axis. Morphologies of grown crystals tended to be bounded by (100), (011) and (201) faces.