• 한국광학회지
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• 제9권3호
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• pp.168-174
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• 1998

본 연구에서는 광학매질의 비선형 특징을 측정하기 위해, 자체집속현상을 이용하는 기존의 측정법과는 다르게, 매질을 통과한 광원의 위상섭동으로 인하여 far-field에 발생한 공간적 광장도 분포를 이용하는 far-field 위상 변조량 측정법을 사용하였다. 미선형 매질을 통과한 조사과의 위상 변화가 far-field 영역에서 나타나는 겅간적 위상 변조량을 실험적으로 측정아였고, 이를 전산시\ulcorner을 통하여 비교분석하였다. 파장 616nm, 펄스폭 106ps의 분포궤한 섹소레이저(DFDL)와 파장 308nm인 DFDL의 제2고조파를 조사광으로 사용하였고, 매질 $CS_2$와 $BaF_2$의 비선형 특성을 실험적으로 측정한후 이 값을 전산시늉값과 비교하였다. 이 실험에서 파장 616nm에 대해 $CS_2$와 $BaF_2$의 비선형 굴절률 $1.2{\times}10^{-11}$ esu와 $1.0{\times}10^{-13}$ esu를 각각 얻었고, 파장 308nm에 대해 $BaF_2$의 비선형 흡수계수 $5.0{\times}10^{-11}$cm/W를 얻었다. 이들 값은 지금까지 발표된 값들과 잘 일치한다.

• 제어로봇시스템학회논문지
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• 제11권9호
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• pp.741-749
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• 2005

This paper presents a nonlinear controller design for optical disk drive systems to improve anti-shock performance. The nonlinear anti-shock controller is added parallel to the original linear servo control loop. In the previous work, a dead-zone nonlinear element is used for the nonlinear controller and a PID control method is used for the linear controller. Although this parallel structure of the controller improves anti-shock performance, it has a narrow stability bound. In this paper, the dead-zone with saturation nonlinear element is proposed for the nonlinear controller. Since this nonlinear element improves stability margin, we can use higher slope gain of dead-zone than that of nonlinear controller using dead-zone only. In the linear controller design, it is shown that the lead-lag control has an improved stability margin over PID control. Numerical simulation results and experimental results show that the proposed method can get better performance to the external shock than previously proposed methods.

• 한국광학회:학술대회논문집
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• 한국광학회 2002년도 하계학술발표회
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• pp.94-95
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• 2002

Photonic crystal (PC) has special interests for their promising applications in three-dimensional photon control and integrated devices. In a nonlinear photonic crystal (NPC), optical intensity in a defect layer is greatly increased due to the location function of NPC and nonlinearity. The nonliearity of the defect layer is very much enhanced because the group velocity is reduced and the interaction time between light and nonlinear medium in the defect layer is enlarged. (omitted)

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.198-203
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• 1997

Two different carbazolylnitrostilbene chromophores with second-order nonlinear optical (NLO) activity were newly synthesized by the reaction of 9-(2-hydroxyethyl)-9H-carbazol-3-carbaldehyde with 4-nitrophenylacetonitrile or 4-nitrophenylacetic acid. The NLO monomers were obtained by reaction of these chromophores with methacryloyl chloride. The side-chain nonlinear optical polymers were synthesized by the copolymerization of NLO monomer with methylmethacrylate using a free radical initiator. The chemical structures of the polymers were identified by spectroscopic means and the polymer properties such as molecular weight, Tg, solubility, UV-visible absorption, and second-harmonic generation (SHG) coefficients were investigated.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.192-195
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• 2007

A high-conversion efficiency, nanosecond pulsed optical parametric generation and amplification with repetition rate of 20 kHz based on a periodically poled MgO-doped stoichiometric lithium tantalate was presented. Pumped by a Q-switched $Nd:YVO_4$ laser at 1064 nm with a pumping power of 4.8W, the generated output power was 1.6W for the signal and idler waves, achieving a slope efficiency of 50%. Using a seed source at signal wave the amplified signal output-pulse energy reached $65{\mu}J$. The obtained maximum gain was 72.4 dB.

• Medical Lasers
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• 제10권2호
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• pp.82-89
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• 2021

Background and Objectives Due to changes in diet and lifestyle, the number of obese people worldwide is steadily increasing. Obesity has an adverse effect on a healthy life, so it needs treatment and improvement. Research related to this is continuously being conducted. Materials and Methods The laser system to compact designed using 808 nm laser diode and Neodymium Yttrium orthovanadate generates a 1064 nm wavelength, the periodically polarized nonlinear crystal pumping laser beam. The pulsed 1064 nm wavelength beam passing through the AO Q-switch is used as the pumping light of the nonlinear optical crystal and is irradiated to the periodic polarized nonlinear optical crystal with a quasi-phase matching period. Nonlinear optical crystals use an oven to control the temperature to generate the desired 1980 nm and 2300 nm wavelengths. Results The 1980 nm and 2300 nm wavelengths generated by temperature control of nonlinear optical crystals are effective for lipolysis. A fiber catheter was used so that the laser could be directly irradiated to the fat cells. In particular, the new wavelength (1980 nm, 2300 nm) can increase the fat reduction effect with low energy (1.3 W). When a laser with a combination wavelength of 1980 nm and 2300 nm was used, an average lipolysis effect of 20% was obtained. Conclusion A mid-infrared lipolysis laser system with excellent absorption of fat and water has been developed. We conducted a princlinical study to confirm the efficacy and safety of the lipolysis laser system, and obtained good results for lipolysis with low energy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.12-13
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• 2002

The performance improvement of 40Gbit/s soliton transmission system employing nonlinear optical loop mirror (NOLM) as all-optical regenerative repeater is investigated. The switching characteristic of NOLM is optimized using our design strategies. By inserting the optical repeater where the eye-penalty of the transmitted signal becomes 1 ㏈, we achieve the improvement of 0.3㏈ eye-penalty resulting in further 480km transmission distance.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
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• pp.360-361
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• 2004

An atomization doping process is proposed to manufacture nonlinear optical fiber containing higher concentration of PbTe nano-particles in the core of the fiber than that by the conventional solution doping process. The absorption peaks appeared near 725nm, 880nm, and 1050nm are attributed to the PbTe quantum dots in the fiber core.

• Journal of Photoscience
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• 제10권2호
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• pp.203-208
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• 2003

Two coupled molecules were successfully synthesized by condensation of amine-donor-substituted barbituric acid derivativies as nonlinear optical chromophores. A flexible spacer of the alkyl chain with different lengths of carbon chains (5 and 6 carbons) was introduced between two chromophores, which prevented crystallization and aggregation of molecules. Two coupled molecules (B-Cn-B, n=5, 6) had glass-transition temperatures on a second heating around 81 and 76$^{\circ}C$ without melting points, respectively. To explore the linear optical properties, thin-films were prepared and examined by a photometry method using Nd:YVO$_4$ CW laser. Also, microscopic and macroscopic nonlinear optical properties were measured by Hyper-Rayleigh Scattering (HRS) and the Maker Fringes method using Nd:YAG ps pulse laser, respectively. In spite of the moderate hyperpolarizabilities of coupled molecules, the second order NLO coefficient (d$\_$33/) was larger than the conventional Disperse Red 1 doped PMMA polymeric system.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.68-68
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• 2000

In this paper a very brief review of historical development of optical science and technology in China is presented. More attention has been pain on Modem Optics, which developed since 1950s. The recent development of optical science and technology in following fields are introduced. 1. Optical engineering and instrumentation (tracking theodolites, high speed cameras, satellite laser ranging systems, satellite flying attitude control, cameras for remote sensing, astronomical optical instrument) 2. Applied optics (adaptive optics, optical metrology, infrared optics, optical processing, optical holography) 3. Laser science and technology (ultrashort pulse lasers, UV-X ray lasers, high power laser facilities and laser fusion, laser isotope separation) 4. Laser and nonlinear materials (rare earth elements doped laser glasses and crystals, tunable laser crystals, borate series and organic nonlinear crystals) 5. Optoelectronic science and technology (Optical communication, optical data storage, optical computing) The current situation and developing prospect of optical and optoelectronic industry in China are presented. Furthermore it points out that the optical industry could be developed vigorously only if products development capacity is enhanced and new products industrialization is heightened. The main research and education institutions in the optics field in China, as well as the Chinese Optical Society (COS) are introduced.