• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.55-60
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• 2006

Thermally stable and solution-processable poly(N-arylcarbazole-alt-aniline) copolymers with high structural integrity were synthesized in good yields via palladium-catalyzed polycondensation of aniline with corresponding N-arylcarbazole monomers such as N-(2-ethylhexyloxyphenyl)-3,6-dibromocarbazole,bis[6-bromo-N-(2-ethylhexyloxyphenyl)carbazole-3-yl] and N-(4-(2-ethylhexyl)-3,5-dibromomethylene-phenyl) carbazole, respectively. The optical and electrochemical properties of these copolymers were measured and compared with those of poly(N-alkylcarbazole-alt-aniline) copolymer. All synthesized poly(N-arylcarbazole-alt-aniline) copolymers showed maximum UV-Vis absorption peaks at around 300 nm in THF solution, and exhibited maximum photoluminescence peaks in the blue emission range from 430 to 460 nm. It was also found that poly(N-arylcarbazole-alt-aniline) copolymers had wider band gap energy than poly(N-alkylcarbazole-alt-aniline) copolymer.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.471-478
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• 2002

Vacuum evaporated cadmium sulphide (CdS) thin films were implanted with $Ar^+$ and $N^+$ for different doses. The properties of the ion implanted CdS thin films have been analysed using XRD, optical transmittance spectra, and Raman scattering studies. Formation of Cd metallic clusters were observed in ion implanted films. The band gap of $Ar^+$ doped films decreased from 2.385 eV of the undoped film to 2.28 eV for the maximum doping. In the case of $N^+$ doped film the band gap decreased from 2.385 to 2.301 eV, whereas the absorption coefficient values increased with the increase of implantation dose. On implantation of both types of ions, the Raman peak position appeared at $299\textrm{cm}^{-1}$ and the FWHM changed with the ion dose.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.178-180
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• 2003

We performed semiempirical (AMl and ZINDO) and ab initio (HF and DFT) calculations, to investigate molecular structures and optical properties of DCM and its derivatives. DCM and its derivatives are used as a red fluorescent dopant of the organic electroluminescent host materials, $Alq_3$. We have studied the relationship between the molecular structure and the optical properties of these molecules for the improvement of EL efficiencies. Wavelength at the absorption maximum was found to be red-shifted when the molecule is substituted with both strong electron donating and withdrawing functional groups. A new red fluorescent dye was predicted by QSPR study based on calculations and experimental data.

• 전자공학회논문지D
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• 제34D권6호
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• pp.20-32
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• 1997

An optimum parasitic inductance is observed for maximizing the modulation bandwidth of the multiple quantum well (MQW) electro-absorption optical modulator. For 1.1 pF device cpaacitance of the current MQW optical modulator, the optimum parasitic inductances for maximum bandwidth are calculated for different terminating resistors. In ase of 50.ohm. terminating resistor, the 3-dB modulation bandwidth can be increased 45% wider by using the optimum parasitic inductance than nothing parasitic inductance. This calculated optimum inductance can be practically implemented, since the parasitic inductance of bondwires can be accurately analyzed using the method of moments (MoM) and controlled by changing the length and shpae of bondwires.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1523-1528
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• 2014

Silicon quantum dots (Si QDs) were synthesized by etching silicon nanopowder with aqueous hydrofluoric acid (HF) and nitric acid ($HNO_3$). Then, the hydride-terminated Si QDs (H-Si QDs) were functionalized by 1- octadecene (ODE). By only controlling the etching time, the maximum luminescence peak of octadecylterminated Si QDs (ODE-Si QDs) was tuned from 404 nm to 507 nm. The average optical gap was increased from 2.60 eV (ODE-Si QDs-5 min) for 5 min of etching to 3.20 eV (ODE-Si QDs-15 min) for 15 min of etching, and to 3.40 eV (ODE-Si QDs-30 min) for 30 min of etching. The electron affinities (EA), ionization potentials (IP), and quasi-particle gap (${\varepsilon}^{qp}_{gap}$) of the Si QDs were determined by cyclic voltammetry (CV). The quasi-particle gaps obtained from the CV were in good agreement with the average optical gap values from UV-vis absorption. In the case of the ODE-Si QDs-30 min sample, the difference between the quasi-particle gap and the average optical gap gives the electron-hole Coulombic interaction energy. The additional electronic levels of the ODE-Si QDs-30 min and ODE-Si QDs-15 min samples determined by the CV results are interpreted to have originated from the Si=O bond terminating Si QD.

• 한국광학회지
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• 제11권4호
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• pp.289-293
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• 2000

다이오드 레이저 뒷면 여기 방식을 이용하여 발진 파장이 $2.02\mu\textrm{m}$인 중적외선 Tm:YAG 레이저를 제작하고, 출력 특성을 조사하였다. 레이저의 출력은 Tm:YAG 결정의 온도에 민감하게 변화하였으며, 레이저의 출력경이 곡면경인 경우에 평면적인 격우보다 더 큰 출력을 얻을 수 있었다. 곡면경을 사용하고 Tm:YAG 결정을 지지하는 구리 지지대의 온도를 $6^{\circ}C$로 낮추었을 때, 최고 1.2W의 출력을 얻을 수 있었다. 이 때, 문턱 여기 출력은 약 1.6W이었고, 기울기 효율(slope efficiency) 및 광학 효율(optical to optical efficiency)은 각각 29%와 20%이었다.

• Current Optics and Photonics
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• 제3권6호
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• pp.577-582
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• 2019

We report on a continuous-wave (cw) optical parametric oscillator (OPO) optimized for mid-infrared emission above 5.0 ㎛. The OPO is based on a magnesium-oxide-doped periodically poled LiNbO₃(MgO:PPLN) crystal with a fan-out grating design. A linear two-mirror cavity resonating both at the pump and signal wavelengths is stabilized to the pump laser by using the modified Pound-Drever-Hall (PDH) method. The idler wavelength is continuously tunable from 4.7 ㎛ up to 5.3 ㎛ by varying the poling period of the fan-out grating crystal. Pumped by a diode-pumped solid state (DPSS) laser with a power of 1.1 W at 1064 nm, the maximum idler output power is measured to be 5.3 mW at 4.8 ㎛. The output power above 5.0 ㎛ is reduced to the hundreds of ㎼ level due to increased absorption in the crystal, but is stable and strong enough to be measured with a conventional detector.

• 한국가스학회지
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• 제18권2호
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• pp.48-54
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• 2014

본 논문에서는 알코올 측정용 센서의 광학적 특성 향상을 위한 고유한 광학적 구조를 제안하였으며, 모의해석을 실시하였다. 광 도파관은 한쪽에 공통초점을 갖는 두 개의 타원형 광 도파관으로 구성되었으며, 각 광 도파관의 서로 다른 초점에 적외선 광원과 적외선 센서를 갖는다. 두 타원형 광 도파관의 각도가 30도에서 90도로 증가시켰을 때, 단위면적당 최대 입사광량은 $2.23{\times}10^6W/m^2$에서 $5.74{\times}10^5W/m^2$로 감소하였다. 그러나 조사 빔의 반지름은 1.86 mm로 최소값을 나타내었고, 전체 입사 에너지는 90도 각도를 갖는 구조와 비교하여 약 10 % 작은 값을 보였다. 모의해석 결과로부터 본 논문에 제안한 구조는 긴 흡수파장을 갖는 광학적 가스센서의 감도향상에 기여할 것으로 판단된다.

• ETRI Journal
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• 제23권3호
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• pp.97-105
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• 2001

$1.6\;{\mu}m$ emission originated from $Pr^{3+}:\;(^3F_3,\;^3F_4)\;{\longrightarrow}\;^3H_4$ transition in $Pr^{3+}-\;and\;Pr^{3+}/Er^{3+}$-doped selenide glasses was investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and fullwidth at half-maximum of the fluorescent emission are ~1650nm and 120nm, respectively. A moderate lifetime of the thermally coupled upper manifolds of ${\sim}212{\pm}10{\mu}s$ together with a high stimulated emission cross-section of ${\sim}(3{\pm}1){\times}10^{-20}\;cm^2$ promises to be useful for $1.6{\mu}m$ band fiber-optic amplifiers that can be pumped with an existing high-power 1480 nm laser diode. Codoping $Er^{3+}$ enhances the emission intensity by way of a nonradiative $Er^{3+}:\;^4I_{13/2}\;{\longrightarrow}\;Pr^{3+}:\;(^3F_3,\;^3F_4)$ energy transfer. The Dexter model based on the spectral overlap between donor emission and acceptor absorption describes well the energy transfer from $Er^{3+}$ to $Pr^{3+}$ in these glasses. Also discussed in this paper are major transmission loss mechanisms of a selenide glass optical fiber.

• 한국광학회지
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• 제28권4호
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• pp.158-165
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• 2017

광 흡수체로부터 측정되는 광음향 신호의 크기가 광 흡수계수 값의 증가에 따라 증가하다가 포화되는 광음향 비선형성에 대한 기존의 분석에서는 초음파 측정기의 물리적 형태를 고려하지 않았다. 이 논문에서는 초음파 측정기의 구면 초점 형태가 광음향 비선형성에 미치는 영향을 분석하였다. 구면 초점 초음파 측정기의 공간 필터링에 의한 광음향 공명 현상을 고려하고 기존의 광음향 비선형성에 대한 연구 방법을 보완하여 구면 초점 초음파 측정기로 측정한 광음향 신호에 대한 해석식을 이론적으로 유도하였다. 이 해석식에 의한 결과는 광음향 신호가 특정한 광 흡수계수 값에서 최대값을 나타내고 최대값 이후로는 광 흡수계수 값의 증가에 따라 오히려 감소함을 보였다. 주파수 영역에서 구면 초점 초음파 측정기에 의해 측정된 광음향 신호의 공명 스펙트럼과 초음파 측정기의 주파수 전달 함수를 비교하여 이 기존의 통념과는 다른 특징을 보이는 광음향 비선형성을 이해하였다. 또한, 이 주파수 영역에서의 물리적 해석으로 인해 광음향을 발생시키는 광 흡수체 내부의 광 조도 형태도 광음향 비선형성에 영향을 미친다는 것을 알 수 있었다.