• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 하계학술발표회 논문집
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• pp.317-318
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• 2006

• 한국재료학회지
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• 제29권12호
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• pp.747-752
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• 2019

Environmental pollution remains a considerable health risk source all over the world; however, hazards are usually higher in developing countries. Iraq has long been suffering from the problem of pollution and how to treat pollution. Photocatalytic degradation has turned out to be most productive process for dye degradation. In this investigation, Rhodamine B (RhB), dye has been selected for degradation under visible light illumination. To address this issue, we fabricate erbium trioxide nanoparticles (Er₂O₃/NPs). Erbium trioxide nanoparticles are prepared and utilized for photo-catalytic degradation. The characterization of Er₂O₃/NPs is described and confirmed by utilizing of XRD (X-ray diffraction) and SEM (Scanning Electron Microscopy). The average size of Er₂O₃ nanoparticles is observed to be 16.00 nm. Er₂O₃/NPs is investigated for its ability of photo-catalytic degradation through certain selected parameters such as concentration and time. The methodological results show that the synthesized Er₂O₃/NPs is a good photo-catalytic for Rhodamine degradation.

• 한국광학회지
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• 제21권4호
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• pp.139-145
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• 2010

본 논문에서는 고농도로 도핑된 Bismuth 기반 어븀첨가 광섬유 증폭기의 이득 및 노이즈 특성을 정확히 예측하기 위하여 필요한 이론적 모델링 기법에 대한 연구를 수행 하였다. 고농도의 Erbium 이온이 첨가되었을 때 발생하는 Clustering 현상에 기인한 Inhomogeneous Broadening현상, Cooperative Upconversion 현상, Pump Excited State Absorption과 Signal Excited State Absorption 현상 등 모든 현상을 고려하여 6 레벨 증폭기 System Model을 제시하고 이를 전산모사하여 실험치와 비교함으로써 제시된 모델의 유효성을 검증하였다.

• 전기전자학회논문지
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• 제8권1호
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• pp.117-120
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• 2004

단일 광섬유 격자와 Yb와 Er이 첨가된 광섬유를 이용한 스트레인 및 온도의 동시 측정을 시행하였다. 스트레인과 온도에 대해서 $1100\;{\mu}{\varepsilon}$ and $50-180\;^{\circ}C$ 범위에서 $55.8\;{\mu}{\varepsilon}$ 와 $3\;^{\circ}C$의 오차를 가지고 측정하였다. 본 센서의 소형 및 저가의 특성으로 미루어 볼 때 넓은 범위의 스트레인 센서로 활용가치가 높다고 사료된다.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.342-350
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• 2010

An optimal wideband gain flattened hybrid erbium-doped fiber amplifier/fiber Raman amplifier (EDFA/FRA) has been introduced. A new and effective optimization method called particle swarm optimization (PSO) is employed to find the optimized parameters of the EDFA/FRA. Numerous parameters which are the parameters of the erbium-doped fiber amplifier (EDFA) and the fiber Raman amplifier (FRA) define the gain spectrum of a hybrid EDFA/FRA. Here, we optimize the length, $Er^{3+}$ concentration, and pump power and wavelength of the EDFA and also pump powers and wavelengths of the FRA to obtain the flattest operating gain spectrum. Hybrid EDFA/FRA with 6-pumped- and 10-pumped-FRAs have been studied. Gain spectrum variations are 1.392 and 1.043 dB for the 6-pumped- and 10-pumped-FRAs, respectively, in the 108.5 km hybrid EDFA/FRAs, with 1 mW of input signal powers. Dense wavelength division multiplexing (DWDM) system with 60 signal channels in the wavelength range of 1529.2-1627.1 nm, i.e. the wide bandwidth of 98 nm, is studied. In this work, we have added FRA's pump wavelengths to the optimization parameters to obtain better results in comparison with the results presented in our previous works.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.162-166
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• 2014

The impact of booster section length made from passive erbium-doped fiber (EDF) on the L-band multiwavelength Brillouin-Erbium fiber laser (MBEFL) is studied experimentally in this paper. The influence on the performance of MBEFL in term of number of generated Stokes lines, tuning range and lasing threshold were investigated. A comparison was made between MBEFL without a booster section and with booster sections of different lengths. Through comparative study and at fixed BP power and 100mW of 1480 pump power, longer passive EDF length of 5m exhibits the highest average number of Stokes lines of 23 with tuning range of 14nm. In contrast, shorter passive EDF length of 1m shows the highest tuning range of 17nm and an average number of 21 Stokes lines.

• 한국광학회지
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• 제6권4호
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• pp.296-301
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• 1995

광섬유격자와 단방향성 광섬유 loop mirror를 이용하여 단일모드로 발진하는 erbium첨가 광섬유레이저를 구성하였다. 이득매질인 erbium첨가 광섬유를 단방향성 loop내에 둠으로써 레이저광이 이득매질내에서 진행파를 이루도록 하고 loop 밖에서 반사 선폭이 0.2nm인 광섬유격자로 파장선택적 귀환시켜 주는 방식으로 공진기를 구성하였다. 수동형 광섬유 링공진기 형태의 광스펙트럼 분석기를 별도로 구성하여 광섬유레이저의 모드 스펙트럼을 관찰한 결과, 외부 온도변화로 인한 분 단위의 모드 튐을 제외하고는 대부분의 시간에 안정적인 단일모드 및 단일편광 상태의 특성을 나타냄을 확인할 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.79-87
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• 2014

PURPOSE. The aim of this study was to determine the efficiency of Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet laser in different output powers for removing permanent resin cement residues and therefore its influence on microshear bond strength compared to other cleaning methods. MATERIALS AND METHODS. 90 extracted human molars were sectioned in 1 mm thickness. Resin cement was applied to surface of sliced teeth. After the removal of initial cement, 6 test groups were prepared by various dentin surface treatment methods as follows: no treatment (Group 1), ethylene diamine tetra acetic acid application (Group 2), Endosolv R application (Group 3), 1.25 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 4), 2 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 5) and 3.5 W Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet laser irradiation (Group 6). The topography and morphology of the treated dentin surfaces were investigated by scanning electron microscopy (n=2 for each group). Following the repetitive cementation, microshear bond strength between dentin and cement (n=26 in per group) were measured with universal testing machine and the data were analyzed by Kruskal Wallis H Test with Bonferroni correction (P<.05). Fracture patterns were investigated by light microscope. RESULTS. Mean microshear bond strength ${\pm}$ SD (MPa) for each group was $34.9{\pm}17.7$, $32.1{\pm}15.8$, $37.8{\pm}19.3$, $31.3{\pm}12.7$, $44.4{\pm}13.6$, $40.2{\pm}13.2$ respectively. Group 5 showed significantly difference from Group 1, Group 2 and Group 4. Also, Group 6 was found statistically different from Group 4. CONCLUSION. 2 W and 3.5 W Erbium, Chromium: Yttrium-Scandium-Gallium-Garnet laser application were found efficient in removing resin residues.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.309-313
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• 2008

We studied the sapphire and germanium fibers to determine which optical fiber best transmits Erbium:YAG laser for intracorporeal lithotripsy. Human calculi were ablated with an Erbium:YAG laser in contact mode using two fibers. Optical outputs at the distal end of fibers were measured before and after laser lithotripsy. Upon the irradiation on the calculus with the 50 mJ and 100 mJ pulse energy, the output energy at the distal end of germanium fiber declined to approximately 50% of the input energy. For the sapphire fiber, the output energy at the distal end remained unchanged with 100 mJ input energy; however the output energy had dropped to 50% for 200 mJ input energy. In order to examine how the types of target tissue affect the fiber damage, the sapphire fiber was tested for the irradiation on soft tissue and water as well. No energy decline was observed during soft tissue and water irradiation. We also characterized ablation craters with both optical fibers. Both fibers produced similar craters on calculi in terms of depth and diameter. Sapphire fibers are better suited than germanium fibers for Erbium:YAG lithotripsy in terms of the fiber damage.

• Journal of the Optical Society of Korea
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• 제17권2호
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• pp.117-129
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• 2013

We briefly review the recent progress in passively mode-locked fiber lasers (PMLFLs) based on semiconductor saturable absorber mirrors (SESAMs) and discuss the detailed characterization of a SESAM-based, passively mode-locked erbium-doped fiber (EDF) laser operating in the 1.5-${\mu}m$ spectral range for various configurations. A simple and compact design of the laser cavity enables the PMLFL to generate either femtosecond or wavelength-tunable picosecond pulses with high stability as the intra-cavity filtering method is altered. All the cavities investigated in our experiments present self-starting, continuous-wave mode-locking with no Q-switching instabilities. The excellent stability of the source eventually enables the wavelength-tunable PMLFL to be used as a master oscillator for a power-amplifier source based on a large-core EDF, generating picosecond pulses of >10-kW peak power and >100-nJ pulse energy.