• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.214-215
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• 2000

As silica based optical fibers and preforms are processed at a high temperature, residual stresses are bulit in the strucure when cooled down to the room temperature. The magnitude of the residual stress depends on the difference in the thermal expansion coefficients between core and cladding glass as well as on the temperature difference. Residual stress distribution determines the intrinsic strength and could affect the long term reliability of optical fibers. And furthermore, stress can introduces anisotropy into optical fibers by photoelastic effects. The analysis of thermal stress has been intensively studied for multimode fibers$^{(1)}$ and the authors and co-wokers recently reported the stress distribution in a depressed inner cladding structure$^{(2)}$ . The compositions of the glass in the previous studies, however, have been restricted to conventional glass formers, such as GeO2, B2O3, P2O5, Fluorine. (omitted)

• 반도체디스플레이기술학회지
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• 제16권4호
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• pp.91-96
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• 2017

In this computational study of optical fiber manufacturing, WOW (wet-on-wet) double coating process on freshly drawn glass fiber has been numerical modelled and simulated using a simplified geometry of typical optical fiber coating apparatus. The numerical domain includes primary and secondary coating dies along with secondary coating cup and the interface between primary and secondary coating liquids are investigated using level set method. Coating liquid viscosity is an important parameter and its dependence on temperature is also considered. Since there would be possibility for pressure and temperature of primary coating liquid to be increased substantially at high fiber drawing speed, the effects of increased pressure and temperature of primary coating liquid are examined on flow patterns of coating liquids in secondary coating cup. In case that both pressure and temperature of primary coating liquid are high enough, liquid interface becomes noticeably unstable and this flow instability could adversely affect the uniform coatings and final quality of produced optical fiber.

• 한국결정성장학회지
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• 제23권1호
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• pp.44-50
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• 2013

E-glass 섬유는 항공기, 자동차, 레져기구의 복합재료 보강용으로 가장 널리 사용되는 유리섬유이다. 그러나 최근 E-glass 섬유의 원재료비 상승, 환경문제 및 화학적 저항성과 기계적 특성을 향상시키기 위해 산화붕소 함량을 8 %에서 0(제로)까지 감소시키는(소위 'Boron free E-glass'라고 불리는) 연구가 진행되고 있다. 본 연구에서는 'BF(Boron free E-glass)' 조성의 벌크유리와 섬유유리를 제조하고, 열적특성 및 광학적특성을 평가하였다. 5~10 %의 서로 다른 알루미나 함량을 갖는 배치를 $1550^{\circ}C$에서 2시간 용융하여 'BF(Boron free E-glass)'가 얻어졌고, 81~86 %의 높은 가시광투과율, $4.2{\sim}4.9{\times}10^{-6}/^{\circ}C$의 낮은 열팽창계수, $907{\sim}928^{\circ}C$의 연화점을 갖는 투명하고 맑은 유리가 얻어졌다. 'BF' 섬유 시편에 대한 화학적내구성 시험에 있어서는 알루미나 함량이 높아질수록 더 좋은 침식저항성을 나타냄을 확인할 수 있었다.

• Current Optics and Photonics
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• 제6권1호
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• pp.32-38
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• 2022

Erbium-doped fiber amplifiers (EDFAs) have saturated the technological market but are still widely used in high-speed and long-distance communication systems. To overcome EDFA saturation and limitations, its erbium-doped fiber is co-doped with other materials such as zirconia and bismuth. This article demonstrates and compares the performance using three different fibers as the gain medium for zirconia-erbium-doped fibers (Zr-EDF), bismuth-erbium-doped fibers (Bi-EDF), and commercial silica-erbium-doped fibers (Si- EDF). The optical amplifier was configured with a double-pass amplification system, with a broadband mirror at the end of its configuration to allow double-pass operation in the system. The important parameters in amplifiers such as optical properties, optical amplification and noise values were also examined and discussed. All three fibers were 0.5 m long and entered with different input signals: 30 dBm for low input and 10 dBm for high input. Zr-EDF turned out to be the most relevant optical amplifier as it had the highest optical gain, longest transmission distance, highest average flatness gain with minimal jitter, and relevant noise figures suitable for the latest communication technology.

• ETRI Journal
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• 제27권4호
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• pp.446-448
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• 2005

Using tightly focused femtosecond laser pulses, we produce an optical waveguide and devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three-dimensional optical devices. In this paper, an optical splitter and U-grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near-IR femtosecond laser pulses. The fiber- aligned optical splitter has a low insertion loss, less than 4 dB, including an intrinsic splitting loss of 3 dB and excess loss due to the passive alignment of a single-mode fiber. Finally, we present an output field pattern, demonstrating that the splitting ratio of the optical splitter becomes approximately 1:1.

• Composites Research
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• 제13권1호
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• pp.89-97
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• 2000

광섬유센서를 이용한 복합적층판의 피로손상 감지 및 진동측정, 그리고 스틸 보에 대한 충격위치 검출에 관한 연구가 수행되었다. 피로과정중의 신호는 복합재료 내에 삽입된 광섬유와 표면에 부착한 광강도형 광섬유센서, 그리고 스트레인게이지로부터 동시에 측정되었다. 진동감지 실험은 복합재료 보의 표면에 광섬유센서를 부착하여 자유진동 및 강제진동 신호를 취득하였다. 충격위치 검출에 관한 실험에서 충격위치는 충격에 의해 발생된 구조물의 진동이 두 센서에 도달하는 시간의 차를 이용하여 구할 수 있다. 광강도형 광섬유센서를 이용하여 반복 피로 신호를 잘 취득할 수 있었으며 스트레인게이지에 비하여 피로저항성이 우수함이 확인되었다. 광섬유센서는 갭센서와 동일하게 진동신호를 감지하였고 구조물에 가해진 충격위치를 비교적 정확히 검출할 수 있었다.

• 한국전기전자재료학회논문지
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• 제23권12호
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• pp.978-982
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• 2010

For mass information transfer, the optical communication using optic fiber has been widely used. Especially, in the field of medical image, the large data is digitalized based on the standard image and it is used for telemedicine with this method. Therefore, to transfer the large amount of data fast and effectively POF (Plastic Optical Fiber) can be used and the development of optic connector for connection between POFs is very important. In this study, for stable optical coupling of POF optic fiber Ferrule and Sleeve were designed and produced by considering the bond stability and the insertion loss according to the physical contact and roughness profile was evaluated. As a result of examining the insertion loss by physical contact method of two optic fibers, it showed the loss was about 1.895dB. According to the results from studying the condition of grinding section for POF mass production, the mass production condition was established as POF profile roughness of 6nm and the loss of 0.2dB or lower by controlling the film size and time step by step.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.111-114
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• 2004

Using the embedded optical fiber sensor of totally-reflected extrinsic Fabry-Perot interferometer(TR-EFPI), longitudinal strains(Ex) of the core and skin layers in glass fiber reinforced plastic(GFRP) cross-ply composite laminates have been measured. Transmission optical microscopy was employed to study the damage formation around the TR-EFPI sensor. It was observed that values of ex in the interior of the skin layer and the core layer measured by embedded TR-EFPI sensor was significantly higher than that of the specimen surface measured by strain gauges. The experimental results agreed well with those from finite element analysis on the basis of uniform stress model. Large strains in the core layer led to the occurrence of transverse cracks which drastically reduced the strain at failure of optical fiber sensor embedded in the core layer.

• 대한기계학회논문집A
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• 제29권6호
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• pp.876-888
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• 2005

Tensile properties and fracture toughness of monolithic aluminum, fiber reinforced plastics and glass fiber/aluminum hybrid laminates under tensile loads have been investigated using plain coupon and single-edge-notched specimens. Elastic modulus and ultimate tensile strength of GFMLs showed different characteristic behaviors according to the Al kind, fiber orientation and composition ratio. Fracture, toughness of A-GFML-UD which was determined by the evaluation of $K_{IC}$ and $G_{IC}$ based on critical load was similar to that of GFRP-UD and was much higher than monolithic Al. Therefore, A-GFML-UD presented superior fracture toughness as well as prominent damage tolerance in comparison to its constituent Al. By separating Al sheet from GFMLs after the test, optical microscope observation of fracture zone of GFRP layer in the vicinity of crack tip revealed that crack advance of GFMLs depended on the orientation of fiber layer as well as Al/fiber composition ratio.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.477-482
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• 2004

New materials are being considered for insulator of railroad vehicles. Because people want more environmental material than glass fiber, there are certain needs of finding safe and economical insulating material. We checked the flammability of some kinds insulators such as PE foam, neoprene rubber foam. melamine foam and glass fiber. You could find out the characteristics such as oxygen index. optical smoke density, toxicity index of that insulators.