• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.40-41
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• 2003

대용량 정보 통신 선로로 이용되고 있는 단일모드 광섬유에서, 초고속. 장거리 광신호 전송에서 발생하는 색분산(Chromatic dispersion)을 보상하기 위하여 비주기 광섬유 격자(Chirped fiber Bragg grating ; CFG)를 적용하여 그 특성을 조사, 분석 하였다. 10Gbps의 전송 시스템에서 80km 단일모드 광섬유 전송후의 색분산에 의한 광신호 품질 열화 및 CFG에 의한 보상 특성을 측정하기 위하여 BER 과 eye pattern 테스트를 하였다. 또한 기존에 색분산 보상용으로 사용되고 있는 분산 보상 광섬유(Dispersion compensation fiber ; DCF)와 특성 비교을 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1A
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• pp.1-9
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• 2005

We have studied the dispersion properties of a 40 channel x 10 Gbit/s wavelength division multiplexer(WDM) transmission link using standard single mode fiber with all EDFA amplification over 30 x 100 km spans. The dispersion map of the link was investigated by adding fiber sections with positive or negative dispersion at the transmitter, within each amplifier span, and at the receiver. Optimum combinations of these dispersive fiber lengths were attained to significantly enhance the overall transmission performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.623-625
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• 2022

In this paper, the proton induced attenuation characteristics were evaluated for 5 types of commercial single-mode optical fibers using a proton accelerator. The proton beam used in the irradiation test has a high energy of 100 MeV class, and the test was performed by setting the uniformity of the beam irradiation area to 10% or less. According to the type of optical fiber (internal material, impurities), the radiation induced attenuation by the proton irradiation showed a noticeable difference.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.79-84
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• 2005

To increase the tolerance for passive fiber alignment, a single mode polymer waveguide with a large core structure is demonstrated. The large core waveguide is designed to have a mode profile comparable to that of a thermally expanded core (TEC) fiber, and it can be connected to a high-contrast waveguide through an adiabatic transition taper structure. From a waveguide with a rectangular core of 25 ${\times}$ 25 ${\mu}{\textrm}{m}$$^2$, a single mode propagation is observed when the index contrast is as low as 0.0005. A UV-cured injection molding method is used to fabricate the thick core structure. Due to the large mode size, the insertion loss of the device is below 0.5 dB until the lateral displacement of the TEC fiber is 4.5 ${\mu}{\textrm}{m}$. The low insertion loss is important for reproducible passive alignment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.63-68
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• 2000

A passively mode-locked ring type fiber laser had been installed in order to get the short pulses The single and the double mode-locking were appeared, and the shortest pulse length of 65 fs was obtained with a 110 m long dispersion shifted fiber(DSF) in a local cavity of 139.8 m. Also high order harmonic modelocking of 17th and Q-switched high order harmonic modelocking were obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.188-194
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• 2011

We analyze transmission performance of radio frequency signal in WDM-ROF (wavelength division multiplexing - radio over fiber) system employing photonic crystal fiber. In a WDM-ROF system employing conventional single-mode fiber, transmission performance of radio frequency signal is analyzed depending on each WDM channel. In this case, each WDM channel experiences power fluctuation of received RF signal in remote node because of double sidebands of the modulated signal and wavelength dependent dispersion of single mode fiber. This RF power fluctuation acts as a design constraint in viewpoint of system design. By employing photonic crystal fiber (PCF) with dispersion compensation characteristics, the transmission performance of RF signal can be improved compared with the case with SMF only.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.75-76
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• 2006

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.701-704
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• 2014

In this study, we studied the effect of $Co^{60}$ gamma-radiation on the FBGs written in photo-sensitive and commercial Ge-doped single-mode optical fibers. The FBGs were exposed to gamma-radiation up to a dose of 17.8 kGy at the dose rate of 300 Gy/min. According to the experimental data and analysis results, the lowest Bragg wavelength shift (18 pm) was obtained by a grating written in photosensitive fiber without $H_2$-loading.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.133-135
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• 2006

We propose and fabricate a novel fiber optic sensor for the detection of abnormal structural signals from various constructions. It's advantages are highly sensitive. small in dimension and electro-magnetic immune. Since this sensor was simply constructed with a single-mode fiber at infra-red wavelength and a laser-diode with the wavelength of 625 nm, the modes in the end of the optical fiber were not show as Gaussian distributed. So, we used the change of the mode distribution to get the sensor output by the external abnormal effect of structures. We investigated the resonance by performing the bending test of an aluminum beam attached with the fiber sensor. In the test, we could obtained a feasible signal to sense the abnormal condition of structures.