• Korean Journal of Optics and Photonics
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• v.27 no.5
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• pp.181-187
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• 2016

We report on the parameter-dependent optical characteristics of the unidirectional single-mode lasing square ring cavities. Using the taper-step section in the square cavities, the resonant direction can be selected and we characterize the optical losses by changing the taper lengths. Various kinds of square ring cavities are fabricated, based on InGaAsP/InGaAs multiple quantum well semiconductor materials. From the experimental results we obtain the optimized taper length for a given device structure, while maintaining unidirectional single-mode lasing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.732-735
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• 2013

In this study, we are measured gamma-ray induced loss on single-mode (SM) fibers from a total of four different manufactures. The $Co^{60}$ gamma-ray source was used in this test. The gamma-ray is irradiated for 2 hours at the dose rate of 0.6 kGy/hr, 1.2 kGy/hr, 2.4 kGy/hr. In test results, We clearly confirm the dose rate effect in different fiber types and evaluate the radiation sensitivity by the change of the radiation-induced loss.

• Korean Journal of Optics and Photonics
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• v.9 no.6
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• pp.403-407
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• 1998

The polarizatin properties of an internal-mirror 543 nm He-Ne laser with and without a transverse magnetic field were investigated for single-mode operation. Two orthogonal eigenpolarizations field to the natural tube axes of laser were observed when the emitted laser output was linearly polarized. Polarization unstability between these polarizations occurred when the applying a 500 gauss transverse magnetic field at 35$^{\circ}$ with respect to the natural tube axes of laser. Under such conditions stable single-mode operation which is useful for the frequency stabilization of a 543 He-Ne laser to $I_2$-saturated absorptions was obtained in the tuning range of 880 MHz.

• 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 Optical Society of Korea Conference
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• 1995.06a
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• pp.35-41
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• 1995

광전송 초고속화되면서 광전송시스팀의 성능에 영향을 미치는 여러 가지 물리적 현상 중에서 광섬유의 편광모드분산에 관하여 고찰하였다. 단일모드 광섬유의 편광특성 해석은 Principal States of Polarization의 변화에 대한 확률모델로서 Maxwellqnsvh를 갖는 확률분포함수를 적용하였다. 이 가정하에서 IM/DD 광통신시스팀에서 편광모델로부터 시스템의 페이딩 특성을 예측하고 이를 기준으로 전송용량의 한계 및 미래의 대용량 광전송시스팀의 전송방식에 대해서도 검토하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.216-217
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• 2001

광섬유와 평면 도파로를 결합한 도파로 구조에서 광 결합 현상은 다양한 응용 가능성 때문에 이론적으로 또는 실험적으로 많은 연구가 되어오고 있다. 광섬유는 단일모드를 이용하고 적당한 곡률이 주어진 블록에 고정한 후 연마하여 클래딩의 일부를 제거하고, 그 상부에 다중모드 평면 도파로(Multi-Mode Overlay Waveguide; MMOW)를 구성한다. 제작된 결합기 구조에서 평면 도파로는 광섬유의 감쇠장 결합(Evanescent field coupling)을 유도하게 되므로, 소자의 특성은 평면 도파로의 구조와 조건에 의해 결정된다. (중략)

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.101-102
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• 2012

지수-골롬 부호는 데이터의 무손실 부호화를 위해 사용되는 대표적인 방법으로서 지수 함수 형태로 단일 모드 분포를 가지는 데이터의 부호화에 적합하다. 본 논문에서는 데이터의 분포가 단일 모드가 아닌 이중 모드를 가지는 경우에 적용하기 위해 변형된 지수-골롬 부호를 제안하고 모드의 높이와 모드 사이의 거리에 따른 부호화 성능을 살펴보았으며 실제 데이터에 적용한 실험결과를 제시하였다.

• Korean Journal of Optics and Photonics
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• v.29 no.4
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• pp.159-165
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• 2018

In this paper, we report on the high power amplification of a narrow-linewidth Yb-doped polarization-maintained (PM) fiber laser in a 3-stage, all-fiber master oscillator power amplifier (MOPA) system. The linearly polarized single-mode output power was 400 W with an 85% slope efficiency, with a linewidth of 2.5 GHz (full width at half maximum). Furthermore, mitigation of mode instability (MI) has been demonstrated by tightly coiling the gain fiber to a diameter of 11 cm. In addition, methods for higher power scaling are discussed.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.169-174
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• 2008

In this paper, we have presented techniques to reduce the splicing loss between standard single mode fiber and high ${\Delta}$ single mode fiber based on the mode expanding and mode evolution induced by thermal treatment of the fibers. The experimental results show that mechanical splicing loss can be reduced from 2.3 dB to 0.1 dB through proper thermal treatment of the high ${\Delta}$ fiber. Meanwhile, we achieved $0.2{\sim}0.4dB$ of low splicing loss between two fibers by heating the splicing region using electric arcing or an oxygen flame.