• The Journal of Engineering Research
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• v.2 no.1
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• pp.103-111
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• 1997

EDFA (Erbium Doped Fiber Amplifier) is widely used to compensate the loss in fiber optic transmission system. The characteristics of EDFA are investigated by analyzing the mechanism amplifying the optical power of an input with several factors to obtain the criteria for designing EDFA. When it is used in fiber optic transmission system, signal to noise characteristics in the receiver is deteriorated due to the spontaneous emission noise of EDFA. We investigate the operating conditions of EDFA to reduce BER (Bit Error Rate).

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.144-145
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• 2000

파장 분할 다중화(WDM)기술은 빠른 속도로 발전해 왔으며, 이에 대한 연구는 계속되고 있다. 전송용량의 증가에 의해 전송 채널의 수가 증가하고 이에 따라 이득 대역도 더 넓어져야한다.$^{(1)}$ 파장 분할 다중화(WDM) 시스템의 구성에서 어븀 첨가 광섬유 증폭기(EDFA)는 시스템의 핵심 요소로 각 단계마다 몇 개씩의 EDFA가 사용된다. EDFA에서는 이득의 변화가 10 ms정도로 천천히 일어나므로 입력의 평균값에 의해 이득이 결정된다. 따라서, EDFA는 모든 채널의 입력의 합이 일정할 때 이득의 상호 포화로 인한 채널 간의 누화가 없다는 장점이 있기 때문에 다채널 WDM 시스템의 광섬유 증폭기로 매우 유용하게 이용되고 있다.$^{(2)}$ (중략)

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.24-29
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• 1995

반도체 광증폭기는 어븀첨가 광섬유증폭기게 비하여 높은 잡음지수, 낮은 포화출력파워, 높은 편광의존성, 주파수처핑 등의 성질을 갖기 때문에, 광신호를 증폭하기 위한 응용은 매우 제한적이다. 그러나 이득분포화 현상에 의하여 유도되는 비선형 굴절률 계수가 매우 크기 때문에, 관신호 처리를 위한 기능소자로서의 응용 가능성은 매우 높다. 본 논문에서는 시분할 역다중화기, 고속 파장변환기, 주파수 처핑 보상기 등 반도체 광증폭기의 비선형 굴절률을 이용한 여러 가지 응용분야를 소개하고 이러한 응용에 있어서 반도체 광증폭기의 장점과 한계를 논한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.2037-2042
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• 2014

Three methods for gain saturation tone application were compared for optical wavelength division multiplexing transmission using more than 32 channels. The methods are to use high power distributed feedback laser diodes, to use amplified light sources, and lastly to use one saturation tone and several WDM light sources. 1532.3 nm, 1545.7 nm, and 1558.2 nm for the wavelength dependency of the saturation tone were also compared. As a result, the effect of amplified spontaneous emission noise caused by an amplifier was very slight. long wavelength for a saturation tone caused 1 dB gain reduction and its reason was analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.712-718
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• 2004

We report 1.6 Tb/s (160${\times}$10 Gb/s) WDM transmission over 2,000 km of single mode fiber using distributed hybrid(distributed Raman amplifier＋Erbium-doped fiber amplifier) optical amplifiers. After transmission over 2,000 km of single mode fiber, average optical signal to noise ratios of C/L-band were 20.5 dB, 21.9 dB, respectively. The minimum Q-factors of each band were 14.65 dB (BER=5.8e-8) in C-band, 13.75 dB (BER=5.0e-7) in L-band without forward error correction. We performed 1.6 Tb/s error-free transmission over 2,000 km of single mode fiber using Reed-Solomon (255, 239) forward error correction code.

• Information and Communications Magazine
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• v.11 no.2
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• pp.77-89
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• 1994

High speed optical fiber transmission technology has been remarkably improved during the past 20 years. This paper presents recent research status and future technological issues for the future information society, that is, the Tb/s transmission by frequency division multiplexing and the ultra long-distance by optical soliton transmission. Erbium-doped fiber amplifier and recent optical technology have brought optical transmission system of up to 10 Gb/s to the point of commercialization. Taking into account the future super information highway, that is, B-ISDN network, ultra wide-band picture-based information can be provided for many subscribers via existing optical fiber cables. However, to achieve the high speed transmission, the technologies must be developed not only for transmission lines but also for transmission nodes. Since the conventional signal transmission/processing technique using electronics has the limit in its speed, novel photonic technology is being developed for this purpose. On the other hand, optical solitons propagate stably through optical fibers, without pulse broadening effect of the fiber dispersion. Since the pulse broadening effect becomes serious as the transmission speed increases, optical solitons is the important technologies to realize the high speed, long distance transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1666-1671
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• 2022

The structure of a high-power gain-flattened long wavelength band (L-band) optical amplifier was optimized, which was implemented for 64-channel wavelength division multiplexed optical signals with a channel spacing of 50 GHz. The output characteristics of this L-band amplifier were measured and analyzed. The amplifier of the optimized two-stage amplification configuration had a flattened gain of 20 dB within 1 dB deviation between 1570 and 1600 nm for -2 dBm input power condition. The noise figure under this condition was minimized to within 6 dB in the amplification bandwidth. The gain flattening was realized by considering only the characteristics of gain medium in the amplifier without using additional optical or electrical devices. The proposed amplifier consisted of two stages of amplification stages, each of which was based on the erbium-doped fiber amplifier (EDFA) structure. The erbium-doped fiber length and pumping structures in each stage of the amplifier were optimized through experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2466-2472
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• 2013

Post-dispersion compensation methods for the 3000 km long-haul transmission distance using 10 Gbps 40 wavelength division multiplexing channels were analyzed and compared. First, each channel was compensated by an individual dispersion value, next each group of eight channels by an individual value, and lastly all forty channels by a single value. Considering the lower and highest performance channels and their values, the post-dispersion compensation method by each channel group showed the possibility to simplify the transmission system without sacrifice of signal performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1747-1753
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• 2013

Signal performances according link span dispersion compensation conditions at the 2000 km long-haul transmission distance using 10 Gbps 40 wavelength division multiplexing channels were analyzed and compared. 95%, 97.5%, 100%, 102.5% and 105% compensation conditions were applied and 97.5% gave the best performance without post dispersion compensation. the effects of accumulated dispersion value and average dispersion value per transmission link for each link compensation condition were analyzed. When post dispersion compensation optimization was applied to five link span dispersion compensation conditions, 102.5% was given the best performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.197-203
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• 2013

Optical power optimization of 10 Gbps 40 wavelength division multiplexing channels was analyzed at the 3000 km long-haul transmission distance when the link span distance was changed between 40 km and 140 km. The signal performance of the transmission was obtained as a Q value and it was compared when input power into SSMF and input power into DCF on the transmission link were changed. The optimized input power into SSMF increased linearly to link span distance with 1 dB/km. The optimized power into DCF increased linearly with 0.5 dB/km up to 100 km link span, but it had no variation at longer link span than 100 km.