• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.332-333
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• 2003

Optical Add／Drop Multiplexer (OADM)은 WDM, 즉 파장분할을 이용하여 보다 많은 정보를 보다 빠르게 전송할 수 있는 광통신 시스템에서 가장 중요한 소자 중의 하나이다. WDM (특히, DWDM) 시스템에서는 광신호의 전송 대역이 파장 영역에서 0.8 nm 정도의 매우 좁은 간격으로 배치되기 때문에, 파장 가감을 위한 광필터들은 높은 파장 정확성과 환경적 조건에 대한 안정성을 가져야만 한다. 그러나 광섬유 단주기 격자의 온도 의존성은 일반적으로 0.01 nm／$^{\circ}C$ 정도로 너무 크기 때문에 WDM 시스템에서 응용되기 위해서는 패키징을 통한 온도 보상이 필요하다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.535-541
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• 2005

This paper proposes a hybrid optical lines composed of single-mode fiber(SMF) and multi-mode fiber(MMF) for gigabit-capable Passive Optical Network(GPON) using a WDM method with a single light source per each channel, and reports the results of transmission performance the proposed lines. The transmission link uses a direct modulated DFB-LD for high speed downstreams at the optical line terminal(OLT) of central office(CO) and a low cost SFP type transceiver for low-speed upstream in optical network unit(ONU). To split or combine the transmission channels, wavelength MUX/DEMUX are used in the optical line section, and MMFs not longer than 1 km are attached to the SMF lines at the ONU side of the WDM-PON links. We have performed the transmission experiment on the downstream of 2.5 Gbit/s, and 1.25 Gbit/s, and the upstream of 1.25 Gbit/s, and 622 Mbit/s which are recommended by ITU-T G.984.2. The transmission margin and feasibility of the proposed links have been tested to be suitable up to 2.5 Gbit/s transmission.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.14-21
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• 2003

We investigated the optimum pump light power compensating distorted WDM signal due to both chromatic dispersion and self phase modulation (SPM). The considered system is $3{\times}40$ Gbps intensity modulation direct detection (IM/DD) WDM transmission system with path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and the excellent compensation is obtained when the pump light power of HNL-DSF OPC was selected to equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length. By this approach, it is verified the possibility to realize a long-haul high capacities WDM system by using PAIA MSSI compensation method, which have HNL-DSF OPC with optimal pump light power depending on transmission length.

• Journal of Advanced Navigation Technology
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• v.11 no.2
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• pp.187-195
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• 2007

In this paper, the optimal values of optical phase conjugator (OPC) position and dispersion coefficients of fiber sections depending on the extinction ratio of WDM channel signals are numerically induced in WDM system with OPC used to compensate the distorted signals due to nonlinearities and chromatic dispersion. The considered WDM system consist of 16 channels with 40 Gbps data rate and each channel is assumed to be NRZ format with the extinction ration of 5 dB, 10 dB, or 20 dB. It is confirmed that the only one parameter among two considered parameters is used to effectively compensate overall WDM channels, and each optimal value of these parameters independent on the extinction ratio. That is, overall WDM channels are excellently transmitted within 2 dB power penalty whether by positioning OPC into 496 km or by setting dispersion coefficient difference between two fiber sections to 0.055 ps/nm/km, these optimal values are not dependence on the extinction ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.716-725
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• 2002

In this paper, we showed the applicability of power symmetric MSSI(Mid-Span Spectral Inversion) to the long-haul WDM system with the channel interference due to FWM(Four Wave Mixing). And we showed the degree of performance improvement. We used 1 dB EOP(Eye-Opening Penalty) criterion so as to evaluate the degree of compensation dependent on the variation of chirp parameter of optical pulse for the various input power in high speed tansmission system. And we evaluated the maximum input power of channel be able to be the signal to crosstalk noise (SNR) above 20 dB in the transmission link with the channel interference due to FWM. Consequently the proposed MSSI compensation method is capable to transmitting the total 68 WDM channels simultaneously with a 0.4 nm channel spacing and 5.3 dBm maximum input power in a 10 Gbps transmission link. Therefore the proposed power symmetric MSSI compensation method may be very useful for the implementation of long-haul wideband WDM transmission systems with relatively high power and improved performance.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.437-446
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• 2007

In this paper, we numerically induced the optimal values of optical phase conjugator (OPC) position and dispersion coefficients of fiber sections, which can improve the bit error rate (BER) and design the adaptive WDM transmission system, as a function of the extinction ratio (ER) of 10 dB and 20 dB in $16{\times}40$ Gb/s WDM transmission system. It is confirmed that these optimal parameter values for effectively compensating overall WDM channels are dependence on the extinction ratio of signals as well as modulation format, transmitted channel numbers, which were investigated in previous researches. It is also confirmed that ER of 20 dB has the advantage of designing flexible WDM systems using optimal parameters than ER of 10 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1157-1166
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• 2001

In this paper, we investigated the degree of compensation for optical pulse shape distortion due to both chromatic dispersion and SPM(self phase modulation) in high speed optical transmission system with dispersion shift fiber. We adopted the power symmetric MSSI(mid-span spectral inversion) as compensation method. We used EOP(eye-opening penalty) parameter in order to evaluate the compensation efficiency of distorted optical pulse. We evaluated input signal power range being able to maintain stable reception performance in the case of various chirp parameter of modulated optical pulse. And, in order to verify the applicable to wideband WDM system, we evaluated the wavelength range being able to maintain stable reception performance through the EOP calculation of various dispersion coefficient of first fiber D$\_$11/. We showed that proposed MSSI is effective compensation method to down chirped optical pulse transmission rather than up chirped optical pulse transmission in anomalous dispersion range. And we showed that this method have possibility of relative high power transmission and wideband transmission in WDM system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.845-854
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• 2003

In this paper, the characteristics of compensation for WDM channel signal distortion due to both chromatic dispersion and Ken effect in 1,000 km 200 Gbps(5${\times}$40 Gbps) WDM systems was investigated. The WDM system has a path-averaged intensity approximation(PAIA) mid-span spectral inversion(MSSI) as a compensation method. This system has a highly nonlinear dispersion shifted fiber(HNL-DSF) optical phase conjugator(OPC) in the mid-way of transmission line. In order to evaluate the degree of compensation, 1 dB eye opening penalty(EOP), bit error rate(BER) characteristics and power penalty of 10$\^$-9/ BER are used. It is confirmed that HNL-DSF is an useful nonlinear medium in OPC fur wideband WDM system with PAIA MSSI and that the optimal compensation for WDM channel distortion is achieved by the selection of pump light power of OPC, which equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length, dispersion coefficient of fiber, OPC pump light wavelength, conversion efficiency of WDM channel in OPC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.893-899
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• 2000

WDM technology has been an emerging issue for the efficient use of optical links. WDM uses a number of different wavelengths that are assigned to each channel. The minimal number of optical transcievers and receivers should be used in a node to build an economic WDM transmission system without degrading system performance. Hence, the analysis of performance parameters such as throughput and delay is important to guarantee the WDM system performance. In this paper, the performance of a MAC protocol on a slotted WDM system that has a tunable transmitter(TTX), a tunable receiver(TRX), and a fixed receiver(FRX), respectively, on each node, was statistically analyzed. The computer simulation validates the performance analysis.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.656-661
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• 2009

High-quality transmission of $24{\times}40$ Gbps WDM signals obtained through controling residual dispersion per span (RDPS) in optical transmission links with zero net residual dispersion (NRD) of inline dispersion management (DM) of optical transmission links is researched. It is confirmed that RDPS values, which is improving system performance, depends on launch power of WDM channels, but optimal RDPS, which can simultaneously improve WDM signals with relative wide launch power ranges, becomes to be 210~230 ps/nm. Also, it is shown that effective launch power range that making eye opening penalty (EOP) of worst channel to below 1 dB is more increased as RDPS is more increased.