• Title/Summary/Keyword: WDM Channel Distortion

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Effect of Cross Phase Modulation on Channel Compensation in 320 Gbps Intensity Modulation / Direct Detection WDM Transmission Systems (320 Gbps 강도 변조 직접 검파 WDM 시스템의 채널 보상에서 상호 위상 변조의 영향)

  • 이성렬;김지웅;손성찬
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.5
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    • pp.1134-1140
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    • 2004
  • In this paper, we investigated the effect of cross phase modulation(XPM) on compensation for WDM channel distortion due to chromatic dispersion, self phase modulation and XPM as a function of fiber dispersion coefficient and modulation format in 320 Gbps WDM systems. The considered WDM transmission system is based on mid-span spectral inversion(MSSI) compensation method, which has 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 the maximum channel input power resulting 1 dB eye opening penalty is reduced due to XPM effect on channel distortion, even if MSSI method was applied to WDM system. But, we confirmed that the effect of XPM on channel distortion becomes decrease as fiber dispersion coefficient of WDM system becomes larger. Futhermore, we confirmed that NRZ is better than RZ as a modulation format for similarly compensating overall WDM channels in WDM system with large fiber dispersion coefficient in order to minimize the effect of the XPM on channel distortion.

Characteristics of Compensation for Distorted Optical Pulse with Initial Frequency Chirp in 3 X 40 Gbps WDM Systems Adopted Mid-Span Spectral Inversion

  • Lee, Seong-Real;Lee, Yun-Hyun
    • Journal of electromagnetic engineering and science
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    • v.3 no.2
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    • pp.79-85
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    • 2003
  • In this paper, we investigated the degree of compensation for distorted optical pulse of wavelength division multiplexed(WDM) channel with initial frequency chirp generated in optical transmitter. The WDM channel signal distortion is due to chromatic dispersion, self phase modulation(SPM) and cross phase modulation(XPM) in fiber. The considered system is 3 ${\times}$ 40 Gbps intensity modulation direct detection(IM/DD) WDM transmission systems, which adopted mid-span spectral inversion(MSSI) as compensation method. We confirmed that the effect of initial frequency chirp on compensation for signal distortion due to a SPM is gradually decreased as a dispersion coefficient of fiber becomes gradually small. But, in the aspect of a compensation for signal distortion due to both SPM and XPM, the effect of initial frequency chirp on compensation is gradually decreased as a dispersion coefficient of fiber becomes gradually large.

The Compensation Characteristics of WDM Channel Distortion Dependence on NRZ format and RZ Format (NRZ 형식과 RZ 형식에 따른 WDM채널 왜곡의 보상 특성)

  • 이성렬;조성언
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1184-1190
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    • 2003
  • In this paper, we investigated the characteristics of compensation for distorted NRZ signal and RZ signal in 320 Gbps WDM system as a function of channel input power, fiber dispersion coefficient and transmission length, respectively. The considered WDM transmission system is based on mid-span spectral inversion(MSSI) compensation method having highly nonlinear dispersion shifted fiber(HNL-DSF) optical phase conjugator(OPC) in the mid-way of total transmission line. We confirmed that the signal input power range compensated by MSSI is broadened by using RZ as a signal format in WDM system with small fiber dispersion coefficient, The range of fiber dispersion coefficient compensating overall distorted WDM channels is limited, because degree of compensation for distorted channel with low conjugated-wave power becomes gradually degrade as fiber dispersion coefficient becomes gradually higher. It is showed that RZ format and NRZ format is suited for long-haul transmission in WDM system with small fiber dispersion coefficient and with large fiber dispersion coefficient, respectively.

Compensation Characteristics or Distorted WDM Channel dependence on Variation of Fiber Dispersion (광섬유 분산 변동에 따른 왜곡된 WDM 채널의 보상 특성)

  • Lee, Seong-Real
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.7A
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    • pp.719-726
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    • 2004
  • In this paper, compensation characteristics of distorted WDM channel due to both chromatic dispersion and self phase modulation (SPM) is numerically investigated under the assumptions of non-uniformly distributed fiber dispersion, in order to inspect the application of mid-span spectral inversion (MSSI) to any exact transmission links. The MSSI is compensation method used in this approach. This method has an optical phase conjugator (OPC) placed in mid-way of total transmission length to compensate distorted WDM channels. It is confirmed that MSSI will become applicable to long-haul WDM systems by controlling input light power of transmission channels, when the averaged dispersion of both fiber sections with respect OPC was varied and distributed unequally each other. Applying MSSI to long-haul WDM system, it is possible to remove all in-line compensator, consequently it will be expected to reducing system cost.

Compensation Characteristics of Distorted Channels in 200 Gbps WDM Systems using Mid-Span Spectral Inversion Method (200 Gbps WDM 시스템에서 Mid-Span Spectral Inversion 기법을 이용한 채널 왜곡의 보상 특성)

  • 이성렬
    • 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.

Compensation of WDM Signal Distortion through Non-midway Optical Phase Conjugation and Dispersion Maps of Asymmetric Structure (Non-midway 광 위상 공액과 비대칭 구조의 분산 맵을 통한 WDM 신호의 왜곡 보상)

  • Seong-Real Lee
    • Journal of Advanced Navigation Technology
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    • v.27 no.6
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    • pp.855-860
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    • 2023
  • Long-haul transmission of multiple transmission signals, such as wavelength division multiplexed (WDM), has became possible, because the signal distortion caused by chromatic dispersion and nonlinearity can be compensated by applying dispersion management, optical phase conjugation and combination of the two methods into the transmission link. The biggest obstacle to applying optical phase conjugation to an optical link is that the optical phase conjugator (OPC) must be located only in the middle of the entire transmission line. This paper shows that the location constraints of OPC can be overcome through the application of an asymmetric dispersion map. The location of the OPC considered in this paper exists between the 8th and 9th fiber spans out of a total of 48 fiber spans. Additionally, the dispersion map has an asymmetric cumulative dispersion profile with respect to the OPC. As a result of the simulation, it was confirmed that the distortion compensation effect of the WDM channel can be increased compared to the link to which the traditional dispersion map is applied, depending on the overall shape of the cumulative dispersion profile distribution of the proposed asymmetric dispersion map and the selection of the profile slope.

Dispersion Management and Optical Phase Conjugation in Optical Transmission Links with a Randomly Distributed Single-Mode Fiber Length

  • Lee, Seong-Real
    • Journal of information and communication convergence engineering
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    • v.11 no.1
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    • pp.1-6
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    • 2013
  • Suppressing or mitigating signal distortion due to group velocity dispersion and optical Kerr effects is necessary in ultra-high speed and long-haul wavelength division multiplexing (WDM) transmission systems. Dispersion management (DM), optical phase conjugation (OPC), and the combination of these two are promising techniques to compensate for signal distortion. In this paper, to implement a flexible optical WDM network, a new optical link configuration with a randomly distributed single-mode fiber (SMF) length and fixed residual dispersion per span in the combination of DM and OPC is proposed and investigated. The simulation results show that the best net residual dispersion (NRD) in the proposed optical links is +10 ps/nm, which is independent of pre- and postcompensation. The effective launch power of the WDM channel is increased more in the optical links with NRD = +10 ps/nm controlled by only precompensation. Furthermore, the system performance difference between the proposed optical link configuration with the best NRD and the conventional optical link with uniform distribution of the SMF length had little significance. Consequently, it is confirmed that the proposed optical link configuration with the best NRD is effective and useful for implementing a reconfigurable long-haul WDM network.

Pump Light Power of Wideband Optical Phase Conjugator using HNL-DSF in WDM Systems with MSSI (MSSI 기법을 채택한 WDM 시스템에서 HNL-DSF를 이용한 광대역 광 위상 공액기의 펌프 광 전력)

  • Lee Seong real;Cho Sung eun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.3A
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    • pp.168-177
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    • 2005
  • In this paper, we numerically investigated the optimum pump light power resulting best compensation of pulse distortion due to both chromatic dispersion and self phase modulation (SPM) in long-haul 3×40 Gbps wavelength division multiplexing (WDM) systems. We used mid-span spectral inversion (MSSI) method with path-averaged intensity approximation (PAIA) as compensation approach, which 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 in order to achieve the excellent compensation the pump light power is selected to equal the conjugated light power into the latter half fiber section with the input light power of WDM channel depending on total transmission length. Also we confirmed that compensation degree of WDM channel with small conversion efficiency is improved by using pump light power increasing power conversion ratio upper than 1.

BER Improvements of 0.96 Tbps WDM Signals through Optimal Parameter Values of Optical Phase Conjugator (광 위상 공액기의 최적 파라미터 값 도출을 통한 0.96 Tbps WDM 신호의 BER 개선)

  • Lee, Youngkyo
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.11 no.1
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    • pp.79-88
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    • 2015
  • In this paper, it is investigated that the limitation due to the asymmetry of optical power and chromatic dispersion with respect to optical phase conjugator (OPC) for compensating optical signal distortion in WDM system is overcomed by using OPC position offset and optimal dispersion coefficients of fiber sections, which depend on OPC position offset. It is confirmed that overall WDM channels are efficiently compensated by applying the optimal parameter values obtained from the proposed method into 24 channels ${\times}40$ Gbps WDM system with non zero - dispersion shifted fiber (NZ-DSF) of 1, 000 km, such as power penalties of inter-channel are reduce to almost 3.5 dB from the infinite value. It is also confirmed that the flexible design of WDM system with OPC is possible by using the optimal parameters, in which OPC is placed at ${\pm}15km$ from 500 km for efficiently compensating overall channels. Thus, the methods proposed in this research will be expected to alternate with the method of making a symmetrical distribution of power and local dispersion in real optical link which generates a serious problem if it was not made but it is the condition in the case of applying the OPC into multi-channels WDM system.

System Performance Depending on the Fiber Span Number in Dispersion Managed Optical Transmission Links with Uniform Distributions of SMF Lengths and Residual Dispersion Per Span (SMF 길이와 RDPS가 분포가 균일한 분산 제어 광전송 링크에서 광섬유 중계 구간 수에 따른 시스템 성능)

  • Lee, Seong-Real
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.620-621
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    • 2015
  • The system performances of WDM channel signals as a function of the number of fiber spans in optical link with the uniform distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS) for the compensation for the distorted WDM signals due to the group velocity dispersion (GVD) are evaluated and compared.

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