Wavelength filter detuning for improved carrier reuse in loop-back WDM-PON

Lee, W.; Cho, S.H.; Park, M.Y.; Lee, J.H.; Kim, C.; Jeong, Gi Young; Kim, B.W.

doi:10.1049/el:20060289

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…The directly modulated downstream light was transmitted to the RSOA at the ONU passing through the wavelength multiplexer at the OLT, two circulators, the feeder fiber, and the demultiplexer at the remote node. The upstream optical signal was also generated from an RSOA at the ONU; however, in this case the modulated downstream optical signal was used as seed light for wavelength selection [3,4,7,9,11,12]. We used FFCI gain control to erase the residual downstream signal in the 1 level of the upstream signal to improve the quality of the upstream signal [11].…”

Section: Methodsmentioning

confidence: 99%

“…The reflective semiconductor optical amplifier (RSOA) has attracted much attention as an excellent remodulator [5]. The upstream transmission performance of this type of loopback link is very sensitive not only to the injection power into the RSOA but also to the extinction ratio (ER) of the optical downstream data injected into the RSOA [4,6,7]. This is because the downstream signal cannot be perfectly erased from the gain saturation characteristic of the RSOA, resulting in a thickened 1 level of the optical upstream signal [8].…”

Section: Introductionmentioning

confidence: 99%

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Improving upstream transmission performance using a receiver with decision threshold level adjustment in a loopback WDM-PON

Cho

Lee

Shin

2010

Optical Fiber Technology

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improving upstream transmission performance using a receiver with decision threshold level adjustment in a loopback WDM-PON

Cho

Lee

Shin

2010

Optical Fiber Technology

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“…Moreover, WDM-PON is also faced with large capital and operational expenditures caused by the high number of light sources. The scheme of employing reflective modulators at the optical network units (ONUs) to remodulate the downstream (DS) signal for upstream (US) transmission is a practical solution to laser saving in WDM-PON and has been extensively investigated [8][9][10][11][12][13][14]. The advantages of this wavelength-reused architecture are that the number of lasers can be reduced by half and that colorless ONUs can be realized.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of a 40 Gb/s Wavelength-Reused WDM-PON Using Coding and Equalization [Invited]

Guo¹,

Tran

2013

J. Opt. Commun. Netw.

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The wavelength-division-multiplexed passive optical network (WDM-PON) has been generally regarded as a promising solution to the next-generation access network that will be required to deliver services over 40 Gb∕s. However, fiber dispersion often limits the capacity and reach of WDM-PONs. Compared with dispersion compensation fiber, which is bulky and expensive with significant power loss, digital signal processing is a more suitable way to mitigate chromatic dispersion in PONs. Furthermore, expense is a critical concern in the WDM-PON, due to its need for a large number of lasers and a complex wavelength control mechanism. One practical solution is to reuse the downstream (DS) signal as the carrier for the upstream (US) modulation. In this case, the residual DS signal after remodulation can seriously degrade US transmission. In addition, system performance can be deteriorated by the unwanted reflection as uplinks and downlinks share one wavelength. In this paper, we propose using modified duobinary (MD) coding in the DS to improve its dispersion tolerance and reduce the crosstalk between DS and US induced by remodulation and reflection. MD is a correlative level code that can reduce signal bandwidth and achieve DC balance. We demonstrate a 15 km WDM-PON delivering a 40 Gb∕s MD-coded signal in the downlink and a 10 Gb∕s on-off keying signal in the uplink. Compared with no coding, the maximal allowable extinction ratio of the DS signal (ER d ) is improved by 4 dB. Moreover, the reflection tolerance of the uplink and downlink is enhanced by 5 and 4 dB, respectively. In addition, investigations on the use of different equalizers in the DS to further suppress fiber dispersion confirm that the superior performance of nonlinear equalization in MD-coded transmission and that the network reach can be extended to 25 km by a nonlinear decision feedback equalizer. Index Terms-Dispersion; Passive optical network (PON); Reflection; Remodulation; Wavelength division multiplexing (WDM).Recently, we proposed the application of a dicode level code, which alters the signal spectrum to have zero content at the direct current (DC), in a wavelength-reused WDM-PON with 10 Gb∕s downlink and 2.5 Gb∕s uplink [15]. The results verify the great ability of dicode coding in suppressing remodulation noise and reflection noise, but the network capacity needs to be further upgraded to meet the rapidly growing bandwidth demand. For a higher transmission rate, such as 40 Gb∕s, the impact of fiber dispersion becomes much more significant and limits the http://dx.

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“…The two wavelengths arrangement not only increases the implementation cost of each connection (between the CO and each ONU), but also halves the maximum user number supported by one PON for a given operation wavelength band. To circumvent this problem, downstream carrier remodulation approaches have been proposed recently [103][104][105][106][107][108][109][110][111][112][113][114][115][116][117]. The downlink signals can be modulated at either baseband or onto subcarriers.…”

Section: Downlink Wavelength Remodulationmentioning

confidence: 99%

“…Even if the RSOA is operated in the saturated region, the extinction ratio of the downstrealn signal should be still sufficiently small [106]. Some experiinents have demonstrated that the use of the negatively detuned demultiplexer at the CO in a downlink wavelength-reuse WDM-PON based on an RSOA can further suppress the residual downstream component included in optical upstream data [107].…”

Section: Baseband Modulationmentioning

confidence: 99%

Wavelength division multiplexed passive optical networks with colorless light sources

Xu¹

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My foremost and earnest appreciation goes to my supervisor, Associate Professor Wen-De Zhong. I am truly grateful for his professional guidance, invaluable assistance and encouragement throughout my graduate studies. I want to express my sincere thanks to my co-supervisor, Dr. Yang Jing Wen, of Institute for Infocomm Research for his countless hours of brainstorming discussion and good instruction. I am also deeply indebted to Professor Chao Lu who was my supervisor and led me to this exciting research area. I have benefited tremendously from his guidance. Throughout my thesis-writing period, the useful advice, good teaching, and well understanding from Prof. Zhong and Dr. Wen benefit me a lot. Without the endless supports of my supervisors, this work would not have come to fruition.

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Wavelength filter detuning for improved carrier reuse in loop-back WDM-PON

Cited by 9 publications

References 5 publications

Improving upstream transmission performance using a receiver with decision threshold level adjustment in a loopback WDM-PON

Improving upstream transmission performance using a receiver with decision threshold level adjustment in a loopback WDM-PON

Demonstration of a 40 Gb/s Wavelength-Reused WDM-PON Using Coding and Equalization [Invited]

Wavelength division multiplexed passive optical networks with colorless light sources

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