• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.10
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• pp.43-47
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• 2002

A simple optical signal to noise ratio monitoring method using fiber Bragg grating is proposed for monitoring performance of OADM. OSNR of each channel is determined by monitoring the optical power transmitted and reflected from fiber Bragg gratings, simultaneously. We have obtained OSNR with accuracy better than 0.8㏈ compared with OSA of 0.1nm optical resolution in the wide input power range between -6 ㏈m and -23㏈m per channel.

• Journal of IKEEE
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• v.13 no.2
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• pp.200-207
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• 2009

In this paper, novel traffic gromming algorithms are proposed with a primary goal of maximize the throughput in WDM(Wavelength Division Multiplexing) ring networks. To achieve this goal, we analyze two network designs that are Lightpath Designs and Virtual Topology Designs and simulate the throughput in various traffic environments. From this methods, we propose novel traffic gromming algorithms to maximize the throughput.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.595-600
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• 2015

The implementation possibility of the flexible optical network configuration using the non-midway optical phase conjugator (OPC) in the dispersion-managed (DM) optical link for wavelength division multiplexed (WDM) transmission is demonstrated in this paper. It is confirmed that the implementation possibility of flexible link configuration is more increased, as number of fiber spans is more bigger and the residual dispersion per span (RDPS) is more large. It is also confirmed that the non-midway OPC link, in which RDPS of the latter half transmission section (after OPC) is decided by the averaged RDPS of the former half transmission section (before OPC), has more advantage for the flexible network configuration.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.16-23
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• 2013

The effects of dispersion coefficient of dispersion compensating fiber (DCF) and residual dispersion per span (RDPS) on in the dispersion managed optical links for compensating the distorted 960 Gbps wavelength division multiplexd (WDM) signals due to group velocity dispersion (GVD) and optical nonlinear effects of single mode fiber (SMF) are investigated. It is confirmed that optimal net residual dispersion (NRD), which greatly affects compensating for optical signals, should be induced under the large launch power condition, irrelevant on the considered dispersion coefficient of DCF and RDPS. It is also confirmed that system performances are greatly improved by selecting the very small RDPS and very large dispersion coefficient of DCF.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.208-217
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• 2013

The optimal residual dispersion per span (RDPS) slope is induced through the analyses of the compensation characteristics of the wavelength division multiplexed (WDM) channels depending on RDPS slope in the optical links with a dispersion management (DM) and an optical phase conjugation. The simulation results show that the effective launch power of WDM is more increased and the performance difference between the channels is more decreased as RDPS slope is more increased. The simulation results also show that the effective net residual dispersion (NRD) range is more increased as RDPS slope is more increased, and consequently, it is more advantageous to use the large RDPS slope for implementing the flexible optical links.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.455-463
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• 2004

In this paper, we deal with a ring-mesh network design problem arising from the deployment of WDM for the optical internet. The ring-mesh network consists of ring topology and full mesh topology for satisfying traffic demand while minimizing the cost of OAOMs and OXCs. The problem seeks to find an optimal clustering of traffic demands in the network such that the total number of node assignments is minimized, while satisfying ring capacity and node cardinality constraints. We formulate the problem as a mixed-integer programming model and prescribe a tabu search heuristic procedure Promising computational results within 3% optimality gap are obtained using the proposed method.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.319-325
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• 1994

The performance of Manchester-coded DPSK optical wavelength division multiplexing (WDM) systems using a stochastic approach is evaluated taking into account the shot noise and the four-wave mixing (FWM) caused by fiber nonlinearities. The result of Manchester-coded system is compared to conventional non-return-to-zero (NRZ) systems for DPSK modulation formats. Further, the dynamic range, defined as the ratio of the maximum input power (limited by the FWM), to the minimum input power (limited by receiver sensitivity), is evaluated. For $1.55.{\mu}m$16 channel WDM systems, the dynamic range of DPSK Manchester coded systems shows a 2.1 dB improvement with respect to the NRZ. This result holds true for both dispersion-shifted fiber and conventional fiber; it has been obtained for 10 GHz channel spacing, 1 Gbps/channel bit rate.t rate.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.248-255
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• 2011

An investigation has been carried out, by computer simulation, to evaluate the impact of dispersion compensation configurations on 960 Gbps wavelength division multiplexed (WDM) system with optical phase conjugator (OPC). The considered dispersion compensation configurations in this research are conventional one-end type and bi-end type. One-end and bi-end type are made by using one dispersion compensating fiber (DCF) and two DCFs to decrease dispersion accumulated in one single mode fiber (SMF) span, respectively. It is found that bi-end compensation configuration offers the equal performance with that of one-end configuration in WDM system with residual dispersion per span (RDPS) of 400 ps/nm if net residual dispersion (NRD) had to be optimized in each cases.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.15-21
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• 2005

One of the core technology in WDM-PON system is a generation and modulation technique of the optical source in Optical Network Unit (ONU). In this paper, we propose a reflective semiconductor optical amplifier (RSOA) as a modulator in WDM-PON system. Its performance is analyzed by simulation and actual experimentation. Using RSOA in WDM-PON system as a modulator, it obtains higher gain compared to the conventional SOA due to the double pass gain effect. Furthermore RSOA can provide high gain with comparatively low input power. This is very helpful when we set up the actually system because using lower input power, it can reduce the load of the driving circuit which makes very economical module structure. Therefore, when RSOA is used as a modulator, not only it gives noise suppression effect, but also provides certain amount of gain as well. In addition, comparing with conventional SOA which gives fairly large insertion loss, RSOA can provides more important merits.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.1-8
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• 2003

In this paper. we develop an analytical model to evaluate the virtual topology reconfiguration phase of optical Internet networks. To counter the continual approximation problem brought by traditional heuristic approach, we take the traffic prediction into consideration and propose a new heuristic reconfiguration algorithm called Prediction based Multi-stage Reconfiguration approach. We then use this analytical model to study the different configuration operation policies in response to the changing traffic patterns in the higher layer and the congestion level on the virtual topology. This algorithm persists to decide the optimal instant of reconfiguration easily based on the network state. Simulation results show that our virtual topology management Policy significantly outperforms the conventional one, while the required physical resources are limited.