Han-hyub Lee

First Commercial Deployment of a Colorless Gigabit WDM/TDM Hybrid PON System Using Remote Protocol Terminator

Colorless gigabit wavelength-division-multiplexing (WDM)/time-division-multiplexing (TDM) hybrid passive optical network (PON) using a remote protocol terminator is proposed and experimentally demonstrated. The system consists of reflective semiconductor optical amplifier-based WDM-PON and a legacy TDM-PON, combined with a simple and efficient remote node structure in order to provide high-speed fiber-to-the-home service to a large area with a high population density. The demonstrated system can support 512 subscribers with a single feeder fiber. The performance and feasibility of the system were evaluated by transmitting gigabit per second data including the effects of Rayleigh backscattering and 20 km attenuation. The system has been used by Korea Telecom to provide commercial services in Gwangju, Korea, since March 2009, after successfully passing through the benchmark test. This is the first commercial deployment of a WDM/TDM hybrid PON. It can accommodate field-deployed TDM-PON link without any modification and extend the maximum total reach of PON link by the use of remote protocol termination. Number of subscribers and the allocated bandwidth to the subscribers can be designed by simply changing the splitting ratio.

First commercial service of a colorless Gigabit WDM/TDM hybrid PON system

We describe the first RSOA-based WDM/TDM hybrid PON system to enter commercial service. The system, consisting of a 16 × 1.25 Gb/s colorless Gigabit WDM-PON and a legacy TDM-PON with optical-electrical-optical converters, provides the triple-play service using fiber-to-the-home and fiber-to-the-node in a new residential area in Korea.

Demonstrations of RSOA based loop-back WDM-PON with 100 Gb/s (80 × 1.25 Gb/s) capacity employing spectrum sliced incoherent light injection

We have successfully demonstrated a loop-back WDM-PON with a 100 Gb/s (80×1.25 Gb/s) capacity using spectrally sliced ASE injected RSOA. To mitigate the RIN degradations, we proposed injection current adjustment, dispersion management and the use of receiver with optimized decision threshold level.

A linear bus wavelength-reuse WDM-PON with simple add/drop nodes

We demonstrate a linear bus wavelength-reuse WDM-PON with simple add/drop nodes. By using RSOA transmitters at the OLT and the ONT, 16 downstream and upstream signals with 1.25 Gb/s were successfully transmitted over four OADMs spaced at 5-km intervals.

Improving transmission performance in EIN limited 2.5 Gb/s spectral slicing loop-back WDM-PON based on RSOA employing the dispersion management

We successfully demonstrated EIN-limited 2.5 Gb/s spectral slicing loop-back WDM-PON based on RSOA by using the dispersion management.

Nonlinear effects in optical fiber: Advantages and disadvantages for high capacity all-optical communication application

This paper presents, in the form of a review, some of the results of our study addressing the advantages and disadvantages of the nonlinear effects in optical fibers for their use in high-speed, high capacity, all-optical telecommunication applications. Nonlinear effects that we cover include: self-phase modulation (SPM), cross-phase modulation (CPM), stimulated Raman scattering (SRS), and stimulated Brillouin scattering (SBS). We have found that nonlinear effects can play useful and important roles in enhancing the fiber performances and creating new functions by way of fiber lasers, amplifiers, switches, logic devices, demultiplexers, signal format conversion and wavelength conversion devices. But we also have found that they can play degenerative roles limiting the performances of optical fiber communication. Trade-off between the advantages and the disadvantages of the nonlinear effects should be carefully examined in order to utilize their effects to the fullest extent.

Effects of RSOA gain ripples on upstream transmission in a SML-seeded loop-back WDM-PON

In a SML-seeded loop-back WDM-PON, the upstream BER plots show variation of power penalty by 2 dB, depending on the difference of seed and ripple peak wavelength, which is related to the RSOA transient chirp.

QoE enhancement schemes for video in converged OFDMA wireless networks and EPONS

Bandwidth requirements of both wireless and wired clients in access networks continue to increase rapidly, primarily due to the growth of video traffic. Application awareness can be utilized in access networks to optimize quality of experience (QoE) of end clients. In this study, we utilize information at the client-side application (e.g., video resolution) to achieve superior resource allocation that improves user QoE. We emphasize optimizing QoE of the system rather than quality of service (QoS), as user satisfaction directly relies on QoE and optimizing QoS does not necessarily optimize QoE, as shown in this study. We propose application-aware resource-allocation schemes on an Ethernet passive optical network (EPON), which supports wireless (utilizing orthogonal frequency division multiple access) and wired clients running video-conference applications. Numerical results show that the application-aware resource-allocation schemes improve QoE for video-conference applications for wired and wireless clients.