Jaedon Kim

Broadcast Transmission in WDM-PON using a Broadband Light Source

A novel method to broadcast a video stream to all subscribers in WDM-PON is proposed and experimentally implemented. Using a broadband light source, we have achieved successful transmission performance with our proposed method.

Optical Burst Transport: A Technology for the WDM Metro Ring Networks

We propose a sublambda traffic-grooming scheme on wavelength-division-multiplexing ring networks, named optical burst transport. The network protocol and architecture are designed to support dynamic bandwidth allocation, which is more reasonable for bursty data traffic. To verify our network protocol and architecture, we build a testbed which supports burst-mode transmission. Also, we transmit streaming video over Ethernet as an application

Smooth upgrade of existing passive optical networks with spectral-shaping line-coding service overlay

A simple and cost-effective upgrade of existing passive optical networks (PONs) is proposed, which realizes service overlay by novel spectral-shaping line codes. A hierarchical coding procedure allows processing simplicity and achieves desired long-term spectral properties. Different code rates are supported, and the spectral shape can be properly tailored to adapt to different systems. The computation can be simplified by quantization of trigonometric functions. DC balance is achieved by passing the dc residual between processing windows. The proposed line codes tend to introduce bit transitions to avoid long consecutive identical bits and facilitate receiver clock recovery. Experiments demonstrate and compare several different optimized line codes. For a specific tolerable interference level, the optimal line code can easily be determined, which maximizes the data throughput. The service overlay using the line-coding technique leaves existing services and field-deployed fibers untouched but fully functional, providing a very flexible and economic way to upgrade existing PONs.

Ground state absorption in thulium-doped fiber amplifier: experiment and modeling

S-band ground state absorption in a thulium-doped fiber amplifier (TDFA) has been studied in detail experimentally and theoretically. While traditionally considered difficult to measure, its presence is shown to have significant impact on amplifier power excursion during dynamic wavelength add-drop, due to the energy transitions inherent to the Tm3+ ion. For specific pumping scheme and operating conditions, gain increases with increasing signal input, a behavior significantly different from conventional three-level optical amplifiers. Numerical models are presented that correctly account for these phenomena. This promises to provide insight for gain control algorithms for TDFAs under bursty traffic conditions in a future reconfigurable wavelength division multiplexed environment

Traffic grooming for WDM rings using optical burst transport

A sublambda traffic-grooming scheme on wavelength-division-multiplexed (WDM) rings, which is called optical burst transport (OBT), is proposed. The network protocol and architecture allow increased flexibility to tailor the transport network behavior for efficient delivery of bursty data traffic. Using different network parameters, its performance is analyzed via simulation, and the implementation issues including the media-access-control (MAC) protocol, tunable-filter controller, and burst-mode receiver are addressed. Finally, the feasibility of the OBT with an experimental testbed built by the authors is demonstrated and a streaming-video application is used to present its overall functionality.

Gain dynamics of 14xx-nm-pumped thulium-doped fiber amplifier

Upconversion pumping in the 14xx-nm range gives the thulium-doped fiber amplifier (TDFA) a 3-dB dynamic range of 15 dB, and transient power excursion much lower than the conventional erbium-doped fiber amplifier during dynamic wavelength add-drop, due to the energy transitions inherent to the Tm/sup 3+/ ion. For specific pumping scheme and operating conditions, gain increases with increasing signal input, a behavior significantly different from conventionally optical amplifiers. This phenomenon is studied experimentally and theoretically, and promises to provide insight for gain control algorithms for TDFAs under bursty traffic conditions in a metropolitan area network environment.

OBT: Optical Burst Transport in Metro Area Networks

For the past few years, the evolution of electro-optical technology has driven change in optical networks in the access and backbone areas. Optical bypassing and traffic aggregation mitigate the scalability problem in backbone networks, and burst mode transmission can provide a cost-efficient solution for access networks. Using those technologies, a new solution can be found for metro area networks, which interconnect access and backbone networks. In this article, we introduce a new solution for metro area networks, called optical burst transport (OBT). OBT is designed to use the promising technologies of backbone and access networks so that it provides all benefits, such as dynamic bandwidth provisioning, scalability, and robustness for unbalanced traffic. The performance evaluation of OBT also is verified by means of a testbed implementation.

Demonstration of 2.5 Gbps Optical Burst Switched WDM Rings Network

We present a 2.5 Gbps OBS network testbed named Optical Burst Transport (OBT). OBT combines a reliable control channel with a tightly controlled high speed burst mode transmission. The result is verified by burst mode BER test.

Modeling gain dynamics of thulium-doped fiber amplifiers

The transient response of single-(14xx nm) and dual-(14xx + 1550 nm) wavelength-pumped thulium-doped fiber amplifiers is modeled. With an optimally chosen method for numerical integration of rate equations involving several energy levels, we can estimate the transient response and frequency dependent characteristics during add-drop transitions. Results correspond to the experimental data with good accuracy.

SUCCESS-LCO: instant and cost-effective upgrade of existing passive optical networks by spectral shaping line codes

Novel line codes combined with WDM techniques allow simple and cost-effective overlay of higher bitrate services in existing fiber optical access networks. The solution leaves the existing services and field-deployed fibers untouched. The design of the spectral shaping line codes is presented, along with the analyses for different code rates and processing window sizes. The computation can be simplified by employing vector quantization for the trigonometric functions. DC balance is achieved by forwarding the DC residual to the following window. The spectral shape can be manipulated in various ways to optimize the system performance. Experiments have been conducted to demonstrate and compare several different optimized line codes. For a specific tolerable interference level, the optimal line code can easily be determined which maximizes the data throughput. The service overlay by the line coding technique provides a very flexible and economic way to upgrade existing passive optical networks.