Eui Seung Son

Bidirectional WDM passive optical network for simultaneous transmission of data and digital broadcast video service

We have demonstrated an easily upgradable bidirectional passive optical network for the simultaneous transmission of wavelength-division-multiplexing channels and digital broadcast video signals. The proposed network could transmit 15 2.5-Gb/s downstream channels, 15 155-Mb/s upstream channels, and one broadcast signal consisting of more than 70 digital video channels.

Bidirectional WDM PON using light-emitting diodes spectrum-sliced with cyclic arrayed-waveguide grating

We proposed and demonstrated a bidirectional wavelength-division-multiplexing passive optical network by using spectrum-sliced light-emitting diodes (LEDs) with cyclic arrayed-waveguide gratings (AWGs). When the spectrum-slicing technique is used, it is often difficult to secure an adequate amount of system margin due to the large slicing loss and low output power of LED. To overcome this problem, we reduced the slicing loss by using all the peaks of the spectrum-sliced light (separated by the free-spectral range of AWG) and improved the receiver sensitivity by using the forward-error correction technique. The excessive dispersion penalty (caused by using multiple peaks) was suppressed by using a simple dispersion precompensation circuit.

Survivable network architectures for WDM PON

We propose and demonstrate a simple self-protecting architecture for WDM PON. The protection time was less than 10 ms, and the power penalty caused by the protection process was negligible.

Fault localization in WDM passive optical network by reusing downstream light sources

We propose and demonstrate a simple and cost-effective technique to detect and localize the fiber failures in wavelength-division-multiplexed (WDM) passive optical networks. By reusing the downstream lasers as WDM light sources for the optical time-domain reflectometry, the proposed technique can localize the failures in both feeder and drop fibers without using the expensive tunable laser.

Statistics of polarization-dependent gain in fiber Raman amplifiers

We developed an analytical model for the statistics of polarization-dependent gain (PDG) in both copumped and counterpumped fiber Raman amplifiers (FRAs). The validity of this model was confirmed by using experimental data and numerical simulations. The results show that the PDG in a counterpumped FRA cannot be neglected since it is only about 3 times smaller than that in a copumped FRA. Using the proposed model, we also evaluated the effects of various parameters on the PDG including the wavelength difference between the signal and pump, degree-of-polarization (DOP) of pump laser, polarization-mode dispersion, and fiber loss at the pump wavelength. In addition, the proposed model was used to analyze the requirement of the DOP of pump for the suppression of PDG within 1 dB.

Effects of Downstream Modulation Formats on the Performance of BidirectionalWDM-PON using RSOA

We evaluate the effects of the downstream modulation formats (NRZ, IRZ, and Manchester) on the performance of the RSOA-based bidirectional WDM-PON. The results show that, by using Manchester format, the performances of upstream signals become insensitive to the operating conditions of RSOA.

Gain variation of Raman amplifier in birefringent fiber

We developed a simple analytical expression for the statistics of the polarization-dependent gain in a co-pumped Raman amplifier. Using this analysis, we evaluated the effects of PMD, wavelength difference between pump and signal, and pump loss on the polarization-dependent gain.

Localization of fiber failures in WDM PON by reusing downstream light sources

We propose and demonstrate a simple and cost-effective technique to detect and localize the fiber failures in WDM passive optical networks. By reusing the downstream lasers as WDM light sources for the optical time-domain reflectometry, the proposed technique can localize the failures in both feeder and drop fibers without using the expensive tunable laser.

Quasi Single-Mode Fiber for the Cost-Effective Implementation of Broadband Access Networks

We designed and fabricated a quasi single-mode fiber (QSMF) for the cost-effective implementation of broadband access networks. The core diameter of the fabricated QSMF was 20 mum. Using this fiber, we demonstrated the transmission of 10-Gb/s signal over 2 km.

Effect of temperature variation on performance of optical phase conjugation

We investigated the effect of temperature variation on the performance of fiber-based optical phase conjugation (OPC). The efficiency and bandwidth of OPC were degraded significantly by temperature variation due to the shift of zero-dispersion wavelength.