Ki-Man Choi

Dense WDM-PON based on wavelength-locked Fabry-Pe/spl acute/rot laser diodes

We demonstrate a bidirectional 12-channel wavelength-division-multiplexing passive optical network (WDM-PON) with 50-GHz channel spacing based on wavelength-locked Fabry-Pe/spl acute/rot laser diodes. The maximum transmission length is 30 km including 20 km of feeder fiber and 10 km of distribution fiber. The proposed WDM-PON system can accommodate 80 channels with erbium-doped fiber amplifier-based broad-band light sources. We also propose a few methods for the wavelength-independent operation of an optical network termination.

WDM-PON experiences in Korea (Invited)

Feature Issue on Passive Optical Network Architectures and TechnologiesWDM-PON activities in Korea including research and development were reviewed. The WDM-PON commercialized in Korea is aimed at delivering a 100 Mbits/s dedicated symmetric bandwidth to each home, based on the prediction of a small statistical gain for future video-centric services. The developed 32-channel WDM-PON based on wavelength-locked Fabry-Perot LDs was qualified by Korea Telecom (KT) and was deployed in KTs networks. Many studies have been conducted with the aim of enhancing the performance of the WDM-PON. High-speed data rate per channel, longer reach, narrow channel spacing, and a high split ratio with the help of subcarrier multiple access or time-division multiple access have been demonstrated. A protection method for feeder fiber fault and OSP fault-monitoring methods were also demonstrated. A gradual upgrade solution from the existing time-division multiplexing-PON to WDM-PON has also been proposed.

Overlay of broadcasting signal in a WDM-PON

We demonstrate an overlay method for broadcasting signal transmission in a wavelength division multiplexed-passive optical network. We used a low noise broadband light source based on mutually injected Fabry-Perot laser diodes to increase the transmission capacity.

Effects of Back-Reflection in WDM-PONs Based on Seed Light Injection

We investigate the effects of back-reflection in wavelength-division-multiplexing passive optical networks having an injected seed light for color-free operation of an optical network unit. The back-reflection-induced penalty is reduced as the linewidth of the seed light is increased. The wavelength-locked Fabry-Perot laser diode to an injected spectrum-sliced amplified spontaneous emission light shows a high robustness on the back-reflections, while a coherent seed light exhibits a high-reflection-induced penalty. We also estimate the maximum allowable fiber loss according to the linewidth of the seed light.

An Efficient Evolution Method From TDM-PON to Next-Generation PON

An efficient evolution method from a time-division-multiplexing passive optical network (TDM-PON) is proposed and demonstrated for a next-generation PON. A single-type three-port wavelength band combiner/splitter enables a simple and efficient evolution of TDM-PON maintaining the current PON infrastructure and wavelength plan. The crosstalk between the TDM-PON and next-generation PON is negligibly small

Broad-band light source using mutually injected Fabry-Pe/spl acute/rot laser diodes for WDM-PON

We propose and demonstrate a new broad-band light source (BLS) for a wavelength division multiplexing-passive optical network (WDM-PON) based on the wavelength locked Fabry-Pe/spl acute/rot laser diodes (F-P LDs). By mutual injection between two antireflection-coated F-P LDs, we realized a broad-band light with a low relative intensity noise. By using the proposed BLS for wavelength locking of the F-P LD, we achieve color-free operation of the optical network termination with Manchester coded data. We also demonstrate a WDM-PON based on the proposed BLS.

A theoretical model of a wavelength-locked Fabry-Pe/spl acute/rot laser diode to the externally injected narrow-band ASE

We propose a theoretical model of the wavelength-locked Fabry-Pe/spl acute/rot laser diode (F-P LD) to the externally injected narrow-band amplified spontaneous emission. The model explains the dynamics of the wavelength-locked F-P LD. The simulation results with the proposed model show good agreement with the experimental results.

An Automatic Wavelength Control Method of a Tunable Laser for a WDM-PON

We propose a novel automatic wavelength control method of a tunable laser for a wavelength-division-multiplexed passive optical network (WDM-PON). By sending a low-power amplified spontaneous emission light generated from a broadband light source (BLS) to a tunable laser through a wavelength-division multiplexer, we match the wavelength of the tunable laser to a peak transmission wavelength of the multiplexer. The deviation of the wavelength of the tunable laser was less than 0.05 nm from the center of the target channel. We demonstrate up to 10-Gb/s transmission in a WDM-PON by using the proposed method. We also show that system impairments induced by the BLS are negligible.

Color-free operation of dense WDM-PON based on the wavelength-locked fabry-Pe/spl acute/rot laser diodes injecting a low-noise BLS

We demonstrate color-free operation of a dense wavelength-division-multiplexing passive optical network based on the wavelength-locked Fabry-Peacuterot laser diodes with injection of a low-noise broadband light source (BLS). The color-free operation, i.e., wavelength-independent operation, was obtained at 50-GHz channel spacing with the help of a narrow injection bandwidth of the low-noise BLS. We also demonstrate three-channel upstream transmission with 100-Mb/s Manchester coded data

Decision Threshold Control Method for the Optical Receiver of a WDM-PON

We demonstrate an improvement of optical receiver performance for an optical signal with beat noises. The decision threshold level is adjusted automatically according to the detected average optical power. This simple method improves optical receiver performance under a wide range of input signal conditions, e.g., beat noise level and extinction ratio. Thus this proposed method is useful to optical receivers for WDM-PONs. By employing this control circuit, we successfully demonstrate a WDM-PON based on a wavelength-locked Fabry–Perot laser diode at 1.25 Gb/s per channel with 100 GHz spacing.