JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 29, NO. 4, FEBRUARY 15, 2011 463 A 135-km 8192-Split Carrier Distributed DWDM-TDMA PON With 2 32 10 Gb/s Capacity Peter Ossieur, Member, IEEE, Cleitus Antony, Member, IEEE, Aisling M. Clarke, Member, IEEE, Alan Naughton, Heinz-George Krimmel, Y. Chang, Colin Ford, Anna Borghesani, David G. Moodie, Alistair Poustie, Member, IEEE, Richard Wyatt, Bob Harmon, Ian Lealman, Member, IEEE, Graeme Maxwell, Dave Rogers, David W. Smith, Derek Nesset, Member, IEEE, Russell P. Davey, and Paul D. Townsend, Member, IEEE Abstract—We present a hybrid dense wavelength-division-mul- tiplexed time-division multiple access passive optical network (DWDM-TDMA PON) with record performance in terms of reach (135.1 km of which 124 km were field-installed fibers), number of supported optical network units (ONUs—8192) and capacity (symmetric 320 Gb/s). This was done using 32-, 50-GHz-spaced downstream wavelengths and another 32-, 50-GHz-spaced up- stream wavelengths, each carrying 10 Gb/s traffic (256 ONUs per wavelength, upstream operated in burst mode). The 10 Gb/s downstream channels were based upon DFB lasers (arranged in a DWDM grid), whose outputs were modulated using a electro-ab- sorption modulator (EAM). The downstream channels were terminated using avalanche photodiodes in the optical networks units (ONUs). Erbium-doped fiber amplifiers (EDFAs) provided the gain to overcome the large fiber and splitting losses. The 10 Gb/s upstream channels were based upon seed carriers (arranged in a DWDM grid) distributed from the service node towards the optical network units (ONUs) located in the user’s premises. The ONUs boosted, modulated, and reflected these seed carriers back toward the service node using integrated 10 Gb/s reflective EAM-SOAs (EAM-semiconductor optical amplifier). This seed carrier distribution scheme offers the advantage that all wave- length referencing is done in the well-controlled environment of the service node. The bursty upstream channels were further supported by gain stabilized EDFAs and a 3R 10 Gb/s burst-mode receiver with electronic dispersion compensation. The demon- strated network concept allows integration of metro and optical access networks into a single all-optical system, which has poten- tial for capital and operational expenditure savings for operators. Manuscript received July 12, 2010; revised September 20, 2010; accepted October 08, 2010. Date of publication October 18, 2010; date of current version February 02, 2011. This work was supported in part by the Science Foundation Ireland under Grant 06/IN/I969 and in part by the EU under the FP6 project PIEMAN and FP7 Network of Excellence EuroFOS. P. Ossieur, C. Antony, A. M. Clarke, and A. Naughton are with the Photonics Systems Group, Tyndall National Institute and the Department of Physics, Uni- versity College Cork, Ireland (e-mail: peter.ossieur@tyndall.ie). H. G. Krimmel is with Alcatel-Lucent, Bell Labs, D-70435 Stuttgart, Ger- many. Y. F. Chang is with Vitesse Semiconductor Corporation, Transport Systems Engineering, Camarillo, CA 93012 USA. C. Ford, A. Borghesani, D. Moodie, A. Poustie, R. Wyatt, B. Harmon, I. Lealman, G. Maxwell, D. Rogers, and D. W. Smith are with the Centre for In- tegrated Photonics, IP5 Ipswich, U.K. D. Nesset and R. P. Davey are with BT, Adastral Park, Martlesham Heath, Ipswich, IP5 3RE, U.K. P. D. Townsend is with the Photonics Systems Group, Tyndall National Insti- tute and the Department of Physics, University College Cork, Ireland, and also with the School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. Digital Object Identifier 10.1109/JLT.2010.2088109 Index Terms—Burst-mode receiver (BMRx), electroabsorption modulator (EAM), erbium-doped fiber amplifier (EDFA), passive optical network (PON), semiconductor optical amplifier (SOA). I. INTRODUCTION W ITH the recent emergence of the new ITU-T G.987.x XGPON1 and IEEE 802.3av 10GEPON Standards [1]–[3], we are now witnessing the emergence of optical access systems with bit rates up to 10 Gb/s. First, field trials and demonstrations of this next generation of systems have been reported in [4], [5]. Research is now taking new steps and is aiming at optical access network concepts known as hybrid dense wavelength-division-multiplexed time-division multiple access passive optical networks (DWDM-TDMA PONs) [6]. These systems differ from today’s optical access systems in three major aspects. First of all, DWDM is used to dramatically increase the capacity of optical access networks. Second, the physical reach is increased significantly from today’s usual 20 km (60 km in the case of ITU-T G.984.6 extended reach GPON [7]) to over 100 km. Finally, a single system will serve several thousand optical network units (ONUs) rather than the typical 32 of today’s deployed optical access systems. These new types of networks potentially allow the integration of metro and optical access networks into a single all-optical system, thus drastically reducing the number of network elements, interfaces, and electro-optical conversions required to serve a given customer base. This may lead to capital expenditure sav- ings. Furthermore, such an approach may also offer significant savings in electrical power consumption and the footprint of the network, thus leading to operational expenditure savings [8]–[10]. The introduction of DWDM into optical access networks comes with significant challenges. Indeed the transmit wave- length of each ONU must stay tuned to the chosen DWDM grid, with an accuracy determined by the passband of the wavelength multiplexing devices used. This must be achieved at the lowest possible cost for an economically viable network. Conse- quently, network operators do not want to keep a large stock of customer premises equipment or ONUs with wavelength-spe- cific lasers as this brings additional inventory and management costs. Rather, a colorless transmitter is the preferred choice in 0733-8724/$26.00 © 2010 IEEE