A filterless coherent PON with channel spacing down to 2.8 GHz and real-time processing in an FPGA is demonstrated. 64-channel operation is verified experimentally using SSB generation at the OLT and fully integrated ONU transceivers.

A fully reconfigurable add/drop node for use in metro DWDM networks based on a novel switched reflective architecture is demonstrated. The scheme saves power and avoids the need for expensive tunable lasers on equipment cards.

We report on a hybrid DWDM-TDM A optical access network that provides a route for integrating access and metro net- works into a single all-optical system. The greatest challenge in using DWDM in optical access networks is to precisely align the wavelength of the customer transmitter (Tx) with a DWDM wave- length grid at low cost. Here, this was achieved using novel tunable, external cavity lasers in the optical network units (ONUs) at the customer's end. To further support the upstream link, a 10 Gb/s burst mode receiver (BMRx) was developed and gain-stabilized erbium-doped fiber amplifiers (EDFAs) were used in the network experiments. The experimental results show that 10 Gb/s bit rates can be achieved both in the downstream and upstream (operated in burst mode) direction over a reach of 100 km. Up to 32 50 GHz spaced downstream wavelengths and another 32 50 GHz spaced upstream wavelengths can be supported. A 512 split per wave- length was achieved: the network is then capable of distributing a symmetric 320 Gb/s capacity to 16384 customers. The proposed architecture is a potential candidate for future optical access net- works. Indeed it spreads the cost of the network equipment over a very large customer base, allows for node consolidation and integration of metro and optical access networks into an all-optical system.

We present a hybrid dense wavelength-division-multiplexed 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 upstream 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-absorption 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 wavelength 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 demonstrated network concept allows integration of metro and optical access networks into a single all-optical system, which has potential for capital and operational expenditure savings for operators.

We describe 480 Mbps, bi-directional ultra-wideband (UWB) radio signal transmission over 1 km of single-mode optical fiber. Key components are a highly linear, reflective electro absorption transducer (EAT) and commercially available 1308-nm and 1564-nm VCSELs with 4.8-GHz bandwidth. Detailed EAT and 1308-nm VCSEL distortion analyses and measurements are presented highlighting the low intermodulation and harmonic distortion necessary for typical -18-dB wireless channel error vector magnitudes (EVMs). Direct VCSEL modulation with Wimedia supported band group 1 (3.1-4.8 GHz) MB-OFDM UWB signals was modelled with VPItransmissionMaker, suggesting a minimum EVM of -18.733 dB at 0.4502 OMI. This was confirmed by 480 Mbps upstream and downstream EVM measurements over fiber of -21.4 dB or better. Fully functional, half-duplex, bi-directional data transfer was achieved with interlocked RF switches.

Giuseppe Talli, Chi Wai Chow, Paul Townsend, Russell Davey, Tine De Ridder, Xing-Zhi Qiu, Peter Ossieur, Heinz-Georg Krimmel, David Smith, Ian Lealman, Alistair Poustie, Sebastian Randel, Harald Rohde 1 Photonic Systems Group, Tyndall National Institute and Department of Physics, University College Cork, Cork, IRELAND Tel.: +353 214904874, Fax: +353 214904880, E-mail: giuseppe.talli@tyndall.ie 2 BT, 3 INTEC/IMEC, 4 Alcatel-Lucent, 5 CIP, 6 Siemens AG, Corporate Technology, 7 Nokia Siemens Networks GmbH & Co.