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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 demonstrate a remotely seeded flexible passive optical network (PON) with multiple low-speed subscribers but only a single optical line terminal transceiver operating at a data rate of 31.25 Gbits/s. The scheme is based on a colorless frequency division multiplexing (FDM)-PON with centralized wavelength control. Multiplexing and demultiplexing in the optical network unit (ONU) is performed in the electronic domain and relies either on FDM with Nyquist sinc-pulse shaping or on orthogonal frequency division multiplexing (OFDM). This way the ONU can perform processing at low speed in the baseband. Further, the ONU is colorless by means of a remote seed for upstream transmission and a remote local oscillator for heterodyne reception, all of which helps in keeping maintenance and costs for an ONU potentially low and will simplify wavelength allocation in a future software defined network architecture. To extend the reach, semiconductor optical amplifiers are used for optical amplification in the downstream and upstream.

The ACCORDANCE OFDMA-PON architecture has been proposed as an attractive candidate for next generation PON networks. The benefits brought by this concept include ultra-high data rates, extensive node consolidation and convergence of multiple services within the same optical distribution network infrastructure, more flexible, two-dimensional bandwidth management, as well as the opportunity for cross-layer optimization. Moreover, OFDMA-PON is expected to scale better to increased (> 10 Gbps) aggregate data rates than existing TDMA-PONs. The ACCORDANCE project addresses a wide range of aspects related to OFDMA-PON. This includes architectural issues, physical layer OFDM transmission studies, OLT/ONU Tx/Rx system design, MAC protocol and algorithm design/implementation and wireless backhauling/fronthauling. This paper provides an overview of the activities within the ACCORDANCE consortium and the solutions selected by the project partners to address the aforementioned issues.

This paper reports performance tests on a DC-coupled 10Gb/s burst-mode receiver with on-chip reset, designed for 10G-GPONs. Record short 2R settling time, high sensitivity and large loud/soft ratio is demonstrated in burst-mode operations at 2.5G/5G/10Gb/s.

A DWDM-TDMA PON using carrier distribution with symmetric 320Gb/s capacity is demonstrated over 124km field-installed fibers. The upstream channels feature a 3R 10Gb/s burst-mode receiver with electronic dispersion compensation, burst-mode EDFAs and integrated reflective SOA-EAMs.

We demonstrate a DWDM-TDMA PON with symmetric 320Gb/s capacity shared between 16384 customers. The upstream channels were tested in burst-mode and feature low-cost tuneable lasers, monolithically integrated SOA-EAMs, burst-mode EDFAs and a 10Gb/s burst-mode receiver.

Long-reach access networks such as the hybrid TDM-WDM-PON studied in the EU-funded project PIEMAN reduce node count and increase bandwidth per customer, but require challenging opto-electronic component development. We review PIEMAN's achievements and future possibilities.

Gigabit PON /10 Gbps PON coexistence with two ONU generations on a single 1490 nm downstream wavelength is enabled by bitstacking and affiliated framing measures forming a novel electrical multiplexing technique.

A 10 Gbit/s DC-coupled burst-mode limiting amplifier (BM-LA) with two-level integration time constants for fast/slow feedback offset cancellation respectively during preamble/payload of the incoming bursts is presented. A 10 Gbit/s APD-based burst-mode receiver (BM-Rx) using this feedback type BM-LA achieves a Rx sensitivity of -30.6 dBm under a loud/soft ratio of 24.6 dB at a bit error rate of 10 -3 within a short settling time of only

A new technique is presented for seamlessly upgrading an existing passive optical network (PON) to a higher bitrate on a different wavelength without the need to retrofit any of the existing legacy ONUs. On the OLT side, the standard compliant legacy and advanced signals are combined by an additional box, the only specific device, to create the wavelength intensity multiplexing signal.

A novel DWDM-TDMA PON with symmetric 320Gb/s capacity shared between 16384 customers is demonstrated. Upstream channels were tested in burst-mode and featured low-cost tuneable lasers, monolithically integrated SOA-EAMs, burst-mode EDFAs and a 10Gb/s burst-mode receiver.

A remotely seeded flexible WDM network solution with 31.25 Gbit/s based on Nyquist sinc-pulses is demonstrated. The low-speed, colorless ONUs use remote heterodyne detection with electrical up- and down-conversion and SOAs for potential cost reduction.