Russell Davey

Next-generation PON-part I: Technology roadmap and general requirements

Gigabit-class passive optical networks have been standardized and are now being deployed. This article presents possible migration scenarios toward the next-generation PON and proposes a technology roadmap of evolutionary growth (termed NG-PON1) vs. revolutionary change (termed NG-PON2). This article then details the general requirements for NG-PON1 to support various popular applications many service providers expressed interests on as well as to enable smooth migration from Gigabit PON.

The future of fibre access systems

It is clear that there is a huge potential demand for high bandwidth services that, at some point in the future, could be deliveredover the fixed network. The most promising technology to provide the delivery mechanism to the customer is optical accessnetworks. The major issue for the telecommunications industry is how to do this at sufficiently low cost. This paper looks at theeconomic issues and suggests some possible ways forward if we are to move to delivery of services well beyond the capability ofADSL and cable-modem technologies.

A 135-km 8192-Split Carrier Distributed DWDM-TDMA PON With 2

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 users 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.

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Feature Issue on Passive Optical Network Architectures and TechnologiesWe describe how a passive optical network (PON) extender box can be implemented at standard PON wavelengths (1310 and 1490nm) using either optical fiber amplifiers (praseodymium and thulium) or semiconductor optical amplifiers to further increase the physical reach and split of a current standardized PON system such as a G-PON or GE-PON. The transparency to PON protocol of this approach means no changes to the existing standards are required. This is attractive as operators and vendors are keen to fully exploit the investment made in current PON standards.

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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 customers 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.

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This paper is a tutorial reviewing research and development performed over the last few years to extend the reach of passive optical networks using technology such as optical amplifiers.

10 Gb/s Capacity

We report operation of a GPON (gigabit-capable passive optical network) (2.488 Gbit/s downstream, 1.244 Gbit/s upstream) over 135 km giving performance consistent with ITU-T standards. Advanced DWDM equipment is used to extend the physical reach and provide fibre gain.

Amplified gigabit PON systems [Invited]

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

Demonstration of a 32

A 1300 nm semiconductor optical amplifier has been developed for extended reach GPON applications. The high gain of 29 dB has and enabled a commercial GPON system to operate over 60 km and with 128-way split.

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This paper describes the service scenarios and economic analysis that lead to the conclusion that a radial approach for optical access and core is required. It then discusses a way forward for the evolution of the access and core optical network architecture that could provide a high capacity, multi-service capability to all types of customers with minimum number of tiers and network nodes at costs significantly lower than traditional price declines could realise.