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Photonic technologies for ultra high speed information highways


HIGHWAY addresses promising ultra-high speed optoelectronic components and subsystem technologies for photonic 40 Gbit/s time division multiplexed (TDM) transport systems. Advanced TDM system lab demonstrators are to be realised and tested over field-installed fibre. The field experiments aim to demonstrate that the 40 Gbit/s TDM system technologies developed offer promising options for a field deployment of high capacity information highways in future trans-European telecommunication networks.
HIGHWAY will further test and optimise the options of high speed optoelectronic components and subsystems in the 40 Gbit/s system test beds, and finally implement the most promising versions in 40 Gbit/s OTDM/ETDM laboratory system demonstrators for evaluation.
Advanced 40 Gbit/s TDM system demonstrator configurations will be operated over different field fibre infrastructures provided by the telecom partners. The 40 Gbit/s system field experiments will allow the testing of alternative options for dispersion accommodation (e.g. MSSI, DCF) over standard fibre infrastructure, and of specific system configurations over different types of fibre links (SSMF, DSF, DFF).
Expected Impact
The current dynamic market growth for high speed interoffice networks (e.g. in the US) is characterised by strong competition between equipment suppliers offering wavelength-division-multiplexed (n x 2.5 Gbit/s WDM) systems, and those offering the new generation of TDM (10 Gbit/s) transport systems (e.g. OC-192). The same competition will arise with respect to the next bit rate hierarchy (n x 10 Gbit/s WDM vs. 40 Gbit/s TDM). Since future WDM networks will always be based on a mature generation of TDM systems, it is essential to demonstrate the technological capabilities and constraints of state-of-the-art TDM technology.
HIGHWAY aims to demonstrate the potential of the next generation of TDM systems (40 Gbit/s) in order to provide a solid technological base for techno-economic decisions by network operators, about cost effective transport systems at the beginning of the next decade. The upgrade of single optical channel transmission capacity to 40 Gbit/s TDM is a challenging task at the limits of existing technologies. OTDM allows for an early investigation of most of the system related limitations associated with 40 Gbit/s RZ transmission over long-haul fibre links (e.g. dispersion accommodation, polarisation-mode dispersion, nonlinearities). However, it is likely that in the near to medium term, advances in high speed electronic circuit design will allow 40 Gbit/s electronic processing. Therefore, it is an important objective of HIGHWAY to provide electronic test circuits (mux/demux) for 40 Gbit/s ETDM and novel ultra-high speed (40 Gbit/s) optoelectronic components and subsystems in order to use the most efficient combination of photonics and electronics for next generation TDM systems.
The 40 Gbit/s single optical channel transmission tests should demonstrate the potential of advanced TDM system technologies for high-capacity point-to-point transport. The 40 Gbit/s field tests should answer the important question of whether future ultra-high bit rate systems could be operated over existing fibre infrastructure (SSMF), or if new types of fibre (e.g. DSF) are required. Finally the field trials should demonstrate the potential and implications of optical and electrical TDM system technologies with respect to future TDM/WDM based transparent photonic networks.

Main contributions to the programme objectives:
Main deliverables
Long distance, high speed single wavelength transmission at 40 and 80 GBit/s over standard in-field installed telecommunications optical-fibre, accomodating the PMD.
Contribution to the programme
Development of long-haul 40 Gb/s transmission systems in Europe.
Technical Approach
The consortium aims to develop and demonstrate advanced photonic and electronic components and subsystems for 40 Gbit/s TDM-based optical transport systems, including integrated laser sources, electro-absorption (EA) and travelling wave Mach-Zehnder (MZ) modulators, semiconductor optical amplifiers (SOAs) for non-linear signal processing (mid-span-spectral-inversion (MSSI), add-and-drop), optical demultiplexers with low polarisation dependence, high speed PIN detectors with integrated SOA preamplifier, and high speed electronic circuits. The components, subsystems and devices will be tested and optimised in 40 Gbit/s testbeds and integrated into 40 Gbit/s system laboratory demonstrators using optical TDM (OTDM) and electrical TDM (ETDM) to prove the key functionalities, benefits and implications of TDM-based photonic transport networks (e.g. high capacity point-to-point transport, add-and-drop multiplexing (ADM)). The subsystem/system tests will also allow evaluation of the potential and optimum combinations of advanced photonic and electronic high speed system technologies (e.g. OTDM vs. ETDM).
Summary of Trial
40 Gbit/s TDM system demonstrators will be tested in the field, in fibre testbeds provided by two of the participating telecom operators. BT's East Anglian Network will be used for 40 Gbit/s field testing with dispersion compensation by mid-span-spectral-inversion (MSSI) over existing standard fibre links (Norwich-Ipswich). DT's Berlin FZ fibre testbed offers all possible options of existing or future fibre infrastructure for 40 Gbit/s system field testing, including standard (non-dispersion-shifted) single-mode fibre (SSMF), dispersion-shifted fibre (DSF), and dispersion flattened fibre (DFF).
Key Issues
40 Gbit/s system design and building blocks (e.g. transmitter, mux/demux, fibre link, receiver, ADM);
Components and subsystems for optical 40 Gbit/s signal generation, mux/demux and detection;
Dispersion accommodation techniques (e.g. MSSI) and the impact on fibre infrastructure (SSMF vs. DSF);
Basic limitations for 40 Gbit/s transport, e.g. chromatic dispersion, polarisation mode dispersion (PMD);
Linear vs. non-linear 40 Gbit/s transmission regime (non-soliton vs. soliton);
Signal modulation format (RZ vs. NRZ);
4x10 Gbit/s multiplexing/demultiplexing (OTDM vs. ETDM);
Add-and-drop multiplexing;
High sensitivity 40 Gbit/s signal detection (optical preamplifier);
Supporting high speed technologies (e.g. high speed integrated circuits).
HIGHWAY has so far achieved substantial progress with respect to component/subsystem development, subsystem/system functional tests, 40 Gbit/s transmission tests and the definition and preparation of field test infrastructures.

All basic system functionalities for 40 Gbit/s TDM transport have been demonstrated using the above-mentioned elements, including RZ signal generation, 40 Gbit/s (4x10 Gbit/s) pattern generation and modulation, 4x10 Gbit/s, 2x20 Gbit/s OTDM multiplexing, 10/20 GHz clock recovery from 40 Gbit/s, 40/10 Gbit/s optical demultiplexing, 10/40 Gbit/s ADM, 10/20 Gbit/s detection, 40 Gbit/s dispersion accommodation (MSSI);
40 Gbit/s (4x10 Gbit/s) transmission experiments over SSMF and DSF have been performed successfully, including clock extraction and BER measurements. 40 Gbit/s has been transmitted over up to 400 km of SSMF using MSSI for dispersion accommodation. These laboratory experiments have confirmed the viability of the proposed options;
Theoretical models for the evaluation of basic system limitations (chromatic dispersion, PMD, nonlinearities) and of dispersion accommodation (MSSI) at 40 Gbit/s have been developed and used for the analysis of long-haul transmission, in laboratory experiments. This work provides a solid theoretical background for the reliable prediction of system performance and final system specification;
The fibre link infrastructures for the system field tests have been defined and specified by the respective telecom operators.


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Participants (9)

Alcatel Alsthom Recherche
Route De Nozay
91460 Marcoussis
British Telecommunications plc
United Kingdom
Deutsche Telekom AG
Eidgenoessische Technische Hochschule
France Télécom
38-40 Rue Du Général Leclerc
92131 Issy-les-moulineaux
Heinrich Hertz Institut
University of Bristol
United Kingdom
Senate House Tyndall Avenue
BS8 1TH Bristol