The main objective is to validate new concepts to achieve high speed (2.5 Gbit/s), high capacity (Tbit/s) switching systems needed for ATM based IBC optical networks. These concepts are applied to centralised switches for public and to decentralised switches for corporate networks. Supporting demonstrators are designed with advanced photonic technologies scaleable to real system dimensions and are tested in quasi-real traffic conditions, to provide a basis for the longer term objective of optimised switching systems.
The main objective of the research was to validate new concepts for achieving the high speed (2.5 gigabytes per second) and high capacity switching systems needed for asynchronous transfer node (ATM) based integrated broadband communications (IBC) optical networks. These concepts are applied to centralized switches for the public network and to decentralized switches supporting metropolitan area network (MAN) services in corporate networks.
The demonstrators are designed using technologies scaleable to real system dimensions and will be tested in quasi real traffic conditions to provide a sound basis for the longer term objective of optimized switching systems.
The research has resulted in the following:
performance requirements for ATM optical switches have been established;
Modular switching systems have been established and analyzed;
demonstrator architecture has been defined;
specifications of building blocks have been issued;
hardware implementation has started;
the basic functionality of key building blocks has been demonstrated including wavelength switching at high speed (greater than 2.5 gigabytes per second) over 20 nm using wavelength conversion devices and buffering of high bit rate cells using 2 types of optical fibre memory (delay lines and loop);
world state of the art performances on photonic switching devices have been achieved;
wavelength tuneable lasers (50 nm) and high speed (greater than 2.5 gigabytes per second) wavelength converters have been tested;
semiconductor optical amplifier gates have been operating at 2.5 gigabytes per second;
polarization insensitive indium phosphide space switches have been tested;
multifunction optoelectronic integrated circuit (OEIC) fast tuneable filters have been tested;
polymeric space switches have been tested.
The system concepts employ switch architectures using photonic techniques (space and wavelength switching for routing and multiplexing, time switching using optical fibre buffers to overcome the limitations of ATM electronic switches. These techniques are used where high operation speed and high throughput are required to perform cell routing, multiplexing and buffering. Use of electronics is reserved for the complex functionality of the switch, where speed is not a limiting factor, especially for control. The concepts are validated in experimental testbeds built from state-of-the-art photonic technology.
- Optical switching in ATM networks, requirements and evolutionary concepts and introduction strategies for optical switching systems, including ATM network-node interfaces and adapted information formats analysis.
- Definition of multistage modular systems with appropriate interfaces, feasibility assessment of high-speed/high capacity modular multistage switches including traffic and optical performance evaluation, specification and test of elementary switching modules including electronic control.
- Specification, design, realisation and test of functional blocks and subsystems.
- Optimisation, fabrication and evaluation of the key photonic components' and ICs' performance for the sub-system functional blocks, with special attention to packaging and to complexity performance trade-off analysis.
At the network and system levels, the main impact will be to provide the technological background, as well as viable solutions, for the introduction in the medium term (5-10 year objective) of high speed (greater than or equal to 2.5 Gbit/s) optical switching systems in the ATM based IBC.