The European ACTS project optical pan-European network (OPEN) aims at assessing the feasibility of an optical pan-European overlay network, interconnecting major European cities by means of a mesh of high-capacity optical fiber links, cross-connected through transparent photonic nodes. Both the transmission links and the routing network elements rely on wavelength division multiplexing (WDM) all-optical technologies, such as wavelength translation. This paper presents results obtained in the following domains covered within the project: network topology considerations (optimization and dimensioning); network physical layer simulation; fabrications of packaged functional modules based on advanced optoelectronic devices; laboratory demonstrations of N/spl times/10 Gb/s transmission and routing; feasibility of an optical time division multiplexing/WDM (OTDM/WDM) interface; and the field implementation of a 4/spl times/4 multiwavelength crossconnect prototype, featuring all-optical space and wavelength routing. This implementation was realized in two cross-border field trials, one conducted between Norway and Denmark and the other between France and Belgium. The final results of the Norway to Denmark field trials are presented, featuring the successful cascade of three wavelength-translating optical crossconnects (OXCs), along with the transmission over 1000 km of a mix of standard/submarine cable links for four channels at 2.5 Gb/s.

The objective of this paper is to give an overview of the different studies we have performed at the research level regarding the design and implementation of a photonic wavelength division multiplexing (WDM) layer providing transparent transport services to client layers (SONET/SDH, ATM, etc.). Such a network requires a number of enabling factors to be assessed in order to become a reality. Among these factors are the availability of high-capacity WDM transmission systems and efficient optical routing nodes based on mature technology, the design of robust networks optimizing the utilization of resources, and the development of a management system in accordance with presently applied standards for transport networks. We review our achievements in these different fields.

A space-division photonic switch which has the potential to achieve high dimensionality is presented. The proposed switch, which resembles a collapsed network, does not use optical crosspoints; rather a dedicated path is provided for all input/output port connections on a common high-bandwidth transmission medium. This eliminates the restrictions imposed by 2*2 switching elements in classical space-division switching fabrics. The demonstration of a fully connected 120*120 space-division time-multiplexed photonic switch is reported. The dimensionality and blocking performance of a shared-medium photonic switch that uses time-multiplexing is analyzed.>

Synchronous code-division multiple access (S/CDMA) is investigated for fiber-optic local area networks. It is shown that the large bandwidth expansion required by spread-spectrum techniques, such as CDMA, can be accommodated by using a fiber-optic channel for transmission and incoherent optical signal processing for code generation and correlation. Prime sequence codes, previously developed for a fiber-optic network using (asynchronous) CDMA, are modified to fit a synchronous transmission format. A performance comparison of CDMA and S/CDMA systems reveals that S/CDMA can accommodate a larger number of subscribers and more simultaneous users than CDMA. An environment for which S/CDMA would be suited is discussed.>

A reliable and economical new transmission code is presented with the following properties: zero dc content, baseband bandwidth conservation, self-clocking capability, and data-rate-transparent decoding and synchronization. Simple encoder/decoder and clock extractor circuits are given. The code is demonstrated in a wavelength-multiplexed fiber-optic communication system.