M. Chbat

Toward wide-scale all-optical transparent networking: the ACTS optical pan-European network (OPEN) project

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.

Long term field demonstration of optical PMD compensation on an installed OC-192 link

We demonstrate the worlds first long term optical PMD compensation for an OC-192 (9.95328 Gb/s SONET) signal on the installed fiber infrastructure of a network operator in East Texas. With a line PMD of 30 ps, BER improvement greater than 4 orders of magnitude has been achieved.

Experimental investigation of dispersion management for an 8/spl times/10 Gbit/s WDM transmission over non-zero dispersion shifted fiber

We experimentally demonstrate that an 8/spl times/10 Gbit/s wavelength-division multiplexing (WDM) transmission with 200-GHz channel spacing over nonzero-dispersion-shifted fiber requires dispersion management when using field channel powers. This is then investigated and optimized.

Investigation of self-phase modulation limitation on 10-Gbit/s transmission over different types of fiber

Summary form only given. For multichannel systems over various types of fiber infrastructures, one option for increasing the throughput is the increase of the individual channel rate, which imposes an increase in the required signal-to-noise ratio (SNR) at the receiver, hence in the output power of in-line amplifiers. The other option is to increase the number of channels, with the total output power of the amplifiers set for an adequate SNR for all channels. However, should several channels not be transmitted, the power per channel rapidly increases, in absence of gain control, as in present commercially available systems. In both scenarios, self-phase modulation (SPM) can become the limiting factor. The experimental setup for the investigation of SPM-induced limitation at 10 Gbit/s is given. Various types of dispersive fibre are experimented with.

Investigation of cross-phase modulation limitations on 10 Gbit/s transmission over various types of fiber infrastructures

We measure the impact of cross phase modulation (XPM) on the transmission performance of a 2/spl times/2 Gbit/s multiplex. In contrast to the other investigated fiber schemes, dispersion-compensated SMF is virtually not affected by XPM down to 50-GHz channel spacing.

Time impulse response of second order PMD in single-mode fibers

The paper provides, for the first time, the exact linear frequency response for PMD fibers, lip to second order. Power overshoots on the transmitted sequences are generated by a linear rotation of the principal states of polarization (PSP). We give for the first time a closed-form expression for the time impulse response of PMD, up to second order. It allows a fast estimation of the PMD induced time pulse deformation on long bit sequences. We showed, both numerically and experimentally, that the effects of a PSP linear rotation is to generate power overshoots, well focalized on the transmitted bit sequence.

Investigation of the limitations of WDM typical terrestrial transmissions over NZDSF and SMF

WDM transmission limitations at 10Gbit/s over NZDSF are analyzed numerically on uncompensated and dispersion-managed links. The results are then compared to that obtained with a dispersion-managed transmission based on SMF.

Systems aspects of fluoride-based EDFAs

We describe EDFFAs (Er-doped fluoride fiber amplifiers) and their design criteria, discuss the EDFFA gain-flatness control mechanism and new amplifier designs giving improved gain flatness, and present in detail system applications that have been explored in our laboratory. Among these are a study of EDFFA cascade in multichannel systems, and WDM transmission and routing systems using EDFFAs.

Recent progress in the Optical Pan-European Network project (ACTS/OPEN)

Summary form only given. Summary form only given. The OPEN project aims at the assessment of the feasibility of an Optical Pan-European overlay Network (OPEN), 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. OPEN demonstrates the concept of a core network, built upon an existing optical fiber infrastructure, offering long-distance transparent transport. It addresses the transport both in the optical transmission medium layer (physical layer) and the optical path sublayer. The potential capacity of each fiber link will be upgradable up to at least 40 Gbit/s, each channel supporting STM-16 SDH/OC-48 SONET or higher data-rate. The high degree of transparency offered by the OPEN concept pertains to the bit-rate and to the digital frame format, which is made possible by the use of all-optical WDM technologies for transmission between the network nodes and routing through multiwavelength optical cross-connects (MOXCs) without any electrical regeneration. In particular, wavelength translation within the MOXC is a key element in this approach. The project encompasses modeling, laboratory experiments, and field implementation of a photonic network prototype, in order to determine the feasibility of the OPEN concept.

WDM Networking: Lessons from ACTS OPEN Field Trials

Gain-clamped semiconductor optical amplifiors (GCSOAs) me promising candidates for wavelength division multiplexing (WDM) applications due to their low inter-channel crosstalk and high saturation output power, obtained by the gain-clamping [I]. However, in this presentation we will show that, although thegain is clamped, some inter-channel orossldk still occurs due to longitudinal spatial hole burning. A strong longitudinal spatial hole burning (LSHB) oecum in GCSOAs due to the low mirror reflections (% 1%) wich me required to provide the high internal chip gain (m 20 dB) 111. By means of a detailed numerical model we will analyse the dependence of the LSHB on injection current snd input powers. We will show that when an optical signal is injPctPd iiito the GCSOA, the carrier density distribution inside the active layer changes largely, resulting in a small variation of the gain spectrum. Therefore, a kind of cross-gain rnodiilat,ion OCCUTS, leading t o inter-channel crosstalk when the GCSOA is used as a multi-channel amplifier in WDM-applications. However, our modeling rPsult8 show that the introduced crosstalk is rather small (less than 0.6 dB gain variation) and occurs mainly at high signal input powers, when the lasing mode is nearly switched off. Rrtl iermore, r e will siiow thal, by employing asymnetric B r a g mirror reflectivities in the GCSOA-cavity, the carrier density profile can be adapted, which can lead to a significmt redirtinn of the LSHB-induced crosstalk.