Silvia Di Bartolo

Evolution of Optical Access Networks

This chapter reviews the current developments in access network architectures and protocols to communicate dynamically the emerging broadband services to end-users at low cost. Following a summary of Gigabit Ethernet and Passive Optical Network (PON) standards and deployment issues with reference to Ethernet (EPON) and Gigabit-capable PON (GPON) infrastructures, an original transparent network architecture is presented to allow interoperability of time division multiplexing (TDM) and wavelength division multiplexing (WDM) PONs, by means of coarse routing. To provide flexible connectivity at extended service reach hybrid wireless and free space optic technologies have been investigated to terminate mobile end users to high bandwidth PON terminals. To demonstrate independent bandwidth management of the constituent sectors of such architectures developed dynamic bandwidth allocation (DBA) algorithms are summarised followed by an original control plane to coordinate the various mandatory access control (MAC) protocols. Finally, to provide reliable service delivery several protection schemes have been analysed.

Experimental evaluation of modulation induced by continuous waves in a semiconductor optical amplifier

Many simulative approaches have been proposed to investigate Semiconductor Optical Amplifier (SOA) behaviour, in order to model its performance when used in several scenarios. Most of the applications of SOAs are based on the propagation of maximum two signals within the active medium, thus, higher order phenomena due to beating of more than two signals are not always correctly predicted by usual simulative models. In this paper we report some experimental results which validate an accurate model for SOA nonlinearities. This model is based on calculation of nonlinear susceptibility whose expression depends on multicarrier propagation. In particular, three signals are considered and their nonlinear interaction is evaluated by measuring a modulation arising on one of the signals.

Enabling Optical Network Test Bed for 5G Tests

ABSTRACT In this work, we show some experimental approaches concerning optical network design dedicated to 5G infrastructures. In particular, we show some implementations of network slicing based on Carrier Ethernet forwarding, which will be very suitable in the context of 5G heterogeneous networks, especially looking at services for vertical enterprises. We also show how to adopt a central unit (orchestrator) to automatically manage such logical paths according to quality-of-service requirements, which can be monitored at the user location. We also illustrate how novel all-optical processes, such as the ones based on all-optical wavelength conversion, can be used for multicasting, enabling development of TV broadcasting based on 4G–5G terminals. These managing and forwarding techniques, operating on optical links, are tested in a wireless environment on Wi-Fi cells and emulating LTE and WiMAX systems by means of the NS-3 code.

Integration of optical telecommunications and radio access networks to assure quality of service

In this work, we show how to control a Quality of Service in optical networks integrated with WiMAX access radio by means of the MPLS and WiMAX Class of Services, even in condition of traffic congestions.

Enhanced Transmission Techniques

Next generation Passive Optical Networks (ngPONs) that offer increased bandwidth and distance-reach to a higher number of customers may require some modifications in the network infrastructure and in the technology of its devices. Nevertheless, these changes should not require a significant increased cost nor upgrading complexity. Optical Network Units (ONUs) at customer premises of currently deployed PONs include a fixed laser at a non-controlled wavelength, launching the light into the upstream fibre or into a single fibre via a coarse WDM multiplexer. In future PONs, Wavelength division multiplexing (WDM) can be effectively used to upgrade the overall PON capacity in several ways. Thus, new generation ONUs may be wavelength-controlled, wavelength-tuneable or wavelength-agnostic. WDM allows superposing different TDMA PONs over the access fibre line. The number of wavelengths then corresponds to two times the number of TDMA PON systems. This solution offers desirable characteristics for an access infrastructure as the use of one single fibre for both upstream and downstream transmission reduces the network size and connection complexity.

Experimental investigation on DVB-T over CATV-RoF constraints in long haul Passive Optical Networks

The future installation of FTTB infrastructures could totally change the broadcasting television market thanks to the introduction of a wavelength channel dedicated to CATV Radio over Fibre (RoF). In this paper we report an experimental investigation on the optical transmission of the Italian digital terrestrial broadcast television (DVB-T) signal in Passive Optical Network (PON), analyzing the impact of the TV spectrum characteristics on the optical transmission and achieving transmission distances up to 40 km in G.652 links, upgradable to > 60 km. The investigation was carried out by adopting a Lithium Niobate (LiNbO3) Mach-Zehnder (MZ) modulator. Various critical points are examined, especially regarding on Harmonic, Intermodulation and Cross-modulation Distortions (HD, IMD, X-MOD) due to intrinsic nonlinear Power-Voltage (P-V) response of Mach-Zehnder modulator.

Infrared emitting Erbium-doped quinolines for Silicon Organic Hybrid technology

The emerging application of organic materials to the integrated photonics led to the definition of the Silicon Organic Hybrid (SOH) technology, that is a promising approach to bring active functionalities on an intrinsically passive silicon substrate. Erbium-doped molecular materials were demonstrated to provide IR emission in the C band when grown on silicon as solution processed thin films, enabling potential low cost processing of organic sources integrated on silicon. The contribution is meant to provide an overview of the recent results of the molecular enhancement of the Er-doped quinolines as IR emitters and their application into a slot waveguide structure designed over a SOI platform for compatibility to standard CMOS processing technologies.

Preliminary investigations of the effects of air turbulences on the performance of an indoor optical wireless link

Photonic technologies are becoming more and more necessary for data centre (DC) networks to meet the requirements of data transfer speed and energy saving. The use of optical hybrid wired/wireless solutions, where fibre links are coupled to free space optical links within the same DC facility can contribute to reduce the complexity of the network architecture and increase the efficiency of cooling. Although indoor optical wireless is immune by detrimental weather conditions on the free space optical link, the specific environmental conditions of a data centre room, such as strong local thermal variations and high intensities air flows, can introduce effects over the optical channel that can affect the link performance. The aim of this work is to provide a preliminary evaluation of the effects of controlled turbulences in terms of temperature and air flow speed on the power of the free space optical signal, with the purpose of enabling an initial understanding of the involved phenomena. Finally, the effects of the hot air flow-perturbed FSO link on the quality of a video service delivered on a photonic network are compared to a fully fiber-based link.

Applications and Low Cost Processing of Erbium Quinolinolates for Active Integrated Photonic Devices

Rare earth-doped organic materials represent a promising alternative to play the role of active materials for Photonic Integrated Circuits (PICs), meeting the requirement of low cost integration. In particular, Erbium Quinolinolates (ErQ) attracted a strong interest in the last decade for their good efficiency of emission in the C band of the optical communications centered at 1550 nm. In this paper, a resume of the application of ErQ for processing of photonic devices is presented. Results deriving from the optical characterization of the ErQ materials and their application as active materials into optical waveguides and light emitting devices are reported. Finally, the results of the improvement of the ErQs via a purposed chemical synthesis towards more efficient and lower cost solution processed devices are presented.

Remotely Power Assisted Optical Network Terminals in Gigabit Ethernet Passive Optical Access Scenarios

In this paper we experimentally analyze the possibility to remotely assist, both in terms of voltage and optical carrier, a gigabit ethernet optical network unit device.