N. Andriolli

Scuola Superiore Sant'Anna, Pisa, Tuscany, Italy

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Publications (108)68.58 Total impact

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    ABSTRACT: In wavelength switched optical networks (WSONs), the placement of opto-electronic regenerators has always been optimized to keep the cost and power consumption contained, while ensuring the quality of transmission (QoT) for the optical signals. Nowadays, with the increase of the transmission rates and the spectral efficiency of the modulation formats, optical signal regeneration is still relevant for ensuring QoT. The progress in integrated photonics makes possible the realization of integrated optical regenerators that can replace the traditional opto-electronic regenerators. All-optical regenerators enable a reduction of size and energy consumption. However, differently from opto-electronic regenerators, recently fabricated integrated optical regenerators neither perform wavelength conversion nor regenerate multiple lightpaths at the same wavelength. Thus, novel constraints and limitations are introduced to the conventional regenerator placement problem, which has been well studied in the past for opto-electronic regenerators. This paper addresses the all-optical regenerator placement (ORP) problem in WSONs with guaranteed QoT. A genetic algorithm (GA) is proposed for optimizing the ORP while jointly solving the routing and wavelength assignment problem. GA results are compared with the optimal solutions found by solving a binary linear programming (BLP) formulation. When properly tuned, GA is able to quickly achieve the optimal solutions found by the BLP solver. The performance analysis indicates that the additional constraints have a negligible impact on the overall number of regenerators, compared to the case with opto-electronic regenerators.
    Journal of Optical Communications and Networking. 11/2014; 6(11).
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    ABSTRACT: Interconnection networks within modern data centers suffer from bandwidth and scalability limitations, and important power consumption. Optical switching solutions can help to overcome such issues when properly designed and optimized. This paper discusses three areas of improvement beyond state of the art: i) the use of more energy-efficient optical devices to realize high-capacity and energy-efficient optical space switches; ii) the enhancement of their scalability by combining space switching with time switching into a space-time interconnection network architecture (STIA); iii) the planning of an energy-efficient STIA-based network meeting data center bisection bandwidth requirements. Performance assessment shows that i) by combining different switching devices in the same space switch, up to 90% of the power can be saved with respect to conventional SOA-based space switches; ii) STIA allows scalability to increase by a factor of 8, thanks to the combined use of space and time switching domains, while limiting the energy per bit; iii) STIA allows the realization of data center topologies, such as folded Clos and flattened butterfly, whose optimized design can lead to power saving up to 50% with respect to an energy unaware design.
    2014 European Conference on Networks and Communications (EuCNC); 06/2014
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    ABSTRACT: This paper presents an integrable optical network-on-chip based on multiple microrings, named multimicroring (MMR). The network consists of a central resonating microring with local microrings connected to the input/output ports. Multiple parallel communications can be supported through wavelength division multiplexing by properly tuning local microrings. The paper reports progress towards the realization and control of the MMR network-on-chip using a silicon-based CMOS compatible platform. Strained silicon is selected and demonstrated to be a valid material for realizing integrated devices suitable for packet switching. Then a mathematical model based on the transfer matrix method is used to assess the MMR physical performance, showing that the network is robust to crosstalk. Finally a novel scheduling framework is proposed for arbitrating the packet transmissions. Simulation results of the network performance indicate that adding tunability to the transmitters allows full exploitation of WDM multiplexing, leading to a significant reduction of the packet latency.
    EuCNC 2014 - European Conference on Networks and Communications; 06/2014
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    ABSTRACT: We demonstrate a novel InP-PIC for all-optical wavelength conversion that monolithically integrates a digitally tunable 4-channel multi-wavelength laser and a SOA-MZI. Operations up to 5 Gb/s are shown by BER-measurement with moderate power penalty.
    Optical Fiber Communication Conference; 03/2014
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    ABSTRACT: Scalability is assessed by propagating WDM packets through multiple SOAs using a loop. Experimental results show that high SOA gain is more energy-efficient for single-stage space switch while low gain enhances the scalability of multi-stage architectures.
    Optical Fiber Communication Conference; 03/2014
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    ABSTRACT: An optical multi microring network-on-chip (MMR NoC) is proposed and evaluated through numerical simulations. The network architecture consists of a central resonating microring with local microrings connected to the input/output ports. A mathematical model based on the transfer matrix method is used to assess the MMR NoC performance and to analyze the fabrication tolerances. Results show that the proposed architecture exhibits a limited coherent crosstalk with a bandwidth suitable for 10 Gb/s signals, and it is robust to coupling ratio variations and ring radii fabrication inaccuracies.
    Optics Letters 02/2014; 39(4):797-800. · 3.39 Impact Factor
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    ABSTRACT: Energy-proportional optical interconnections are enabled by semiconductor optical amplifiers (SOAs) remaining off (or idle) when not routing data. In this letter, the physical layer scalability of SOA-based optical space switches configured with different gain and loss is assessed using an experimental recirculating loop. Results show that for a gain/loss configuration of 13.0 dB, optical multichannel packets successfully propagate through a series of 14 SOAs with a bit-error-rate (< 10^{-9}) , which indicates that a single-stage space switch can scale up to (10^{9}) ports. Scalability improves for lower gain/loss configuration at the cost of more SOAs per routing path. As expected, scalability is limited by cross-gain modulation and optical signal-to-noise ratio degradation, but their detrimental impact depends on the architecture configuration.
    IEEE Photonics Technology Letters 01/2014; 26(16):1683-1686. · 2.04 Impact Factor
  • IEEE Photonics Technology Letters 11/2013; 25(22):2178-2181. · 2.04 Impact Factor
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    ABSTRACT: In this letter, we present an integrated solution for bidirectional WDM optical interconnection based on semiconductor optical amplifiers and nonreciprocal micro-ring resonators in Si3N4/Ce:YIG. The circuit performance has been numerically evaluated, demonstrating a reduction of crosstalk and back-reflection of for a 10-channel 100-GHz-spaced WDM bidirectional active optical interconnect. Although a silicon-nitride platform has been considered, the proposed solution can be effective also on a silicon platform, where back-scattering induced by the waveguide roughness is much stronger.
    IEEE Photonics Technology Letters 10/2013; 25(20):1973-1976. · 2.04 Impact Factor
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    ABSTRACT: This paper presents a novel Indium Phosphide based photonic integrated circuit (PIC) for all-optical regeneration of both nonreturn-to-zero (NRZ) and return-to-zero (RZ) on-off-keying (OOK) signals. The PIC exploits cross gain compression in two semiconductor optical amplifiers to simultaneously obtain a wavelength-preserved and reshaped copy, and a wavelength-converted yet inverted copy of the input signal. Regeneration of 10 Gb/s signals on multiple wavelengths is demonstrated, showing a Q-factor improvement from 1.5 to 4 for NRZ-OOK signals and from 2.3 to 3.6 for RZ-OOK signals, and a BER improvement up to 1.5 decades.
    Optics Express 09/2013; 21(18):20649-20655. · 3.55 Impact Factor
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    ABSTRACT: We report the fabrication and characterization of an InP monolithically integrated optical circuit for all-optical wavelength-conversion. The device is based on double stage cross-gain modulation/compression in SOAs. We experimentally demonstrate 10 Gb/s operation with low power penalty.
    OptoElectronics and Communications Conference and Photonics in Switching; 06/2013
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    ABSTRACT: Optical space switches are key elements for the next generation of switching fabrics in backbone routers, high performance computing systems, and large data processing and storage systems. A number of architectures and alternative options for gating elements have been proposed, assessed, and implemented for a limited port count. The challenge is to further enhance the scalability and energy efficiency of space switches to support future traffic loads. This paper proposes a heterogeneous implementation of the space switches based on two different types of gating elements, namely semiconductor optical amplifiers (SOA) and Mach-Zehnder Interferometers (MZI). With respect to the existing homogeneous implementations, a higher energy efficiency can be achieved by minimizing the number of SOAs, but crosstalk is introduced by MZI. To reduce the power consumption while still guaranteeing adequate physical layer performance, the design of both Spanke and multi-stage architectures is optimized by strategically placing the different gating and amplification elements, and a physical layer analysis is carried out to validate the performance. The proposed heterogeneous implementation is able to achieve power savings up to 10% and 50% in the Spanke and multi-stage Beneš architectures, respectively, with respect to SOA-based space-switch implementations. Moreover, an improvement of the physical layer performance is achievable in the Spanke architecture thanks to the different placement of the SOAs.
    Journal of Lightwave Technology 06/2013; 31(11):1713-1719. · 2.56 Impact Factor
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    ABSTRACT: This paper considers a space-time interconnection architecture (STIA) based on optical devices, and proposes its introduction in data center networks. The space switch used by STIA is assumed to be based on Benes architecture and realized with energy-proportional utilization of the semiconductor optical amplifiers (SOAs). A STIA-based network is designed for data centers using folded Clos and butterfly topologies, and optimized for power efficiency. Results show that large size STIAs are an energy-efficient solution and allow a power reduction around an order of magnitude with respect to Ethernet.
    Transparent Optical Networks (ICTON), 2013 15th International Conference on; 01/2013
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    ABSTRACT: By exploiting non-reciprocal magneto-optic micro-ring resonators, hybrid III-V semiconductor optical amplifiers can be effectively integrated to provide crosstalk-free bidirectional interleaved WDM communication between racks.
    Optical Interconnects Conference, 2013 IEEE; 01/2013
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    ABSTRACT: This paper considers a space-time interconnection architecture (STIA) based on optical devices and proposes its introduction in data center networks. The power consumption of the STIA is modeled, accounting for the energy proportionality of the optical devices in the STIA. Using such a model, a STIA-based network is designed using three different topologies, tree, folded Clos, and flattened butterfly, and optimized for power efficiency. Results show that, for a fixed topology, small-size STIAs are an energy-efficient solution for data center networks and allow a power reduction of more than an order of magnitude with respect to the Ethernet-based network. The comparison for the same bisection bandwidth shows that folded Clos and flattened butterfly outperform tree, whose power consumption is strongly dependent on the oversubscription ratio selected.
    IEEE Journal of Selected Topics in Quantum Electronics 01/2013; 19(2):3700209-3700209. · 4.08 Impact Factor
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    ABSTRACT: The idle mode of switching gates leads to energy-proportional interconnection networks while operating conditions and performance have an impact on their scalability. SOA-based gates are modeled and their operating conditions are optimized for scalability.
    Optical Interconnects Conference, 2013 IEEE; 01/2013
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    ABSTRACT: This paper proposes an optical network-on-chip consisting of a central microring resonating with the local microrings connected to the ports. The mathematical model of the multi microring (MMR) architecture shows good crosstalk robustness.
    Optical Interconnects Conference, 2013 IEEE; 01/2013
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    ABSTRACT: In this paper, we present and investigate a new architecture of a silicon photonic transponder aggregator as a new interconnect subsystem enabling the implementation of colorless, directionless, and contentionless ROADMs. Such subsystem is based on a microring resonator switching fabric integrated in a silicon photonics platform to achieve high functional integration together with reduction of cost, footprint, and power consumption. In the proposed device, microring resonators perform simultaneous add and drop of wavelength channels which suffer from two detrimental effects: residual dropped signal crosstalk and residual added signal crosstalk, respectively. Considering three microring-based switching elements, the transfer matrix method has been used to compute the add/drop transfer functions of the switches as a function of their geometrical parameters. The two crosstalk effects have been evaluated jointly with other important transmission parameters, such as bandwidth, insertion losses, side lobe suppression, adjacent channel rejection, extinction ratio, and group dispersion. In addition, device sensitivity with respect to the ring-waveguide coupling coefficients has been calculated. Finally, the performance of the different switches has been assessed to demonstrate that, by a proper design, the proposed transponder aggregator can support 100 Gb/s DP-QPSK modulated signal transmission.
    Journal of Lightwave Technology 01/2013; 31(24):3943-3955. · 2.56 Impact Factor
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    ABSTRACT: We demonstrate a novel InP-PIC for all-optical regeneration. The PIC exploits cross-gain compression in SOA obtaining, at the same time, wavelength-preserving regeneration and wavelength conversion. 10 Gb/s operation is shown by Q-factor and BER improvement.
    Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC), 2013; 01/2013
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    ABSTRACT: All-optical regeneration has attracted growing interest due to the possibility to increase the all-optical reach. However, to be really competitive with optoelectronic regenerators, all-optical regenerators should process an entire wavelength division multiplexed (WDM) signal comb at once and significantly reduce the footprint and the power consumption, as possible, in principle, by exploiting photonic-integrated circuits (PICs). Moreover, since constant envelope modulation format signals have come into play in recent years, all-optical regenerators dealing with a multiplex of these signals are of particular interest. This paper presents a monolithically integrated indium-phosphide-based PIC acting as an all-optical regenerator for constant envelope WDM signals. The regeneration scheme is based on hard-limiting amplification in saturated semiconductor optical amplifiers (SOAs), which removes the signal intensity noise. The presented PIC, designed and fabricated within the JePPIX technology platform, can handle up to four WDM signals, which are demultiplexed and enter an array of SOAs to undergo regeneration before being multiplexed again. The channel-by-channel regeneration of both polarization shift keying and frequency shift keying signals at 10 Gb/s is experimentally demonstrated in terms of Q-factor improvement.
    Journal of Lightwave Technology 01/2013; 31(2):322-327. · 2.56 Impact Factor

Publication Stats

411 Citations
68.58 Total Impact Points

Institutions

  • 2005–2013
    • Scuola Superiore Sant'Anna
      Pisa, Tuscany, Italy
  • 2004–2013
    • Scuola Normale Superiore di Pisa
      Pisa, Tuscany, Italy
  • 2011
    • McGill University
      • Department of Electrical & Computer Engineering
      Montréal, Quebec, Canada
  • 2006–2010
    • Technical University of Denmark
      • Department of Photonics Engineering
      København, Capital Region, Denmark
  • 2005–2006
    • Università di Pisa
      Pisa, Tuscany, Italy