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  • 1.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    An Optimal Model for LSP Bundle Provisioning in PCE-based WDM Networks2011In: 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2011, Washington: Optical Society of America , 2011Conference paper (Refereed)
    Abstract [en]

    A time-efficient resource optimization model for dynamic concurrent provisioning of connection requests at PCE is proposed. It is shown that a significant performance improvement can be achieved without noticeable increase in connection setup-time.

  • 2.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Bulk provisioning of LSP requests with shared path protection in a PCE-based WDM network2011In: ONDM 2011 - 15th Conference on Optical Network Design and Modeling, 2011Conference paper (Refereed)
    Abstract [en]

    The Path Computation Element (PCE) is a network entity utilized for network path computation operations, especially useful in optical networks based on wavelength division multiplexing (WDM). In the PCE paradigm, the communication between a node and the PCE is specified by the Path Computation Element Communication Protocol (PCEP). According to PCEP protocol, multiple LSP (Label Switched Path) requests can be bundled together before being sent to the PCE in order to reduce the control overhead. Multiple bundles received by the PCE can then be provisioned at once as a single bulk. Enabling bulk provisioning of LSP requests at the PCE in a concurrent manner can bring significant improvements in terms of higher network resource utilization and control plane overhead reduction. However, these advantages come at a cost of a longer connection setup-time and of an instantaneous increase in the network load, which may lead to a degradation of the network performance, e.g. blocking probability. In this study pros and cons of bulk provisioning are explored in shared path protection (SPP) by comparing sequential and concurrent path computation strategies. An efficient meta-heuristic named GRASP-SPP-BP (Greedy Random Adoptive Search Procedure for Shared Path Protection with Bulk Provisioning) is proposed for concurrent provisioning of primary and shared backup path pairs. GRASP-SPP-BP minimizes the backup resource consumption while requiring minimal path computation time. The presented results demonstrate that, in a SPP network scenario, a significant reduction in the PCEP control overhead, network blocking probability and backup resource consumption can be achieved via LSP bulk provisioning at the PCE with the proposed GRASP-SPP-BP approach.

  • 3.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Concurrent processing of multiple LSP request bundles on a PCE in a WDM network2010In: 2010 Conference on Optical Fiber Communication, Collocated National Fiber Optic Engineers Conference, OFC/NFOEC, New York: IEEE , 2010, 5465298- p.Conference paper (Refereed)
    Abstract [en]

    Concurrent RWA algorithm for differentiated services to process multiple LSP bundles at PCE is proposed. Significant blocking probability reduction has been observed at the expense of slightly increased LSP setup-time compared to a sequential approach.

  • 4.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    LSP Request Bundling in a PCE-Based WDM Network2009In: OFC: 2009 Conference on Optical Fiber Communication, IEEE , 2009, 989-991 p.Conference paper (Refereed)
    Abstract [en]

    LSP requests may be bundled to improve the network optimization process at the expense of an increased connection setup delay. A detailed study is conducted to evaluate the pros and cons of the bundling approach.

  • 5.
    Ahmed, Jawwad
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Solano, Fernando
    Warsaw University of Technology.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Traffic re-optimization strategies for dynamically provisioned WDM networks2011In: ONDM 2011 - 15th Conference on Optical Network Design and Modeling, Bologna, 2011Conference paper (Refereed)
    Abstract [en]

    In Wavelength Division Multiplexed (WDM) networks with dynamic lightpath provisioning, connection requests are served without any prior knowledge of their arrival and departure times. As time passes, network resources may become fragmented because of the network dynamism. Under these circumstances it is highly beneficial to re-optimize (i.e., de-fragment) the existing lightpath configuration at some specific time instances to improve the network resource utilization and reduce the risk that future connection requests will be blocked. Assuming that this de-fragmentation process occurs during a re-optimization phase, this paper presents a set of strategies which govern the time instances when this re-optimization phase should be triggered as well as a set of strategies to decide which of the currently active lightpaths should be optimized at any given re-optimization phase. These strategies are referred to as when-to-re-optimize (when-t-r) and what-to-re-optimize (what-t-r) strategies, respectively. During the evaluation process particular attention is devoted to study the impact that when-t-r and what-t-r strategies have on the traffic disruption metrics (i.e., number of total disrupted connections, disruption time, reconfiguration time) inherent with the re-optimization process. Based on the evaluation results, it can be concluded that the choice of an optimal "when" and an optimal "what" to re-optimize strategy is dependent upon the performance objective (e.g. lower blocking probability or network disruption) in a given network scenario.

  • 6.
    Ako, Thomas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Design of invisibility cloaks with an open tunnel2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, no 26, 27060-27066 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we apply the methodology of transformation optics for design of a novel invisibility cloak which can possess an open tunnel. Such a cloak facilitates the insertion (retrieval) of matter into (from) the cloak's interior without significantly affecting the cloak's performance, overcoming the matter exchange bottleneck inherent to most previously proposed cloak designs. We achieve this by applying a transformation which expands a point at the origin in electromagnetic space to a finite area in physical space in a highly anisotropic manner. The invisibility performance of the proposed cloak is verified by using full-wave finite-element simulations. (C) 2010 Optical Society of America

  • 7.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Olsson, Fredrik
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Experimental characterization of high-speed 1.55 mu m buried heterostructure InGaAsP/InGaAlAs quantum-well lasers2009In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 26, no 2, 318-327 p.Article in journal (Refereed)
    Abstract [en]

    Detailed experimental characterization is performed for 1550 nm semi-insulating regrown buried heterostructure Fabry-Perot (FP) lasers having 20 InGaAsP/InGaAlAs strain-balanced quantum wells (QWs) in the active region. Light-current-voltage performance, electrical impedance, small-signal response below and above threshold, amplified spontaneous emission spectrum below threshold and relative intensity noise spectrum are measured. Different laser parameters such as external differential quantum efficiency eta(d), background optical loss alpha(i), K-factor, D-factor, characteristic temperature T-0, differential gain dg/dn, gain-compression factor epsilon, carrier density versus current, differential carrier lifetime tau(d), optical gain spectrum below threshold, and chirp parameter alpha are extracted from these measurements. The FP lasers exhibited a high T-0 (78-86.5 degrees C) and very high-resonance frequency (23.7 GHz). The results indicate that appropriately designed lasers having a large number of InGaAsP well/InGaAlAs barrier QWs with shallow valence-band discontinuity can be useful for un-cooled high-speed direct-modulated laser applications.

  • 8.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Olsson, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    High-Speed Performance of 1.55 µm Buried Hetero-Structure Lasers with 20 InGaAsP/InGaAlAs Quantum-Wells2006In: 2006 European Conference on Optical Communications Proceedings, ECOC 2006, IEEE , 2006, 1-2 p.Conference paper (Refereed)
    Abstract [en]

    1550 nm re-grown FP lasers having 20 InGaAsP/InGaAlAs strain-balanced QWs exhibit low threshold current density, high T0 (78.0 #x000B0;C) and high resonance frequency (24 GHz) indicating that a large number of shallow barrier QWs are attractive for un-cooled high-speed direct-modulation applications.

  • 9.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    On the Possibilities to Create a Negative Permittivity Metamaterial with Zero Imaginary Part of the Permittivity at a Specific Frequency-Electrical Network Theory Approach2012In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 48, no 4, 507-511 p.Article in journal (Refereed)
    Abstract [en]

    A permittivity function suggested in the literature describing a material that exhibits negative permittivity and no loss at a specific frequency (and losses at other frequencies) is analyzed using electrical network theory. An equivalent circuit of the polarization admittance consisting of RLC components is derived. Further, a proof is given showing that if the admittance is lossless at a specific frequency, then all components with losses (resistances) in the circuit have to be short circuited or blocked or virtually disconnected at this frequency by the use of ideal lossless resonant LC circuits. However, in the literature, inductors in metamaterials are associated with inherently lossy metal nanoparticles, hence invalidating the suggested permittivity function unless a lossless inductor at optical frequencies is found or proved possible.

  • 10.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Plasmonic/metallic passive waveguides and waveguide components for photonic dense integrated circuits: a feasibility study based on microwave engineering2010In: IET Optoelectronics, ISSN 1751-8768, Vol. 4, no 1, 1-16 p.Article in journal (Refereed)
    Abstract [en]

    To investigate the potential for dense integration of photonic components, we analyse passive plasmonic/metallic waveguides and waveguide components at optical frequencies by using mostly microwave engineering approaches. Four figures of performance are formulated that are utilised to compare the characteristics of four different slab waveguides with zero frequency cut-off modes. Three of these are metallic based whereas the fourth one, which also serves as a reference, is dielectric based with high index-contrast. It is found that all figures of performance cannot be optimised independently; in particular there is a trade-off between the waveguide Q-value and the transversal field confinement. Microwave methods are used to design several photonic transmission line components. The small Q-value of the metallic waveguides is the main disadvantage when using materials and telecom frequencies of today. Hence plasmonic waveguides do not offer full functionality for some important integrated components, being severe for frequency-selective applications. To achieve a dense integration, it is concluded that new materials are needed that offer Q-values several orders of magnitude higher than metals.

  • 11.
    Billenahalli, Shreejith
    et al.
    The University of Texas at Dallas.
    Razo, Miguel
    The University of Texas at Dallas.
    Huang, Wanjun
    The University of Texas at Dallas.
    Sivasankaran, Arularasi
    The University of Texas at Dallas.
    Tang, Limin
    The University of Texas at Dallas.
    Vardhan, Hars
    The University of Texas at Dallas.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Tacca, Marco
    The University of Texas at Dallas.
    Fumagalli, Andrea
    The University of Texas at Dallas.
    A wavelength sharing and assignment heuristic to minimize the number of wavelength converters in resilient WDM networks2009In: Proceedings of the 2009 7th International Workshop on the Design of Reliable Communication Networks, DRCN 2009 / [ed] Medhi, D; Tipper, D; Doucette, J, 2009, 319-326 p.Conference paper (Refereed)
    Abstract [en]

    With the successful introduction of reconfigurable optical add-drop multiplexers (ROADMs) and related technologies, WDM networks are now growing in the number of optical nodes, wavelengths, and lambda services supported. In addition, shared path protection mechanisms - whereby lambda services are allowed to share protection wavelength channels - are possible at the optical (WDM) layer. Efficient strategies must be devised to both determine the set of services that must share a common protection wavelength channel and assign wavelengths to every service. One objective of these strategies is to minimize the total number of wavelength converters (WCs), which are required every time the wavelength continuity constraint cannot be met. This paper presents a scalable and efficient heuristic, whose goal is to minimize the number of WCs in resilient WDM networks supporting static sets of shared path protection lambda services. The heuristic comprises a set of polynomial algorithms that are executed sequentially to obtain a sub-optimal solution. In small size instances of the problem, the heuristic is compared against the optimal solution obtained from ILP formulation. For large size instances - tens of thousands of lambda services and hundreds of nodes - the heuristic yields an average number of WCs that is close to be linear in the number of services, despite the fact that the wavelength sharing factor increases.

  • 12. Blaaberg, S.
    et al.
    Mulvad, H. C. H.
    Oxenløwe, L. K.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Stoltz, B.
    All-optical characterization of large-signal modulation bandwidth of a monolithically integrated DFB-EA2009In: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009, Optical Society of America, 2009, 1283-1284 p.Conference paper (Refereed)
    Abstract [en]

    We use an all-optical method to characterize the modulation bandwidth of a DFB-EA designed for 100 Gb/s Ethernet. In a large-signal wavelength conversion set-up, we show the device has an all-optical bandwidth of 83 GHz.

  • 13. Callegati, F.
    et al.
    Aracil, J.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Andriolli, N.
    Careglio, D.
    Giorgetti, A.
    Fdez-Palacios, J.
    Gauger, C.
    Klinkowski, M.
    de Dios, O. G.
    Hu, E. K. G.
    Matera, F.
    Overby, H.
    Raffaelli, C.
    Rea, L.
    Sengezer, N.
    Tornatore, M.
    Vlachos, K.
    Research on Optical Core Networks in the e-Photon/ONe Network of Excellence2006In: 25TH IEEE INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS, VOLS 1-7, PROCEEDINGS IEEE INFOCOM 2006, 2006, 2987-2991 p.Conference paper (Refereed)
    Abstract [en]

    This papers reports the advances in optical core networks research coordinated in the framework of the e- photon/ONe and e-photon/ONe+ networks of excellence.

  • 14. Callegati, F.
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Tornatore, M.
    Cugini, F.
    Research in Optical Transport Networks: The e-Photon/ONe+ Experience2007In: ICTON 2007: Proceedings of the 9th International Conference on Transparent Optical Networks, Vol 1 / [ed] Marciniak, M, 2007, Vol. 1, 3-6 p.Conference paper (Refereed)
    Abstract [en]

    This paper reports the view of the e-Photon/ONe community regarding the research directions in optical transport networks. Results stemming from joint international research activities in the framework of the project are summarized. This summary presents, necessarily, little details, but wants to draw the attention of the reader towards the most advanced research activities ongoing on the broad topics of optical core networks, from wavelength routed network, to optical burst switching and optical packet switching.

  • 15.
    Cavdar, Cicek
    et al.
    Istanbul Technical University.
    Buzluca, F.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Energy-Efficient Design of Survivable WDM Networks with Shared Backup2010In: Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE, 2010, 1-5 p.Conference paper (Refereed)
    Abstract [en]

    In recent years, energy-efficient design of optical WDM networks has become increasingly important as efforts to reduce the operational expenditure (Opex) and the carbon footprint of the internet are prioritized. In this paper we focus on energy- efficient survivable network design where backup resources are shared for efficient capacity consumption. However there is a trade-off between energy-efficiency and survivability. Survivable network design strategies lead to lightly loaded links in order to minimize the risk in case of a failure and to increase the shareability of backup resources. On the contrary, energy-efficient network design strategies tend to increase the load in a set of links as a consequence of concentrating the traffic in order to be able to switch off as much network resources as possible. In this study, we present a novel method to simultaneously minimize Capex and Opex while providing an energy-efficient, shared backup protected network, under the assumption of backup capacity in sleep mode. For the first time we propose an ILP formulation for the energy-efficient shared backup protection problem. By exploiting the sleep mode for the backup resources, we observe that the ILP solution of our mathematical model brings up to 40% gain in energy efficiency in comparison to energy-unaware shared backup protection approach.

  • 16.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yayimli, A.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    How to cut the electric bill in optical WDM networks with time-zones and time-of-use prices2011In: European Conference on Optical Communication, ECOC, Geneva, 2011Conference paper (Refereed)
    Abstract [en]

    We investigate the benefit of utilizing electric price difference between time intervals of the day for networks covering multiple time-zones. We show that by exploiting this time-and-price variation electric bill can be significantly reduced.

  • 17.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Yayimli, Aysegul
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cutting the Electric Bill by Routing and Wavelength Assignment with Time-zones and Time-of-use Prices2011In: Proceedings of SPIE: Network Architectures, Management, and Applications IX, SPIE , 2011Conference paper (Refereed)
    Abstract [en]

    We consider an energy-aware WDM core network, where the electric prices direr according to time intervals of the day, referred to as time-of-use rates. Since a large backbone network may have nodes scattered over several time zones, we exploit the time-of-use rates to lower the electric bill of the network provider. By using an ILP formulation of the bill minimization problem, we investigate the gain of total electric bill over two approaches where capacity and energy are optimized under different network traffic load conditions.

  • 18.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Dynamic Characterization of Semiconductor Lasers and Intensity Modulators2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The research work presented in this thesis deals with characterization ofdynamics of active photonic devices that are based on semiconductormaterials. The thesis contains an introduction and a collection of publishedarticles in peer reviewed international journals and conferences.The introduction starts with the physical background and a review of thesemiconductor material properties which both affects the design andfabrication of the devices and determine their performance in applicationssuch as wavelength, optical power and attenuation, drive current andvoltage, temperature sensitivity and modulation bandwidth.The next chapter of the introduction is dedicated to various kinds ofsemiconductor lasers. It describes the physical principles, steady stateoperation and the dynamical response. The laser is essentially an opticalcavity consisting of a material with optical gain inbetween two reflectivemirrors. Special attention is given to the spectral shape of the mirrorreflectivity and its effect on the laser dynamics and how these effects canbe distinguished from those of the gain material.In order to improve dynamic performance, it is common that the laser,instead of being directly modulated by varying the drive current, isconnected to a separate modulator. The next chapter is therefore devotedto electroabsorption modulators for high speed intensity modulation andtheir integration to lasers. In order to fully take advantage of the highintrinsic modulation bandwidth of these devices it is important to havea good microwave design to avoid electrical parasitics. A segmented paddesign to achieve this is briefly described.The last part of the introduction covers measurements techniques that wereimplemented to experimentally investigate above devices. A description ofthe measurement methods, including practical hints and methods forevaluation of the measured results are provided.

  • 19.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Sundgren, Petrus
    Marcks von Würtemberg, Rikard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    1.3 um InGaAs VCSELs: Influence of the Large Gain-Cavity Detuning on the Modulation and Static Performance2004In: Proc. of 30th European Conference on Optical Communication 2004, 2004Conference paper (Refereed)
  • 20.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Djupsjoebacka, Anders
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Fonjallaz, Pierre-Yves
    Tipsuwannakul, Ekawit
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Udvary, Eszter
    400km Transmission of STM-16 Data on Baseband and DVBT on 40GHz Subcarrier2008In: 2008 INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS, VOLS 1 AND 2, NEW YORK: IEEE , 2008, 350-352 p.Conference paper (Refereed)
    Abstract [en]

    A 400 km standard single mode fiber (SSMF) link with a single light-intensity modulator was upgraded for simultaneous transmission of STM-16 2.5Gbps baseband data and Digital-Video-Broadcast-Terrestrial DVBT utilizing a 40GHz subcarrier. An optical circulator and narrowband fiber Bragg gratings (FBG) were used to separate the signals in the optical domain and allow for simple direct baseband detection of both.

  • 21.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Impact of losses in the Bragg section on the dynamics of detuned loaded DBR lasers2010In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 46, no 9, 1360-1367 p.Article in journal (Refereed)
    Abstract [en]

    The dynamics of a distributed Bragg reflector laser with optical losses in the Bragg section is studied in detail. It is found that the modulation response depends not only on the detuning of the lasing wavelength from the Bragg reflectivity peak but also on the magnitude of the waveguide losses in the Bragg section. Depending on the losses, the damping of the relaxation peak can either increase or decrease when the laser is detuned on the long wavelength flank of the Bragg peak. Hence, in order to achieve maximum modulation bandwidth of the laser, the laser needs not only to have the correct detuning but also an optimized waveguide loss in the Bragg section. The physical reason for this dependence is discussed in terms of a modified rate equation model.

  • 22.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Berggren, Jesper
    Yu, X.
    KTH.
    Marcks Von Würtemberg, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Dynamic properties of electrically p-n confined, epitaxially regrown 1.27 μm InGaAs single-mode vertical-cavity surface-emitting lasers2009In: IET optoelectronics, ISSN 1751-8768, Vol. 3, no 3, 163-167 p.Article in journal (Refereed)
    Abstract [en]

    The dynamic performance including chirp measurements of 1.27 mu m single-mode InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a large gain-cavity offset is presented. The VCSELs are based on a novel p-n confinement structure with selective area epitaxial regrowth. A resonance frequency of 9.11 GHz, a slope efficiency of 0.25 W/A and an alpha-factor of 5.7 were measured. The modulation bandwidth is limited by electrical parasitics. Eye diagrams at 5 Gb/s with 7 dB extinction ratio and Q-factor around 5 were obtained. The results are compared with the performance of oxide-confined VCSELs with similar active layer and negative gain-cavity detuning.

  • 23.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Djupsjöbacka, Anders
    Extension of 40 Gbps Link with a Directly Detected 2.5 Gbps Subcarrier Channel2009In: ICTON: 2009 11TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, VOLS 1 AND 2, NEW YORK: IEEE , 2009, 204-207 p.Conference paper (Refereed)
    Abstract [en]

    Simultaneous transmission was achieved of 40 Gbps at baseband and 2.5 Gbps modulation on a 50 GHz subcarrier utilizing a single 40 Gbps light-intensity modulator. A novel reception method based on optically separated baseband and single sideband channel permits direct detection of both signals with use of bandwidth limited photodiodes and dispersion tolerant transmission. This method can be used to increase the total capacity of an original 40 Gbps optical link to also carry a secondary signal.

  • 24.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Stoltz, Björn
    Syntune AB, Kista, Sweden .
    Driad, Rachid
    Makon, Robert Elvis
    Hurm, Volker
    Rosenzweig, Josef
    Li, Jie
    Steffan, Andreas Gerhard
    Transceiver modules utilizing travelling-wave electro-absorption modulator2010In: 2010 Conference on Optical Fiber Communication, Collocated National Fiber Optic Engineers Conference, OFC/NFOEC 2010, 2010, 5465732- p.Conference paper (Refereed)
    Abstract [en]

    Electro-Absorption-Transceiver (EAT) structures used as efficient Travelling-Wave Electro-Absorption-Modulator (TWEAM) as well as Travelling-Wave-Photo-Detector (TWPD) are investigated. Clear eye-openings at 100Gb/s for operation as modulator and/or as detector, as well as 80Gb/s transmission between a pair of EATs, are presented.

  • 25.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Stoltz, Björn
    Syntune AB, Kista, Sweden.
    Hammerfeldt, Stefan
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Monolithically Integrated 100 GHz DFB-TWEAM2009In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 7, no 16, 3410-3415 p.Article in journal (Refereed)
    Abstract [en]

    A monolithically integrated distributed feedback (DFB) laser and traveling-wave electro-absorption modulator (TWEAM) with >= 100 GHz -dBe bandwidth suitable for Non-return-to-zero (NRZ) operation with on-off keying (OOK) is presented. The steady-state, small-signal modulation response, microwave reflection, chirp characteristic, and both data operation and transmission were investigated. The DFB-TWEAM was found to be an attractive candidate for future short distance communication in high bitrates systems.

  • 26.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylen, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Schatz, Richards
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Li, J.
    Djupsjobacka, A.
    Stoltz, B.
    Modulation and chirp evaluation of 100 GHz DFB-TWEAM2010In: European Conference on Optical Communication, ECOC, NEW YORK: IEEE , 2010Conference paper (Refereed)
    Abstract [en]

    The modulation and chirp performance of an InGaAsP based monolithically integrated distributed feedback (DFB) laser and travelling wave electro-absorption modulator (TWEAM) designed for 100Gb/s operation is presented. Open eye-diagrams at 100Gb/s, and error free 50Gb/s BER (limited by measurement system) were achieved. The chirp factor varied between 1.5 and 0 for absorptions between 10% and 90%.

  • 27. Chacinski, Marek
    et al.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Willén, Bo
    Stoltz, Björn
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Electroabsorption Modulators Suitable for 100-Gb/s Ethernet2008In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 29, no 9, 1014-1016 p.Article in journal (Refereed)
    Abstract [en]

    The design of a traveling-wave electroabsorption modulator (TWEAM) has been improved to decrease the drive voltage. The absorption layer was optimized and together with a novel segmentation of microwave design was introduced to increase the active modulator length. The resulting -3-dBe bandwidth of fabricated devices was estimated to be 99 GHz. Extinction ratios of 10 dB back-to-back and 6.7 dB after transmission over 2.2-km long fiber were measured with an incident drive voltage of only 2 V peak to peak. This TWEAM performance is believed to constitute a new state of the art for modulators suitable for 100-Gb/s Ethernet with on-off keying.

  • 28.
    Chen, Biao
    et al.
    Centre for Optical and Electromagnetic Research, Joint Laboratory of Optical Communications, Zhejiang University, Hangzhou 310027, China.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Efficient and fine scheduling algorithm for bandwidth allocation in Ethernet passive optical networks2006In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 12, no 4, 653-660 p.Article in journal (Refereed)
    Abstract [en]

    A novel fine scheduling algorithm is introduced for upstream bandwidth allocation in an Ethernet-based passive optical network. This scheduling algorithm consists of an inter optical network unit (ONU) scheduler at the optical line terminal (OLT) and an intra-ONU scheduler at each ONU. In the inter-ONU scheduling, a novel GATE/REPORT approach is introduced to eliminate the unused remainders without transmission delay and maximize the utilization of bandwidth. Our novel intra-ONU scheduler gives fair bandwidth allocation to the queues of different priorities for each user in a hierarchical and decentralized way. Numerical results have shown that our overall scheduling algorithm can fulfill various requirements of delay and throughput for the transmission of multimedia traffic for each end user..

  • 29. Chen, Biao
    et al.
    Guo, Changjian
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Zhang, Linjian
    Jiang, Qiong
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Add/drop multiplexing and TDM signal transmission in an optical CDMA ring network2007In: Journal of Optical Networking, ISSN 1536-5379, Vol. 6, no 8, 969-974 p.Article in journal (Refereed)
  • 30.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Chen, Biao
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    A novel algorithm for intra-ONU bandwidth allocation in ethernet passive optical networks2005In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 9, no 9, 850-852 p.Article in journal (Refereed)
    Abstract [en]

    A novel decentralized algorithm is introduced for the intra-ONU bandwidth allocation in an Ethernet Passive Optical Network (EPON). The algorithm is of low computational complexity, and can guarantee both the priority and fairness of the differentiated services. Simulation results are presented and compared with those of two existing bandwidth allocation algorithms.

  • 31.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Chen, Biao
    Centre for Optical Electromagnetic Research, Joint Laboratory of Optical Communications, Zhejiang University, Hangzhou 310027, China.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Self-protection scheme against failures of distributed fiber links in an Ethernet passive optical network2006In: Journal of Optical Networking, ISSN 1536-5379, Vol. 5, no 9, 662-666 p.Article in journal (Refereed)
    Abstract [en]

    A novel self-protection scheme for an Ethernet passive optical network is introduced and studied at both the physical and the media access control layers. The scheme is simple and fast and can provide 1: 1 protection and automatic traffic restoration against the fiber link failure between a remote node ( RN) and any optical network unit (ONU). Simulation results show that fiber failure does not degrade the transmission performance, and the restoration time depends mainly on the switch time of the physical layer. Our protection scheme saves many long fibers, does not influence other normal ONUs, and requires no active device in the RN.

  • 32.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Chen, Biao
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Joint Bandwidth Scheduling to Support Differentiated Services and Multiple Service Providers in 1G and 10G EPONs2009In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, ISSN 1943-0620, Vol. 1, no 4, 343-351 p.Article in journal (Refereed)
    Abstract [en]

    Dynamic bandwidth allocation (DBA) is one of the key issues for the current (1G) and next-generation (10G) Ethernet-based passive optical network (EPON) systems. We present a novel bandwidth scheduling scheme that integrates specific scheduling implementations in the optical line terminal and optical network units. This scheduling enables multiservice access with scalable quality of service support for the triple-play (video, voice, and data) services and open access. Our simulation results show that the proposed scheduling algorithm performs very well in supporting service differentiation and fair allocation of bandwidth to different service providers. A performance comparison between 1G and 10G systems is also presented. To the best of our knowledge, no detailed study of DBA in a 10G EPON can be found in the literature so far.

  • 33.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    De Andrade, M.
    Skubic, Björn
    Ericsson Research.
    Ahmed, Jawwad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Enhancing IPACT with limited service for multi-thread DBA in long-reach EPON2010In: Communications and Photonics Conference and Exhibition (ACP), 2010 Asia, 2010, 629-630 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we propose an enhanced IPACT with limited service for multi-thread DBA in long-reach EPON. We evaluate our scheme by simulations in single-thread and double-thread cases and show that the DBA performance in terms of average delay and jitter can be significantly improved by the proposed algorithm.

  • 34.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Jirattigalachote, Amornrat
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Novel Node Architectures for Wavelength-Routed WDM Networks with Wavelength Conversion Capability2008In: 34th European Conference and Exhibition on Optical Communication ECOC’08, 2008, 2008Conference paper (Other academic)
    Abstract [en]

    We present and evaluate two novel node architectures based on optical switch matrices and wavelength converters (WCs). Relatively small and cheap switches are required while WCs efficiently improve blocking probability

  • 35.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Kantor, Miroslaw
    Wajda, Krzysztof
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Network Protection2008In: Next-Generation FTTH Passive Optical Networks: Research towards unlimited bandwidth access / [ed] Josep Prat, Springer, 2008, 111-124 p.Chapter in book (Refereed)
    Abstract [en]

    The significance of broadband and multimedia telecommunications is still increasing and the use of fibre-optic technology in the access network is growing very fast in order to meet customers demand. Along with the higher bandwidth demand, increasing number of subscribers, and advances in the Wavelength Division Multiplexing (WDM) device technology, the WDM Passive Optical Network (PON) and hybrid WDM/TDM (Time Division Multiplexed) PON has been considered as a next generation solution for the broadband access. Meanwhile, in order to meet Service Level Agreement (SLA) and guarantee the appropriate level of connection availability, fault management within any type of the PONs becomes more significant for the reliable service delivery and business continuance. Connection availability is an issue of deep concern to network operators since failure of any access network component, and thus interruption of their services, could result in significant losses of revenue. This chapter reviews some protection schemes in PONs and provides reliability performance evaluation for the considered architectures. A customer typically expects the end-to-end service availability at least at the same level as that provided by the traditional copper based systems. Thus, before investing in a new technology network operators need to make sure that it will not degrade the service quality perceived by the customers. To avoid misunderstanding we provide the set of definitions used in this chapter. Next, we review the protection schemes in PONs and follow with the reliability analysis and performance evaluation. Finally, we draw some conclusions.

  • 36.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Khanmohamadi, Sahar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Abtahi, Farzad
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Xu, Zhenyu
    Cassidy, Andrew
    Tremblay, Christine
    Littlewood, Paul
    Asselin, Serge
    Belanger, Michel P.
    Passive wide area network solutions: Filterless and semi-filterless optical networks2011In: 13th International Conference on Transparent Optical Networks (ICTON) / [ed] Jaworski, M; Marciniak, M, 2011Conference paper (Refereed)
    Abstract [en]

    Advances in optical coherent transmission and electrical compensation technologies (such as coherent receiver and forward error correction FEC) have stimulated ideas for novel optical network architectures. Recently proposed passive wide area network solution, referred to as filterless optical network [1 #x2013;2] eliminates or minimizes the usage of active photonic reconfigurable network elements. In this approach, only the passive splitters and combiners for interconnecting the fiber links are utilized, which makes this network architecture more cost- and energy-effective as well as more reliable compared with networks based on active optical switching. However, the filterless optical network architecture implies some constraints on fiber interconnection design, maximum fiber-tree length and wavelength reuse due to its broadcast nature. Consequently, filterless solution always requires more resources (i.e. number of wavelengths) compared with the active switched optical networks which are allowed to utilize reconfigurable and coloured components. In order to improve the wavelength utilization while maintaining flexibility of resource allocation, this work extends the idea of filterless optical network by introducing some passive coloured components (e.g., fiber Bragg grating FBG, red/blue filters, etc) to drop local signals at some determined nodes. This approach is referred to as semi-filterless optical network. Furthermore, the semi-filterless solution maintains the passive feature, enabling high reliability and efficiency of cost and energy. Meanwhile, its non-broadcast property at some determined nodes has potential to decrease the transmission impairments and hence relax the constraints on fiber interconnection design and the maximal transparent length, which are strict in the filterless optical network. Our preliminary results confirm the advantages of semi-filterless solution.

  • 37.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Advances in Fiber Access Networks Development: Efficient Resource Allocation and Cost Effective Protection2011In: BROADBAND ACCESS COMMUNICATION TECHNOLOGIES V / [ed] Dingel, B; Jain, R; Tsukamoto, K, 2011, Vol. 7958, 795808-1-795808-10 p.Conference paper (Refereed)
    Abstract [en]

    Access networks based on optical fiber can easily fulfill high bandwidth demand and cover large service areas. Fiber access networks are also scalable to meet the future capacity request. Among several alternatives, passive optical network (PON)is considered as the most promising one, because its passive point-to-multipoint architecture is characterized by relatively low deployment and operational cost. On the other hand, the passive point-to-multipoint feature in PONs also creates a number of challenges, such as efficient resource allocation and cost-effective protection. This paper provides an overview of the advances related to these two issues and points out the research topics that are still open and need to be investigated.

  • 38.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Analysis of protection schemes in PON compatible with smooth migration from TDM-PON to hybrid WDM/TDM-PON2007In: Journal of Optical Networking, ISSN 1536-5379, Vol. 6, no 5, 514-526 p.Article in journal (Refereed)
    Abstract [en]

    We propose what we believe to be a novel protection scheme compatible with smooth migration from a time-division multiplexing (TDM) passive optical network (PON) to a WDM/TDM-PON. We show that our scheme is very cost effective while keeping connection availability, recovery time, and power budget at an acceptable level. We focus on the protection schemes, overview the existing methods, and introduce a link protection scheme compatible with smooth migration from TDM-PON to hybrid WDM/ TDM-PON. Furthermore, we analyze the cost, connection availability, recovery time, and optical link budget for different protection schemes in order to find the cost-effective solution both for the TDM-PON and hybrid WDM/ TDM- PON. (c) 2007 Optical Society of America.

  • 39.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Performance Analysis of Protection Schemes Compatible with Smooth Migration from TDM-PON to Hybrid WDM/TDM-PON2007In: OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007, 2007Conference paper (Refereed)
    Abstract [en]

    We propose a novel protection scheme compatible with smooth migration from TDM-PON to WDM/TDM-PON. We show that our scheme is very cost-effective while keeping connection availability, recovery time and power budget at the acceptable level.

  • 40.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chughtai, Mohsan Niaz
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Forzati, Marco
    Scalable Passive Optical Network Architecture for Reliable Service Delivery2011In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 3, no 9, 667-673 p.Article in journal (Refereed)
    Abstract [en]

    A scalable and reliable architecture for both a wavelength division multiplexing passive optical network and a hybrid wavelength and time division multiplexing passive optical network with self-healing capability is presented and evaluated. Our protection scheme is compatible with a cascaded arrayed waveguide grating that can accommodate an ultra-large number of end users. A simple interconnection pattern between two adjacent optical network units (ONUs) is applied in order to provide protection for distributed fibers between a remote node and the ONUs. Therefore, the investment cost on a per-user basis can be significantly reduced. Meanwhile, the performance evaluation shows that our approach can achieve high connection availability while maintaining the support of long reach and high splitting ratio.

  • 41.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    A novel protection scheme for a hybrid WDM/TDM PON2007In: NETWORK ARCHITECTURES, MANAGEMENT, AND APPLICATIONS V, 2007, Vol. 6784, F7840-F7840 p.Conference paper (Refereed)
    Abstract [en]

    This paper proposes a novel protection scheme based on the cyclic property of an array waveguide grating (AWG) and neighboring connection pattern between two adjacent optical network units (ONUs) for the hybrid WDM/TDM passive optical networks (PONs). Our scheme uses 50% fewer wavelengths while offering one order of magnitude better connection availability than the existing scheme.

  • 42.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    High utilization of wavelengths and simple interconnection between users in a protection scheme for passive optical networks2008In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, no 5-8, 389-391 p.Article in journal (Refereed)
    Abstract [en]

    A novel protection architecture for passive optical networks (PONs) is presented and evaluated. It is based on the cyclic property of arrayed waveguide gratings (AWGs) and the interconnection between two adjacent optical network units. The proposed scheme is compatible with both wavelength-division-multiplexing (WDM) PONs and hybrid WDM/time-division-multiplexing PONs. It is compared with two existing schemes and shown to have several advantages: 1) 50% less wavelengths is needed; 2) the fiber interconnections are simplified; 3) the connection availability is improved by one order of magnitude.

  • 43.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Novel Architectures of Asynchronous Optical Packet Switch2007In: 33rd European Conference and Exhibition on Optical Communication ECOC’07, 2007, IEEE conference proceedings, 2007Conference paper (Other academic)
    Abstract [en]

    We propose two asynchronous optical packet switch architectures, with efficient contention resolution based on controllable optical buffers and tunable wavelength converters TWCs. Providing a few shared optical buffers significantly boosts the performance obtained by TWCs.

  • 44.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Kantor, M.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Comparison of hybrid WDM/TDM passive optical networks (PONs) with protection2008In: 34th European Conference on Optical Communication, 2008, ECOC 2008, 2008Conference paper (Refereed)
    Abstract [en]

    We present the evolution of PON protection and compare reliability performance related to investment and management cost for some representative cases. Our results can indicate the most cost efficient architectures.

  • 45.
    Chen, Jiajia
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Tacca, Marco
    Fumagalli, Andrea
    Dynamic routing based on information summary-LSA in WDM networks with wavelength conversion2008In: Proceedings of 2008 10th Anniversary International Conference on Transparent Optical Networks, ICTON, NEW YORK: IEEE , 2008, 50-54 p.Chapter in book (Other academic)
    Abstract [en]

    This Study investigates the use of information Summary (IS) applied to the advertised available resources to reduce the amount of link state advertisement (LSA) overhead, which is necessary to achieve distributed dynamic routing in WDM networks,. As illustrated in the Study, if carefully designed, the resulting IS-LSA protocol can significantly contain the size of the advertised data set without excessively affecting the network performance, i.e., the blocking probability caused by routing decisions based on incomplete link state information.

  • 46.
    Chen, Xi
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Chen, Yiting
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Cui, T.
    Photothermal direct writing of metallic microstructure for frequency selective surface at terahertz frequencies2012In: Proceedings of the 2012 International Workshop on Metamaterials, Meta 2012, IEEE , 2012, 6464923- p.Conference paper (Refereed)
    Abstract [en]

    Maskless photothermal direct writing technique was investigated to fabricate planar microscale metallic structures. In this technique, we use a tightly focused nanosecond pulsed infrared light to heat the metallic thin film on substrate. With sufficient volumic power density, the metal inside a "hot spot" could be removed from substrate. This technique benefits from not only the enhanced optical absorption, thanks to the surface plasmon resonance of metallic thin film, but also the reduced thermal conductivity, due to the frequent boundary scattering of phonons inside the thin film. To verify the performance of our direct writing technique, a cross-slot periodic array is scribed in gold thin film on silica substrate. Such a pattern can serve as a frequency selective surface at terahertz, which has many applications in terahertz radio system, e. g. rejecting thermal noise before terahertz receiver or serving as reflectors in Fabry-Perot etalon for astronomy spectroscopy.

  • 47.
    Chen, Xi
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chen, Yiting
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wang, Jing
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Hao, Jiaming
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Photothermal phenomena in plasmonics and metamaterials2011In: ADVANCES IN OPTICAL THIN FILMS IV, 2011, 81681K- p.Conference paper (Refereed)
    Abstract [en]

    Our recent theoretical and experimental investigation of the photothermal effect in a planar metamaterial absorber is reviewed in the present paper. The observed ultrasensitive photothermal heating in such an absorber nanostructure irradiated by a pulsed white-light source is elaborated with a simple yet compelling heat transfer model, which is subsequently solved with a finite-element method. The simulation results not only agree with the experimental finding, but also provide more detailed understanding of the temperature transition in the complex system.

  • 48.
    Chen, Zhihui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hellström, Staffan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yu, Zhong-Yuan
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Fu, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Time-resolved photocurrents in quantum well/dot infrared photodetectors with different optical coupling structures2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 4, 043502- p.Article in journal (Refereed)
    Abstract [en]

    Temporal developments of photocurrents excited by an infrared radiation pulse in quantum well/dot infrared photodetectors with different optical coupling structures have been theoretically studied. It is shown that the light diffraction in a conventional reflective grating structure is a near-field effect containing severe crosstalk from neighboring pixels. A concave reflector not only eliminates the crosstalk but also strongly diffracts and focuses the incident electric field into deep active layers, which significantly increases the photocurrents in the photodetectors.

  • 49.
    Chughtai, Mohsan Niaz
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101). KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Study of physical layer impairments in high speed optical networks2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work done in this thesis focuses on the impact of transmission impairments in high speed optical networks. Specifically it focuses on the impact of nonlinear impairments in long haul fiber optic data transmission. Currently deployed fiber optic transmission networks are running on NRZ OOK modulation formats with spectral efficiency of only 1 bit/symbol. To achieve spectral efficiency beyond 1 bit/symbol, fiber optic communication systems running on advanced modulation formats such as QPSK are becoming important candidates. The practical deployment of QPSK based fiber optic communication system is severely limited by Kerr-induced nonlinear distortions such as XPM and XPolM, from the neighboring NRZ OOK channels. In this thesis we focus on the impact of nonlinear impairments (XPM and XPolM) in fiber optical transmission systems running on QPSK modulation with both differential and coherent detection. The dependence of impact of nonlinear impairments on SOP, baud rate of the neighboring NRZ OOK channels and PMD in the fiber, is analyzed in detail through numerical simulations in VPItransmission Maker®. In this thesis we also analyze digital signal processing algorithms to compensate linear and nonlinear impairments in coherent fiber optic communication systems. We propose a simplification of the existing method for joint compensation of linear and nonlinear impairments called "digital back propagation". Our method is called "weighted digital back propagation". It achieves the same performance of conventional digital back propagation with up to 80% reduction in computational complexity.In the last part of the thesis we analyze the transmission performance of a newly proposed hybrid WDM/TDM protection scheme through numerical simulation in VPItransmission Maker®. The transmission performance of the hybrid WDM/TDM PON is limited by impairments from passive optical devices and fiber optical channel.

  • 50.
    Chughtai, Mohsan Niaz
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Forzati, Marco
    AcreoNetlab, Kista.
    Mårtensson, Jonas
    AcreoNetlab, Kista.
    Tipsuwannakul, Ekawit
    Chalmers University of Technology.
    Karlsson, Magnus
    Chalmers University of Technology.
    Analysis of Non-Linear Impairments in 40 Gbaud PM DQPSK and D8PSK Transmission2010In: ICTON 2010, IEEE Press, 2010Conference paper (Refereed)
    Abstract [en]

    In this paper, 40 Gbaud transmission of single polarization (SP) and Polarization-Multiplexed (PM), RZ-DQPSK and RZ-D8PSK signals is analyzed numerically. The impact of nonlinear crosstalk arising from the presence of neighbouring intensity-modulated channels is analyzed in terms of required OSNR for the BER of 10-3versus launch power.

12345 1 - 50 of 241
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