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  • 1. Abbas, Syed Sohail
    et al.
    Popov, Sergei Yu
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Compact Er 3+-doped ZBLAN green upconversion fibre laser2011In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, E-ISSN 2070-3740, Vol. 78, 756-758 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, a fibre laser at 546 nm has been studied for a signal power of -30 dB. Er 3+-doped ZBLAN fibre has been used by upconversion pumping of a 980 nm laser diode. Gain saturation effect has been investigated in detail. Laser performance has also been discussed. An efficiency of 35% has been calculated with a length of 5 mm fibre laser. Results show that Er 3+-doped ZBLAN is a promising candidate for optical amplification at 546 nm.

  • 2.
    Aggerstam, Thomas
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Electron and hole capture cross-sections of Fe acceptors in GaN:Fe epitaxially grown on sapphire2007In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 36, no 12, 1621-1624 p.Article in journal (Refereed)
    Abstract [en]

    Carrier trapping of Fe (3+)/Fe2+ deep acceptors in epitaxially grown GaN:Fe on sapphire was studied by time-resolved photoluminescence. For the investigated Fe doping levels on the order of 10(18) cm(-3), the luminescence decay times are strongly dependent on the Fe concentration, indicating that Fe centers act as predominant nonradiative recombination channels. Linear dependence of the decay time on the iron concentration allows estimation of the electron capture cross-section for the Fe3+ ions, which is equal to 1.9 x 10(-15) cm(2). The upper bound for the cross-section of the hole capture of Fe2+ was evaluated as 10 x 10(-15) cm

  • 3.
    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.

  • 4.
    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.

  • 5.
    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.

  • 6.
    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.

  • 7.
    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.

  • 8. Akabori, M.
    et al.
    Hidaka, S.
    Iwase, H.
    Yamada, S.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Realization of In0.75Ga0.25As two-dimensional electron gas bilayer system for spintronics devices based on Rashba spin-orbit interaction2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 11, 113711- p.Article in journal (Refereed)
    Abstract [en]

    Narrow gap InGaAs two-dimensional electron gas (2DEG) bilayer samples are fabricated and confirmed to have good electronic qualities as well as strong Rashba-type spin-orbit interactions (SOIs). The 2DEG systems are realized by molecular beam epitaxy in the form of wide quantum wells (QWs) with thicknesses tQW∼40-120nm modulation doped in both the upper and lower InAlAs barriers. From the Hall measurements, the overall mobility values of μe ∼15 m2/V s are found for the total sheet electron density of ns ∼8 × 1011/cm2, although the ns is distributed asymmetrically as about 1:3 in the upper and lower 2DEGs, respectively. Careful low temperature magneto-resistance analysis gives large SO coupling constants of α ∼20 × 10 -12eV m as well as expected electron effective masses of m*/m0 ∼0.033-0.042 for each bilayer 2DEG spin sub-band. Moreover, the enhancement of α with decrease of tQW is found. The corresponding self-consistent calculation, which suggests the interaction between the bilayer 2DEGs, is carried out and the origin of α enhancement is discussed.

  • 9.
    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

  • 10.
    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.

  • 11.
    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.

  • 12.
    Almlöf, Jonas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Quantum Electronics and Quantum Optics, QEO (moved to SCI 2011-07-01).
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Quantum Electronics and Quantum Optics, QEO (moved to SCI 2011-07-01).
    A short and efficient quantum-erasure code for polarization-coded photonic qubits2009In: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009, 5191786- p.Conference paper (Refereed)
  • 13.
    Almlöf, Jonas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar G. E.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    A short and efficient error correcting code for polarization coded photonic qubits in a dissipative channel2011In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 284, no 1, 550-554 p.Article in journal (Refereed)
    Abstract [en]

    We propose a short and efficient non-degenerate quantum error correcting code that is adapted for qubits encoded on two orthogonal, single-photon states (e.g., horizontally and vertically polarized) subject to a dissipative channel. The proposed code draws its strength from the fact that it is adapted to the physical characteristics of the information-carrying basis states under the action of the channel. The code combines different energy manifolds and consists of only 3 spatio-temporal modes and on average 2 photons per code word.

  • 14. Alonso, M. A.
    et al.
    Setala, T.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Optimal pulses for arbitrary dispersive media2011In: Journal of the European Optical Society - Rapid Publications, ISSN 1990-2573, E-ISSN 1990-2573, Vol. 6, 11035- p.Article in journal (Refereed)
    Abstract [en]

    A variational procedure is given for finding the pulses for which the initial temporal rms width and the rate of increase of this width are jointly minimized for propagation in non-absorbing media with arbitrary dispersive properties. We show that, while in linearly dispersive media the optimal pulses are Gaussian, in other situations such as a hollow metallic waveguide or for purely cubic dispersion departures from Gaussian behavior become evident. An interpretation of the results in terms of suitable phase-space representations is also given.

  • 15. Andersen, U. L.
    et al.
    Tipsmark, A.
    Laghaout, A.
    Dong, R.
    Jezek, M.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101).
    Quantum information processing with discrete and continuous variables2011In: Optics InfoBase Conference Papers, 2011Conference paper (Refereed)
    Abstract [en]

    By means of a hybrid detector we suggest and implement two protocols. We theoretically propose a feasible loophole-free violation of Bell's inequality and we experimentally realize a Hadamard transform of coherent superposition states.

  • 16. Bengtsson, Ingemar
    et al.
    Björk, GunnarKTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.Bourennane, Mohamed
    International Conference on Quantum Information and Computation, Stockholm, 4-8 October, 2010: Book of Abstracts2010Conference proceedings (editor) (Other academic)
  • 17.
    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.

  • 18.
    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.

  • 19. Bertulis, K.
    et al.
    Krotkus, A.
    Aleksejenko, G.
    Pacebutas, V.
    Adomavicius, R.
    Molis, G.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    GaBiAs: A material for optoelectronic terahertz devices2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 20Article in journal (Refereed)
    Abstract [en]

    GaBiAs layers have been grown by molecular beam epitaxy at low (270-330 degrees C) temperatures and were characterized by several experimental techniques. It was shown that the spectral photosensitivity cutoff wavelength reaches similar to 1.4 mu m when the growth temperature is as low as 280 degrees C. Optical pump-terahertz probe measurements made on these layers have evidenced that the electron trapping time decreases with decreasing growth temperature from 20 to about 1 ps. GaBiAs layers were used for manufacturing photoconductive terahertz emitters and detectors, which, when excited with Ti:sapphire laser pulses, have demonstrated a signal bandwidth of 3 THz.

  • 20.
    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.

  • 21.
    Björk, Gunnar
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Söderholm, Jonas
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Sanchez-Soto, Luis L.
    Klimov, Andrei B.
    Ghiu, Iulia
    Marian, Paulina
    Marian, Tudor A.
    Quantum degrees of polarization2010In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, no 22, 4440-4447 p.Article in journal (Refereed)
    Abstract [en]

    We discuss different proposals for the degree of polarization of quantum fields. The simplest approach, namely making a direct analogy with the classical description via the Stokes operators, is known to produce unsatisfactory results. Still, we argue that these operators and their properties should be basic for any measure of polarization. We compare alternative quantum degrees and put forth that they order various states differently. This is to be expected, since, despite being rooted in the Stokes operators, each of these measures only captures certain characteristics. Therefore, it is likely that several quantum degrees of polarization will coexist, each one having its specific domain of usefulness.

  • 22. 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.

  • 23. Blomstedt, K.
    et al.
    Setala, T.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Effect of absorption on the spatial coherence in scalar fields generated by statistically homogeneous and isotropic sources2005In: Physical Review E, ISSN 1539-3755, Vol. 72, no 5Article in journal (Refereed)
    Abstract [en]

    We investigate the behavior of the spectral degree of coherence of fluctuating scalar wave fields generated by statistically homogeneous and isotropic sources within absorbing media. In the limit of negligible losses, the degree of coherence is shown to be of a known universal form (sinc function), whereas in the limit of infinite losses it is shown to asymptotically approach the degree of coherence of the source. The intermediate cases are studied for fields produced by sources with Gaussian and sinc-type coherence functions. These studies show that the concept of negligible losses is meaningful only when defined with respect to specific source distribution statistics, and that even for arbitrarily small nonzero losses, the coherence length of the field can be arbitrarily short.

  • 24. Blomstedt, K.
    et al.
    Setala, T.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Effective degree of coherence: general theory and application to electromagnetic fields2007In: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 9, no 10, 907-919 p.Article in journal (Refereed)
    Abstract [en]

    The concept of overall or effective degree of coherence has proven useful and insightful in the scalar theory of light. In this paper we extend the concept to fields represented over arbitrary vector (Hilbert) spaces. We show that the effective degree of coherence remains unaltered by scaled unitary mappings, which describe for instance many physical interactions. In the context of random, vector-valued electromagnetic fields the invariance implies that the effective degree of coherence assumes the same value in commonly used representation spaces. Thereby, in contrast to the local degree of coherence, this quantity can be taken as an intrinsic property of the electromagnetic wave field. In particular, the effective degree of coherence does not change when the field is scattered by a lossless medium and it can be determined from the far-field pattern. Hence the effective degree of coherence of electromagnetic fields is readily measurable.

  • 25. Blomstedt, Kasimir
    et al.
    Setala, Tero
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Arbitrarily short coherence length in wave fields within finite lossless source regions2007In: Physical Review E, ISSN 1539-3755, Vol. 75, no 2Article in journal (Refereed)
    Abstract [en]

    We show that it is possible to construct stochastic source distributions that generate wave fields with any desired spatial coherence properties inside a prescribed finite region, regardless of the refractive-index distribution therein. In particular, we demonstrate that there is no universal sinc-function form for the field correlations produced by statistically homogeneous and isotropic source distributions within large lossless regions, contrary to what is suggested by previous work. The results also disprove the commonly held belief that in lossless source regions the coherence length of the light is bounded below by the blackbody coherence length-that is, by approximately half the wavelength of the field.

  • 26. Bratkovsky, Alexander
    et al.
    Ponizovskaya, Ekaterina
    Wang, Shih-Yuan
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Fu, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    A metal-wire/quantum-dot composite metamaterial with negative epsilon and compensated optical loss2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, no 19, 193106- p.Article in journal (Refereed)
    Abstract [en]

    Numerical simulations of a binary mixture of quantum dots exhibiting gain with silver nanorods are performed, showing the feasibility of lossless negative epsilon operation for realistic material structures and parameters.

  • 27.
    Burvall, Anna
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Martinsson, Per
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Communication modes in large-aperture approximation2007In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 32, no 6, 611-613 p.Article in journal (Refereed)
    Abstract [en]

    Simplified versions of the communication modes in the Fresnel domain are derived when the system apertures are large. The approximate modes, which are in the form of spherical waves and sinc functions with a spherical curvature, give physical insight into the communication modes approach and the basic limits of free-space optical communication systems. They also show that Gabor's information theory is readily derived from the communication modes.

  • 28. 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.

  • 29. 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.

  • 30.
    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.

  • 31.
    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.

  • 32.
    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.

  • 33.
    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.

  • 34.
    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)
  • 35.
    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.

  • 36.
    Chacinski, Marek G.
    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.
    Isaksson, Mats
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Wang, Qin
    Effects of detuned loading on the modulation performance of widely tunable MG-Y lasers2008In: Semiconductor Lasers And Laser Dynamics III / [ed] Panajotov, KP; Sciamanna, M; Valle, AA; Michalzik, R, 2008, Vol. 6997, 99709-99709 p.Conference paper (Refereed)
    Abstract [en]

    The Detuning Loading Effect, i.e., the effects of the modulation performance on the position of the lasing mode relative to the Bragg reflection peak, is investigated in a Modulated Grating Y-branch laser. By proper adjustment of the lasing mode position, simultaneous chirp reduction and modulation bandwidth enhancement can be obtained. The lasing mode position is also crucial for side mode suppression ratio and output power.

  • 37.
    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.

  • 38.
    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.
    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), Integrated Devices and Circuits.
    Marcks von Würtemberg, Rickard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Mogg, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Single-mode 1.27 μm InGaAs vertical cavity surface-emitting lasers with temperature-tolerant modulation characteristics2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 21, 211109-1-211109-3 p.Article in journal (Refereed)
    Abstract [en]

    The dynamic performance of InGaAs/GaAs 1.27 μ m single-mode vertical cavity surface emitting lasers (VCSELs) is presented. In order to reach such a long wavelength, the devices utilize highly strained double-quantum wells and a large detuning between the material gain peak and cavity resonance. It is found that the large detuning improves the temperature stability of both static and modulation characteristics. A resonance frequency of 7.8-9.5 GHz and optical power of 0.30 mW in fiber was maintained throughout the investigated temperature range of 20-90 ° C. The intrinsic response of the device suggests that long-wavelength InGaAs/GaAs VCSELs have the potential to be used as low cost uncooled optical transmitters at 10 Gbit/s. © 2005 American Institute of Physics. © 2005 American Institute of Physics.

  • 39.
    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.

  • 40.
    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.

  • 41.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Scholes, A.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Ericsson, P
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Isaksson, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammerfeldt, S.
    A silicon optical bench for flip chip mounting of widely tunable modulated grating Y-branch lasers2005In: CAOL 2005: Proceedings of the 2nd International Conference on Advanced Optoelectronics and Lasers, Vol 1 / [ed] Sukhoivanov, IA, 2005, 64-66 p.Conference paper (Refereed)
    Abstract [en]

    A silicon optical bench for flip chip mounted widely tunable lasers is presented. Its impact on the static and dynamic characteristics of the laser device is evaluated and compared with a conventional aluminium nitride carrier.

  • 42. Chacinski, Marek
    et al.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Stoltz, Bjoern
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Monolithically Integrated DFB-EA for 100 Gb/s Ethernet2008In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 29, no 12, 1312-1314 p.Article in journal (Refereed)
    Abstract [en]

    The world's first monolithically integrated distributed feedback laser and electroabsorption (EA) modulator with an expected >= 100 GHz -3 dBe bandwidth suitable for 100 Gb/s operation with on-off keying is presented. The design of the EA modulator uses a traveling-wave structure with three active segments and a total active length of 180 mu m resulting in similar to 2.5 V peak-to-peak drive voltage for 10 dB optical extinction ratio and low electrical reflection.

  • 43.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Stoltz, Bjorn
    Driad, Rachid
    Makon, Robert Elvis
    Hurm, Volker
    Steffan, Andreas Gerhard
    100 Gb/s ETDM Transmitter Module2010In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 16, no 5, 1321-1327 p.Article in journal (Refereed)
    Abstract [en]

    Components of a 100 Gb/s transmitter with electrical time-division multiplexing are presented as following: electrical multiplexer, driver amplifier, and large-bandwidth distributed feedback-traveling-wave electro-absorption modulator module. The performance of the parts of the transmitter, as well as the complete chain, is investigated for data operation and transmission in future 100 Gb/s Ethernet (100GbE). Clearly open eye diagrams at 100 Gb/s are demonstrated together with data transmission over 300 m long standard single mode fiber link.

  • 44.
    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.

  • 45.
    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.

  • 46.
    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%.

  • 47.
    Chacinski, Marek
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Stoltz, Björn
    Rosenzweig, Josef
    Driad, Rachid
    Makon, Robert E.
    Li, Jie
    Steffan, Andreas
    ETDM Transmitter Module for 100-Gb/s Ethernet2010In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 22, no 2, 70-72 p.Article in journal (Refereed)
    Abstract [en]

    Performance of a packaged distributed-feedback travelling-wave electroabsorption modulator module for data transmission at 100 Gb/s is presented for the first time. Clearly open eye diagrams at 80 Gb/s with an extinction ratio ( ER) of 4.9 dB and 100 Gb/s with ER 4.2 dB ( limited by measurement setup) are demonstrated together with data transmission over 100-m-long standard single-mode fiber and over dispersion-compensated 10-km fiber link.

  • 48. 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.

  • 49. Chamaillard, K.
    et al.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Dainty, Chris
    Coherency matrix description for statistical linear regression of Stokes parameters in rough small-particle scattering2010In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, no 22, 4519-4524 p.Article in journal (Refereed)
    Abstract [en]

    A statistical analysis of the Stokes parameters in light scattering by randomly rough small particles shows a linear regression law between the squares of the first two components I-s and Q(s) of the Stokes vector. While the coefficients of this linear regression contain physical characteristics of the particles, they cannot be directly interpreted in terms of the degree of polarization of the scattered field. We propose an interpretation of this relationship between the Stokes parameters on the basis of the general coherence-density matrix formalism. The link between the statistical regression results and the polarization properties of the stochastic scattered components of the field is established through the coherency matrix elements.

  • 50.
    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..

1234567 1 - 50 of 494
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