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  • 151. Jacobsen, Gunnar
    et al.
    Lidon, Maria Sol
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Influence of pre-and post-compensation of chromatic dispersion on equalization enhanced phase noise in coherent multilevel systems2011In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, p. 257-261Article in journal (Refereed)
    Abstract [en]

    In this paper we present a comparative study of the equalization enhanced phase noise (EEPN) for preand post-compensation of chromatic dispersion in high capacity and high constellation systems. This is - to our knowledge - the first detailed study in this area for precompensation systems. Our main results show that the local oscillator phase noise determines the EEPN influence in post-compensation implementations whereas the transmitter laser determines the EEPN in pre-compensation implementations. As a result of significance for the implementation of practical longer-range systems it is to be emphasized that the use of chromatic dispersion equalization in the optical domain - e.g. by the use of dispersion compensation fibers - eliminates the EEPN entirely. Thus, this seems an efficient solution for such systems operating at high constellations in the future.

  • 152. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    EEPN and CD study for coherent optical nPSK and nQAM systems with RF pilot based phase noise compensation2012In: Optics Express, E-ISSN 1094-4087, Vol. 20, no 8, p. 8862-8870Article in journal (Refereed)
    Abstract [en]

    A radio frequency (RF) carrier can be used to mitigate the phase noise impact in n-level PSK and QAM systems. The systems performance is influenced by the use of an RF pilot carrier to accomplish phase noise compensation through complex multiplication in combination with discrete filters to compensate for the chromatic dispersion (CD). We perform a detailed study comparing two filters for the CD compensation namely the fixed frequency domain equalizer (FDE) filter and the adaptive least-mean-square (LMS) filter. The study provides important novel physical insight into the equalization enhanced phase noise (EEPN) influence on the system bit-error-rate (BER) versus optical signal-to-noise-ratio (OSNR) performance. Important results of the analysis are that the FDE filter position relative to the RF carrier phase noise compensation module provides a possibility for choosing whether the EEPN from the Tx or the LO laser influences the system quality. The LMS filter works very inefficiently when placed prior to the RF phase noise compensation stage of the Rx whereas it works much more efficiently and gives almost the same performance as the FDE filter when placed after the RF phase noise compensation stage.

  • 153. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Receiver implemented RF pilot tone phase noise mitigation in coherent optical nPSK and nQAM systems2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 15, p. 14487-14494Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel method for extracting an RF pilot carrier signal in the coherent receiver is presented. The RF carrier is used to mitigate the phase noise influence in n-level PSK and QAM systems. The performance is compared to the use of an (ideal) optically transmitted RF pilot tone. As expected an electronically generated RF carrier provides less efficient phase noise mitigation than the optical RF. However, the electronically generated RF carrier still improves the phase noise tolerance by about one order of magnitude in bit error rate (BER) compared to using no RF pilot tone. It is also found, as a novel study result, that equalization enhanced phase noise - which appears as correlated pure phase noise, amplitude noise and time jitter - cannot be efficiently mitigated by the use of an (optically or electrically generated) RF pilot tone.

  • 154. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Zhang, Yimo
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Error-rate floors in differential n-level phase-shift-keying coherent receivers employing electronic dispersion equalisation2011In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, p. 191-193Article in journal (Refereed)
    Abstract [en]

    A model for the phase noise influence in differential n-level phase shift keying (nPSK) systems and 2nlevel quadrature amplitude modulated (2nQAM) systems employing electronic dispersion equalization and quadruple carrier phase extraction is presented. The model includes the dispersion equalization enhanced local oscillator phase noise influence. Numerical results for phase noise error-rate floors are given for dual polarization (DQPSK, Dl6PSK and D64PSK) system configurations with basic baud-rate of 25 GS/s. The transmission distance in excess of 1000 km requires local oscillator lasers with sub-MHz linewidth.

  • 155. Jain, Sakshi
    et al.
    Muralidharan, Sreraman
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Panigrahi, Prasanta K.
    Secure quantum conversation through non-destructive discrimination of highly entangled multipartite states2009In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 87, no 6, p. 60008-Article in journal (Refereed)
    Abstract [en]

    "Quantum conversation" is a way in which two parties can communicate classical information with each other using entanglement as a shared resource. We present this scheme using a multipartite entangled state after describing its generation through appropriate circuit diagrams. We make use of a discrimination scheme which allows one to perform a measurement on the system without destroying its entanglement. We later prove that this scheme is secure in a noiseless and a lossless quantum channel.

  • 156. Jaroszewicz, Zbigniew
    et al.
    Adamkiewicz, Grazyna
    Duran-Bosch, Vicente
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Kolodziejczyk, Andrzej
    Kowalik, Andrzej
    Lancis, Jesus
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Kinoform apodization by using of programmable diffractive optical elements2004In: Proceedings of SPIE - The International Society for Optical Engineering: Volume 5456, 2004 / [ed] Frank Wyrowski, SPIE - International Society for Optical Engineering, 2004, p. 153-156Conference paper (Refereed)
    Abstract [en]

    The apodizationof diffractiveopticalelementscan be realized by a local change of their diffraction efficiency. In the case of lithographic elementswith step-like structure of the period, the variable diffraction efficiency can be achieved by a gradual transformation of the 2m stepkinoform into its conjugate counterpart across theapodization region. In the present contribution we show experimental results confirming this idea, which until no was verified only by simulations. The apodized quaternary grating with locally varying diffraction efficiency was obtained on a SLM device as aprogrammablediffractiveopticalelement by changing gradually the period's profile. Knowledge of the phase heights of the SLM's pixels is required for successful implementation of theapodization function. It was determined from Fresnel images of the binary phase gratings with different phase step height programmed on the SLM. The Fresnel images become then binary and their visibility depends on the phase height of the grating in a known way, what makes possible to calibrate the SLM.

  • 157.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National university of Ireland, Galway.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Garcia-Sucerquia, Jorge Ivan
    Kolodziejkzyk, Andrzej
    Nowakowski, Arkadiusz
    Focal segments obtained by interference of multiple Bessel beams: experimental results2004In: PHOTON MANAGEMENT  : PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE), vol 5456 / [ed] Frank Wyrowsky, SPIE , 2004, p. 484-489Conference paper (Other academic)
    Abstract [en]

    In the present communicate the experimental results are shown, which deal with the interference pattern created by superposition of multiple Bessel beams. They confirm our earlier results obtained analytically as well as by simulations. The interfering Bessel beams were obtained in a standard way, i.e., a field produced by a set of concentric annular apertures of narrow width illuminated by a plane wave was transformed by a lens into a set of Bessel beams.

  • 158.
    Jaroszewicz, Zbigniew
    et al.
    Institute of Applied Optics, Warsaw.
    Burvall, Anna
    National university of Ireland, Galway.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Axicon:  the most important optical element2005In: Optics and photonics news (Print), ISSN 1047-6938, E-ISSN 1541-3721, Vol. 16, no 4, p. 34-39Article in journal (Refereed)
    Abstract [en]

    Last year, the optics community celebrated the 50th anniversary of the formal naming of the axicon. Long before that, however, axicons generated vivid discussions and disagreements, often of fundamental importance to our understanding of optics.

  • 159.
    Jaskorzynska, Bozena
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Qiu, Min
    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.
    Dainese, Matteo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Zawistowski, Zygmunt J.
    Applications of wavelength dispersion in 1D and 2D photonic crystals2005In: Proceedings of SPIE - The International Society for Optical Engineering / [ed] Waclaw Urbanczyk, Bozena Jaskorzynska, Philip St. J. Russell, SPIE - International Society for Optical Engineering, 2005, p. 1-9Conference paper (Refereed)
    Abstract [en]

    One of the most distinctive features of photonic crystals (PhCs) is their unique wavelength dispersion allowing novel device concepts for enhancement of photonic functionality and performance. Here, we present examples of our design and demonstrations utilizing dispersion properties of 1D and 2D photonic crystals. This includes the demonstration of negative refraction in 2D PhC at optical wavelengths, filters based on 1D and 2D PhC waveguides, and the design of a widely tunable filter involving 1D PhC.

  • 160.
    Jaskorzynska, Bozena
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Song, Yi
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    Tradeoff between mode confinement, loss, and cross-talk, for dielectric and metal slot waveguides2009In: Photonics Letters of Poland, ISSN 2080-2242, Vol. 1, p. 172-174Article in journal (Refereed)
    Abstract [en]

    Slot waveguides formed in high-index dielectrics or metals provide strong field enhancement in the slot region. When filled with nonlinear or lasing materials, they have the potential for highly efficient components for intensity dependent signal processing in integrated photonic circuits. In view of the increasing demand for high integration, metal slot waveguides have the great advantage of sub-diffraction mode confinement but they suffer from serious transmission loss. The total lateral field extent in their low-loss dielectric counterparts is, in turn, diffraction limited. Considering those tradeoffs, we show that at 24dB/ÎŒm cross-talk and the attenuation length of at least 5ÎŒm, gold slot waveguides can be spaced only ca 3.5 times denser than slot waveguides in silicon.

  • 161.
    Jaskorzynska, Bozena
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Song, Yi
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Zhu, Ning
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Wang, Zhechao
    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.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Dielectric and Plasmon Slot Waveguides for Photonic Integration2009In: ICTON 2009: 11th International Conference on Transparent Optical Networks: 2009 11TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, VOLS 1 AND 2, NEW YORK: IEEE , 2009, p. 653-656Conference paper (Refereed)
    Abstract [en]

    Slot waveguides formed either in high-index dielectrics or in metals attract great interest because they provide sub-wavelength confinement in the slot region. While this feature is very attractive for devices relying on stimulated emission or nonlinear effects, it does not necessarily improve the integration density. The spacing between dielectric slot waveguides is still limited by diffraction. Although for metal (plasmon) waveguides the total field can be shrunk far beyond the diffraction limit, the associated increase in propagation loss will set practical limits on both the minimum waveguide width and edge-to-edge separation. Here we compare the packing densities for 3D slot waveguides in silicon and plasmon waveguides in gold with a silicon slot. As a reference we also consider silicon photonic wire. We calculate center-to-center waveguide separations (pitch) versus cross-talk level. We show that at ca 24 dB/mu m cross-talk and requiring the attenuation length of at least 5 mu m, plasmon slot waveguides can be packed ca 3.5 times denser than silicon slot waveguides, and ca 2.5 times denser than photonic wires. We also show examples of the fabricated devices.

  • 162.
    Jaskorzynska, Bozena
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Silicon-based photonic crystals and nanowires2008In: Photonic Crystals: Physics and Technology / [ed] Sibilia, C.; Benson, T.M.; Marciniak, M.; Szoplik, T., Springer, 2008, p. 149-169Chapter in book (Refereed)
    Abstract [en]

    This Chapter highlights issues related to dense photonic integration based on silicon platform and reviews two alternatives to achieve this goal within the diffraction limit; photonic nanowires and photonic crystal waveguides. Examples of the device concepts and demonstrators, as well as the fabrication techniques for passive Si based mesostructures, are presented. Promising prospects and recent breakthroughs in heterogeneous integration of silicon with optically active materials are indicated.

  • 163.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Monti, Paolo
    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.
    Tzanakaki, Anna
    Dynamic provisioning strategies for energy efficient WDM networks with dedicated path protection2011In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 8, no 3, p. 201-213Article in journal (Refereed)
    Abstract [en]

    Energy consumption in optical backbone networks is increasing due to two main reasons: (i) the exponential growth of bandwidth demands, and (ii) the increase in availability requirements in order to guarantee protection of the ultra high capacity optical channels provided by wavelength division multiplexing (WDM) networks. Although state of the art reliability mechanisms are very efficient in guaranteeing high availability, they do not consider the impact of the protection resources on the network's energy consumption. Dedicated (1:1) path protection (DPP) is a well-known mechanism that provides one extra link-disjoint path for the protection of a connection request. This secondary path is reserved and maintained in an active mode even though it is not utilized most of the time. This means that in-line optical amplifiers and switching nodes/ports are always consuming power even when they are not used to reroute any primary traffic. Moreover secondary paths are on average longer than their respective primary paths. These observations motivated us to investigate the energy savings, when all unused protection resources can be switched into a low-power, stand-by state (or sleep mode) during normal network operation and can be activated upon a failure. It is shown that significant reduction of power consumption (up to 25%) can be achieved by putting protection resources into sleep mode. Moreover, in order to enhance this energy saving figure, this paper proposes and evaluates different energy-efficient algorithms, specifically tailored around the sleep mode option, to dynamically provision 1:1 dedicated path protected connection. The trade-off between energy saving and blocking probability is discussed and an efficient mechanism to overcome this drawback is devised. Our results reveal that a 34% reduction of energy consumption can be obtained with a negligible impact on the network's blocking performance.

  • 164.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Katrinis, Kostas
    Athens Information Technology.
    Tzanakaki, Anna
    Athens Information Technology.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Quantifying the Benefit of BER-based Differentiated Path Provisioning in WDM Optical Networks2009In: ICTON: 2009 11TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, VOLS 1 AND 2, NEW YORK: IEEE , 2009, p. 1097-1100Conference paper (Refereed)
    Abstract [en]

    In this paper we propose the use of Bit Error Rate (BER) as a differentiation of service parameter for connection provisioning in optical Wavelength Division Multiplexing (WDM) networks. This is achieved through the use of Impairment Constraint Based Routing (ICBR), whereby various BER thresholds are set for accepting/blocking requests at the connection provisioning phase, depending on QoS requirements. The performance of the proposed scheme is evaluated through simulations, using dynamic traffic demands as an input at 10 Gb/s bit rate. The evaluation results reveal significant improvement in term of connection blocking, as compared to non-differentiated conventional RWA and ICBR algorithms.

  • 165.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Monti, Paolo
    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.
    Katrinis, Kostas
    Athens Information Technology.
    Tzanakaki, Anna
    Athens Information Technology.
    ICBR-Diff: An Impairment Constraint Based Routing Strategy with Quality of Signal Differentiation2010In: Journal of Networks, E-ISSN 1796-2056, Vol. 5, no 11, p. 1279-1289Article in journal (Refereed)
    Abstract [en]

    Latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build all-optical transparent networks, which are considered to be able to satisfy the rapidly growing capacity demand. However, in a transparent WDM network the optical signal transmitted from a source to a destination node might be degraded due to physical layer impairments induced by transmission through optical fibers and components. Several Impairment Constraint Based Routing (ICBR) algorithms have been proposed to consider physical layer impairments during the connection-provisioning phase in order to prevent selecting a lightpath with poor signal quality. However, these algorithms support only a single quality of transmission threshold for all connection requests, while next generation networks and the future Internet are expected to support a variety of services with potentially disparate QoS requirements. In this paper, we propose the use of bit error rate (BER) as a differentiation of service parameter for connection requests in optical WDM networks. This is achieved through the use of ICBR, whereby various BER thresholds are set depending on the QoS requirements for accepting/blocking the connection requests during the connection-provisioning phase. The evaluation results reveal that significant network performance improvement in terms of connection blocking can be achieved, compared to non-differentiated conventional routing and wavelength assignment (RWA) and ICBR algorithms.

  • 166.
    Jirattigalachote, Amornrat
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Skorin-Kapov, Nina
    Furdek, Marija
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sparse power equalization placement for limiting jamming attack propagation in transparent optical networks2011In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 8, no 4, p. 249-258Article in journal (Refereed)
    Abstract [en]

    The latest advances in Wavelength Division Multiplexing (WDM) technology are making it possible to build all-optical transparent WDM networks, which are expected to be able to satisfy the rapid growth of today's capacity demand. However, the transparency of such networks makes them highly vulnerable to deliberate attacks, specifically targeting the physical layer. Physical-layer attacks, such as high-power jamming, can cause severe service disruption or even service denial, enhanced by their capability to propagate through a transparent optical network. Several attack-aware routing and wavelength assignment algorithms have been proposed to reduce the possible disruption caused by high-power jamming attacks. However, even with network planning approaches which take network security, specifically physical-layer attacks, into account, resilience to deliberate attacks in such scenarios remains an issue. In this paper, we propose the use of wavelength-selective attenuators as power equalizers inside network nodes to limit the propagation of high-power jamming attacks. Due to the increased cost of optical switching nodes associated with the addition of power equalizers, we aim at minimizing their number through sparse power equalization placement. We developed a set of greedy algorithms to solve what we call the Power Equalization Placement (PEP) problem with the objective of minimizing the number of power equalizers needed to reduce, to a desired level, the propagation of high-power jamming attacks for a given routing scheme. We further improved upon these results by proposing a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic with a somewhat longer execution time, but with significantly superior results. The performance evaluation results indicate that the proposed GRASP heuristic can achieve the same attack propagation reduction as can be obtained by equipping all nodes with power equalizers by placing them at less than 50% of the nodes on average, potentially yielding significant cost savings.

  • 167.
    Jirattigalachote, Amornrat
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Katrinis, Kostas
    Tzanakaki, A.
    Impairment aware routing with service differentiation in heterogeneous WDM networks2009In: Network Architectures, Management, and Applications VII, SPIE - International Society for Optical Engineering, 2009, p. 763307-Conference paper (Refereed)
    Abstract [en]

    In transparent Wavelength Division Multiplexing (WDM) networks, the signal is transported from source to destination in the optical domain through all-optical channels, or lightpaths. A lightpath may traverse several fiber segments and optical components that in general degrade the optical signal. This effect introduces the need for considering physical layer impairments during the connection-provisioning phase. Physical layer impairments can be divided into linear and non-linear. Both types of impairments are highly dependent on the fiber characteristics, which in turn are sensitive to length, temperature and age. A close look at the fiber infrastructure of today's network operators reveals a situation where old and newly deployed fibers coexist in the network. This heterogeneous fiber plant presents a challenge. A tradeoff should be found between the QoS requirements of connection requests and the use of the available (old and new) network resources. This calls for a provisioning mechanism able to adapt to the various fiber composition scenarios. In parallel, given the need for service differentiation, the authors recently proposed an Impairment Constraint Based Routing (ICBR) algorithm, referred to as ICBR-Diff, supporting differentiation of services at the BER (Bit Error Rate) level in a network with a homogeneous fiber infrastructure. In this paper the ICBR-Diff algorithm is extended to heterogeneous network; particularly, it is evaluated in WDM networks with fiber links having varying Polarization Mode Dispersion characteristics, i.e., with old and new fiber coexisting. Simulation results show that the ICBR-Diff algorithm exhibits high adaptability in a heterogeneous fiber composition scenario. This translates into improved performance in terms of blocking probability, when compared to traditional impairment aware routing algorithms.

  • 168.
    Jirattigalachote, Amornrat
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Katrinis, Kostas
    Athens Information Technology.
    Tzanakaki, Anna
    Athens Information Technology.
    Impairment aware routing with service differentiation in heterogeneous WDM networks2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, p. 1-2Conference paper (Refereed)
    Abstract [en]

    We evaluate an Impairment Constraint Based Routing algorithm with service differentiation (ICBR-Diff) applied in WDM networks with fiber links having varying Polarization Mode Dispersion characteristics. Simulation results show high adaptability of the ICBR-Diff approach to this heterogeneous fiber scenario when compared to conventional routing schemes.

  • 169.
    Jirattigalachote, Amornrat
    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.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Katrinis, Kostas
    Athens Information Technology.
    Tzanakaki, Anna
    Athens Information Technology.
    Impairment Constraint Based Routing (ICBR) with service differentiation in survivable WDM networks2009In: European Conference on Optical Communication, ECOC, 2009, p. 1-2Conference paper (Refereed)
    Abstract [en]

    We propose and evaluate a novel survivable impairment constraint based routing (ICBR) algorithm with service differentiation at the bit error rate level. Simulations show significant improvement in connection blocking compared to conventional ICBR solutions.

  • 170. Jouttenus, T.
    et al.
    Setala, T.
    Kaivola, M.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Connection between electric and magnetic coherence in free electromagnetic fields2005In: Physical Review E, ISSN 1539-3755, Vol. 72, no 4Article in journal (Refereed)
    Abstract [en]

    We introduce quantitative measures for the description of the electric and magnetic coherence in a stationary, random electromagnetic field at two points, in a volume, and in the Fourier space. These quantities are applied to free electromagnetic fields, and several theorems regarding the relationship between the two types of coherences in such fields are established. Fields which are statistically homogeneous, and those which, in addition, are statistically isotropic are considered separately. Furthermore, the connection between the electric and magnetic coherence is exemplified for some specific statistically homogeneous fields.

  • 171. Kabaciński, Wojciech
    et al.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Danilewicz, Grzegorz
    Kleban, Janusz
    Spyropoulou, Maria
    Tomkos, Ioannis
    Varvarigos, Emmanouel A.
    Vlachos, Kyriakos
    Węclewski, Slawomir
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yiannopoulos, Konstantinos
    Novel Switch Architectures2009In:  Towards Digital Optical Networks, Springer, 2009Chapter in book (Refereed)
  • 172. Kantor, Miroslaw
    et al.
    Chen, Jiajia
    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.
    Wajda, Krzysztof
    Techno-economic Analysis of PON Protection Schemes2007Conference paper (Refereed)
  • 173. Kantor, Miroslaw
    et al.
    Wajda, Krzysztof
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Techno-ekonomiczna analiza mechanizmów protekcji w optycznych sieciach dostępowych2009Conference paper (Refereed)
  • 174.
    Karlsson, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Bladh, Henrik
    Bengtsson, Per-Erik
    Accurate method for predicting light scattering from soot aggregates with subparticles of arbitrary shape and structure2009Article in journal (Refereed)
    Abstract [en]

    Soot particles can be formed in hydrocarbon flames as a result of an inefficient combustion process. The particles are near-spherical, and at later stages in the soot growth process, they form chainlike sparse aggregates. When applying optical diagnostic methods, this aggregation influences the evaluation of soot properties based on assumptions of isolated particles. In this paper an efficient and accurate method for calculating scattering of light from these structures is presented. The method can handle aggregates with several hundred subparticles with no restrictions on shape, internal structure, or coagulation of the subparticles. The basic idea is that the induced dipole moments of the subparticles are determined from the solution of a quasi-static problem that can be solved with high accuracy by, e.g., the finite element method.

  • 175.
    Karlsson, Anders
    et al.
    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, Photonics.
    Microcavity lasers in communication applications: Present status and prospects1994In: Proceedings of European Conference on Optical Communication, Firenze, Italy, Sept 26 - 30, 1994, 1994Conference paper (Refereed)
  • 176.
    Karlsson, Stefan
    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, Photonics.
    Yu, Yichuan
    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, Photonics.
    Liu, C.P.
    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, Photonics.
    Chuang, C.H.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Westergren, Urban
    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.
    Tsegaye, Tedros
    Seeds, A.J.
    A Packaged Reflective Electroabsorption Modulator/Detector with Optimized Dynamic Range2005In: Broadband Europe 2005, Bordeaux, 2005Conference paper (Refereed)
  • 177.
    Karlsson, Stefan
    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, Photonics.
    Yu, Yichuan
    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, Photonics.
    Liu, C.P.
    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, Photonics.
    Chuang, C.H.
    Westergren, Urban
    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.
    Tsegaye, Tedros
    Krysa, A. B.
    Roberts, J.S.
    Seeds, A. J.
    A Packaged Resonant Electroabsorption Transceiver for Fiber-Radio Applications2005In: Photonics in Wireless Communication, PWCom 2005, Särö, 2005Conference paper (Refereed)
  • 178. Kellock, H.
    et al.
    Setälä, T.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics. Aalto University, Espoo, Finland .
    Shirai, T.
    Temporal double- and triple-intensity correlation imaging with classical light2010In: 2010 9th Euro-American Workshop on Information Optics, WIO 2010, 2010, p. 5582500-Conference paper (Refereed)
    Abstract [en]

    The second- and third-order temporal ghost imaging setups with classical light are discussed. The second-order scheme has a single reference arm with a temporal lens and dispersive elements, and an object arm containing an object surrounded by dispersive media. The third-order imaging setup contains two reference arms instead of one. Both setups have a temporally completely incoherent light source providing maximum resolution. The dependence of visibility and resolution of the images on system parameters is considered in both setups.

  • 179.
    Khan, Salman Naeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Dai, Daoxin
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Liu, Liu Ming
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Optimal design for a flat-top AWG demultiplexer by using a fast calculation method based on a Gaussian beam approximation2006In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 262, no 2, p. 175-179Article in journal (Refereed)
    Abstract [en]

    Passband broadening of an AWG (array waveguide grating) demultiplexer with an MMI (multimode interference) coupler connected at the end of a tapered input waveguide is considered. An explicit formula based on the field propagation of an approximate Hermit-Gaussian beam is used to calculate quickly and reliably the spectral response of the AWG demultiplexer. The widths of the input waveguide, the output waveguides and the MMI coupler are optimized. The optimal design is verified with the experimental measurement.

  • 180. Khanmohamadi, Sahar
    et al.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Abtahi, Farzad
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Cassidy, Andrew
    Archambault, émile
    Tremblay, Christine
    Asselin, Serge
    Littlewood, Paul
    Bélanger, Michel
    Semi-filterless optical network: a cost-efficient passive wide area network solution with effective resource utilization2011Conference paper (Refereed)
  • 181. Khoptyar, D.
    et al.
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Experimental determination of the energy-transfer parameters for homogeneous upconversion in Er-doped silica2005In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 22, no 10, p. 2091-2098Article in journal (Refereed)
    Abstract [en]

    Applying a nonlinear spectroscopic technique, we accurately monitor the dynamics of the homogeneous upconversion (HUC) in Er-doped fibers. We provide the first experimental confirmation, to our knowledge, of the earlier theoretical predictions that, for low erbium concentrations, a decay of HUC-influenced excitation probability of Er ions can be well approximated by the formula describing the static HUC. By correlating the experimentally obtained HUC dynamics with the results of our analytical model in a wide range of Er concentrations, we accurately estimate energy-transfer parameters for Er-doped silica glass and experimentally assess the validity of the model.

  • 182. Khoptyar, D.
    et al.
    Sergeyev, S.
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Homogeneous upconversion in Er-doped fibers under steady state excitation: analytical model and its Monte Carlo verification2005In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 22, no 3, p. 582-590Article in journal (Refereed)
    Abstract [en]

    We present an extension to our earlier proposed statistical model for studying migration-assisted homogeneous upconversion in erbium-doped fibers. The extension takes into account minimum proximity distance between erbium ions randomly distributed in the host material and the nonuniformity of the excitation distribution among them. We derive a transcendental equation for the population inversion and find the dependence of the upconversion rate on the population inversion and the pump power for the entire range of feasible Er concentrations. We verify the validity and accuracy of the model by means of time-resolved Monte Carlo simulations.

  • 183. Khoptyar, D.
    et al.
    Sergeyev, S.
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Upconversion assisted decay of population inversion in Er-doped silica after delta-pulse excitation2005In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 41, no 2, p. 205-212Article in journal (Refereed)
    Abstract [en]

    We investigate homogeneous upconversion (HUC) assisted decay of the population inversion in Er-doped silica after delta-pulse excitations by means of Monte Carlo simulations. We derive an analytic expression for this decay when energy migration among Er is negligible and show that it is essentially an extension of the Forster-type donor-acceptor quenching decay for the case when donor and acceptor ions are the same species. We compare HUC during the decay to HUC while pumping CW and show that they considerably differ at the low and moderate Er concentrations. Based on Monte Carlo (MC) simulations, we construct a neuristic approximation to the HUC assisted decay, which makes our MC results readily available for the future experimental and theoretical studies and provides simple means for determination of HUC parameters by fitting to experimental data.

  • 184. Kivisto, Samuli
    et al.
    Puustinen, Janne
    Guina, Mircea
    Herda, Robert
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Dianov, Evgueny M.
    Okhotnikov, Oleg G.
    Pulse dynamics of a passively mode-locked Bi-doped fiber laser2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 2, p. 1041-1048Article in journal (Refereed)
    Abstract [en]

    The pulse evolution in Bi-doped soliton fiber laser with slow and fast saturable absorber has been studied both experimentally and numerically. Semiconductor saturable absorbers with balanced slow and fast absorption recovery mechanisms exhibit a bi-temporal recovery dynamics which permits both reliable start-up of passive mode-locking and short pulse generation and stabilization. The pulse dynamics within the Bi fiber laser cavity have been investigated.

  • 185. Klimov, A. B.
    et al.
    Björk, Gunnar
    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.
    Madsen, L. S.
    Lassen, M.
    Andersen, U. L.
    Heersink, J.
    Dong, R.
    Marquardt, Ch.
    Leuchs, G.
    Sanchez-Soto, L. L.
    Assessing the Polarization of a Quantum Field from Stokes Fluctuations2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, no 15, p. 153602-Article in journal (Refereed)
    Abstract [en]

    We propose an operational degree of polarization in terms of the variance of the Stokes vector minimized over all the directions of the Poincare sphere. We examine the properties of this second-order definition and carry out its experimental determination. Quantum states with the same standard (first-order) degree of polarization are correctly discriminated by this new measure. We argue that a comprehensive quantum characterization of polarization properties requires a whole hierarchy of higher-order degrees.

  • 186.
    Kothe, Christian
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Applications and characterisation of correlations in quantum optics2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantum optics offers a huge variety of exciting phenomena. Many of them are still in their infancy and especially when it comes to implementing devices using these effects for more than a proof of principle demonstration still many things have to be investigated and understood. In this thesis I discuss the role of correlations in some areas of quantum optics and in some cases compare it to classical optics. Four papers form the core of the thesis.

    In the first paper, I propose a new measure for entanglement. This measure is based on correlations between two states. I show, how this measure relates to another measure, the concurrence. It turns out that the measure is a bijective map of the concurrence for a pure state of two qubits. I motivate why the new measure is useful if one wants to implement it experimentally. I discuss its behaviour for the case of two qubits and show its properties when dealing with pure and with mixed states.

    The second paper extends the result of the first one to the case where one has higher-dimensional states than qubits.

    In the third paper I look at phase super-resolution. I show that it can be interpreted as a purely classical effect and I analyse what is needed and what is not needed to achieve it. Specifically, I show that quantum correlations in terms of entanglement is not needed to demonstrate phase super-resolution. By doing so I propose how one could achieve arbitrarily high phase super-resolution.

    Finally, the last paper looks at the efficiency of quantum lithography and quantum imaging. It shows, that some basic assumptions in the original proposals of quantum lithography seems unfounded and that, as a consequence, the efficiency is poor. I give formulæ for the explicit scaling behaviour when changing the number of photons in a mode or when changing the number of pixels. The effect of the results on the future of quantum lithography is discussed as well.

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  • 187.
    Kothe, Christian
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Bourennane, Mohamed
    Arbitrarily high super-resolving phase measurements at telecommunication wavelengths2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 81, no 6, p. 063836-Article in journal (Refereed)
    Abstract [en]

    We present two experiments that achieve phase super-resolution at telecommunication wavelengths. One of the experiments is realized in the space domain and the other is realized in the time domain. Both experiments show high visibility and are performed with standard lasers and single-photon detectors. The first experiment uses six-photon coincidences, whereas the latter experiment needs no coincidence measurements, is easy to perform, and achieves, in principle, arbitrarily high phase super-resolution. Here, we demonstrate a 30-fold increase of the resolution. We stress that neither entanglement nor joint detection is needed in these experiments, which demonstrates that neither is necessary to achieve phase super-resolution.

  • 188.
    Kothe, Christian
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Inoue, Shuichiro
    Bourennane, Mohamed
    On the efficiency of quantum lithography2011In: New Journal of Physics, E-ISSN 1367-2630, Vol. 13, p. 043028-Article in journal (Refereed)
    Abstract [en]

    Quantum lithography promises, in principle, unlimited feature resolution, independent of wavelength. However, in the literature, at least two different theoretical descriptions of quantum lithography exist. They differ in the extent to which they predict that the photons retain spatial correlation from generation to absorption, and although both predict the same feature size, they vastly differ in predicting how efficiently a quantum lithographic pattern can be exposed. Until recently, essentially all quantum lithography experiments have been performed in such a way that it is difficult to distinguish between the two theoretical explanations. However, last year an experiment was performed that gives different outcomes for the two theories. We comment on the experiment and show that the model that fits the data unfortunately indicates that the trade-off between resolution and efficiency in quantum lithography is very unfavourable.

  • 189.
    Kothe, Christian
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Sainz, Isabel
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Detecting entanglement through correlations between local observables2007In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 84, p. 012010-Article in journal (Refereed)
    Abstract [en]

    We propose a measure of two-qubit entanglement that is invariant under local unitary transformations, and which is based on local measurements covariances. It measures the Hilbert-Schmidt distance between the state and the product state obtained by multiplying the local density matrices. The measure has the benefit that the experimentalist need not have any a priori knowledge of the state to make the measurements. For pure states, the measure provides the state's concurrence directly, without resorting to state tomography. For statistically mixed states, the measure provides bounds for the concurrence. The two-qutrit case is also studied.

  • 190. Kourtessis, Pandelis
    et al.
    Almeida, Carlos
    Chang, Ching-Hung
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Bartolo, Silvia Di
    Fasser, Peter
    Gagnaire, Maurice
    Leitgeb, Erich
    Lima, Mario
    Löschnigg, Markus
    Marciniak, Marian
    Pavlovic, Natasa
    Shachaf, Y.
    Teixeira, Antonio Luis Jesus
    Beleffi, Giorgio Maria Tosi
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Evolution of Optical Access Networks2009In: COST 291 - Towards Digital Optical Networks, Springer, 2009Chapter in book (Refereed)
  • 191. Kulbickas, A.
    et al.
    Tamuliene, J.
    Rasteniene, L.
    Franckevicius, M.
    Vaisnoras, R.
    Marcos, M.
    Serrano, J. L.
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Optical study and structure modelling of PPI liquid crystalline dendrimer derivatives2007In: Photonics and Nanostructures-Fundamentals and Applications, ISSN 1569-4410, Vol. 5, no 4, p. 178-183Article in journal (Refereed)
    Abstract [en]

    Optical study of two families of poly(propylene imine) (PPI) dendrimers (G = 1-5) are reported. The enlarging of the chain number (generations) of the PPI dendrimer leads to the spectra shift to IR region in solvent until 8 and 19 nm for both families, respectively. The theoretical modelling of the dendrimer structure was performed. The geometric characterization of dendrimer structure demonstrates that the preferable free space for encapsulation is periphery of the PPI dendrimer.

  • 192.
    Laghaout, Amine
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Feasibility of Bell tests with the W state2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 81, no 3Article in journal (Refereed)
    Abstract [en]

    The feasibility of Bell tests depends to a large extent on the tradeoff of difficulty between the preparation and the measurement of entangled systems. Polarization-entangled systems, though easy to measure, pose a relative challenge in their preparation. The opposite holds with entangled energy eigenstates for which the preparation is relatively straightforward. A way to perform measurements using a photodetector along the x, y, and z axes (in a Bloch sphere picture) on such Fock-state qubits shall be worked out, taking the W state as our entangled system. This will, by the same token, allow us to determine the minimum quantum efficiency required to perform a conclusive Bell test with the W energy eigenstate.

  • 193. Lajunen, Hanna
    et al.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ostlund, Petter
    Quasi-stationary plane-wave optical pulses and the van Cittert-Zernike theorem in time2006In: Journal of the Optical Society of America a-Optics Image Science and Vision, ISSN 1084-7529, Vol. 23, no 10, p. 2530-2537Article in journal (Refereed)
    Abstract [en]

    We study the properties of quasi-stationary, partially coherent, plane-wave optical pulses in the space-time and space-frequency domains. A generalized van Cittert-Zernike theorem in time is derived to describe the propagation of the coherence function of quasi-stationary pulses. The theory is applied to rectangular pulses chopped from a stationary light source, and the evolution characteristics of such pulse trains with different states of coherence are discussed and illustrated with numerical examples.

  • 194. Lajunen, Hanna
    et al.
    Torres-Company, Victor
    Lancis, Jesus
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Resolution-enhanced optical coherence tomography based on classical intensity interferometry2009Article in journal (Refereed)
    Abstract [en]

    We propose a fourth-order interference scheme for optical coherence tomography operating with broadband incoherent (or quasi-incoherent) light. It is shown that using this proposal, an axial resolution improvement by a factor of root 2 and a better sensitivity for weakly reflecting samples are obtained than with the standard second-order correlation scheme. From a practical perspective, we suggest the use of broadband Q-switched pulses and performing ultrafast intensity correlation with a nonlinear crystal. The global performance of our proposal is illustrated by means of numerical simulations.

  • 195. Li, J.
    et al.
    Schubert, C.
    Derksen, R. H.
    Makon, R. E.
    Hurm, V.
    Djupsjöbacka, A.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Bach, H. -G
    Mekonnen, G. G.
    Steffan, A. G.
    Driad, R.
    Walcher, H.
    Rosenzweig, J.
    112 Gb/s field trial of complete ETDM system based on monolithically integrated transmitter & receiver modules for use in 100GbE2010In: 2010 36th European Conference and Exhibition on Optical Communication (ECOC), 2010, p. 5621466-Conference paper (Refereed)
    Abstract [en]

    112 Gb/s field trial demonstration of a complete ETDM system based on monolithically integrated transmitter and receiver modules was achieved for the first time, with BER performance below FEC error-free threshold at 231-1 PRBS tributary data word-length.

  • 196. Li, Jingjing
    et al.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Bratkovsky, Alexander
    Wang, Shih-Yuan
    Williams, R. Stanley
    Optical magnetic plasma in artificial flowers2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 13, p. 10800-10805Article in journal (Refereed)
    Abstract [en]

    We report the design of an artificial flower-like structure that supports a magnetic plasma in the optical domain. The structure is composed of alternating "petals" of conventional dielectrics (epsilon > 0) and plasmonic materials (Re(epsilon) < 0). The induced effective magnetic current on such a structure possesses a phase lag with respect to the incident TE-mode magnetic field, similar to the phase lag between the induced electric current and the incident TM-mode electric field on a metal wire. An analogy is thus drawn with an artificial electric plasma composed of metal wires driven by a radio frequency excitation. The effective medium of an array of flowers has a negative permeability within a certain wavelength range, thus behaving as a magnetic plasma.

  • 197.
    Li, Qiang
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Silicon Based Photonic Devices and Their Applications2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The integration of modern electronic devices for information processing is rapidly ap-proaching an interconnect bottleneck. Silicon photonics can be a promising solution forcircumventing this bottleneck, as already being anticipated by many electronics manu-facturers including HP, IBM and Intel. In particular, optical interconnects can expeditedata transfer both between and within microchips. This thesis aims at two basic buildingblocks of silicon photonics: waveguides and resonators and addresses their applications inoptical signal processing and their potential integration with plasmonic devices.

    Firstly, the basic theories of waveguide and resonator are introduced. For a singleresonator which acts as a basic signal processing unit, the transmission, phase shift andgroup delay exhibit unique characteristics. Mode splitting is observed in both a singleresonator and a coupled-resonator system. By tuning the configuration of the coupled-resonator system, one can obtain different transmission characteristics for more advancedsignal processing.

    Secondly, the fabrication and characterization of silicon waveguides and resonatorsused in the thesis are introduced. The fabrication is carried out with e-beam lithographyfollowed by inductively coupled plasma etching. A vertical grating coupling method isadopted to characterize the transmission spectrum.

    Thirdly, based on a single-ring resonator, three kinds of signal processing are ex-perimentally demonstrated: (1) 10 Gb/s format conversion from non-return-to-zero toalternate-mark-inversion signal; (2) a microwave photonic phase shifter providing a tun-able phase shift of 0–4.6 rad for a 20 GHz signal; (3) a delay line providing maximaldelay times of 80 ps, 95 ps, 110 ps and 65 ps, respectively, for signals in return-to-zero,carrier-suppressed return-to-zero, return-to-zero duobinary, and return-to-zero alternate-mark-inversion formats.

    Fourthly, based on a single-ring resonator with mode-splitting, two kinds of signalprocessing are experimentally demonstrated: (1) a dense wavelength conversion using thefree carrier dispersion effect with a data rate ranging from 500 Mb/s to 5 Gb/s; (2) amaximum pulse advancement of 130 ps for a 1 ns signal pulse.

    Since silicon photonic devices are limited by diffraction limit, we further look intotheir hybridization with the diffraction-limit-free plasmonic devices. Two directional cou-plers from a Si photonic waveguide to a hybrid Si-metal plasmonic waveguide and to ametal-insulator-metal plasmonic waveguide are investigated. The proposed hybrid cou-plers feature a short coupling length, a high coupling efficiency, a high extinction ratioand a low insertion loss.

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    FULLTEXT01
  • 198.
    Li, Qiang
    et al.
    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.
    Structurally-tolerant vertical directional coupling between metal-insulator-metal plasmonic waveguide and silicon dielectric waveguide2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 15, p. 15531-15543Article in journal (Refereed)
    Abstract [en]

    Vertical directional coupling between a metal-insulator-metal (MIM) plasmonic waveguide and a conventional dielectric waveguide is investigated. The coupling length, extinction ratio, insertion loss and coupling efficiency of the hybrid coupler are analyzed. As an example, when the separation between the two waveguides is 250 nm, a maximum coupling efficiency of 73%, an insertion loss of -1.4 dB and an extinction ratio of 16 dB can be achieved at a coupling length of 4.5 mu m at 1.55 mu m wavelength. A particular feature of this hybrid coupler is that it is highly tolerant to the structural parameters of the plasmonic waveguide and the misalignment between the two waveguides. The performance of this hybrid coupler as a TM polarizer is also analyzed and a maximum extinction ratio of 44 dB and an insertion loss of -0.18 dB can be obtained. The application of this hybrid coupler includes the signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits and the polarization control between TE and TM modes. In addition, it provides an approach for efficiently exciting MIM plasmonic modes with conventional dielectric modes. (C) 2010 Optical Society of America

  • 199.
    Li, Qiang
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Song, Yi
    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.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Efficient directional coupler based on plasmonic waveguide for photonic integrated circuits2010In: International Conference on Optical Communications and Networks 2010: 24-27 October 2010, Nanjing, China, 2010, no 574 CP, p. 366-368Conference paper (Refereed)
    Abstract [en]

    Two asymmetric directional couplers, including the dielectric-hybrid plasmonic coupler and the dielectric-metalinsulator-metal plasmonic coupler, are investigated. The proposed hybrid coupler features short coupling length, high coupling efficiency and can be integrated into the siliconbased platform. The applications of these hybrid couplers include the signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits and efficient excitation of plasmonic modes with conventional dielectric modes. Besides, a symmetric directional coupler based on silver nanowires is also demonstrated.

  • 200.
    Li, Qiang
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Song, Yi
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Zhou, Gan
    Su, Yikai
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Asymmetric plasmonic-dielectric coupler with short coupling length, high extinction ratio, and low insertion loss2010In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 35, no 19, p. 3153-3155Article in journal (Refereed)
    Abstract [en]

    Asymmetric directional coupling between a hybrid plasmonic waveguide with subwavelength field confinement and a conventional dielectric waveguide is investigated. The proposed hybrid coupler features short coupling length, high coupling efficiency, high extinction ratio, and low insertion loss; it can also be integrated into a silicon-based platform. This coupler can be potentially adopted for signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits. Furthermore, it can be exploited to efficiently excite hybrid plasmonic modes with conventional dielectric modes.

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