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  • 51.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Malm, Gunnar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    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.
    Electrical conduction through a 2D InP-based photonic crystal - art. no. 63220J2006In: Tuning the Optic Response of Photonic Bandgap Structures III / [ed] Braun, PV; Weiss, SM, 2006, Vol. 6322, p. J3220-J3220Conference paper (Refereed)
    Abstract [en]

    This work investigates the current transport across two-dimensional PhCs dry etched into InP-based low-index-contrast vertical structures using Ar/Cl-2 chemically assisted ion beam etching. The electrical conduction through the PhC field is influenced by the surface potential at the hole sidewalls, which is modified by dry etching. The measured current-voltage (I-V) characteristics are linear before but show a current saturation at higher voltages. This behaviour is confirmed by simulations performed by ISE-TCAD software. We investigate the dependence of the conductance of the PhC area as a function of the geometry of the photonic crystal as well as the material parameters. By comparing the experimental and simulated conductance of the PhC, we deduce that the Fermi level is pinned at 0.1 eV below the conduction band edge. The method presented here can be used for evaluating etching processes and surface passivation methods. It is also applicable for other material systems and sheds new light on current driven PhC tuning.

  • 52.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Talneau, A.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Feature size effects in Ar/Cl-2 chemically assisted ion beam etching of InP-based protonic crystals2006In: 2006 International Conference on Indium Phosphide and Related Materials Conference Proceedings, NEW YORK: IEEE , 2006, p. 341-344Conference paper (Refereed)
    Abstract [en]

    This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields The slope of the etch,with varying hole size and periods were etched with different etching times. depth versus diameter cures (lag-curves) reveals an aspect ratio dependence, with an etch limiting aspect ratio of the order of 25. A model of the etch rate specific to Ar/Cl-2 CAIBE is proposed. We calculate the etch rate using a physico-chemical model which takes in to account the effect of Ar-ion sputtering and surface chemical reactions. lit addition, it combines the aspect ratio dependence of the gas conductance of the etched holes. Finally, the bottom roughness of the etched holes is examined; its origin and evolution are discussed.

  • 53.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Talneau, A.
    Ferrini, R.
    Houdre, R.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Feature size effects in chemically assisted ion beam etching of InP-based photonic crystals - art. no. 6327072006In: Nanoengineering: Fabrication, Properties, Optics, and Devices III / [ed] Dobisz, EA; Eldada, LA, BELLINGHAM, WA: SPIE-INT SOC OPTICAL ENGINEERING , 2006, Vol. 6327, p. 32707-32707Conference paper (Refereed)
    Abstract [en]

    This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields with varying hole size and periods were etched with different etching times. The slope of the etch depth versus diameter curves (lag-curves) reveals a hole size dependence, with a critical aspect ratio higher than 25. A model for the etch rate specific to Ar/Cl-2 CAIBE is proposed. We calculate the etch rate using a physico-chemical model which takes in to account the effect of Ar-ion sputtering and surface chemical reactions. In addition, it combines the aspect ratio dependence of the gas conductance of the etched holes. The origin and evolution of the bottom roughness of the etched holes is examined. The impact of the feature size dependence of the etching on the photonic crystal optical properties is then assessed by measuring the quality-factor of one-dimensional Fabry-Perot cavities using the Internal Light Source method, and discussed in terms of hole shape and depth. A systematic trend between the determined quality factor (Q) and the lag-effect is evidenced: Q decreases from about 250 to 60 when the hole depth drops from 5 mu m to 2 mu m.

  • 54.
    Bilien, Johan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Key Agreement for Secure Voice over IP2003Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis reviews the usual properties and requirements for key agreement protocols. It then focuses on MIKEY, a work-in-progress protocol designed to conduct key agreements for secure multimedia exchanges. The protocol was implemented and incorporated in a SIP user agent - minisip. This implementation was used to measure the additional delay required for key exchange during call establishment. Finally, some schemes are proposed regarding the use of MIKEY in advanced VoIP scenarios, such as conferences and terminal mobility.

  • 55.
    Bilien, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Eliasson, Erik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Orrblad, Joachim
    KTH, School of Information and Communication Technology (ICT).
    Vatn, Jon-olov
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Secure VoIP: call establishment and media protection2005In: Proceedings of 2nd Workshop on Securing Voice over IP, 2005Conference paper (Refereed)
    Abstract [en]

    In this paper we study the possibility of establishing a secure VoIP telephone call using SIP. Different security services relevant for VoIP are presented and we argue that end-to-end authentication and encryption should be provided by default. For media protection we evaluate the possibility of using either SRTP or IPSec, and we examine several alternatives of how a secure VoIP call can be established. The solution we suggest is based on SRTP for media protection, S/MIME and MIKEY for end-to-end authentication and keying, and TLS for hop-by-hop protection of SIP messages. We also present measurements of secure call establishment for MIKEY, SRTP and IPSec using our own SIP user agent (minisip). Our conclusion is that the call establishment delay will not be significantly affected by introducing these security protocols.

  • 56.
    Björk, Gunnar
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Klimov, Andrei B.
    Sanchez-Soto, Luis L.
    The discrete Wigner function2008In: Progress in optics / [ed] Wolf, E, 2008, Vol. 51, p. 469-516Chapter in book (Refereed)
  • 57. Björling, T.
    et al.
    Noréus, D.
    Jansson, K.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Leonova, E.
    Edén, M.
    Hålenius, U.
    Häussermann, U.
    SrAlSiH: A polyanionic semiconductor hydride2005In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 44, no 44, p. 7269-7273Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) Stable and semiconducting: Polyanionic hydrides represent a new class of main-group-metal hydrides with unforeseen hydrogen-coordination environments. The hydrogen atom in SrAlSiH is attached exclusively to Al and forms part of a layered [AlHSi]2- polyanion (see figure). This material is the first narrow bandgap semiconductor hydride and combines the high thermal stability of saline hydrides with the air and moisture stability of interstitial transition-metal hydrides.

  • 58. Blank, T. V.
    et al.
    Goldberg, Y. A.
    Kalinina, E. V.
    Konstantinov, O. V.
    Konstantinov, A. O.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Temperature dependence of the photoelectric conversion quantum efficiency of 4H-SiC Schottky UV photodetectors2005In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 20, no 8, p. 710-715Article in journal (Refereed)
    Abstract [en]

    Ultraviolet Schottky photodetectors based on n-4H-SiC (N-d - N-a = 4 x 10(15) cm(-3)) epitaxial layers of high purity have been fabricated. Their spectral sensitivity range is 3.2-5.3 eV peaking at 4.9 eV (quantum efficiency is about similar to 0.3 electron/photon), which is close to the bactericidal ultraviolet radiation spectrum. The temperature dependence of the quantum efficiency of 4H-SiC Schottky structure has been investigated to determine the temperature stability and the mechanism of the photoelectric conversion process. At low temperatures (78-175 K) the quantum efficiency increases with increasing temperature for all photon energy values and then tends to saturate. We suppose that some imperfections in the space-charge region act as traps that capture both photoelectrons and photoholes. After some time the trapped electron-hole pairs recombine due to the tunnelling effect. At high temperatures (more than 300 K), the second enhancement region of the quantum efficiency is observed in the photon energy range of 3.2-4.5 eV. It is connected with a phonon contribution to indirect optical transitions between the valence band and the M-point of the conduction band. When the photon energy is close to a direct optical transition threshold this enhancement region disappears. This threshold is estimated to be 4.9 eV. At photon energies more than 5 eV a drastic fall of the quantum efficiency has been observed throughout the temperature interval. We propose that in this case the photoelectrons and photoholes are bound to form hot excitons in the space-charge region due to the Brillouin zone singularity, and do not contribute to the following photoelectroconversion process.

  • 59.
    Blomqvist, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electro-Optical Na0.5K0.5NbO3 Films2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Ferroelectric oxides are a group of advanced electronic materials with a wide variety of properties useful in applications such as memory devices, resonators and filters, infrared sensors, microelectromechanical systems, and optical waveguides and modulators.

    Among the oxide perovskite-structured ferroelectric thin film materials, sodium potassium niobate or Na0.5K0.5NbO3 (NKN) has recently emerged as one of the most promising materials in radio frequency (rf) and microwave applications due to high dielectric tenability and low dielectric loss.

    This thesis presents results on growth and structural, optical, and electrical characterization of NKN thin films. The films were deposited by rf-magnetron sputtering of a stoichiometric, high density, ceramic Na0.5K0.5NbO3 target onto single crystal LaAlO3 (LAO), Al2O3 (sapphire), SrTiO3, and Nd:YAlO3, and polycrystalline Pt80Ir20 substrates. By x-ray diffractometry, NKN films on c-axis oriented LaAlO3, SrTiO3 and Nd:YAlO3 substrates were found to grow epitaxially, whereas films on r-cut sapphire and polycrystalline Pt80Ir20 substrates were found to be preferentially (00l) oriented. The surface morphology was explored using atomic force microscopy.

    Optical and waveguiding properties of the Na0.5K0.5NbO3/substrate heterostructures were characterized using prism-coupling technique. Sharp and distinguishable transverse magnetic and electric propagation modes were observed for NKN thicknesses up to 2.0 μm. The extraordinary and ordinary refractive indices were calculated together with the birefringence of the NKN material. The electro-optic effect in transverse geometry was measured in transmission, where the effective linear electro-optic response was determined to reff = 28 pm/V for NKN/Al2O3 with an applied dc field up to 18 kV/cm.

    The ferroelectric state in NKN films on Pt80Ir20 at room temperature was indicated by a polarization loop with saturated polarization as high as 33.4 μC/cm2 at 700 kV/cm, remnant polarization of 10 μC/cm2, and coercive field of 90 kV/cm. Current-voltage characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties, with the leakage current density for an NKN IDC on the order of 30 nA/cm2 at 400 kV/cm. Rf dielectric spectroscopy demonstrated low loss, low frequency dispersion, and high voltage tunability. At 1 MHz, NKN/LAO showed a dissipation factor tan δ = 0.010 and a tunability of 16.5 % at 200 kV/cm. For the same structure the frequency dispersion was Δεr = 8.5 % between 1 kHz and 1 MHz.

  • 60.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electro-optic effect in ferroelectric Na0.5K0.5NbO3 thin films on oxide substrates2006In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 80, no 1, p. 97-106Article in journal (Refereed)
    Abstract [en]

    We have deposited Na0.5NbO3 (NKN) films oil single crystal Al2O3(1 (1) under bar 02) and SrTiO3(001) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. Using x-ray diffraction it was confirmed that NKN grows preferentially c-axis oriented on sapphire substrate and epitaxially oil the perovskite SrTiO3(001) substrate. Electro-optical (EO) properties were measured in visible light through a transverse method. With an applied dc field up to 20 kV/cm, the effective linear EO response was determined to r(eff) = 28 pm/V for NKN/Al2O3 and r(eff) = I I pm/V for NKN/SrTiO3, where a superlinear dependence was observed.

  • 61.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electrooptic ferroelectric Na0.5K0.5NbO3 films2005In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, no 8, p. 1638-1640Article in journal (Refereed)
    Abstract [en]

    We report on waveguiding and electrooptic properties of epitaxial Na0.5K0.5NbO3 films grown by radio-frequency magnetron sputtering on Al2O3 (1102) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.

  • 62.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Visible and IR light waveguiding in ferroelectric Na0.5K0.5NbO3 thin films2005In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 69, p. 277-286Article in journal (Refereed)
    Abstract [en]

    High-quality ferroelectric thin films are attractive materials for integrated optics applications including electro-optic waveguide modulators and frequency doubling secondharmonic generators. Several fefroelectric thin film materials, such as BaTiO3, KNbO3, LiNbO3, and (Pb,La)(ZrTi)O-3, have been investigated regarding their optical and waveguiding properties. Recently the first results on waveguiding in ferroelectric Na0.5K0.5NbO3 (NKN) thin films were presented. Perovskite NKN films have previously been investigated as electrically tunable material for low loss rf and microwave applications. Na0.5K0.5NbO3 thin films of thickness 0.5-1.0 mum have been deposited on Nd:YAlO3(001) and Al2O3(0112) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. X-ray diffraction measurements confirmed films grown highly (00l) oriented on the perovskite Nd:YAlO3 substrate and preferentially c-axis oriented on the single crystal r-cut sapphire substrate. Optical and waveguiding properties were characterized using a Metricon 2010 prism-coupling apparatus with a rutile prism. Dark-line spectra were obtained at visible light (lambda = 632.8 nm) as well as at infrared optical communication wavelengths, lambda = 1319 nm and lambda = 1549 nm, in both transverse electric (TE) and transverse magnetic (TM) polarizations. Sharp dips corresponding to waveguide propagation modes in the thin film layers where observed for both substrates. The calculated refractive index values and corresponding birefringence (Deltan = n(TM) - n(TE) = n(e) - n(o)) as a function of wavelength has been compared. Generally a larger birefringence is observed for the NKN film on Nd:YAlO3, which is in agreement with the larger degree of preferential c-axis orientation measured by XRD.

  • 63. Borgström, Johannes
    et al.
    Nestmann, Uwe
    Onana, Luc Alima
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Gurov, Dilian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Verifying a structured peer-to-peer overlay network: The static case2005In: GLOBAL COMPUTING, 2005, Vol. 3267, p. 250-265Conference paper (Refereed)
    Abstract [en]

    Structured peer-to-peer overlay networks are a class of algorithms that provide efficient message routing for distributed applications using a sparsely connected communication network. In this paper, we formally verify a typical application running on a fixed set of nodes. This work is the foundation for studies of a more dynamic system. We identify a value and expression language for a value-passing CCS that allows us to formally model a distributed hash table implemented over a static DKS overlay network. We then provide a specification of the lookup operation in the same language, allowing us to formally verify the correctness of the system in terms of observational equivalence between implementation and specification. For the proof, we employ an abstract notation for reachable states that allows us to work conveniently up to structural congruence, thus drastically reducing the number and shape of states to consider. The structure and techniques of the correctness proof are reusable for other overlay networks.

  • 64.
    Borison, Torbjorn
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Object Synchronization and Security for Mobile Communications Devices2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main objective of this master’s thesis project was to investigate and find solutions to the problem of how to combine the SyncML synchronisation specification with object security and thus protection of personal information, such as contacts and calendar entries in mobile devices.

    SyncML is a new synchronisation specification agreed upon by major device developers (Ericsson, Palm, Motorola, etc.) and the major synchronisation server developers (Starfish, Puma, fusionOne, etc.). It is independent of transport (HTTP, WSP, or OBEX) platform, operating system, and application and simplifies synchronisation of personal information between dissimilar SyncML supportive devices.

    SyncML compliant devices are fully capable of synchronising information with a third party operated Internet based server and a desktop computer. This allows us to access, up-date and maintain information independent of Intranets or geographical position. However, synchronising and storing confidential personal information on an third party operated Internet based server entails weaknesses in our personal information security. Even if transport and storage security are used, how secure is the server where this information is stored since this server has the highest probability of being attacked. Can we really trust that an employee or other person with valid appropriated administrators access to the storage facility with the appropriate knowledge, working together with the third party server operator, won’t try to access our stored information? To prevent this, the personal information’s confidentiality must be guaranteed before the information leaves the device.

    When synchronising and exchanging personal information, the information is often marked according to a specific format. The three de-facto standard PIM formats are: (1) vCard (contact information), (2) vCalendar, and (3) iCalendar (calendar and scheduling information). These formats divide the personal information into properties. Each property is assigned to contain a small piece of the personal information entry (e.g. a telephone number, an e-mail address, the time when the calendar event begins, etc.).

    Furthermore to preserve the interoperability between different devices given by SyncML, authorised recipients must automatically be able to reverse the encryption process and decrypt the encrypted property value. Therefore general cryptographic formats are used (e.g. CMS, PGP and the newly developed XML Encryption). They add information needed by the recipients (e.g. algorithm used, padding method used on the plain text, etc.), encrypt the plaintext into cipher text, and decrypt the cipher text into plain text given the correct key.

  • 65. Borseth, T. M.
    et al.
    Christensen, J. S.
    Maknys, K.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Kuznetsov, A. Y.
    Annealing study of Sb+ and Al+ ion-implanted ZnO2005In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 38, no 4-6, p. 464-471Article in journal (Refereed)
    Abstract [en]

    In this work we have studied diffusion and electrical activation in Al+ and Sb+ implanted ZnO samples using secondary ion mass spectrometry (SIMS), scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM). The samples were hydrothermally grown and post-implant annealing was performed at 800, 900 and 1000 degrees C in pure oxygen atmosphere, After each annealing step the samples were characterized with SSRM/SCM and SIMS. The thermal treatments did not induce any significant impurity redistribution as measured by SIMS, while electrical compensation is observed by SSRM/SCM for the Sb-implanted sample yielding less n-doping than in the as-grown samples. In the Al-implanted samples, an increase in carrier concentration is observed; we ascribe this to Al-related donors and possibly interstitial lithium, a common residual impurity in the samples that have been shown to be very mobile by SIMS.

  • 66.
    Brade, Dirk
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    The need for credible Modeling and simulation in the context of the network based defense2006In: Modeling and Simulation Tools for Emerging Telecommunication Networks: Needs, Trends, Challenges and Solutions / [ed] Ince, AN; Topuz, E, 2006, p. 423-447Conference paper (Refereed)
    Abstract [en]

    In concert with numerous other western world nations, in Sweden military doctrine is changing focus from a platform-oriented towards a network-based approach. Military platforms become participants in "the network", share information, and provide services that allow them to sense, decide, and act beyond their individual capabilities in a cooperative and distributed manner. The information exchange occurs through an information infrastructure, the so called "infostructure" which constitutes a communication network spanned by the participating nodes. Although technologically not far beyond the edge of today's state of the art, are functional and technological requirements on the infostructure high: Mobile units exposed to lethal threats and electronic countermeasures shall connect and disconnect rapidly and reliably to build networks in an adhoc manner, ensuring secure and fault tolerant communication with sufficiently high quality of service. Nodes in the infostructure consist of heterogeneous systems provided by numerous nations, providing various types of end-user and communication services. Various alternative approaches can be taken for the creation of the infostructure, which must be expected to become a highly complex system, challenging to control and administrate. Modeling and Simulation are considered to be the mandatory enablers to optimize its design, maintenance, use, and improvement. This concept paper describes a vision of the infostructure, operational conditions, and desired properties, and identifies challenges which must be met on order to early avoid dead-end roads. Finally, it outlines application areas for communication related Modeling and Simulation to support the transition to and continuous improvement of a Network Based Defense.

  • 67.
    Brade, Dirk
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Pohl, S.
    Youngblood, S.
    Findings from the combined convention on international VV&A standardization endeavors2005In: European Simulation Interoperability Workshop 2005, 2005, p. 412-421Conference paper (Refereed)
    Abstract [en]

    Several international working groups develop, evaluate, and harmonize guidelines and a "best practice" for Verification, Validation, and Accreditation (VV&A) with the objective to define common guidelines and standards for VV&A. These working groups include (1) The NATO Modeling and Simulation Group 019, Task Group 016, "Verification, Validation, and Accreditation of Federations"; (2) The International Test Operations Procedure (ITOP) Working Group of Experts (WGE) 7.2 "Verification and Validation"; (3) The Western European Armament Group THALES Joint Program 11.20, "A Common Verification, Validation, and Accreditation Framework for Simulations" (WEAG THALES JP11.20); and (4) The Simulation Interoperability Standardization Organization (SISO) Product Development Group (PDG) "Verification, Validation, and Accreditation of Federations". Although focusing on different aspects of VV&A, these working groups have numerous related topics and areas of interest, which were discussed during the Combined Convention of International VV&A Standardization Endeavors, October 20-23, 2004, Munich. With the above working groups presenting the current state of their work, the convention attracted audience not only from the "VV&A community", but also model developers and program managers. This paper presents the outcomes of the convention, the commonalities and differences of the individual working groups, and a common future perspective on VV&A.

  • 68. Brocke, R. G.
    et al.
    Cao, J.
    Fontaine, N. K.
    Ji, C.
    Chubun, N.
    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.
    Kolner, B. H.
    Heritage, J. P.
    Yoo, S. J. B.
    Phase characterization of an InP based Optical-CDMA encoder using Frequency-Resolved Optical Gating (FROG)2005In: 2005 IEEE LEOS Annual Meeting Conference Proceedings (LEOS), 2005, p. 123-124Conference paper (Refereed)
    Abstract [en]

    We demonstrate the optical phase characterization of a monolithically integrated InP optical-CDMA encoder/decoder chip using frequency-resolved optical gating.

  • 69. Broeke, Ronald G.
    et al.
    Cao, Jin
    Ji, Chen
    Seo, Sang-Woo
    Du, Yixue
    Fontaine, Nick K.
    Baek, Jong-Hwa
    Yan, John
    Soares, Francisco M.
    Olsson, Fredrik
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Pham, Anh-Vu H.
    Sheam, Michael
    Scherer, Axel
    Yoo, S. J. Ben
    Optical-CDMA in InP2007In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 13, no 5, p. 1497-1507Article in journal (Refereed)
    Abstract [en]

    This paper describes the InP platforms for photonic integration and the development on these platforms of an optical code division multiple access (O-CDMA) system for local area networks. We demonstrate three building blocks of this system: an optical pulse source, an encoder/decoder pair, and a threshold detector. The optical pulse source consists of an integrated colliding pulse-mode laser with nearly transform-limited 10 Gb/s pulses and optical injection locking to an external clock for synchronization. The encoder/decoder pair is based on arrayed waveguide gratings. Bit-error-rate measurements involving six users at 10 Gb/s showed error-free transmission, while O-CDMA codes were calibrated using frequency resolved optical gating. For threshold detection after the decoder, we compared two Mach-Zehnder interferometer (MZI)-based optical thresholding schemes and present results on a new type of electroabsorber-based MZI.

  • 70.
    Broms, Daniel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Access restrictions in surrogates using Portable Channel Representation2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master thesis investigates how content with access restrictions can be handled in a Content Distribution Network (CDN). The thesis focuses on CDNs where the distribution is made using Portable Channel Representation (PCR), a description of content that enables installation on any platform. There has been a demand from customers for access restriction support when distributing web sites. Ranging from personal homepages wanting to restrict access using some simple password authentication protocol to corporate websites wanting HTTPS support.

    This thesis starts with a survey of available authentication mechanisms as well as available publication protocols with support for protection. This provided the basis for the design of the new protection element for PCR spanning most protection requirements. The PCR model is realized using XML in the Lokomo Software Suite. The new design has been implemented in the context of the Lokomo Software Suite. The protection has been shown to correctly install basic authentication on both Apache’s HTTP Server and Microsoft’s Internet Information Server.

  • 71.
    Brundin, Peter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    LESpy - PCM Link Analyzer2002Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report will discuss the design of a test tool, a PCM link analyzer, LESpy. The development of LESpy is based upon reuse of C++ source code from previous test equipment from INEO, LESim. The purpose of LESpy is a tool for analyzing two telephony interfaces in Ericsson’s ”Radio in the Local Loop” system RAS 1000. Monitoring the Channel Associated Signaling (CAS) interface was the primary goal. As second goal was to find a solution to analyze the ISDN interface.

    The report presents some background information about telephony, computer telephony, the RAS 1000 system, and the development and target environment (IBM’s operating system OS/2). It also describes building blocks and functionality, i.e. the nodes, components, classes, and use cases of LESpy through UML diagrams.

    The result of the project is a test tool where most of the requirements were fulfilled through inheritance of new classes and new functionality by polymorphism. As required supervision and address signaling could be monitored and saved to a file.

  • 72. Bugge, Audun Nystad
    et al.
    Sauge, Sebastien
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Ghazali, Aina Mardhiyah M.
    Skaar, Johannes
    Lydersen, Lars
    Makarov, Vadim
    Laser Damage Helps the Eavesdropper in Quantum Cryptography2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 7, p. 070503-Article in journal (Refereed)
    Abstract [en]

    We propose a class of attacks on quantum key distribution (QKD) systems where an eavesdropper actively engineers new loopholes by using damaging laser illumination to permanently change properties of system components. This can turn a perfect QKD system into a completely insecure system. A proof-of-principle experiment performed on an avalanche photodiode-based detector shows that laser damage can be used to create loopholes. After similar to 1 W illumination, the detectors' dark count rate reduces 2-5 times, permanently improving single-photon counting performance. After similar to 1.5 W, the detectors switch permanently into the linear photodetection mode and become completely insecure for QKD applications.

  • 73.
    Bülow, Jonas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mobile IP and AAA Services2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Networks providing Authentication, Authorization and Accounting services are found all over the world. The number of mobile devices is growing rapidly and the need to have a seamless, user friendly, and stable integration between mobile devices and AAA enabled networks is an important development trend right now.

    This thesis will give an overview of the work taking place in the field of AAA and Mobile IP. Issues when Mobile IP and AAA meet will be discussed.

    The thesis will describe sample tests of a Mobile IP network and a simple test using the forthcoming AAA protocol Diameter.

    Conclusions based on these tests are described along with some obvious future work.

  • 74. Caballero Bayerri, Juan
    et al.
    Malmkvist, Daniel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Experimental Study of a Network Access Server for a public WLAN access network2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wireless access networks have gained popularity due to the flexibility they allow the user, who is able to move away from his or her desk while still being able to access information. Among the different Wireless LAN standards, the most widespread, by far, is IEEE 802.11.

    Public WLAN access networks are being set up in hotspots, i.e. areas expected to have high demand for bandwidth. Access to the Internet and to corporate networks is provided at these hotspots with limited coverage but high available bandwidth. Airports and hotels have often been the first targeted locations for these hotspots, but conference centres, cafes, and train stations follow. In the near future, any person who owns at least one access point and has a connection to the Internet can become a small operator and offer access to the Internet using these resources.

    Existing solutions for such WLAN access networks lack support for security, flexible accounting, mobility, multiaccess, roaming and user-friendly login. The aim of this Master's Thesis was to study if it was possible to solve these problems and how to integrate all this new functionality into existing public WLAN access networks by building and evaluating a prototype of a public WLAN access network

    System requirements were defined, currently available solutions analysed and a prototype was built. Most of the functionality of the prototype is placed in the Network Access Server, which is the main element providing security, mobility, and accounting.

    Flexible accounting, improvements in security, an easy and fast way to login the user, a feedback module to provide information about the current session and integration of the RADIUS architecture with the Mobile IP distribution have all been implemented.

  • 75. Cai, Y.
    et al.
    Chen, Yuntian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Eyyuboglu, H. T.
    Baykal, Y.
    Propagation of laser array beams in a turbulent atmosphere2007In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 88, no 3, p. 467-475Article in journal (Refereed)
    Abstract [en]

    The propagation of phase-locked and non-phase-locked laser array beams of radial and rectangular symmetries in a turbulent atmosphere are investigated based on the extended Huygens-Fresnel integral. The beamlet used in our paper for constructing the laser array beams is of elliptical Gaussian mode. Analytical formulae for the average irradiance of phase-locked and non-phase-locked radial and rectangular laser array beams are derived through vector integration and tensor operation. The irradiance properties of these laser array beams in a turbulent atmosphere are studied numerically. It is found that both phase-locked and non-phase-locked radial and rectangular laser array beams eventually become circular Gaussian beams in a turbulent atmosphere, which is much different from their propagation properties in free space. The propagation properties are closely related to the parameters of laser array beams and the structure constant of the turbulent atmosphere.

  • 76.
    Cao, J.
    et al.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Broeke, R. G.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Fontaine, N.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Cong, W.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Ji, C.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Du, Y.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Chubun, N.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Aihara, K.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Pharn, Anh-Vu
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Heritage, J. P.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Kolner, B. H.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Yoo, S. J. B.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Olsson, F.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Stephan, P. L.
    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA..
    Error-free spectral encoding and decoding operation of InPO-CDMA encoder2006In: 2006 OPTICAL FIBER COMMUNICATION CONFERENCE/NATIONAL FIBER OPTIC ENGINEERS CONFERENCE, VOLS 1-6, OPTICAL SOC AMERICA , 2006, p. 843-+Conference paper (Refereed)
    Abstract [en]

    We report error-free spectral encoding and decoding operation of an InP monolithic, ultra-compact optical-CDMA encoder/decoder photonic chip pair. The experimental results demonstrate the strong potential for realizing high performance O-CDMA networks with InP micro-systems. (C) 2006 Optical Society of America.

  • 77. Cao, J.
    et al.
    Broeke, R. G.
    Ji, C.
    Du, Y.
    Chubun, N.
    Bjeletich, P.
    Yoo, S. J. B.
    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.
    Stephan, P. L.
    A monolithic ultra-compact inp o-cdma encoder with: Planarization by hvpe regrowth2006In: OFC/NFOEC, Optical Society of America, 2006Conference paper (Refereed)
    Abstract [en]

    We report a monolithic, ultra-compact optical-CDMA encoder/decoder photonic chip in InP with surface planarization by low-pressure Hydride-Vapor-Phase-Epitaxy regrowth. The chip consists of an AWG pair and eight electro-optic phase shifters and demonstrated excellent encoding operation.

  • 78. Cao, J.
    et al.
    Broeke, R. G.
    Ji, C.
    Du, Y.
    Chubun, N.
    Bjeletich, P.
    Yoo, S. J. B.
    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.
    Stephan, P. L.
    A monolithic ultra-compact inp o-cdma encoder with: Planarization by hvpe regrowth2005In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2005Conference paper (Refereed)
    Abstract [en]

    We report a monolithic, ultra-compact optical-CDMA encoder/decoder photonic chip in InP with surface planarization by low-pressure Hydride-Vapor-Phase-Epitaxy regrowth. The chip consists of an AWG pair and eight electro-optic phase shifters and demonstrated excellent encoding operation.

  • 79.
    Cao, Jing
    et al.
    Department of Electrical and Computer Engineering, University of California.
    Broeke, R. G.
    Department of Electrical and Computer Engineering, University of California.
    Fontaine, N. K.
    Department of Electrical and Computer Engineering, University of California.
    Ji, C.
    Department of Electrical and Computer Engineering, University of California.
    Du, Y.
    Department of Electrical and Computer Engineering, University of California.
    Chubun, N.
    Department of Electrical and Computer Engineering, University of California.
    Aihara, K.
    Department of Electrical and Computer Engineering, University of California.
    Pham, Anh-Wu
    Department of Electrical and Computer Engineering, University of California.
    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.
    Yoo, S. J. Ben
    Department of Electrical and Computer Engineering, University of California.
    Demonstration of Spectral Phase O-CDMA Encoding and Decoding in Monolithically Integrated Arrayed-Waveguide-Grating-Based Encoder2006In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, no 21-24, p. 2602-2604Article in journal (Refereed)
    Abstract [en]

    We report on successful spectral phase encoding and decoding operation in a pair of monolithically integrated InP encoder chips, each consisting of an arrayed waveguide grating (AWG) pair and an eight-channel electrooptic phase shifter array. The monolithic fabrication process includes anisotropic reactive ion etching and planarizing hydride-vapor-phase-epitaxy lateral regrowth to realize buried hetero-waveguide structures in AWGs and phase shifters. Electrooptical modulation in the phase shifter arrays in the encoder chip achieved Walsh-code-based optical code-division multiple access (O-CDMA) encoding and decoding. The matched-code encoding-decoding operation resulted in error-free performance in the presence of an interferer, indicating good potential for O-CDMA network applications.

  • 80.
    Carlzon, Malin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hagsand, Olof
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Widell, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Danielsson, Björn
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Blocking web-pages using BGP - measurements and observations2005In: 3rd Swedish National Computer Networking Workshop, SNCNW 2005, Halmstad, Sweden, 2005Conference paper (Refereed)
  • 81.
    Carrara, Elisabetta
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Security for IP multimedia applications over heterogeneous networks2005Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Personal mobile multimedia services are rapidly become popular. They leverage the combination of mobile and Internet-based communications, the increased capabilities of the third generation of mobile communications (3G), and the flexibility of a common transport and service platform.

    Cost and quality are critical factors for the success of IP multimedia services. 3G is based on hetereogeneous networks, characterized by a mixture of wired and wireless links with very different requirements on the communication itself. Furthermore, the "always best connected" paradigm requires the design of the new applications to accomodate different types of access. It turns out that the cellular link is typically the most constrained, e.g. in terms of limited bandwidth and high delay, especially when IP is used as transport.

    Security is an important aspect of the service. Never before has this awareness been more present, not only among technicians, but also among users. Users want the possibility to protect themselves and their data and private matters, in a way that no one else can interfere and that private communications are guaranteed to remain private. The use of the Internet as a common transport backbone, a notoriously open and adverse environment, and in general the use of the IP technology, which is receiving a bad (media) reputation in terms of the security breaches it opens, calls for an end-to-end security solution for IP multimedia services. There are also scenarios where end-to-end protection of other information is an absolute must, for example public safety communication, catastrophe and emergency communication, corporate, or government communication.

    This research addresses the design of a security solution for IP multimedia, striving in particular for the promotion of end-to-end security on a large scale. This research builds on the concept of a "transport-friendly" security solution: security always comes at a cost, hence it is important to control its impact on services, otherwise security is generally sacrificed.

    This research focused on the protection of the media traffic. It first identified the requirements that arise from IP multimedia applications in hetereogeneous networks, examined existing security solutions, and concluded that they did not fullfil the requirements raised by 3G environments. This has motivated the design of two new security protocols that are transport-friend to meet the identified requirements, so as to have a low impact on services. These two protocols have then been integrated to provide a security solution for IP multimedia in hetereogeneous networks. The research leading to this licentiate has been mostly conducted in the IETF (a standardisation body), and its results were also adopted byothers, e.g. 3GPP services.

  • 82.
    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)
  • 83.
    Chacinski, Marek
    et al.
    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.
    Schatz, Johan Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    High-speed direct Modulation of widely tunable MG-Y laser2005In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, no 6, p. 1157-1159Article in journal (Refereed)
    Abstract [en]

    The dynamic performance of the modulated-grating Y-branch laser is presented. In order to reach over 40-nm tuning range, the devices utilize an additive Vernier effect and relative tuning of two reflecting gratings. The device shows high (> 13 dBrn ex-facet) and uniform (< 1.2-dB variation) steady state output power over the tuning range, and sidemode suppression ratio > d40 dB. The laser behavior under small- and large-signal operation conditions is investigated. The laser exhibits a resonance frequency of 7.4-8.8 GHz at 80-mA bias. A 10-Gb/s eye diagram measurement showed, high extinction ratio and signal-to-noise ratio.

  • 84.
    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), Centres, Kista Photonics Research Center, KPRC.
    Isaksson, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    D'Oosterlinck, W.
    Morthier, G.
    Widely Tunable Wavelength Conversion 10 Gb/s Using a Modulated Grating Y-branch Laser Integrated with an Optical Amplifier2007In: OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007, 2007Conference paper (Refereed)
    Abstract [en]

    A simple integrated tunable wavelength converter is presented. 10 Gb/s XGM conversion of signals at wavelength 1530-1560 nm to 1531-1556 nm and transmission at 2.5 Gb/s over 25 km SSMF of the converted signals were achieved.

  • 85.
    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, p. 211109-1-211109-3Article in journal (Refereed)
    Abstract [en]

    The dynamic performance of InGaAs/GaAs 1.27 &mu; 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 &DEG; 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. &COPY; 2005 American Institute of Physics. &COPY; 2005 American Institute of Physics.

  • 86.
    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, p. 163-167Article 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.

  • 87.
    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, p. 64-66Conference 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.

  • 88. Chang, J.
    et al.
    Sassa, Y.
    Guerrero, S.
    Mansson, M.
    Shi, M.
    Pailhes, S.
    Bendounan, A.
    Mottl, R.
    Claesson, T.
    Tjernberg, Oscar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Patthey, L.
    Ido, M.
    Oda, M.
    Momono, N.
    Mudry, C.
    Mesot, J.
    Electronic structure near the 1/8-anomaly in La-based cuprates2008In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 10Article in journal (Refereed)
    Abstract [en]

    We report an angle-resolved photoemission study of the electronic structure of the pseudogap state in La1.48Nd0.4Sr0.12CuO4 (T-c < 7 K). Two opposite dispersing Fermi arcs are the main result of this study. Several scenarios that can explain this observation are discussed.

  • 89. Chen, M.
    et al.
    Lutz, J.
    Domeij, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Felsl, H. P.
    Schulze, H. -J
    A novel diode structure with controlled injection of backside holes (CIBH)2006Conference paper (Refereed)
    Abstract [en]

    In this paper we present a novel 3.3kV diode structure with controlled injection of backside holes, i.e. CIBH diode. This new diode structure features buried floating p layers at the cathode side. These p doped areas prevent the formation of high electric field strength at the nn+ junction and accordingly avoid the avalanche generation at the nn+ junction. The CIBH diode concept provides, compared to diodes without p layers and the same design, significantly improved dynamic ruggedness and improved sott reverse recovery at low current densities. Simulations and results of the first fabricated diodes show the readability of this new promising diode concept.

  • 90.
    Chen, Ta-wei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Optimization of Transport Security for Securing Peer-to-Peer Communication in Heterogeneous Networks2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis concerns the security of tomorrow’s peer-to-peer real-time communication in heterogeneous networks. Because of the additional delay caused by inband handshake and the poor compatibilities of some transport protocols, it was determined that existing security protocols such as transport layer security (TLS) and datagram transport layer security (DTLS) are not suitable in such a user scenario and a new security protocol should be designed. This new security protocol is called transport encapsulation security payload (TESP). TESP not only has the advantage of low initialization delay, but also fully supports transport protocols including TCP, UDP, stream control transmission protocol (SCTP), and datagram congestion control protocol (DCCP). Also a security analysis of TESP was carried out and no security flaws were found.

  • 91.
    Chen, Xu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Performance Analysis of Wireless Multiplayer Games on Terraplay Systems2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis project was sponsored by Terraplay System AB. Terraplay System is a wireless online multiplayer game service provider in Europe. The purpose of this project was to provide a convenient and free latency test tool named Terraplay Test Toolkit (TTK) for game developers who utilize the Terraplay platform. Since wireless multiplayer games are latency sensitive, it’s necessary for game developers to estimate the real-time game latency before their development. TTK is based on Java Mobile Edition (J2me) technology, it can performs a real-time Round Trip Time (RTT) latency test. This project explored the application of the mobile development. Mobile development is a brand new field and becoming more and more popular. The design process and source code can be used as reference for mobile developers. Based on the Terraplay Test Toolkit, a series of experiments were conducted to test the ability of TTK. These experiments focused on end-to-end latency effects of wireless multiplayer games under different situations such as different packet size, different sending rates, high speed movement, and so on. Although TTK is not a professional test tool, it still reflects the latency variance under different conditions correctly. From these experiments, it was found that for the Terraplay enabled wireless multiplayer games, large average packet size (300 bytes) is NOT a factor with regard to the latency on the Terraplay System; the packet rate can affect the game latency. In a high speed-moving environment, game latency doesn’t obvious increase. Using HTTP can cause three times higher latency than simply using TCP. These conclusions are based on experimental results. These conclusions should guide wireless multiplayer game developers and game players.

  • 92. Chen, Yuntian
    et al.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Generation and detection of photonic qutrit states by linear optics2008In: Quantum information & computation, ISSN 1533-7146, Vol. 8, no 5, p. 386-398Article in journal (Refereed)
    Abstract [en]

    We address the problem of generation and detection of the four mutually unbiased biphoton polarization-qutrit bases by linear optics. First, the generation of the bases is studied. Our numeric results show that the linear optics method can be used to generate the 4 mutually unbiased basis qutrit states probabilistically with high fidelity. Second, we investigate whether or not linear polarization-optics components are sufficient to realize the simultaneous detection of the qutrit states forming a complete basis. Analytical results show that every state in two of the bases, namely only half of the 4 mutually unbiased bases qutrit states can be identified.

  • 93. Cheremisin, A. B.
    et al.
    Loginova, S. V.
    Velichko, A. A.
    Putrolaynen, V. V.
    Pergament, A. L.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Modification of Atomic Structure of Thin Amorphous V2O 5 Films under UV Laser Irradiation2008In: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY, 2008Conference paper (Refereed)
    Abstract [en]

    Influence of ultra-violet radiation of the KrF laser (wave length 248 nm, pulse duration 20 ns) on atomic structure of amorphous vanadium pentoxide thin films, prepared by the pulsed laser deposition method, is studied. Calculations of the short-range order characteristics (radii and diffusiveness of coordination spheres, coordination numbers) were performed by the Finbak -Warren method. It is established that minimal structure unit of amorphous V 2O5 film before and after irradiation is a strongly deformed oxygen octahedron. Distortions of tetragonal pyramids in the initial and modified film are different. Also, oxygen deficiency in a tetragonal pyramid is observed.

  • 94. Christensen, J. S.
    et al.
    Kuznetsov, A. Yu.
    Gunnaes, A. E.
    Svensson, B. G.
    Radamson, Henry H.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Phosphorus diffusion in the presence of threading dislocations in strain relaxed SiGe films2006In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 9, no 4-5, p. 650-654Article in journal (Refereed)
    Abstract [en]

    We have studied phosphorus diffusion in strain relaxed Si1-xGex films (x = 0.1 and 0.2) by secondary ion mass spectrometry (SIMS). The relaxed films were grown with low-pressure chemical vapor deposition (LPCVD) on a Si substrate followed by a graded SiGe layer. Two sets of samples were prepared under different growth conditions, and by transmission electron microscopy (TEM) it was shown that these conditions resulted in one set of samples containing a high density of threading dislocations in the relaxed films, and one set with a low dislocation density. The SIMS profiles of the phosphorus distributions in the samples, after annealing in N-2-ambient in the temperature range of 700-950 degrees C, show that the phosphorus diffusion is significantly faster in the films with the high dislocation density. Furthermore, the data suggests that the fast diffusion is due to a higher mobility of the diffusing complex rather than an increase in the point defect concentration mediating the diffusion, a result which indicates that the threading dislocations may act as channels for the rapid dopant diffusion in SiGe.

  • 95.
    Cohen, Mika
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Dam, Mads
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Epistemic logic, Cryptography, Logical Omniscience, BAN Logic2005Conference paper (Refereed)
    Abstract [en]

    BAN logic is an epistemic logic for verifying cryptographic protocols. While BAN has been quite successful from a practical point of view, the semantics of the epistemic modality is unclear. Several Kripke semantics have been proposed, but they do not attempt at anything beyond a soundness result. Completeness is prevented by the so called logical omniscience problem: Agents in BAN can draw only feasibly computable consequences of their knowledge, whereas agents in Kripke semantics are not so constrained. To circumvent this problem, we index the epistemic possibility relation of Kripke semantics with a message renaming, relating how cipher texts at the current state correspond to cipher texts at the epistemically possible state. An agent is said to know a property of a message if corresponding messages at epistemically possible states satisfy that property. We obtain completeness with respect to message passing systems, and decidability, by transferring canonical model and filtration constructions from Kripke semantics.

  • 96.
    Cohen, Mika
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Dam, Mads
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Logical Omniscience in the Semantics of BAN Logics2005Conference paper (Refereed)
    Abstract [en]

    BAN logic is an epistemic logic for verification of cryptographic protocols. A number of semantics have been proposed for BAN logic, but none of them capture the intended meaning of the epistemic modality in a satisfactory way. This is due to the so-called logical omniscience problem : Agents are ”ideal reasoners” in existing semantics, while agents in BAN logic have only limited cryptographic reasoning powers. Logical omniscience is unavoidable in Kripke semantics, the standard semantical framework in epistemic logic. Our proposal is to generalize the epistemic accessibility relation of Kripke semantics so that it changes not only the current execution point, but also the currently predicated message. When  nstantiated on message passing systems, the semantics validates BAN logic. It makes agents introspective (”self-aware”) of their own knowledge and of their own actions of sending, receiving and extracting.

  • 97.
    Cordella, Marco
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    User-to-Network Interface in Optical Network2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This masters thesis work was carried out at the Optical Network Research Laboratory Ericsson Telecom AB in Kungens Kurva (Sweden). Its primary objective is to study the O-UNI (Optical User-to-Network Interface), a service control interface between client devices (e.g., IP routers and ATM switches) and the transport network, and the different signaling protocols running over it.

    This thesis was conducted for the Institute for Microelectronics and Information Technology (IMIT) at the Royal Institute of Technology (KTH) in Stockholm (Sweden) and for the Department of Telecommunications at Politecnico di Torino in Turin (Italy).

    Recently, the Internet Engineering Task Force (IETF), the Optical Internetworking Forum (OIF) and the International Telecommunication Union (ITU) have all started working on standards for routing and signaling protocols for the Optical Transport Network (OTN). While these efforts aim to create a set of protocols to act as the interface to an optical core, the emerging architectures are different enough to present difficult choices for vendors and service providers. The goal of this thesis work was to analyze the state of the art of the OIF based UNI (User-to-Network Interface) in order to gain competence in the area and study this UNI model by implementing some of the abstract messages defined in the UNI 1.0. In particular, the UNI signaling protocols, adapted from the GMPLS RSVP-TE (Generalized Multi-Protocol Label Switching) (Resource Reservation Protocol - Traffic Engineering) and LMP (Link Management Protocol) specifications were implemented.

  • 98.
    Coyet, Peter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mobil Positionering med Kartstöd2003Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis was conducted on behalf of SL Infrateknik AB. The goal of the master thesis was to examine the possibilities for SL to create a mobile positioning service with map support for their travellers. The result would give SL a basis for making decisions relating to the development of such a service.

    The studies have focused on different techniques of positioning and the existing operators in the Swedish market that provide positioning. To acquire understanding of services with map support, the construction and usage of geographic information systems have been examined. These studies have also involved the use of geographic information systems for map presentation on mobile units.

    Since SL’s traffic covers the whole county of Stockholm, it was important to study how SL can reach as many travellers as possible with the new service. However, the accuracy of mobile positioning varies significantly depending on the geographic location. Measurements showed that the accuracy outside Stockholm’s city centre is poor. With 3G, the accuracy is expected to be a bit better. The current conditions are therefore not suitable for creating a positioning service with acceptable accuracy for the whole county of Stockholm.

    The conclusion is that SL should not invest in a mobile positioning service at present. This conclusion is mainly based on such factors as accuracy, choice of operator and communication performance.

  • 99.
    Croné, Maria
    et al.
    KTH, Superseded Departments, Computer and Systems Sciences, DSV.
    Eliasson, Erik
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mattsson, Johan
    KTH, Superseded Departments, Computer and Systems Sciences, DSV.
    Wiatr, Pawel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    The Magic Bowl: a Tangible User Interface for Configuration of Interactive Environments2004In: Proceedings of the 6th International Conference on the Design of Cooperative system (COOP04), 2004Conference paper (Refereed)
    Abstract [en]

    This paper describes our work with the design and deployment of a tangible user interface for controlling an interactive workspace. Our intention was to design a user interface that makes it possible to use the room without focusing on the technology behind. We found that the problems are especially at the beginning of a work session when a group enters a totally shut-down workspace and have to spend valuable time starting and configuring every device before they are able to start working. The Magic Bowl makes it possible to quickly start the interactive workspace with a personalized configuration.

  • 100.
    Dahir, Sarmad Jamal
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Functional Self-Test of DSP cores in a SOC2007Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The rapid progress made in integrating enormous numbers of transistors on a single chip is making it possible for hardware designers to implement more complex hardware architectures in their designs. Nowadays digital telecommunication systems are implementing several forms of SOC (System-On-Chip) structures. These SOCs usually contain a microprocessor, several DSP cores (Digital-Signal-Processors), other hardware blocks, on-chip memories and peripherals.

    As new IC process technologies are deployed, with decreasing geometrical dimensions, the probabilities of hardware faults to occur during operation are increasing. Testing SOCs is becoming a very complex issue due to the increasing complexity of the design and the increasing need of a test mechanism that is able to achieve acceptable fault coverage in a short test application time with low power consumption without the use of external logic testers.

    As a part of the overall test strategy for a SOC, functional self-testing of a DSP core is considered in this project to be applied in the field. This test is used to verify whether fault indications in systems are caused by permanent hardware faults in the DSP. If so, the DSP where the fault is located needs to be taken out of operation, and the board it sits on will be later replaced. If not, the operational state can be restored, and the system will become fully functional again.

    The main purpose of this project is to develop a functional self-test of a DSP core, and to evaluate the characteristics of the test. This project also involves proposing a scheme on how to apply a functional test on a DSP core in an embedded environment, and how to retrieve results from the test. The test program shall run at system speed.

    To develop and measure the quality of the test program, two different coverage metrics were used. The first is the code coverage metric achieved by simulating the test program on the RTL representation of the DSP. The second metric used was the fault coverage achieved. The fault coverage of the test was calculated using a commercial Fault Simulator working on a gate-level representation of the DSP. The results achieved in this report show that this proposed approach can achieve acceptable levels of fault coverage in short execution time without the need for external testers which makes it possible to perform the self-test in the field. This approach has the unique property of not requiring any hardware modifications in the DSP design, and the ability of testing several DSPs in parallel.

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