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  • 301.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    Yu, S.
    Nilson, K.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Thermal effects on order at organic/inorganic interfaces: TiOPc on IOnSb(001)c(8x2)2007Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528Artikkel i tidsskrift (Annet vitenskapelig)
  • 302.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nilson, K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J.-M.
    Le Lay, Guy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Interface properties in organic thin films: FePc on TiO2(110)Inngår i: Journal of Physical Chemistry, ISSN 1932-7447Artikkel i tidsskrift (Fagfellevurdert)
  • 303.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nilson, K.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    Angot, T.
    Nlebedim, Cajetan Ikenna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Layet, J. -M
    Le Lay, G.
    Götelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Strong interactions in dye-sensitized interfaces2008Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, nr 15, s. 5972-5977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phthalocyanines (Pcs) are capable of converting sunlight into electric energy when adsorbed on TiO2 in a dye-sensitized solar cell. Of special interest in this type of cell is the energy level alignment as well as how molecules adsorb on the surface as it determines the output of the cell. We investigated the FePc-TiO2(110) interface using scanning tunneling microscopy, synchrotron-based photoelectron spectroscopy, and X-ray absorption spectroscopy. We found a strong coupling of the first-layer FePc to the substrate resulting in an alteration of the electronic structure and charge transfer from the molecules. The FePc in the second layer is not severely affected by the bonding to the surface and has bulk-like electronic properties. The growth of FePc thin films proceeds in a layer plus island mode, and the molecular plane is parallel to the surface. The energy level alignment at the interface is determined, and the lowest unoccupied molecular orbital is found above the conduction band minimum of the oxide substrate.

  • 304.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Priya, Baskar Rao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Niraj, N. Pio Peter
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Self-ordering of metal-free phthalocyanine on InAs(100) and InSb(100)2006Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 18, nr 48, s. 10707-10723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The adsorption and surface ordering of metal-free phthalocyanine (H2PC) on InAs(100)(4 x 2)/c(8 x 2) and InSb(100) c(8 x 2) is investigated using scanning tunnelling microscopy (STM) and synchrotron based photoelectron spectroscopy. The two systems show structural similarities; at submonolayer coverage the preferred adsorption site of H2PC is on top of the In rows, and above 1 monolayer and after thermal treatment the first molecular layer is ordered in a densely packed 'x3' structure observed with both low energy electron diffraction and STM.

    The electronic properties and the surface bonds of the two systems are quite different: the InAs-H2PC interface is semiconducting after room temperature adsorption but becomes metallic upon thermal treatment whereas InSb(100) H2PC is semiconducting at all preparations. These differences are reflected in pronounced differences in the C 1s line shape between the two systems. N 1s core level spectra from both surfaces reveal deprotonation of the molecules, i.e. the central hydrogen atoms are lost upon thermal treatment.

  • 305.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hennies, F.
    MAX-lab., Lund University.
    Nilson, K.
    Department of Physics, Uppsala University.
    Åkermark, B.
    Organic Chemistry, Stockholm University.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Changing adsorption mode of FePc on TiO2(110) by surface modification with bipyridine2008Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, nr 7, s. 074707-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Surface modification of reactive oxide substrates to obtain a less strongly interacting template for dye adsorption may be a way to enhance performance in dye-sensitized solar cells. In this work, we have investigated the electronic and structural properties of 4,4(')-bipyridine (bipy) as modifier adsorbed on the TiO2(110) surface. The modified surface is then coated with iron phthalocyanine (FePc) and the properties of this heterostructure are investigated with synchrotron based photoelectron spectroscopy, x-ray absorption spectroscopy, and scanning tunneling microscopy. We find that a saturated monolayer consisting of standing bipy molecules with one nitrogen atom pointing outward is formed on the oxide surface. FePc adsorb in molecular chains along the [001] direction on top of bipy and ordered in a tilted arrangement with adjacent molecules partially overlapping. Already from the first layer, the electronic properties of FePc resemble those of multilayer films. FePc alone is oxidized on the TiO2(110) surface, but preadsorbed bipy prevents this reaction. The energy level lineup at the interface is clarified.

  • 306.
    Palmgren, Pål
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åhlund, J.
    Nilson, K.
    Göthelid, E.
    Schiessling, J.
    Puglia, C.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Adsorption site of phthalocyanines on the InSb(001)c(8x2) surfaceManuskript (Annet vitenskapelig)
  • 307. Park, Hyundai
    et al.
    Sysak, Matthew N.
    Chen, Hui-Wen
    Fang, Alexander W.
    Liang, Di
    Liao, Ling
    Koch, Brian R.
    Bovington, Jock
    Tang, Yongbo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wong, Kristi
    Jacob-Mitos, Matt
    Jones, Richard
    Bowers, John E.
    Device and Integration Technology for Silicon Photonic Transmitters2011Inngår i: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 17, nr 3, s. 671-688Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The device and integration technology for silicon photonic transmitters are reviewed in this paper. The hybrid silicon platform enables on-chip lasers to be fabricated with silicon photonic circuits and can be integrated in the CMOS back-end flow. Laser arrays from multiple die bonding and quantum well intermixing techniques are demonstrated to extend the spectral bandwidth from the laser array of the transmitter. Two modulator technologies, silicon modulators and hybrid silicon modulators, are also described.

  • 308. Persson, J.
    et al.
    Zhou, Yan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Phase-locked spin torque oscillators: Impact of device variability and time delay2007Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, nr 9, s. 09A503-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have carried out detailed Landau-Lifshitz-Gilbert simulations of pairs of serially connected spin torque oscillators (STOs) in parallel with a resistive load. To study the impact of realistic process variations on STO synchronization we let the two STOs have different in-plane anisotropy fields (H-k). The simulation also provides for a time delay (tau). We construct a phase diagram of the STO synchronization as a function of H-k and direct current (I-dc) at different tau. The phase diagram turns out to be quite rich with different types of synchronized precession modes. While the synchronized state is originally very sensitive to STO process variations and can only sustain up to 4% H-k variation, the addition of a small time delay dramatically improves its robustness and allows as much as 145% H-k variation in the entire out-of-plane precession regime.

  • 309. Persson, P. O. A.
    et al.
    Hultman, L.
    Janson, M. S.
    Hallén, Anders.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ostwald ripening of interstitial-type dislocation loops in 4H-silicon carbide2006Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The annealing behavior of interstitial-type basal plane dislocation loops in Al ion implanted 4H-SiC is investigated. It is shown that the loops undergo a dynamical ripening process. For annealing below 1700 degrees C the total area of dislocation loops increases, indicating that point defects are still available for accumulation, but for annealing times longer than 100 min at this temperature the value of the total loop area saturates. For longer annealing times, or higher temperatures, the dislocation loops are subjected to a conservative coarsening process, also known as Ostwald ripening. In this process the mean loop radius increases with increasing annealing time and temperature while the number of loops decreases. Meanwhile the summarized area of the loops stays constant. The observed ripening is suggested to occur by a mechanism, which involves coarsening by direct loop coalescence. Through this mechanism, loops on the same basal plane move towards each other until they coalesce into one, but loops on neighboring basal planes can only move until their loop edges meet (in a basal plane projection) where they remain. Climb along the c axis is not favorable as shown by experimental results and is suggested to be caused by the atomic configuration of the loop. Upon continuous annealing, this results in a situation where the loops are confined in clusters.

  • 310.
    Petermann, Ingemar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Fibre Bragg Gratings: Characterization, Realization and Simulation2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main topic of this thesis is realization and characterization of fibre Bragg gratings.

    A novel versatile grating fabrication technique is developed and a number of gratings are realized, showing the potential of the system. Arbitrarily-shaped gratings are sequentially imprinted in the fibre by a moving interference pattern created with a continuous-wave ultraviolet (UV) source. This scheme allows for a very good control and stability of the grating shape, which is also shown experimentally. As opposed to most other present fabrication techniques, the proposed method offers a total control over the grating parameters by software, enabling simple implementation of new designs.

    Different kinds of error sources when stitching long gratings are identified and investigated regarding impact on the final grating result.

    Another important question within this field is how to characterize gratings. We propose a new characterization method based on optical low-coherence reflectometry (OLCR). A new interferometer design allows for simple simultaneous detection of the reflection response from two different points in the interrogated grating, so that differential measurements can be performed. The advantage of this is that the sensitivity to noise caused by e.g. thermal fluctuations in the system is substantially reduced. Several test gratings have been investigated and a very good agreement to the expected results is noted.

    A second characterization technique using interferometric detection of the side diffraction from the grating under test is investigated both theoretically and experimentally. With aid of two-dimensional theory for wave propagation, it is shown that there is a linear relation between the detected phase and modulation depth and the corresponding grating properties. The technique is evaluated with a novel scheme of implementation where the UV source provided in a fabrication setup is used assource for the side probe. This approach results in a very simple implementation and opens for an integration of the characterization and fabrication systems.

    Finally, a tuning method for transmission filters based on local heating of linearly chirped fibre Bragg gratings is analysed and further developed to allow for fully software-controlled operation. The potential of this technique is illustrated by some promising initial experimental results.

  • 311.
    Petermann, Ingemar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Helmfrid, Sten
    Proximion Fibre Systems AB, Kista.
    Stitch error effect on group-delay ripple for long chirped fiber Bragg gratings2005Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 44, nr 20, s. 4375-4383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different sources of stitch errors are identified and simulated in a 200 mm. long chirped grating. In each case, the effect on the group-delay ripple and transmission spectrum is investigated. The anticipated response in a typical 10 Gbit/s transmission system is specifically considered. From the simulations, it is clear that information about error source and magnitude can be gained directly from the transmission spectrum.

  • 312.
    Petermann, Ingemar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Helmfrid, Sten
    Proximion Fibre Systems AB, Kista.
    Gunnarsson, Ola
    Acreo AB, Kista.
    Kjellberg, Leif
    Acreo AB, Kista.
    Tunable and programmable optical bandpass filter2007Inngår i: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 9, nr 11, s. 1057-1061Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate a novel tunable and programmable optical bandpass filter with a transmission peak less than 5 pm wide that is tunable over 18.5 nm. The number of transmission windows within the stop band, as well as each window's position and strength, is set by applying a heat profile to a chirped fibre Bragg grating with the aid of a thermal printer head comprising a 640 pixel array. It is shown that the width of a transmission peak formed by local heating is mainly determined by the refractive index modulation depth and chirp rate and not by the width of the heated region.

  • 313.
    Pinos, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Marcinkevicius, Saulius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Liu, K.
    Shur, M. S.
    Yang, J.
    Shatalov, M.
    Gaska, R.
    Carrier lifetimes in AlGaN quantum wells: electric field and excitonic effects2008Inngår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 41, nr 15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoexcited carrier dynamics in a 280 nm AlGaN quantum well (QW) light emitting diode has been studied by time-resolved photoluminescence at forward and reverse bias. Long ( for AlGaN QWs with high Al content) room temperature carrier lifetimes of about 600 ps were measured with only a slight dependence on bias. These lifetimes are much longer than calculated free carrier tunnelling and thermionic emission times, pointing out the importance of excitonic effects for carrier dynamics in AlGaN QWs.

  • 314. Poe, Dennis
    et al.
    Zou, Jing
    Zhang, Weikai
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ramadan, Usama Abo
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Pyykkö, Ilmari
    MRI of the Cochlea with Superparamagnetic Iron Oxide Nanoparticles Compared to Gadolinium Chelate Contrast Agents in a Rat Mode2009Inngår i: European Journal of Nanomedicine, ISSN 1662-5986, Vol. 2, nr 2, s. 29-36Artikkel i tidsskrift (Fagfellevurdert)
  • 315. Pohl, A.
    et al.
    Westin, G.
    Ottosson, M.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Khartsev, Sergiy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Fors, Rickard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Porous and dense perovskite films2008Inngår i: NANOSTRUCTURED MATERIALS AND NANOTECHNOLOGY / [ed] Mathur, S; Singh, M, 2008, Vol. 28, nr 6, s. 153-163Konferansepaper (Fagfellevurdert)
    Abstract [en]

    La0.5Sr0.5CoO3 (LSCO) and La 0.67Ca0.33MnO3 (LCMO) films were prepared by sol-gel techniques and their structural and transport properties investigated. Films were spin-coated onto (001) LaAlO3 (LAO), (001) SrTiO 3 (STO), Pt/TiO2/SiO2/Si, and Al 2O3 substrates, and heated to 800C. The structural properties were investigated using X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM). SEM studies showed that the films were crack-free and adhered well to the substrates. No preferential orientation of the perovskite films was observed on Si- or Pt/TiO2/SiO 2/Si-substrates, but films deposited on LAO and STO showed good alignment with the substrate. Transport measurements of epitaxial LCMO films show maximum temperature coefficient of resistivity (TCR) of 6.1% K-1 at 241 K and colossal magnetoresistance (CMR) of 32% at 246 K. The conductivity LSCO polycrystalline film was 1.7 mcm, while a epitaxial film had a conductivity of around 1.9 mcm.

  • 316. Ponizovskaya, Ekaterina
    et al.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bratkovsky, Alexander
    Fu, Ying
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Binary metal and semiconductor quantum dot metamaterials with negative optical dielectric constant and compensated loss for small volume waveguides, modulators and switches2009Inngår i: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 95, nr 4, s. 1029-1032Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study numerically and analytically a binary mixture of quantum dots exhibiting gain and loss. For a mixture of gain quantum dots and silver nanoparticles, we find conditions when the composite shows negative dielectric constant operation and lossless operation. The composites of this kind may be used for dense integration of photonic components as well as modulation and switching in optical interconnect systems.

  • 317. Poon, S. J.
    et al.
    Rapp, Östen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Comment on "Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals"2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, nr 21, s. 216201-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a recent paper, Dolinšek [Phys. Rev. B 74, 134201 (2006)] suggested that the insulating behavior of icosahedral (i) Al-Pd-Re is of extrinsic origin. Large resistivities and insulatinglike properties of high resistivity samples were conjectured to result from the porous structure and the observed enhanced oxygen concentration in between the quasicrystal grains in some i-Al-Pd-Re samples. We point out that these hypotheses are incompatible with published work on the structure and properties of i-Al-Pd-Re.

  • 318.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Li, Yanlu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, S.
    Friberg, Ari
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Helsinki University of Technology (TKK), Finland.
    Modeling of terahertz near-field imaging: Rigorous simulation and antenna approach2009Inngår i: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009, s. 5192395-Konferansepaper (Fagfellevurdert)
  • 319.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Li, Yanlu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Helsinki University of Technology (TKK), Finland.
    Terahertz Near-field Imaging: Rigorous Model for Interpreting "Antenna approach"2009Inngår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009, IEEE , 2009, s. 3027-3028Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Classical Mie theory fails to explain high resolution of a terahertz imaging system exploiting scattering of the near-field radiation. Reported numerical model confirms the feasibility of an antenna model which proves the enhanced resolution.

  • 320.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ricciardi, Sebastien
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Even-mode generation in microcavity dye laser2007Inngår i: ICONO 2007: Coherent And Nonlinear Optical Phenomena / [ed] Belyi, VN; Drabovich, KN; Flytzanis, C, 2007, Vol. 6729, s. M7292-M7292Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A solid-state dye laser with a microcavity whose size is comparable to the lasing wavelength is modeled by means of the finite element method. The position of the pumping source affects the lasing mode spectrum. In comparison with a single point source at the edge of the cavity, a random distribution of excitation sources in the central gain part of the microcavity leads to depletion of odd longitudinal modes and to higher output efficiency of the laser radiation in even modes. The simulation results are explained by simple physical considerations.

  • 321.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ricciardi, Sebastien
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Impact of cavity symmetry on mode suppression and increase of free spectral range in solid-state dye microlaser2007Inngår i: Chinese Optics Letters, ISSN 1671-7694, Vol. 5, nr 11, s. 651-653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe modeling the solid-state dye laser with the microcavity size comparable to light wavelength. Certain symmetry in the allocation of gain material leads to depletion of odd longitudinal modes that, in turn, increases the tunability range of the microlaser. We provide simple physical explanation for the modeling results.

  • 322.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ricciardi, Sébastien
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Waterford Inst Technol.
    Mode suppression in a microcavity solid-state dye laser2007Inngår i: Journal of the european optical society-rapid publications, ISSN 1990-2573, Vol. 2, s. 07203-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solid-state dye laser with a microcavity whose size is comparable to the lasing wavelength, is modeled by means of the finite element method. The position of the pumping source affects the lasing mode spectrum. In comparison with a single point source at the edge of the cavity, a random distribution of excitation sources in the central gain part of the microcavity leads to suppression of odd longitudinal modes and to higher output efficiency of the laser radiation in even modes. The modeling and simulation results are explained by simple physical considerations.

  • 323.
    Popov, Sergei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zhang, Rui
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Helsinki University of Technology, Finland.
    Sergeyev, S.
    Mode stability in robust microcavity solid-state dye laser2008Inngår i: Frontiers in Optics - Microcavities and Lasers (2008), Optical Society of America, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Polymeric microcavity dye laser modeled with finite element method demonstrates excellent tolerance against geometrical distortions of the cavity. Mode wavelengths remain stable with two types of potential impairments might occur during the manufacturing process.

  • 324.
    Porta Mana, Piero G. Luca
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Månsson, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Björk, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    On distinguishability, orthogonality, and violations of the second law: contradictory assumptions, contrasting pieces of knowledgeManuskript (Annet vitenskapelig)
    Abstract [en]

    Two statements by von Neumann and a thought-experiment by Peres prompts a discussion on the notions of one-shot distinguishability, orthogonality, semi-permeable diaphragm, and their thermodynamic implications. In the first part of the paper, these concepts are defined and discussed, and it is explained that one-shot distinguishability and orthogonality are contradictory assumptions, from which one cannot rigorously draw any conclusion, concerning e.g. violations of the second law of thermodynamics. In the second part, we analyse what happens when these contradictory assumptions comes, instead, from _two_ different observers, having different pieces of knowledge about a given physical situation, and using incompatible density matrices to describe it.

  • 325.
    Porta Mana, Piero G. Luca
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Månsson, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Björk, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    'Plausibilities of plausibilities': an approach through circumstancesManuskript (Annet vitenskapelig)
    Abstract [en]

    Probability-like parameters appearing in some statistical models, and their prior distributions, are reinterpreted through the notion of `circumstance', a term which stands for any piece of knowledge that is useful in assigning a probability and that satisfies some additional logical properties. The idea, which can be traced to Laplace and Jaynes, is that the usual inferential reasonings about the probability-like parameters of a statistical model can be conceived as reasonings about equivalence classes of `circumstances' - viz., real or hypothetical pieces of knowledge, like e.g. physical hypotheses, that are useful in assigning a probability and satisfy some additional logical properties - that are uniquely indexed by the probability distributions they lead to.

  • 326.
    Porta Mana, Piero G. Luca
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Månsson, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Björk, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    The Laplace-Jaynes approach to inductionManuskript (Annet vitenskapelig)
    Abstract [en]

    An approach to induction is presented, based on the idea of analysing the context of a given problem into `circumstances'. This approach, fully Bayesian in form and meaning, provides a complement or in some cases an alternative to that based on de Finetti's representation theorem and on the notion of infinite exchangeability. In particular, it gives an alternative interpretation of those formulae that apparently involve `unknown probabilities' or `propensities'. Various advantages and applications of the presented approach are discussed, especially in comparison to that based on exchangeability. Generalisations are also discussed.

  • 327.
    Porta Mana, Piero Giovanni Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Distinguishability of non-orthogonal density matrices does not imply violations of the second lawManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The hypothetical possibility of distinguishing preparations described by non-orthogonal density matrices does not necessarily imply a violation of the second law of thermodynamics, as was instead stated by von Neumann. On the other hand, such a possibility would surely mean that the particular density-matrix space (and related Hilbert space) adopted would not be adequate to describe the hypothetical new experimental facts. These points are shown by making clear the distinction between physical preparations and the density matrices which represent them, and then comparing a "quantum" thermodynamic analysis given by Peres with a "classical" one given by Jaynes.

  • 328.
    Porta Mana, Piero Giovanni Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Studies in plausibility theory, with applications to physics2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The discipline usually called `probability theory' can be seen as the theory which describes and sets standard norms to the way we reason about plausibility. From this point of view, this `plausibility theory' is a province of logic, and the following informal proportion subsists:

    plausibility theory is to the common notion of `plausibility', as deductive logic is to the common notion of `truth'.

    Some studies in plausibility theory are here offered. An alternative view and mathematical formalism for the problem of induction (the prediction of uncertain events from similar, certain ones) is presented. It is also shown how from plausibility theory one can derive a mathematical framework, based on convex geometry, for the description of the predictive properties of physical theories. Within this framework, problems like state assignment - for any physical theory - find simple and clear algorithms, numerical examples of which are given for three-level quantum systems. Plausibility theory also gives insights on various fashionable theorems, like Bell’s theorem, and various fashionable `paradoxes', like Gibbs' paradox.

  • 329.
    Porta Mana, Piero Giovanni Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Why can states and measurement outcomes be represented as vectors?Manuskript (Annet vitenskapelig)
    Abstract [en]

    It is shown how, given a "probability data table" for a quantum or classical system, the representation of states and measurement outcomes as vectors in a real vector space follows in a natural way. Some properties of the resulting sets of these vectors are discussed, as well as some connexions with the quantum-mechanical formalism.

  • 330. Pougeoise, E.
    et al.
    Gilet, P.
    Grosse, P.
    Grenouillet, L.
    Chelnokov, A.
    Gerard, J. -M
    Bouillard, J. -S
    Lerondel, G.
    Blaize, S.
    Vilain, S.
    Bachelot, R.
    Royer, P.
    Hamelin, R.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sundgren, Petrus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Experimental study of the lasing modes of 1.3-ÎŒm highly strained InGaAs-GaAs quantum-well oxide-confined VCSELs2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 6, s. 377-379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an experimental study of the main modes involved in the emission properties of InGaAs-GaAs quantum-well oxide-confined long wavelength vertical-cavity surface-emitting lasers. Lasing properties are dominated by the so-called "oxide modes" and by aperture modes, respectively, for small and large driving currents. We present complementary investigations of the laser emission including far-field angular distribution and spectroscopic near-field optical microscopy to a better understanding of the nature of the "oxide modes."

  • 331. Prkna, Ladislav
    et al.
    Talneau, Anne
    Mulot, Mikael
    Berrier, Audrey
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Evidence of the photonic gap contribution to the guiding mechanism for strongly confined modes in the refractivelike domain2006Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, nr 14, s. 2139-2141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The group index dispersion and birefringence of guided modes supported by straight photonic crystal (PhC) waveguides are theoretically and experimentally investigated as a function of the waveguide width within various reduced frequency domains. Within the photonic gap and far from the Brillouin zone edges, strongly confined modes supported by narrow PhC guides exhibit both a group index and a birefringence larger than those of a deep ridge. These two results evidence the contribution of the photonic gap to the guiding mechanism in the refractivelike domain.

  • 332. Pusa, F.
    et al.
    Skagerlund, J.
    Gillner, L.
    Sahlen, O.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Granestrand, P.
    Lundqvist, L.
    Stoltz, B.
    Terlecki, J.
    Wahlin, F.
    Morner, A. -C
    Wallin, J.
    Oberg, O.
    An automatic method to extract the grating coupling coefficient in DFB lasers: evaluation of different types of fabricated lasers1997Inngår i: Integrated Optics and Optical Fibre Communications, 11th International Conference on, and 23rd European Conference on Optical Communications (Conf. Publ. No. 448), 1997, Vol. 2, s. 200-203Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The grating coupling coefficients for a large number of 1.3 mu;m and 1.55 mu;m MQW DFB lasers with no, one, or two facets as-cleaved have been successfully extracted from spontaneous emission spectra

  • 333. Qi, B.
    et al.
    Agnarsson, Björn
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ólafsson, S.
    Gíslason, H. P.
    High-resolution X-ray photoemission spectroscopy study of AlN nano-columns grown by nitridation of Al nano-squares on Si(111) substrates with ammonia2010Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, nr 14, s. 3632-3639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The growth of AlN nano-columns by ammonium nitridation of Al nano-squares embedded in SiO2 on Si(111) substrates was studied by high-resolution X-ray photoemission spectroscopy from a synchrotron radiation source and scanning electron microscopy (SEM). Selective nitridation of the Al nano-squares on the SiO2 mask was obtained in the temperature window of 600 degrees C-700 degrees C. The well-shaped AlN nano-column arrays with diameters confined by the lateral size of the Al nano-squares (similar to 100 nm) were observed in SEM.

  • 334. Qi, B.
    et al.
    Olafsson, S.
    Zakharov, A. A.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Agnarsson, B.
    Gislason, H. P.
    Study of spatial homogeneity and nitridation of an Al nanopattern template with spectroscopic photoemission and low energy electron microscopy2013Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 264, s. 349-357Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a study on the spatial homogeneity and nitridation of a nanopattern template using a spectroscopic photoemission and low energy electron microscopy. The template was composed of Al nanodots which were patterned into a SiO2/Si(1 1 1) surface using e-beam lithography and reactive ion etching. The template exhibited a global inhomogeneity in terms of the local topography, Al composition and structure of the individual nanopatterns. After nitridation, the individual nanopatterns were diminished, more corrugated and faceted. The nitridated nanopatterns were structurally ordered but differently orientated. The nitridation effectively removed the fluorine contaminants by decomposition of the fluorocarbon sidewalls, resulting in the AlN nanopatterns and partially nitridated Si substrate surface outside the nanopattern domains.

  • 335. Qi, B.
    et al.
    Ólafsson, S.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Gislason, H. P.
    Agnarsson, B.
    Photoemission and low energy electron microscopy study on the formation and nitridation of indium droplets on Si (111)7 × 7 surfaces2013Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 531, s. 61-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation and nitridation of indium (In) droplets on Si (111)7 × 7, with regard to In droplet epitaxy growth of InN nanostructures, were studied using a spectroscopic photoemission and low energy electron microscopy, for the In coverages from 0.07 to 2.3 monolayer (ML). The results reveal that the In adatoms formed well-ordered clusters while keeping the Si (111)7 × 7 surface periodicity at 0.07 ML and a single 3×3 phase at 0.3 ML around 440-470 C. At 0.82 ML, owing to the presence of structurally defect areas beside the 7 × 7 domains, 3-D In droplets evolved concomitantly with the formation of 4 × 1-In cluster chains, accompanied by a transition in surface electric property from semiconducting to metallic. Further increasing the In to 2.3 ML led to a moderate increase in number density and an appreciable lateral growth of the droplets, as well as the multi-domain In phases. Upon nitridation with NH3 at ~ 480 C, besides the nitridation of the In droplets, the N radicals also dissociated the InSi bonds to form SiN. This caused a partial disintegration of the ordered In phase and removal of the In adatoms between the In droplets.

  • 336.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Control of slow light in coupled resonator optical waveguide structures with highly dispersive media2008Inngår i: AOE 2007: ASIA OPTICAL FIBER COMMUNICATION & OPTOELECTRONIC EXPOSITION & CONFERENCE, CONFERENCE PROCEEDINGS, SHENZHEN: AOE , 2008, s. 602-602Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dispersive material background may enable dynamic tunability of slow light of the coupled resonator optical waveguides. It may also results in an enhanced transmission spectrum with a time-dependent tuning of the dispersive medium.

  • 337.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Micro-cavities in silicon-on-insulator photonic crystal slabs: Determining resonant frequencies and quality factors accurately2005Inngår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 45, nr 5, s. 381-385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Micro-cavities in two-dimensional silicon-on-insulator (SOI) photonic-crystal slabs are studied. A combination of the finite-difference time-domain (FDTD) technique and the Pad approximation with Baker's algorithm is used to accurately compute the resonant-frequencies and quality,factors simultaneously. The simulations show that, for similar cavity structures, the mode quality factors of cavities in SOI-type photonic-crystal slabs are much smaller than those in membrane photonic-crystal slabs, and deep etching of air holes is still required to obtain relatively higher Omega.

  • 338.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Photonic band structures for surface waves on structured metal surfaces2005Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 13, nr 19, s. 7583-7588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photonic band structures of surface modes on structured metal surfaces with periodic holes in them are obtained using the full-vectorial finite-difference time-domain method. Surface modes do exist for almost all investigated lattice types with any hole size, shape and depth. The results for a square lattice of wax-filled box holes in brass are also in very good agreement with the experimental results. We also show that, for structured surfaces with holes of finite depth, the holes might act as cavities. Thus there exist propagating coupled cavity modes with low group velocity, confined at the surface and decaying exponentially into the dielectric above.

  • 339.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Photonic crystal and plasmonic devices for photonic integration2008Inngår i: AOE 2007: ASIA OPTICAL FIBER COMMUNICATION & OPTOELECTRONIC EXPOSITION & CONFERENCE, CONFERENCE PROCEEDINGS, SHENZHEN: AOE , 2008, s. 162-163Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Our recent research results on photonic crystal and plasmonic devices for photonic integration are reviewed here. Silicon-based photonic crystal waveguides, microcavities, and filters, as well as plasmonic waveguides will be presented.

  • 340.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Vertically coupled photonic crystal optical filters2005Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, nr 12, s. 1476-1478Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel design of optical filters, based on the vertical coupling between channel waveguides and photonic crystal microcavities, is proposed. The choice of channel waveguides can be arbitrary because of the flexibility of the device geometry, which makes it possible to utilize conventional low-loss waveguides. The separation between waveguides and microcavities, which determines filter bandwidths and drop efficiencies, can be accurately controlled by material growth (or deposition). The filters might also be switchable, e.g., by mechanical movements of microcavities. An example of a reflection-type optical filter is demonstrated in numerical experiments using the finite-difference time-domain method.

  • 341.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Li, Qiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zhang, Ziyang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Liu, Fangfei
    Chang, Qingjiang
    Su, Yikai
    Silicon micro-cavities and their system applications2009Inngår i: PHOTONICS PACKAGING, INTEGRATION, AND INTERCONNECTS IX / [ed] Glebov AL; Chen RT, 2009, Vol. 7221Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We experimentally demonstrate resonance-splitting and enhanced notch as a result of the mutual mode coupling in silicon ring resonator. Dense wavelength conversions, wavelength multicasting and optical up-converter are demonstrated in the split silicon ring resonator. A temporal differentiator and format conversion from NRZ to AMI are demonstrated utilizing the filtering effect of ring resonator. Photonic phase shifter and delay line are demonstrated utilizing the phase shift of ring resonator.

  • 342.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Neff, Curtis
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, L. Mauritz
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Coupled resonator optical waveguides with electromagnetically induced transparent media2006Inngår i: Technical digest: July 23 - 26, 2006, OSA Headquarters, Washington, DC, USA, Optical Society of America, 2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We numerically demonstrate ultra slow light in a coupled optical resonator waveguide embedded in a highly dispersive medium. This combination dramatically reduces the propagation speed of light pulses in the structure to below 1% c0.

  • 343.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ruan, Zhichao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berrier, Audrey
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Xiao, S S
    Mulot, M.
    Swillo, M.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Thylen, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik.
    Negative refraction in semiconductor photonic crystals2005Inngår i: SEMICONDUCTOR AND ORGANIC OPTOELECTRONIC MATERIALS AND DEVICES, 2005, Vol. 5624, s. 345-352Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The coupling efficiency between external plane waves and the Bloch waves in photonic crystals are investigated. It is found that the coupling coefficient is highly angular dependent even for an interface between air n=l and a photonic crystal with effective index -1. It is also shown that, for point imaging by a photonic crystal slab owing to the negative refraction, the influence of the surface termination to the transmission and the imaging quality is significant. Finally, we present results demonstrating experimentally negative refraction in a two-dimensional photonic crystal.

  • 344.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Xiao, S.
    Berrier, A.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Mulot, M.
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Ruan, Z.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Negative refraction in two-dimensional photonic crystals2005Inngår i: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 80, nr 6, s. 1231-1236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present some of our recent results for negative refraction in photonic crystals. The concept of negative refraction in photonic crystals is firstly introduced. Then, the propagation of electromagnetic waves in photonic crystals is systematically studied. By the layer Korringa-Kohn-Rostoker method, the coupling efficiency between external plane waves and the Bloch waves in photonic crystals is investigated. It is found that the coupling coefficient is highly angular dependent even for an interface between air with n=1 and a photonic crystal with effective index n(eff)=-1. It is also shown that, for point imaging by a photonic crystal slab, owing to the negative refraction, the influence of the surface termination on the transmission and the imaging quality is significant. Finally, we present results experimentally demonstrating negative refraction in a two-dimensional photonic crystal at optical communication wavelengths.

  • 345.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yan, M.
    Yan, Wei
    Transformation optics and invisibility cloaks2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we briefly summarize the theory of transformation optics and introduce its application in achieving perfect invisibility cloaking. In particular, we theoretically show how the task of realizing cylindrical invisibility cloaks can be eased by using either structural approximation or material simplification. The corresponding invisibility performances of the approximate or simplified cylindrical cloaks are presented in detail.

  • 346.
    Qiu, Min
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hao, Jiaming
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yan, Wei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wang, Jing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Transformation Optics for Designing Superlenses2009Inngår i: ICEAA: 2009 INTERNATIONAL CONFERENCE ON ELECTROMAGNETICS IN ADVANCED APPLICATIONS, NEW YORK: IEEE , 2009, s. 944-947Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We show that by using the recently emerged transformation optics, it is possible to design perfect lenses in new geometries with an imaging performance almost equivalent to the well studied perfect slab lens. In addition, the theory of transformation optics generalizes the complementary bilayer lenses to many other material compositions, including cases where passive or active obstacles are involved in the lens system.

  • 347.
    Ricciardi, Sebastien
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Thermally induced wavelength tunability of microcavity solid-state dye lasers2007Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, nr 20, s. 12971-12978Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wavelength tunability of a microcavity solid-state dye laser is modeled and demonstrated by simulations making use of the finite element method. We investigate the application of two phenomena, thermoelastic expansion of the microcavity material and thermo-induced change of the refractive index, to tune the microcavity mode frequencies by a variation of the effective optical path. An optimized size of the laser microcavity is defined depending on the operation wavelength bandwidth and the glass transition temperature of the gain material.

  • 348.
    Ricciardi, Sebastien
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sergeyev, Sergey
    Tunable microcavity solid-state dye laser for biometrics applications2007Inngår i: ICONO 2007: Coherent And Nonlinear Optical Phenomena / [ed] Belyi, VN; Drabovich, KN; Flytzanis, C, 2007, Vol. 6729, s. N7292-N7292Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wavelength tunability of a microcavity solid-state dye laser is modeled by means of the finite element method. We investigate the application of two phenomena, thermoelastic expansion of the microcavity material and thermo-induced change of refractive index, in order to tune microcavity mode frequencies by the variation of the effective optical path. An optimized size of the laser microcavity is defined depending on the operation wavelength bandwidth and the glass temperature of the gain material.

  • 349.
    Ricciardi, Sébastien
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Polymeric Microcavities for Dye Lasers and Wavefront Shapers2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Over the last few years, the available computing power allows us to have a deeper insight into photonics components than we ever had before. In this thesis we use the finite element method (FEM) to explore the behavior of the waves in 2D planar microcavities. We demonstrate the tunability of the cavity over a wide range of frequencies taking into account both the thermo-mechanical and the thermo-optical effect. Geometry and material choices are done so that the latter is predominant. We also demonstrate an odd mode disappearing phenomenon reported here for the first time as far as we know. Using this knowledge, we design two structures with these remarkable properties.

    One of the devices will be used as micro-sized solid-state dye laser with Rhodamine 6G as the active medium and SU-8 polymer as a cavity material in sizes that have never been reached before. This opens new opportunities not only for future implementation for “labs-on-a-chip” (LOC) but also for a higher integration density of optical communication systems. The second device is a wavefront shaper creating plane waves from a point source performing the functions of beam shaper and beam splitter with plane wave as the output result.

    After an introduction to FEM and comparison with a rival algorithm, some issues related to FEM in electromagnetic simulation are resolved and explained. Finally, some fabrication techniques with feature sizes <100 nm, such as electron beam lithography (EBL) and nano-imprint lithography (NIL), are described and compared with other lithographic techniques.

  • 350.
    Ricciardi, Sébastien
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wavefront shaping: plane waves out of a point source2007Inngår i: Proceedings of the Comsol users conference, 2007, s. 761-764Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Using finite element method (FEM) implemented in Comsol Multiphysics simulation package, we present a model of beam shaper that converts spherical waves into one or two plane waves as a function of wavelength. Thus, the device can realize both wavefront shaping and beam splitting in only one structure. Comparing with different methods already presented, we introduce a solution for a smaller, simpler, and easier to manufacture device. We demonstrate a wavefront shaper using a microstructure of 8 x 8 μm size with commercially available material. We also discuss fabrication methods suitable for implementing the SU-8 polymer in the device.

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