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  • 1.
    Andersson, Mauritz
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Berglind, Eilert
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Björk, Gunnar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Orbital angular momentum modes do not increase the channel capacity in communication links2015In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 17, article id 043040Article in journal (Refereed)
    Abstract [en]

    The orbital momentum of optical or radio waves can be used as a degree of freedom to transmit information. However, mainly for technical reasons, this degree of freedom has not been widely used in communication channels. The question is if this degree of freedom opens up a new, hitherto unused 'communication window' supporting 'an infinite number of channels in a given, fixed bandwidth' in free space communication as has been claimed? We answer this question in the negative by showing that on the fundamental level, the mode density, and thus room for mode multiplexing, is the same for this degree of freedom as for sets of modes lacking angular momentum. In addition we show that modes with angular momentum are unsuitable for broadcasting applications due to excessive crosstalk or a poor signal-to-noise ratio.

  • 2.
    Berglind, Eilert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Björk, Gunnar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Humblet's Decomposition of the Electromagnetic Angular Moment in Metallic Waveguides2014In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 62, no 4, p. 779-788Article in journal (Refereed)
    Abstract [en]

    In a seminal paper, Humblet decomposed the angular momentum of a classical electromagnetic field as a sum of three terms: the orbital angular momentum (OAM), the spin, and the more unfamiliar surface angular momentum. In this paper, we present the result of such decomposition for various metallic waveguides. We investigate two hollow metal waveguides with circular and rectangular cross sections, respectively. The waveguides are excited with two TE eigenmodes driven in phase quadrature. As references, two better known modes are also analyzed: a plane, a circularly polarized wave (a TEM mode), and a TE-Bessel beam, both of infinite transverse extent and with no metallic boundaries. Our analysis shows that modes carrying OAM and spin can also propagate in the metallic waveguides, even when the cross section of the waveguide is distinctly non-circular. However, the mode density of orthogonal modes carrying OAM is at most equal to that of the waveguides' eigenmodes.

  • 3.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    On the Possibilities to Create a Negative Permittivity Metamaterial with Zero Imaginary Part of the Permittivity at a Specific Frequency-Electrical Network Theory Approach2012In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 48, no 4, p. 507-511Article in journal (Refereed)
    Abstract [en]

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

  • 4.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Microwave engineering approach to metallic based photonic waveguides and waveguide components2006In: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials, 2006, p. 247-251Conference paper (Refereed)
    Abstract [en]

    Approaches from microwave engineering are used to analyze metallic waveguides and wave-guiding circuits and to point out the usefulness of these techniques in photonics applications, for design of components and to achieve higher densities of integration in integrated photonics circuits than is the case today. It is also find that the losses are severe for certain applications.

  • 5.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Plasmonic/metallic passive waveguides and waveguide components for photonic dense integrated circuits: a feasibility study based on microwave engineering2010In: IET Optoelectronics, ISSN 1751-8768, Vol. 4, no 1, p. 1-16Article in journal (Refereed)
    Abstract [en]

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

  • 6.
    Fu, Ying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Optical transmission and waveguiding by excitonic quantum dot lattices2006In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 23, no 11, p. 2441-2447Article in journal (Refereed)
    Abstract [en]

    Metal-dielectric-metal configurations of optical waveguides have a very high laterally packaging density at the cost of high optical loss. Photonic crystals based on refractive-index-modulation materials have been used in optics, e.g., two materials having different refractive indices form a well-defined Bragg refraction mirror. Such a waveguide has lower loss but also lower packaging density. From the outset of these two notions, we propose a photonic-crystal device based on the exciton-polariton effect in a three-dimensional array of semiconductor quantum dots (QDs) for ultradense optical planar circuit applications. Excitons are first photogenerated in the QDs by the incident electromagnetic field, the exciton-polariton effect in the QD photonic crystal then induces an extra optical dispersion in QDs. The high contrast ratio between the optical dispersions of the QDs and the background therefore creates clear photonic bandgaps. By carefully designing the QD size and the QD lattice structure, perfect electromagnetic field reflection can be obtained at a specific wavelength in the lossless case, thus providing the fundamental basis for ultradense optical waveguide applications.

  • 7.
    Fu, Ying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Zeng, Yong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
    Nanoscale excitonic-plasmonic optical waveguiding by metal-coated quantum dots2006In: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials, 2006, p. 426-431Conference paper (Refereed)
    Abstract [en]

    A three-dimensional metal-coated semiconductor-quantum-dot (QD) nanoscale lattice structure is designed for optical waveguiding. It is based on three notions: i) Excitons are first photogenerated in the QDs by the incident electromagnetic field which is the optical wave to be guided: ii) The exciton-polariton effect in the QD structure induces an extra optical dispersion in the QDs: iii) The high contrast ratio between the optical dispersions of the QDs and the background material creates clear photonic bandgaps. By carefully designing the QD size and the QD lattice structure, perfect electromagnetic field reflection can be obtained for the incident wave in the lossless case, thus providing the fundamental basis of QDs for optical waveguide applications. Metal coating at the QD surface generates a surface plasmon spatially confined in the QD so that the exciton generation becomes enhanced for a better dielectric modulation.

  • 8. Lewen, R.
    et al.
    Westergren, Urban
    KTH, Superseded Departments, Electronics. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Berglind, Eilert
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Design of inductive p-i-n diode matching for optical receivers with increased bit-rate operation2001In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 19, no 12, p. 1956-1963Article in journal (Refereed)
    Abstract [en]

    We have studied matching of a p-i-n photodiode (PD) with a single serial inductive element for broadband operation. The bit rate and rise time may be significantly improved, compared to a device without inductor for nonreturn-to-zero (NRZ) modulation. The matched device offers improved pulse equalization leading to increased receiver sensitivity, and reduces the need for an additional pulse-equalizing filter. The material is presented so that it can serve as a guideline of how the inductor can be included when choosing the thickness of the absorption layer and/or area for a p-i-n PD design, and ends with typical design examples.

  • 9. Ohlen, P.
    et al.
    Berglind, Eilert
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Measurements and modelling of pattern-dependent BER and jitter in reshaping optoelectronic repeaters2000In: IEE Proceedings - Optoelectronics, ISSN 1350-2433, E-ISSN 1359-7078, Vol. 147, no 2, p. 97-103Article in journal (Refereed)
    Abstract [en]

    A reshaping optoelectronic repeater is investigated in a loop experiment. If such a device is used in an optical network, the jitter accumulation and its influence on the cascadability are important issues. Whereas the RMS jitter was fairly independent for PRBS patterns, the bit-error rate showed a large pattern dependence. In order to explain these results, a simplified model of the repeater is used, where the device is modelled as a filter followed by an ideal limiter.

  • 10.
    Schatz, Richard
    et al.
    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.
    Berglind, Eilert
    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.
    Gillner, Lars
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Parameter extraction from DFB lasers by means of a simple expression for the spontaneous emission spectrum1994In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 6, p. 1182-1184Article in journal (Refereed)
    Abstract [en]

    A simple expression for the amplified spontaneous emission from a laser biased below lasing threshold is applied to semiconductor laser parameter extraction. We demonstrate that accurate measurement of the coupling coefficient for distributed feedback (DFB) lasers with phaseshifts and end reflections is a practical possibility. It is also shown that the used expression, for a reciprocal device, can be derived directly from the wave equation using the Green’s function.<>

  • 11.
    Sorio, Jessica
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Berglind, Eilert
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Optical filter impact on eye opening in vestigial sideband systems2004In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 22, no 2, p. 433-439Article in journal (Refereed)
    Abstract [en]

    An analytical tool is presented in order to analyze and elucidate the impact of the optical filter position and steepness on eye opening in an optical vestigial sideband system with direct detection. It is shown that bit sequences containing solitarities (i.e., bit sequences containing single bits surrounded by several bits of opposite kind) are the major bit sequences to cause eye closure. In comparison with double-sideband modulation format, an eye opening penalty of 3-6 dB can be achieved with vestigial sideband format. The analytical tool helps to understand the interrelation between the bit sequence properties and the optical filter parameters.

  • 12.
    Thylén, Lars
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Nanophotonics and negative ε materials2006In: Journal of Zhejiang University: Science, ISSN 1009-3095, Vol. 7, no 1, p. 41-44Article in journal (Refereed)
    Abstract [en]

    The feasibility of using metal optics or negative ε materials, with the aim of reducing the transversal extent of waveguided photonic fields to values much less than the vacuum wavelength, in order to achieve significantly higher densities of integration in integrated photonics circuits that is possible today is discussed. Relevant figures of merit are formulated to this end and used to achieve good performance of devices with today's materials and to define required improvements in materials characteristics in terms of decreased scattering rates in the Drude model. The general conclusion is that some metal based circuits are feasible with today's metals. Frequency selective metal devices will have Q values on the order of only 10-100, and significant improvements of scattering rates or lowering of the imaginary part of ε have to be achieved to implement narrowband devices. A photonic Moore's law of integration densities is proposed and exemplified.

  • 13.
    Thylén, Lars
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Plasmonics, coherent light matter interactions and photonic crystals: Shaping the future of photonics?2006In: ICTON 2006: 8th International Conference on Transparent Optical Networks, Vol 1, Proceedings: ICTON, MPM, INDUSTRIAL, PICAW, GOWN / [ed] Marciniak, M, 2006, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Photonics is far behind electronics in maturity. There are no large RAM type memories, the circuits are orders of magnitude larger than electronics IC circuits, the functionality is comparatively low. But it appears that few or none of these factors are fundamentally impossible to overcome, and perceiving the enormous potential in photonics, the field continues to be an area of dynamic rapid development. In this paper some of the emerging possibilities that exist are explored, and the possibilities to utilize these comparatively new phenomena to widen the application envelope of photonics technology and generate functions not normally associated with photonics are briefly discussed. These developments could lead to quantum leaps in photonics devices, to complement the forceful engineering improvements.

  • 14.
    Thylén, Lars
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Dai, Daoxin
    Centre for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Photonics (Closed 20120101).
    Bratkovsky, Alex
    Complementing or replacing silicon and III–Vs: The role of plasmonics and novel materials in future integrated photonics for telecom and interconnects2011In: 2011 13th International Conference on Transparent Optical Networks, ICTON 2011, IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    Integrated photonics has largely been based on silicon/silica and III-Vs in recent times. Both have their advantages and disadvantages, but neither seem capable of supporting a further significant reduction of device footprint to sustain the exponential decrease of this important parameter that we have witnessed since decades. The talk will analyze different aspects of plasmonics from this and a functionality point of view and further discuss some possible alternative materials.

  • 15.
    Thylén, Lars
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Dai, Daoxin
    KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Bratkovsky, Alex
    Metamaterials- and Nanotechnology-based Low Power and Small Footprint Integrated Photonics2011In: 2011 IEEE Photonics Conference (PHO), IEEE Communications Society, 2011, p. 537-538Conference paper (Refereed)
    Abstract [en]

    Integrated nanophotonics has shown a remarkable development in recent years and can find applications in virtually all fields of photonics, though its predominant focus has so far been in telecom and lately computer interconnects. This progress has primarily been based on nanoand ΠI-V technology development, the introduction of silicon technology, with larger refractive index contrast than previously available, as well as subwavelength plasmonics structures. For the latter, a main problem, especially for ICT applications, has been the large optical loss associated with deep subwavelength confinement, as in this paper.

  • 16.
    Thylén, Lars
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Dai, Daoxin
    Bratkovsky, Alex
    Integrated photonics for interconnect: Silicon photonics,  plasmonics or something else2011Conference paper (Refereed)
  • 17.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Dainese, Matteo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Berglind, Eilert
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Technology challenges for silicon nanophotonics and beyond2007In: ICTON 2007: Proceedings of the 9th International Conference on Transparent Optical Networks, Vol 1, 2007, p. 183-188Conference paper (Refereed)
    Abstract [en]

    The development of Si-based photonics has been far behind the development of electronics for long time. There are two reasons for that. As silicon is an indirect band gap semiconductor, achieving light emission and gain is quite difficult. On the other hand, for using silicon as a light guiding material for passive devices, the main constrains until recently were relatively high propagation losses and high fiber-to-waveguide incoupling losses. The general trend towards more compact photonic devices together with progress in fabrication techniques resulted in the development of two nano-photonic technologies for next generation optical devices: photonic crystals and nanowire waveguides-based devices. To drastically increase the integration density and achieve subwavelength confinement of light along the propagation direction, plasmonic wavguides have been proposed. Surface plasmons are electromagnetic modes constituted on the interface between a metal and a dielectric. The tradeoff between the light confinement and propagation loss has here a vital importance.

1 - 17 of 17
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