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  • 1.
    Czegledi, Christian B.
    et al.
    Chalmers University of Technology, Sweden.
    Karlsson, Magnus
    Chalmers University of Technology, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Agrell, Erik
    Chalmers University of Technology, Sweden.
    Temporal stochastic channel model for absolute polarization state and polarization-mode dispersion2017In: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings, 2017Conference paper (Refereed)
    Abstract [en]

    We propose and validate a discrete-time channel model for the temporal drift of the absolute polarization state and polarization-mode dispersion for coherent fiber optic systems. The model can be used in simulations to test and develop DSP for coherent receivers.

  • 2.
    Forzati, M
    et al.
    RISE, Swedish ICT, Acreo.
    Mårtensson, J
    RISE, Swedish ICT, Acreo.
    Berntson, A
    RISE, Swedish ICT, Acreo.
    Djupsjöbacka, A
    RISE, Swedish ICT, Acreo.
    Johannisson, Pontus
    RISE, Swedish ICT, Acreo.
    Reduction of intra-channel four-wave mixing using the alternate-phase RZ modulation format2002In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 14, no 9Article in journal (Refereed)
  • 3.
    Fougstedt, Christoffer
    et al.
    Chalmers University of Technology, Sweden.
    Sheikh, Alireza
    Chalmers University of Technology, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Larsson-Edefors, Per
    Chalmers University of Technology, Sweden.
    Filter Implementation for Power-Efficient Chromatic Dispersion Compensation2018In: IEEE Photonics Journal, ISSN 1097-5764, E-ISSN 1943-0655, Vol. 10, no 4, article id 7202919Article in journal (Refereed)
    Abstract [en]

    Chromatic dispersion (CD) compensation in coherent fiber-optic systems represents a very significant DSP block in terms of power dissipation. Since spectrally efficient coherent systems are expected to find a wider deployment in systems shorter than long haul, it becomes relevant to investigate filter implementation aspects of CD compensation in the context of systems with low-to-moderate amounts of accumulated dispersion. The investigation we perform in this paper has an emphasis on implementation aspects such as power dissipation and area usage, it deals with both time-domain and frequency-domain CD compensations, and it considers both A/D-conversion quantization and fixed-point filter design aspects. To enable an accurate analysis on power dissipation and chip area, the evaluated filters are implemented in a 28-nm fully depleted silicon-on-insulator (FD-SOI) process technology. We show that an optimization of the filter response that takes pulse shaping into account can significantly reduce power dissipation and area usage of time-domain implementations, making them a viable alternative to frequency-domain implementations.

  • 4.
    Irukulapati, Maga
    et al.
    Ericsson AB, Sweden.
    Secondini, Marco
    TeCIP Institute, Italy.
    Agrell, Erik
    Chalmers University of Technology, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Wymeersch, Henk
    Chalmers University of Technology, Sweden.
    Improved Lower Bounds on Mutual Information Accounting for Nonlinear Signal--Noise Interaction2018In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 36, no 22, p. 5152-5159Article in journal (Refereed)
    Abstract [en]

    In fiber-optic communications, evaluation of mutual information (MI) is still an open issue due to the unavailability of an exact and mathematically tractable channel model. Traditionally, lower bounds on MI are computed by approximating the (original) channel with an auxiliary forward channel. In this paper, lower bounds are computed using an auxiliary backward channel, which has not been previously considered in the context of fiber-optic communications. Distributions obtained through two variations of the stochastic digital backpropagation (SDBP) algorithm are used as auxiliary backward channels and these bounds are compared with bounds obtained through the conventional digital backpropagation (DBP). Through simulations, higher information rates were achieved with SDBP, which can be explained by the ability of SDBP to account for nonlinear signal--noise interactions

  • 5.
    Johannisson, Pontus
    et al.
    RISE, Swedish ICT, Acreo.
    Anderson, D
    Berntson, A
    RISE, Swedish ICT, Acreo.
    Mårtensson, J
    RISE, Swedish ICT, Acreo.
    Generation dynamics of ghost pulses in strongly dispersion-managed fiber-optic communication systems2001In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 26, p. 1227-29Article in journal (Refereed)
  • 6.
    Johannisson, Pontus
    et al.
    RISE, Swedish ICT, Acreo.
    Anderson, D
    Marklund, M
    Berntson, A
    RISE, Swedish ICT, Acreo.
    Forzati, M
    RISE, Swedish ICT, Acreo.
    Mårtensson, J
    RISE, Swedish ICT, Acreo.
    Suppression of nonlinear effects by phase alternation in strongly dispersion-managed optical transmission2002In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 27, no 12Article in journal (Refereed)
  • 7.
    Johannisson, Pontus
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ohlsson, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Impact-driven up-conversion in piezoelectric MEMS energy harvesters with pulsed excitation2018In: Journal of Physics: Conference Series, 2018, no 1, article id 012106Conference paper (Refereed)
    Abstract [en]

    The potential of impact-driven frequency up-conversion in a MEMS EH is evaluated using numerical simulations. The investigated design is compared to a conventional cantilever EH in terms of output power and loss rate. The upshifting can lead to significantly increased output power at a similar loss rate but as the time scale for the loss is long, the benefit is limited. This also requires an effective upshifting process. The design of the impact introduces a length scale that must be selected with excitation, gravity, and pre-stress taken into account. This makes this type of EH application-dependent as a non-optimal choice may result in low output power.

  • 8.
    Johannisson, Pontus
    et al.
    RISE, Swedish ICT, Acreo.
    Ohlsson, Fredrik
    RISE, Swedish ICT, Acreo.
    Rusu, Cristina
    RISE, Swedish ICT, Acreo.
    Multi-axis piezoelectric energy harvesting using MEMS components with slanted beams2016In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 773, no 1, article id 012080Article in journal (Refereed)
    Abstract [en]

    During the manufacturing of MEMS components, slanted beams can be produced in the etching process. We show that this can be used to produce skew motion that causes deflection of a proof mass out of the device plane also when the excitation is confined to the device plane. This allows construction of an energy harvester that uses a planar manufacturing process and produces power also with in-plane excitation. To obtain this with traditional methods it would be necessary to manufacture separate components and then mount them with their sensitive axes orthogonal to each other.

  • 9.
    Larsson, S.
    et al.
    Linköping University, Sweden.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Kolev, D
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ohlsson, F
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nik, S.
    Liljeholm, J.
    Ebefors, T.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Simple method for quality factor estimation in resonating MEMS structures2018In: Proceedings of the 17th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, 2017, 2018, no 1Conference paper (Refereed)
    Abstract [en]

    The quality factor of a packaged MEMS resonating structure depends on both the packaging pressure and the structure's proximity to the walls. This type of mechanical constraints, which causes energy dissipation from the structure to the surrounding air, are applicable for oscillating energy harvesters and should be considered in the design process. However, the modelling of energy losses or the measurements of their direct influence inside a packaged chip is not trivial. In this paper, a simple experimental method to quantify the energy loss in an oscillating MEMS structures due to the surrounding air is described together with preliminary results. The main advantage of the method is the ability to characterize the damping contributions under different vacuum and packaging conditions without requiring any packaging of the harvester chip or fabrication of multiple devices with different cavity depths. © Published under licence by IOP Publishing Ltd.

  • 10.
    Mårtensson, J
    et al.
    RISE, Swedish ICT, Acreo.
    Berntson, A
    RISE, Swedish ICT, Acreo.
    Westlund, M
    Danielsson, A
    Johannisson, Pontus
    RISE, Swedish ICT, Acreo.
    Anderson, D
    Lisak, M
    Timing jitter owing to intrachannel pulse interactions in dispersion-managed transmission systems2001In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 26, p. 55-57Article in journal (Refereed)
  • 11.
    Ohlsson, Fredrik
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Johannisson, Pontus
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Rusu, Cristina
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Shape effects in doubly clamped bridge structures at large deflections2018In: Journal of Physics: Conference Series, 2018, Vol. 1052, no 1Conference paper (Refereed)
    Abstract [en]

    The shape of a doubly clamped bridge structure depends on its deflection. At large deflections, where the system exhibits nonlinear behaviour, the shape effect becomes significant. We present a general method, based on variational analysis, for computing corrections to the nominal linear regime shape function. The method is used to compute the first non-trivial correction and quantify the corresponding improvement in the large deflection regime. The model obtained is also validated using FEM simulations.

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