Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Engholm, Magnus
    et al.
    Mid Sweden University, Sweden.
    Hammarling, Krister
    Mid Sweden University, Sweden.
    Andersson, Henrik
    Mid Sweden University, Sweden.
    Sandberg, Mats
    RISE - Research Institutes of Sweden, ICT, Acreo. Mid Sweden University, Sweden.
    Nilsson, Hans Erik
    Mid Sweden University, Sweden.
    A bio-compatible fiber optic pH sensor based on a thin core interferometric technique2019In: Photonics, ISSN 2304-6732, Vol. 6, no 1, article id 11Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pH sensors concepts have been proposed, however, there is still a need for improved sensor solutions with respect to reliability, durability and miniaturization but also for multiparameter sensing. Here we present a conceptual verification, which includes theoretical simulations as well as experimental evaluation of a fiber optic pH-sensor based on a bio-compatible pH sensitive material not previously used in this context. The fiber optic sensor is based on a Mach-Zehnder interferometric technique, where the pH sensitive material is coated on a short, typically 20-25 mm thin core fiber spliced between two standard single mode fibers. The working principle of the sensor is simulated by using COMSOL Multiphysics. The simulations are used as a guideline for the construction of the sensors that have been experimentally evaluated in different liquids with pH ranging from 1.95 to 11.89. The results are promising, showing the potential for the development of bio-compatible fiber optic pH sensor with short response time, high sensitivity and broad measurement range. The developed sensor concept can find future use in many medical- or bio-chemical applications as well as in environmental monitoring of large areas. Challenges encountered during the sensor development due to variation in the design parameters are discussed. © 2019 by the authors.

  • 2.
    Kakkar, Aditya
    et al.
    KTH Royal Institute of Technology, Sweden.
    Navarro, Jaime Rodrigo
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Pang, Xiaodan
    RISE, Swedish ICT, Acreo.
    Ozolins, Oskars
    RISE, Swedish ICT, Acreo.
    Louchet, Hadrien
    VPIphotonics GmBH, Germany.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Equalization enhanced phase noise in coherent optical systems with digital pre-and post-processing2016In: Photonics, ISSN 2304-6732, Vol. 3, no 2, article id 12Article in journal (Refereed)
    Abstract [en]

    We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical system for all practical electronic dispersion compensation configurations. It is shown that there are only eight practicable all-electronic impairment mitigation configurations. The non-linear and time variant analysis reveals that the existence and the cause of EEPN depend on the digital signal processing (DSP) schemes. There are three schemes that in principle do not cause EEPN. Analysis further reveals the statistical equivalence of the remaining five system configurations resulting in EEPN. In three of them, EEPN is due to phase noise of the transmitting laser, while in the remaining two, EEPN is caused by the local oscillator. We provide a simple look-up table for the system designer to make an informative decision regarding practicable configuration choice and design.

  • 3.
    Navarro, Jaime Rodrigo
    et al.
    RISE, Swedish ICT, Acreo.
    Kakkar, Aditya
    KTH Royal Institute of Technology, Sweden.
    Pang, Xiaodan
    RISE, Swedish ICT, Acreo.
    Olmedo, Miguel Iglesias
    KTH Royal Institute of Technology, Sweden.
    Ozolins, Oskars
    RISE, Swedish ICT, Acreo.
    Da Ros, Francesco
    DTU Technical University of Denmark, Denmark.
    Piels, Molly
    DTU Technical University of Denmark, Denmark.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Zibar, Darko
    DTU Technical University of Denmark, Denmark.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo.
    Popov, Sergei
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Two-stage n-PSK partitioning carrier phase recovery scheme for circular mQAM coherent optical systems2016In: Photonics, ISSN 2304-6732, Vol. 3, no 2, article id 37Article in journal (Refereed)
    Abstract [en]

    A novel two-stage n-PSK partitioning carrier phase recovery (CPR) scheme for circular multilevel quadrature amplitude modulation (C-mQAM) constellations is presented. The first stage of the algorithm provides an initial rough estimation of the received constellation, which is utilized in the second stage for CPR. The performance of the proposed algorithm is studied through extensive simulations at the forward error correction bit error rate targets of 3.8 10-3 and 1 × 10-2 and is compared with different CPR algorithms. A significant improvement in the combined linewidth symbol duration product (ΔnTs) tolerance is achieved compared to the single-stage n-PSK partitioning scheme. Superior performance in the ΔnTs tolerance compared to the blind phase search algorithm is also reported. The relative improvements with respect to other CPR schemes are also validated experimentally for a 28-Gbaud C-16QAM back-to-back transmission system. The computational complexity of the proposed CPR scheme is studied, and reduction factors of 24.5 | 30.1 and 59.1 | 63.3 are achieved for C-16QAM and C-64QAM, respectively, compared to single-stage BPS in the form of multipliers | adders.

    Download full text (pdf)
    fulltext
  • 4.
    Navarro, Jaime Rodrigo
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Kakkar, Aditya
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Pang, Xiaodan
    KTH Royal Institute of Technology, Sweden.
    Ozolins, Oskars
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Udalcovs, Aleksejs
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Blind phase search with angular quantization noise mitigation for efficient carrier phase recovery2017In: Photonics, ISSN 2304-6732, Vol. 4, no 2, article id 37Article in journal (Refereed)
    Abstract [en]

    The inherent discrete phase search nature of the conventional blind phase search (C-BPS) algorithm is found to introduce angular quantization noise in its phase noise estimator. The angular quantization noise found in the C-BPS is shown to limit its achievable performance and its potential low complexity implementation. A novel filtered BPS algorithm (F-BPS) is proposed and demonstrated to mitigate this quantization noise by performing a low pass filter operation on the C-BPS phase noise estimator. The improved performance of the proposed F-BPS algorithm makes it possible to significantly reduce the number of necessary test phases to achieve the C-BPS performance, thereby allowing for a drastic reduction of its practical implementation complexity. The proposed F-BPS scheme performance is evaluated on a 28-Gbaud 16QAM and 64QAM both in simulations and experimentally. Results confirm a substantial improvement of the performance along with a significant reduction of its potential implementation complexity compared to that of the C-BPS.

  • 5.
    Olmedo, Miguel Iglesias
    et al.
    KTH Royal Institute of Technology, Sweden; VPI Photonics GmBH, Germany.
    Pang, Xiaodan
    RISE, Swedish ICT, Acreo.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Ozolins, Oskars
    RISE, Swedish ICT, Acreo.
    Louchet, Hadrien
    VPI Photonics GmBH, Germany.
    Zibar, Darko
    DTU Technical University of Denmark, Denmark.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo.
    Monroy, Idelfonso Tafur
    DTU Technical University of Denmark, Denmark.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Effective linewidth of semiconductor lasers for coherent optical data links2016In: Photonics, ISSN 2304-6732, Vol. 3, no 2, article id 39Article in journal (Refereed)
    Abstract [en]

    We discuss the implications of using monolithically integrated semiconductor lasers in high capacity optical coherent links suitable for metro applications, where the integration capabilities of semiconductor lasers make them an attractive candidate to reduce transceiver cost. By investigating semiconductor laser frequency noise profiles we show that carrier induced frequency noise plays an important role in system performance. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate systemperformance, and we propose an alternative figure of merit that we name "Effective Linewidth". We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28 Gbaud DP-16QAM over an optical link. Our investigations cover the use of semiconductor lasers both in the transmitter side and as a local oscillator at the receiver. The obtained results show that our proposed "effective linewidth" is easy to measure and accounts for frequency noise more accurately, and hence the penalties associated to phase noise in the received signal.

    Download full text (pdf)
    fulltext
  • 6.
    Pang, Xiaodan
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Ozolins, Oskars
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    El-Taher, Atalla
    Aston University, UK.
    Schatz, Richard
    KTH Royal Institute of Technology, Sweden.
    Jacobsen, Gunnar
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Sergeyev, Sergey
    Aston University, UK.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Experimental evaluation of impairments in unrepeatered DP-16QAM link with distributed raman amplification2017In: Photonics, ISSN 2304-6732, Vol. 4, no 1, article id 16Article in journal (Refereed)
    Abstract [en]

    The transmission impairments of a Raman amplified link using dual-polarization 16-quadrature amplitude modulation (DP-16QAM) are experimentally characterized. The impact of amplitude and phase noise on the signal due to relative intensity noise (RIN) transfer from the pump are compared for two pumping configurations: first-order backward pumping and bi-directional pumping. Experimental results indicate that with increased Raman backward pump power, though the optical signal-to-noise ratio (OSNR) is increased, so is the pump-induced amplitude and phase noise. The transmission performance is firstly improved by the enhanced OSNR at a low pump power until an optimum point is reached, and then the impairments due to pump-induced noise start to dominate. However, the introduction of a low pump power in the forward direction can further improve the system's performance.

  • 7.
    Xu, Tianhua
    et al.
    University College London, UK; Tianjin University, China.
    Jacobsen, Gunnar
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Popov, Sergei
    KTH Royal Institute of Technology, Sweden.
    Li, Jie
    RISE, Swedish ICT, Acreo.
    Liu, Tiegen
    Tianjin University, China.
    Zhang, Yimo
    Tianjin University, China.
    Bayvel, Polina
    University College London, UK.
    Analytical investigations on carrier phase recovery in dispersion-unmanaged n-PSK coherent optical communication systems2016In: Photonics, ISSN 2304-6732, Vol. 3, no 4, article id 51Article in journal (Refereed)
    Abstract [en]

    Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n-PSK) optical fiber communication systems, involving a one-tap normalized least-mean-square (LMS) algorithm, a block-wise average algorithm, and a Viterbi-Viterbi algorithm. The analytical expressions for evaluating the estimated carrier phase and for predicting the bit-error-rate (BER) performance (such as the BER floors) have been presented and discussed in the n-PSK coherent optical transmission systems by considering both the laser phase noise and the equalization enhanced phase noise. The results indicate that the Viterbi-Viterbi carrier phase recovery algorithm outperforms the one-tap normalized LMS and the block-wise average algorithms for small phase noise variance (or effective phase noise variance), while the one-tap normalized LMS algorithm shows a better performance than the other two algorithms for large phase noise variance (or effective phase noise variance). In addition, the one-tap normalized LMS algorithm is more sensitive to the level of modulation formats.

    Download full text (pdf)
    fulltext
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf