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  • 1. Chen, X.
    et al.
    Lin, R.
    Cui, J.
    Gan, L.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ozolins, O.
    Udalcovs, A.
    Jiang, T.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Fu, S.
    Liu, D.
    TDHQ Enabling Fine-Granularity Adaptive Loading for SSB-DMT Systems2018In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 30, no 19, p. 1687-1690, article id 8443443Article in journal (Refereed)
    Abstract [en]

    In this letter, we introduce time domain hybrid quadrature amplitude modulation (TDHQ) for the single sideband discrete multi-tone systems. The experimental results reveal that with a single precoding set and the proposed adaptive loading algorithm, the TDHQ scheme can achieve finer granularity and therefore smoother continuous growth of data rate than that with the conventional quadrature amplitude modulation. Besides, thanks to the frame construction and the tailored mapping rule, the scheme with TDHQ has an obviously better peak to an average power ratio. 

  • 2.
    Chung, Nguyen Xuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Limpens, Rens
    de Weerd, Chris
    Lesage, Arnon
    KTH.
    Fujii, Minoru
    Gregorkiewicz, Tom
    Toward Practical Carrier Multiplication: Donor/Acceptor Codoped Si Nanocrystals in SiO22018In: ACS Photonics, E-ISSN 2330-4022, Vol. 5, no 7, p. 2843-2849Article in journal (Refereed)
    Abstract [en]

    Carrier multiplication (CM) is an interesting fundamental phenomenon with application potential in optoelectronics and photovoltaics, and it has been shown to be promoted by quantum confinement effects in nanostructures. However, mostly due to the short lifetimes of additional electronhole (e-h) pairs generated by CM, major improvements of quantum dot devices that exploit CM are limited. Here we investigate CM in SiO2 solid state dispersions of phosphorus and boron codoped Si nanocrystals (NCs): an exotic variant of Si NCs whose photoluminescence (PL) emission energy, the optical bandgap, is significantly red-shifted in comparison to undoped Si NCs. By combining the results obtained by ultrafast induced absorption (IA) with PL quantum yield (PL QY) measurements, we demonstrate CM with a long (around 100 mu s) lifetime of the additional e-h pairs created by the process, similar as previously reported for undoped Si NCs, but with a significantly lower CM threshold energy. This constitutes a significant step toward the practical implementation of Si-based NCs in optoelectronic devices: we demonstrate efficient CM at the energy bandgap optimal for photovoltaic conversion.

  • 3.
    Da Ros, F.
    et al.
    Tech Univ Denmark, DTU Foton, DK-2800 Lyngby, Denmark..
    Cristofori, V.
    Tech Univ Denmark, DTU Foton, DK-2800 Lyngby, Denmark..
    Ozolins, O.
    Acreo Swedish ICT, NETLAB, SE-16425 Kista, Sweden..
    Chaibi, M. E.
    Univ Rennes 1, CNRS, ENSSAT, FOTON Lab,UMR 6082, F-22305 Lannion, France..
    Pang, X.
    Acreo Swedish ICT, NETLAB, SE-16425 Kista, Sweden..
    Jacobsen, G.
    Acreo Swedish ICT, NETLAB, SE-16425 Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Galili, M.
    Tech Univ Denmark, DTU Foton, DK-2800 Lyngby, Denmark..
    Oxenlowe, L. K.
    Tech Univ Denmark, DTU Foton, DK-2800 Lyngby, Denmark..
    Peucheret, C.
    Univ Rennes 1, CNRS, ENSSAT, FOTON Lab,UMR 6082, F-22305 Lannion, France..
    4-PAM Dispersion-Uncompensated Transmission with Micro-Ring Resonator Enhanced 1.55-mu m DML2017In: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Real-time transmission of 14-GBd 4-PAM signal is demonstrated by combining a commercial 1.55-mu m DML with a silicon MRR. BER below the HD-FEC threshold is measured after 26-km SSMF transmission without offline digital signal processing.

  • 4.
    Hong, Xuezhi
    et al.
    KTH Royal Inst Technol, Sch ICT, Kista, Sweden.;South China Normal Univ, ZJU SCNU Joint Res Ctr Photon, Guangzhou, Guangdong, Peoples R China..
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab). KTH Royal Inst Technol, Sch ICT, Kista, Sweden.;RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Guo, Changjian
    South China Normal Univ, ZJU SCNU Joint Res Ctr Photon, Guangzhou, Guangdong, Peoples R China..
    Nordwall, Fredrik
    Tektronix AB, Stockholm, Sweden..
    Engenhardt, Klaus M.
    Tektronix GmbH, Stuttgart, Germany..
    Kakkar, Aditya
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Rodrigo Navarro, Jaime
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Xiao, Shilin
    Shanghai Jiao Tong Univ, State Key Lab Adv Opt Commun Syst & Networks, Shanghai, Peoples R China..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    200-Gbps DMT Transmission over 1.6-km SSMF with A Single EML/DAC/PD for Optical Interconnects at C-Band2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We report on the first experimental demonstration of 200-Gbps (net rate 166.7-Gbps) 1.55-mu m DMT IMDD transmission over 1.6 km fiber using a single monolithically-integrated-EML, DAC and photodiode, achieving an effective electrical spectrum efficiency of 4.93 bit/s/Hz.

  • 5.
    Horak, Josef
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Jansson, Ronnie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Dev, Apurba
    Uppsala Univ, Ångström Lab, Solid State Elect, Uppsala Box 534, SE-75121 Uppsala, Sweden..
    Nilebäck, Linnea
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Behnam, Kiarash
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Linnros, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Hedhammar, My
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Eriksson Karlström, Amelie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Protein Engineering.
    Recombinant Spider Silk as Mediator for One-Step, Chemical-Free Surface Biofunctionalization2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 21, article id 1800206Article in journal (Refereed)
    Abstract [en]

    A unique strategy for effective, versatile, and facile surface biofunctionalization employing a recombinant spider silk protein genetically functionalized with the antibody-binding Z domain (Z-4RepCT) is reported. It is demonstrated that Z-silk can be applied to a variety of materials and platform designs as a truly one-step and chemical-free surface modification that site specifically captures antibodies while simultaneously reducing nonspecific adsorption. As a model surface, SiO2 is used to optimize and characterize Z-silk performance compared to the Z domain immobilized by a standard silanization method. First, Z-silk adsorption is investigated and verified its biofunctionality in a long-term stability experiment. To assess the binding capacity and protein-protein interaction stability of Z-silk, the coating is used to capture human antibodies in various assay formats. An eightfold higher binding capacity and 40-fold lower detection limit are obtained in the immunofluorescence assay, and the complex stability of captured antibodies is shown to be improved by a factor of 20. Applicability of Z-silk to functionalize microfluidic devices is demonstrated by antibody detection in an electrokinetic microcapillary biosensor. To test Z-silk for biomarker applications, real-time detection and quantification of human immunoglobulin G are performed in a plasma sample and C1q capture from human serum using an anti-C1q antibody.

  • 6.
    Koivurova, Matias
    et al.
    Univ Eastern Finland, Inst Photon, POB 111, FI-80101 Joensuu, Finland..
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood2018In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 10, p. 13474-13482Article in journal (Refereed)
    Abstract [en]

    We report on the experimental determination of the complete two coordinate spatial coherence function of light emitted by a quasi-random laser, implemented on recently introduced dye-doped transparent wood. The spatial coherence was measured by means of a double grating interferometer, which has some advantages over the standard Young's interferometer. Analysis of the spatial coherence reveals that emission from such a material can be considered as a superposition of several spatial modes produced by individual emitters within semi-ordered scattering medium. The overall degree of coherence, (gamma)over-bar, for this quasi-random laser was found to be 0.16 +/- 0.01, having possible applications in speckle free laser imaging and illumination.

  • 7.
    Lin, Rui
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lu, Yang
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Cheng, Yuxin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Tang, Ming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Liu, Deming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    First Experimental Demonstration of Physical-Layer Network Coding in PAM4 System for Passive Optical Interconnects2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We propose to implement physical-layer network coding (PLNC) in coupler-based passive optical interconnects. The PLNC over PAM4 system is for the first time experimentally validated, where simultaneous mutual communications can be kept within the same wavelength channel, doubling spectrum efficiency.

  • 8.
    Lin, Rui
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Belgium.
    Verplaetse, M.
    Belgium.
    Ozolins, O.
    Udalcovs, A.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    China.
    Tang, M.
    China.
    Fu, S.
    China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    China.
    Tong, W.
    China.
    De Keulenaer, T.
    Belgium.
    Torfs, G.
    Belgium.
    Bauwelinck, J.
    Belgium.
    Yin, X.
    Belgium.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Real-time 100 Gbps/λ/core NRZ and EDB IM/DD transmission over 10 km multicore fiber2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    A BiCMOS chip-based real-time IM/DD spatial division multiplexing system is experimentally demonstrated for short-reach communications. 100 Gbps/λ/core NRZ and EDB transmission is achieved below 7%-overhead HD-FEC limit after 10km 7-core fiber with optical dispersion compensation.

  • 9.
    Loiko, Pavel
    et al.
    ITMO Univ, 49 Kronverkskiy Pr, St Petersburg 197101, Russia..
    Maria Serres, Josep
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Delekta, Szymon Sollami
    KTH, School of Information and Communication Technology (ICT).
    Kifle, Esrom
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Mateos, Xavier
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain.;Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Baranov, Alexander
    ITMO Univ, 49 Kronverkskiy Pr, St Petersburg 197101, Russia..
    Aguilo, Magdalena
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Diaz, Francesc
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Griebner, Uwe
    Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Petrov, Valentin
    Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Jiantong
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Integrated devices and circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT).
    Inkjet-Printing of Graphene Saturable Absorbers for similar to 2 mu m Bulk and Waveguide Lasers2017In: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We report on inkjet-printing of graphene saturable absorbers (SAs) suitable for passive Q-switching of similar to 2-mu m bulk and waveguide lasers. Using graphene-SA in a microchip Tm:KLu(WO4)(2) laser, 1.2 mu J/136 ns pulses are generated at 1917 nm.

  • 10.
    Lu, Yang
    et al.
    KTH.
    Agrell, Erik
    Chalmers Univ Technol, Dept Elect Engn, Gothenburg, Sweden..
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Hong, Xuezhi
    KTH.
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cheng, Yuxin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Matrix Receiving Scheme Supporting Arbitrary Multiple-Wavelength Reception for Optical Interconnects2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    An arbitrary multiple-wavelength reception scheme using only a few fixed-wavelength filters is proposed for optical interconnects. Filter matrices design based on error-control coding theory is devised. The feasibility of the proposed scheme is demonstrated in a four-wavelength reception experiment.

  • 11.
    Lu, Yang
    et al.
    Hangzhou Dianzi Univ, Coll Commun Engn, Hangzhou, Zhejiang, Peoples R China..
    Agrell, Erik
    Chalmers Univ Technol, Dept Elect Engn, Gothenburg, Sweden..
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Hong, Xuezhi
    South China Normal Univ, ZJU SCNU Joint Res Ctr Photon, Guangzhou 510006, Guangdong, Peoples R China..
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Cheng, Yuxin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Multi-channel collision-free reception for optical interconnects2018In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 10, p. 13214-13222Article in journal (Refereed)
    Abstract [en]

    A multi channel reception scheme that allows each node to receive an arbitrary set of wavelengths simultaneously (i.e., collision-free) is proposed for optical interconnects. The proposed scheme only needs to use a few receivers and fixed-wavelength filters that are designed based on error-control coding theory. Experiments with up to four channel collision-free reception units are carried out to demonstrate the feasibility of the proposed scheme.

  • 12.
    Marinins, Aleksandrs
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Udalcovs, A.
    Ozolins, O.
    Pang, X.
    Veinot, J.
    Jacobsen, G.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Linnros, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    All-optical intensity modulation in polymer waveguides doped with si quantum dots2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We demonstrate all-optical intensity modulation in integrated PMMA optical waveguides doped with silicon quantum dots. The 1550 nm probe signal is absorbed by free carriers excited in silicon quantum dots with 405 nm pump light.

  • 13. Navarro, J. R.
    et al.
    Udalcovs, A.
    Pang, Xiaodan
    KTH, School of Information and Communication Technology (ICT).
    Ozolins, O.
    Kakkar, Aditya
    KTH, School of Engineering Sciences (SCI).
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI).
    Nordwall, F.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    High phase noise tolerant circular-64QAM with efficient phase recovery for coherent optical systems2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate the significant phase noise tolerance increase of 28Gbaud circular-64QAM constellations against its square-64QAM counterpart with a novel, low complexity and high-performance phase recovery scheme employing only 8 test phases.

  • 14.
    Oxenløwe, L. K.
    et al.
    Denmark.
    Jia, S.
    Denmark.
    Pang, X.
    Ozolins, O.
    Yu, X.
    China.
    Hu, H.
    Guan, P.
    Da Ros, F.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Galili, M.
    Denmark.
    Zibar, D.
    Denmark.
    Morioka, T.
    Denmark.
    100s gigabit/s THz communication2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of recent progress on the topic of using around 0.4 THz carriers for communications. Experimental demonstrations will be described, and concepts and pros & cons of various system-platforms discussed.

  • 15. Ozolins, O.
    et al.
    Da Ros, F.
    Cristofori, V.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, A.
    Schatz, R.
    Oxenløwe, L. K.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Peucheret, C.
    Impact of phase-filtering on optical spectral reshaping with microring resonators for directly-modulated 4-PAM signals2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We investigate microring resonator (MRRs)-based optical spectral reshaping for directly-modulated 4-PAM signals. The phase-filtering of MRR, and consequent dispersion added to the signal, yields 120% reach increase compared to the 95% of amplitude-only filtering.

  • 16. Ozolins, O.
    et al.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, A.
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Gan, L.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Fu, S.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Liu, D.
    Tong, W.
    Torfs, G.
    Bauwelinck, J.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yin, X.
    7×149 Gbit/s PAM4 transmission over 1 km multicore fiber for short-reach optical interconnects2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We transmit 80 Gbaud/λ/core PAM4 signal enabled by 1.55 μm EML over 1 km 7-core fiber. The solution achieves single-wavelength and single-fiber 1.04 Tbit/s post-FEC transmission enhancing bandwidth-density for short-reach optical interconnects.

  • 17. Ozolins, O.
    et al.
    Udalcovs, A.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Djupsjöbacka, A.
    Mårtensson, J.
    Fröjdh, K.
    Gan, L.
    Tang, M.
    Fu, S.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    Tong, W.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    112 Gbps/λ PAM4 inter-DCI with continuous-fiber Bragg grating based dispersion compensators2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    We demonstrate 56 Gbaud/λ PAM4 inter - data center interconnects over 81 km single core single mode fiber and 33.6 km 7-core single mode fiber with continuous-fiber Bragg grating based chromatic dispersion compensators covering C-band.

  • 18.
    Ozolins, Oskars
    et al.
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Pang, Xiaodan
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden.;KTH Royal Inst Technol, Sch ICT, Stockholm, Sweden.;KTH Royal Inst Technol, Sch SCI, Stockholm, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. KTH Royal Inst Technol, Sch ICT, Stockholm, Sweden.;KTH Royal Inst Technol, Sch SCI, Stockholm, Sweden..
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Rodrigo Navarro, Jaime
    Kakkar, Aditya
    KTH.
    Nordwall, Fredrik
    Tektronix AB, Stockholm, Sweden..
    Engenhardt, Klaus M.
    Tektronix GmbH, Stuttgart, Germany..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    100 Gbaud 4PAM Link for High Speed Optical Interconnects2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We demonstrate 100 Gbaud 4PAM transmission over 400 meters SMF with monolithically integrated 1550 nm DFB-TWEAM having 100 GHz 3-dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable two lanes 400 GbE client-side links for optical interconnects.

  • 19.
    Pang, Xiaodan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Storck, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Maisons, Gregory
    mirSense, Ctr Integrat Nanolnnov, F-91120 Palaiseau, France..
    Carras, Mathieu
    mirSense, Ctr Integrat Nanolnnov, F-91120 Palaiseau, France..
    Xiao, Shilin
    Shanghai Jiao Tong Univ, State Key Lab Adv Opt Commun Syst & Networks, Shanghai, Peoples R China..
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lourdudoss, Sebastian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    4 Gbps PAM-4 and DMT Free Space Transmission using A 4.65-mu m Quantum Cascaded Laser at Room Temperature2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate 4Gbps PAM-4 and DMT transmissions using a quantum cascaded laser (QCL) emitting at mid-wavelength infrared of 4.65-mu m and a commercial infrared photovoltaic detector. The QCL is directly modulated and operated at room temperature with Peltier Cooling.

  • 20.
    Pang, Xiaodan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab). DLab., INTEC, Ghent University - Imec, Gent, BelgiumDLab., INTEC, Ghent University - Imec, Gent, Belgium.
    Van Kerrebrouck, J.
    Ozolins, O.
    Lin, R.
    Udalcovs, A.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Spiga, S.
    Amann, M. C.
    Van Steenberge, G.
    Gan, L.
    Tang, M.
    Fu, S.
    Schatz, R.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    Tong, W.
    Torfs, G.
    Bauwelinck, J.
    Yin, X.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    7×100 Gbps PAM-4 transmission over 1-km and 10-km single mode 7-core fiber using 1.5-μm SM-VCSEL2018In: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-3Conference paper (Refereed)
    Abstract [en]

    100 Gbps/λ/core PAM-4 transmission is successfully demonstrated over 1-km and 10-km single mode 7-core fiber links, enabled by directly modulated 1.5-μm single mode VCSEL of 23 GHz modulation bandwidth with pre- and post-digital equalizations. © 2018 OSA.

  • 21.
    Pang, Xiaodan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Belgium.
    Ozolins, O.
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, A.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Spiga, S.
    Germany.
    Amann, M. C.
    Germany.
    Van Steenberge, G.
    Belgium.
    Gan, L.
    China.
    Tang, M.
    China.
    Fu, S.
    China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    China.
    Tong, W.
    China.
    Torfs, G.
    Belgium.
    Bauwelinck, J.
    Belgium.
    Yin, X.
    Belgium.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    7×100 Gbps PAM-4 transmission over 1-km and 10-km single mode 7-core fiber using 1.5-μm SM-VCSEL2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    100 Gbps/λ/core PAM-4 transmission is successfully demonstrated over 1-km and 10- km single mode 7-core fiber links, enabled by directly modulated 1.5-μm single mode VCSEL of 23 GHz modulation bandwidth with pre- and post- digital equalizations.

  • 22.
    Pang, Xiaodan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Belgium.
    Ozolins, O.
    Sweden.
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, A.
    Sweden.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Spiga, S.
    Germany.
    Amann, M. C.
    Germany.
    Van Steenberge, G.
    Belgium.
    Gan, L.
    China.
    Tang, M.
    China.
    Fu, S.
    China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Sweden.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    China.
    Tong, W.
    China.
    Torfs, G.
    Belgium.
    Bauwelinck, J.
    Belgium.
    Yin, X.
    Belgium.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    High-speed SDM interconnects with directly-modulated 1.5-μm VCSEL enabled by low-complexity signal processing techniques2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    We report on our recent work in supporting up to 100 Gbps/λ/core transmissions with a directly modulated 1.5-μm single mode VCSEL and multicore fiber, enabled by low-compleixty pre- and post- digital equalizations.

  • 23.
    Pevere, Federico
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Optical Properties of Single Silicon Quantum Dots2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    For over 60 years silicon (Si) has dominated the semiconductor microelectronics industry mainly due to its abundance and good electrical and material properties. The advanced processing technology of Si has made it the workhorse for photovoltaics industry as well. However, this material has also a big drawback: it is an indirect-bandgap semiconductor in its bulk form, hence an inefficient light emitter. This has hindered the silicon photonics revolution envisioned in 1980s, where photons were thought to replace electrons inside computer chips.

    In parallel with the exponential scaling of Si transistor's size over the years, the discovery of quantum phenomena at the nanoscale raised new hopes for this semiconductor. In the 1990s bright luminescence from nanostructured porous Si was demonstrated claiming the quantum confinement effect as origin of the emission. Since then, an intense research activity has been focused on Si quantum dots (Si-QDs) due to their potential use as abundant and non-toxic light emitters. More precisely, they could be used as fluorescent biolabels in biomedicine, as light-emitting phosphors in e.g. TV screens or as down-converters in luminescent solar concentrators. Nevertheless, in order to realize such applications, it is necessary not only to improve the fabrication of Si-QDs but also to gain a better understanding of their photo-physics. Among different types of optical measurements, those performed at the single-dot level are free of sample inhomogeneities, hence more accurate for a correct physical description.

    This doctoral thesis presents a study of the optical properties of single Si-QDs of different type: encapsulated in an oxide matrix, capped with ligands or covered by a thin passivation layer. The homogeneous photoluminescence (PL) linewidth is found to strongly depend on the type of embedding matrix, being narrower for less rigid ones. A record resolution-limited linewidth of ~200 μeV is measured at low temperatures whereas room-temperature values can even compete with direct-bandgap QDs like CdSe. Such narrow PL lines exhibit intensity saturation at high excitation fluxes without any indication of emission from multiexciton states, suggesting the presence of fast non-radiative Auger recombination. Characteristic Auger-related lifetimes extracted from power-dependent decays show a variation from dot-to-dot and confirm the low biexciton quantum efficiency.

    For the first time, the absorption curve of single Si-QDs is probed by means of photoluminescence excitation in the range 2.0-3.5 eV. A step-like structure is found which depends on the nanocrystal shape considered and agrees well with simulations of the exciton level structure. Rod-like Si-QDs can exhibit ~50 times higher absorption than spherical-like ones due to local field effects and enhanced optical transitions. In contrast with previous studies, evidence of a direct-bandgap red-shift for small Si-QDs is missing at the single dot level, in agreement with atomistic calculations.

    Low-temperature PL decay measurements reveal no triplet-like emission lines, but two ~μs decay constants appearing at low temperatures. They suggest presence of a temperature-dependent fast blinking process based on trapping/detrapping of carriers in the oxide matrix, leading to delayed emission. The proposed model allows to extract characteristic trapping/de-trapping rates for Si-QDs featuring mono-exponential blinking statistics. From PL saturation curves, ligand-passivated Si-QDs do not exhibit such detrimental phenomenon, in agreement with the proposed model.

    Last, Si-QDs demonstrate to be very hard against ~10 keV X-ray radiation, in contrast with CdSe-QDs whose PL quenching is correlated with a change in the blinking parameters. This property could be exploited for example in space applications, where radiation-hard materials are required.

    To conclude, the results achieved in this thesis will help to understand and engineer the properties of Si-QDs whose application potential has increased after several years of research both at the ensemble and at the single-dot level.

  • 24.
    Pevere, Federico
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    von Treskow, Carl
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Marino, Emanuele
    Van der Waals – Zeeman Institute, University of Amsterdam, The Netherlands.
    Anwar, Monib
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Linnros, Jan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    X-ray radiation hardness and influence on blinking in Si and CdSe quantum dotsManuscript (preprint) (Other academic)
  • 25.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Fiber laser overview and medical applications2016In: Tunable Laser Applications, Third Edition, CRC Press , 2016, p. 263-292Chapter in book (Other academic)
  • 26. Rosa, P.
    et al.
    Rizzelli, G.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, O.
    Udalcovs, A.
    Tan, M.
    Sergeyev, S.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ania-Castaño´n, J. D.
    Unrepeatered 64QAM over SMF-28 using Raman amplification and digital backpropagation2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
    Abstract [en]

    Unrepeatered transmission over SMF-28 fibre is investigated using Raman based amplification. Experiments and simulations demonstrate a transmission up to 200 km (41 dB) span length using 28Gbaud 64 QAM modulation employing digital back propagation in DSP.

  • 27.
    Udalcovs, A.
    et al.
    Sweden.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, O.
    Sweden.
    Lin, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Djupsjöbacka, A.
    Sweden.
    Mårtensson, J.
    Sweden.
    Tang, M.
    China.
    Fu, S.
    China.
    Liu, D.
    China.
    Tong, W.
    China.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, G.
    Sweden.
    MCF-enabled self-homodyne 16/64QAM transmission for SDM optical access networks2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a 28-Gbaud circular and square 16/64QAM transmission over a 33.6-km long seven-core fiber with the LO passed through one of the cores for self-homodyne coherent detection employing a low-complexity digital signal processing.

  • 28.
    Udalcovs, Aleksejs
    et al.
    KTH.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Monti, Paolo
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Navarro, Julien R. G.
    KTH, School of Engineering Sciences (SCI).
    Kakkar, Aditya
    KTH, School of Engineering Sciences (SCI).
    Louchet, H.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Wosinska, Lena
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Jacobsen, Gunnar
    Quantifying spectral and energy efficiency limitations of WDM networks due to crosstalk in optical nodes2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
    Abstract [en]

    We demonstrate the significant impact of crosstalk between add and drop ports at optical nodes on energy-efficiency per Hertz in WDM networks employing 32/64 Gbd DP-16QAM transmission, especially when the isolation is reduced to 30dB.

  • 29.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Effect of transparent wood on polarization degree of lightManuscript (preprint) (Other academic)
  • 30.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Light propagation in an anisotropically scattering medium2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Scattering is the main phenomenon of light-matter interaction. In this thesis, we consider one specific case of light propagation in a material whose structure causes anisotropic optical scattering - transparent wood. As a substance with properties interesting for research in optics/photonics, this biocomposite material began to be used quite recently, even though it was initially developed for the study of the internal structure of wood a few decades ago. Besides the anisotropy, the structure has a hierarchal arrangement with features ranging from nanometers up to micrometer sizes, and demonstrates short and long-distance natural ordering which is neither perfect nor totally random. The main interest in transparent wood within the field of optics is due to its remarkable combination of unique structure and optical transparency. There has been much research done on light propagation in diffusive media and/or structurally ordered materials, and in this sense, transparent wood occupies an intermediate niche for investigation. Since transparent wood is a relatively new material, there is a lack of methods of reliable study of its properties. Although there have been some attempts to characterize the optical properties of transparent wood via transmittance and haze (for scattering properties), insufficient understanding of the physical processes behind light propagation within the substance, scattering in particular, leaves a gap in data interpretation for measured parameters and their correlation with the material structure. In this thesis, we present our efforts to fill this gap through means of a more detailed and physically justified description of light propagation in an anisotropically scattering medium. In order to familiarize readers with the subject, we provide a short summary of the structural features, fabrication technology and chemical composition of transparent wood. We discuss issues related to the conventionally applied approach of haze measuring as a characterization method of the scattering in such anisotropic materials as transparent wood. We demonstrate a certain limitation of the haze criterion applicability and instead, suggest a modified characterization routine and parameters, such as transport mean free path, and degree of anisotropic scattering, for estimation of scattering properties of the material. We also discuss the dependence of scattering efficiency on the polarization state of incident light. Due to polarization-dependent scattering, unpolarized light propagating through transparent wood becomes partially polarized, with the angle of polarization oriented perpendicularly to the largest structural components of wood (vessels) which are co-aligned with the wood fibers. At the same time, the polarization degree of completely polarized incident light decreases after propagating through the material. The depolarization of light is attributed to the collective scattering by cellulose fibrils organized in the lamellae of cell walls of the fibers, and is strongly dependent on mutual v orientation of oscillations of the electric field (polarization of light) relative to the long axes of fibers. Transparent wood with its sponge-like structure can be an attractive platform for doping with various additives. In our project, we demonstrate an example of doping of a transparent wood template with organic dye (Rhodamine 6G). The combination of high scattering and optical gain results in the possibility of obtaining laser emission. By analogy with random lasers, there is no external resonator, however, the optical feedback is provided via scattering on inhomogeneity of the internal structure of the medium combining transparent wood and dye. The wood structure has a natural ordering, whereas in random lasers, in general, scatterers are randomly distributed within an active material. Therefore, we refer to such a laser as a “quasi-random” laser, to emphasize this difference. Based on experimental results and the comparative analysis with a reference sample (a polymer-dye), we have shown that wood fibers with highly scattering walls that are the main structural components of the transparent wood can operate as small lasers not correlated with each other. The collective origin of the laser emission of a wood-dye laser is reflected in the emission-line broadening of several nanometers. Measured low spatial coherence and high radiation brightness make this type of laser attractive for the application of speckle-free imaging and illumination. The work demonstrated in this thesis can be useful for further investigation and simulations of light scattering inside the biocomposite and similar anisotropic media. Moreover, the demonstrably successful example of expanding transparent wood functionality definitely creates new opportunities for further research and application of this substance.

  • 31.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Light Scattering by Structurally Anisotropic Media: A Benchmark with Transparent Wood2018In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) is a biocomposite material with hierarchical structure, which exhibits high optical transmittance and anisotropic light scattering. Here, the relation between anisotropic scattering and the internal structure of transparent wood is experimentally studied and the dependence of scattering anisotropy on material thickness, which characterizes the fraction of ballistic photons in the propagating light, is shown. The limitations of the conven-tional haze, as it is implemented to isotropic materials, are discussed, and a modified characteristic parameter of light scattering—the degree of aniso-tropic scattering is defined. This parameter together with the transport mean free path value is more practical and convenient for characterization of the material scattering properties. It is believed that the generic routine described in this paper can be applied for scattering characterization and comparison of other TW materials of either different thickness, optical quality or based on various wood species.

  • 32.
    Xu, Tianhua
    et al.
    Univ Warwick, Coventry CV4 7AL, W Midlands, England..
    Jacobsen, Gunnar
    RISE Acreo AB, SE-16440 Stockholm, Sweden..
    Li, Jie
    RISE Acreo AB, SE-16440 Stockholm, Sweden..
    Leeson, Mark
    Univ Warwick, Coventry CV4 7AL, W Midlands, England..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Dynamic physical layer equalization in optical communication networks2018In: Optoelectronics and Advanced Materials Rapid Communications, ISSN 1842-6573, E-ISSN 2065-3824, Vol. 12, no 5-6, p. 292-298Article in journal (Refereed)
    Abstract [en]

    In optical transport networks, signal lightpaths between two terminal nodes can be different due to current network conditions. Thus the transmission distance and accumulated dispersion in the lightpath cannot be predicted. Therefore, the adaptive compensation of dynamic dispersion is necessary in such networks to enable flexible routing and switching. In this paper, we present a detailed analysis on the adaptive dispersion compensation using the least-mean-square (LMS) algorithm in coherent optical communication networks. It is found that the variable-step-size LMS equalizer can achieve the same performance with a lower complexity, compared to the traditional LMS algorithm.

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