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  • 1. Abbas, Syed Sohail
    et al.
    Popov, Sergei Yu
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Compact Er 3+-doped ZBLAN green upconversion fibre laser2011In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, Vol. 78, p. 756-758Article in journal (Refereed)
    Abstract [en]

    In this paper, a fibre laser at 546 nm has been studied for a signal power of -30 dB. Er 3+-doped ZBLAN fibre has been used by upconversion pumping of a 980 nm laser diode. Gain saturation effect has been investigated in detail. Laser performance has also been discussed. An efficiency of 35% has been calculated with a length of 5 mm fibre laser. Results show that Er 3+-doped ZBLAN is a promising candidate for optical amplification at 546 nm.

  • 2. Al-Awis, S. N.
    et al.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Photonics and Microwave Engineering , FMI.
    Pang, Xiaodan
    RISE ACREO AB.
    Ozolins, O.
    Jacobsen, Gunnar
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Photonics and Microwave Engineering , FMI.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Fattah, A. Y.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Phenomenological formula for modelling of physical layer impairments in elastic optical networks2015In: Asia Communications and Photonics Conference, ACPC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    An empirical modelling technique is introduced to estimate impact of physical layer impairments in elastic optical networks, which can be used to evaluate transmission quality. The model has been verified experimentally with accuracy beyond (97.3%).

  • 3.
    Berglund, Lars
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Fu, Qiliang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Yang, Min
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Modification of transparent wood for photonics functions2018In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 4.
    Chen, Bin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Montanari, Celine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. 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.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    A distortion-map-based method for morphology generation in multi-phase materials - application to wood2023In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 244, article id 110262Article in journal (Refereed)
    Abstract [en]

    Increased use of multi-phase, wood-based biocomposites may contribute to sustainable development. The porous microstructure offers unique possibilities for modification, but global properties are often predicted based on simplified unit cells and homogenization. For materials design, simulations based on complex 3D microstructures with statistical variability are alternatives to better understanding physical properties. Parametric models are developed in a distortion-map-based method to represent 3D wood microstructures. Basic structures of uniform tubular cells and other features are generated followed by distortion mapping. These maps are highly adaptable and can generate realistic features and variability. Fibers, vessels, and ray cells are realistically distributed. The models are realistic, versatile, and scalable, as well as can be used to simulate the mechanical, optical, and hydrodynamic properties of complex composites. The model is promising for generating large sets of data to train deep learning networks for multi-physics research.

  • 5.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Baitenov, Adil
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yan, Max
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

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  • 6.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Montanari, Celine
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Yan, Max
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Refractive index of delignified wood for transparent biocomposites2020In: RSC Advances, E-ISSN 2046-2069, Vol. 10, p. 40719-40724Article in journal (Refereed)
    Abstract [en]

    Refractive index (RI) determination for delignified wood templates is vital for transparent wood composite fabrication. Reported RIs in the literature are based on either single plant fibers or wood powder, measured by the immersion liquid method (ILM) combined with mathematical fitting. However, wood structure complexity and the physical background of the fitting were not considered. In this work, RIs of delignified wood templates were measured by the ILM combined with a light transmission model developed from the Fresnel reflection/refraction theory for composite materials. The RIs of delignified balsa wood are 1.536 ± 0.006 and 1.525 ± 0.008 at the wavelength of 589 nm for light propagating perpendicular and parallel to the wood fiber direction, respectively. For delignified birch wood, corresponding values are 1.537 ± 0.005 and 1.529 ± 0.006, respectively. The RI data for delignified wood scaffolds are important for tailoring optical properties of transparent wood biocomposites, and also vital in optical properties investigations by theoretical modelling of complex light propagation in transparent wood and related composites. The developed light transmission model in combination with the immersion liquid method can be used to determine the RI of complex porous or layered solid materials and composites.

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    fulltext
  • 7. 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), Computer Science, 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. 

  • 8. Cristofori, Valentina
    et al.
    Da Ros, Francesco
    Ozolins, Oskars
    Chaibi, Mohamed E.
    Bramerie, Laurent
    Ding, Yunhong
    Pang, Xiaodan
    Shen, Alexandre
    Gallet, Antonin
    Duan, Guang-Hua
    Hassan, Karim
    Olivier, Segolene
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jacobsen, Gunnar
    Oxenlowe, Leif K.
    Peucheret, Christophe
    25-Gb/s Transmission Over 2.5-km SSMF by Silicon MRR Enhanced 1.55-mu m III-V/SOI DML2017In: 30th Annual Conference of the IEEE Photonics Society  (IPC), Institute of Electrical and Electronics Engineers (IEEE), 2017, Vol. 2017, p. 357-360Conference paper (Refereed)
    Abstract [en]

    The use of a micro-ring resonator (MRR) to enhance the modulation extinction ratio and dispersion tolerance of a directly modulated laser (DML) is experimentally investigated with a bit rate of 25 Gb/s as proposed for the next generation data center communications. The investigated system combines a 11-GHz 1.55-mu m directly modulated hybrid III-V/SOI DFB laser realized by bonding III-V materials (InGaAIAs) on a silicon on-insulator (SOI) wafer and a silicon MRR also fabricated on SOL Such a transmitter enables error-free transmission (BER< 10(-9)) at 25 Gb/s data rate over 2.5-km SSMF without dispersion compensation nor forward error correction (FEC). As both laser and MRR are fabricated on the SOI platform, they could be combined into a single device with enhanced performance, thus providing a cost-effective transmitter for short reach applications.

  • 9. Cristofori, Valentina
    et al.
    Da Ros, Francesco
    Ozolins, Oskars
    Chaibi, Mohamed E.
    Bramerie, Laurent
    Ding, Yunhong
    Pang, Xiaodan
    Shen, Alexandre
    Gallet, Antonin
    Duan, Guang-Hua
    Hassan, Karim
    Olivier, Segolene
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Jacobsen, Gunnar
    Oxenlowe, Leif K.
    Peucheret, Christophe
    25-Gb/s Transmission Over 2.5-km SSMF by Silicon MRR Enhanced 1.55-mu m III-V/SOI DML2017In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 29, no 12, p. 960-963Article in journal (Refereed)
    Abstract [en]

    The use of a micro-ring resonator (MRR) to enhance the modulation extinction ratio and dispersion tolerance of a directly modulated laser is experimentally investigated with a bit rate of 25 Gb/s as proposed for the next generation data center communications. The investigated system combines a 11-GHz 1.55-mu m directly modulated hybrid III-V/SOI DFB laser realized by bonding III-V materials (InGaAlAs) on a silicon-on-insulator (SOI) wafer and a silicon MRR also fabricated on SOI. Such a transmitter enables error-free transmission (BER < 10(-9)) at 25 Gb/s data rate over 2.5-km standard single mode fiber without dispersion compensation nor forward error correction. As both laser and MRR are fabricated on the SOI platform, they could be combined into a single device with enhanced performance, thus providing a cost-effective transmitter for short reach applications.

  • 10.
    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, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS, Optical Network Laboratory (ON Lab). KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE ACREO AB.
    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.
    Oxenløwe, 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-μm DML2017In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2017, Vol. Part F41Conference paper (Refereed)
    Abstract [en]

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

  • 11. da Silva, Edson P.
    et al.
    Borkowski, Robert
    Preussler, Stefan
    Schwartau, Fabian
    Gaiarin, Simone
    Olmedo, Miguel I.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Vedadi, Armand
    Piels, Molly
    Galili, Michael
    Guan, Pengyu
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Bres, Camille-Sophie
    Schneider, Thomas
    Oxenlowe, Leif K.
    Zibar, Darko
    Combined Optical and Electrical Spectrum Shaping for High-Baud-Rate Nyquist-WDM Transceivers2016In: IEEE Photonics Journal, E-ISSN 1943-0655, Vol. 8, no 1, article id 7801411Article in journal (Refereed)
    Abstract [en]

    We discuss the benefits and limitations of optical time-division multiplexing (OTDM) techniques based on the optical generation of a periodic train of sinc pulses for wavelength-division multiplexing (WDM) transmission at high baud rates. It is shown how the modulated OTDM spectrum bandwidth is related to the optical comb parameters and the pulse shaping of the modulating waveforms in the electrical domain. Such dependence may result in broadening of the modulated spectra, which can degrade the performance of Nyquist-WDM systems due to interchannel crosstalk penalties. However, it is shown and experimentally demonstrated that the same technique of optical pulse train generation can be allied with digital pulse shaping to improve the confinement of the modulated spectrum toward the Nyquist limit independently of the number of OTDM tributaries used. To investigate the benefits of the proposed approach, we demonstrate the first WDM Nyquist-OTDM signal generation based on the periodic train of sinc pulses and electrical spectrum shaping. Straight line transmission of five 112.5-Gbd Nyquist-OTDM dual-polarization quadrature phase-shift keying (QPSK) channels is demonstrated over a dispersion uncompensated link up to 640 km, with full-field coherent detection at the receiver. It is shown that such a design strategy effectively improves the spectral confinement of the modulated OTDM signal, providing a minimum intercarrier crosstalk penalty of 1.5 dB in baud-rate-spaced Nyquist-WDM systems.

  • 12.
    Dely, Hamza
    et al.
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Joharifar, Mahdieh
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Gacemi, Djamal
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Salgals, Toms
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sun, Yan-Ting
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Bonazzi, Thomas
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Rodriguez, Etienne
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Todorov, Yanko
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Vasanelli, Angela
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    Udalcovs, Aleksejs
    RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Spolitis, Sandis
    KTH, School of Engineering Sciences (SCI), Applied Physics. Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Bobrovs, Vjaceslavs
    KTH, School of Engineering Sciences (SCI), Applied Physics. Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden.;Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sirtori, Arlo
    Sorbonne Univ, Univ Paris Cite, CNRS, Lab Phys, Ecole Normale Super, ENS, F-75005 Paris, France..
    High bitrate data transmission in the 8-14 mu m atmospheric window using an external Stark-effect modulator with digital equalization2023In: Optics Express, E-ISSN 1094-4087, Vol. 31, no 5, p. 7259-7264Article in journal (Refereed)
    Abstract [en]

    High bitrate mid-infrared links using simple (NRZ) and multi-level (PAM-4) data coding schemes have been realized in the 8 pm to 14 pm atmospheric transparency window. The free space optics system is composed of unipolar quantum optoelectronic devices, namely a continuous wave quantum cascade laser, an external Stark-effect modulator and a quantum cascade detector, all operating at room-temperature. Pre- and post-processing are implemented to get enhanced bitrates, especially for PAM-4 where inter-symbol interference and noise are particularly detrimental to symbol demodulation. By exploiting these equalization procedures, our system, with a full frequency cutoff of 2 GHz, has reached transmission bitrates of 12 Gbit/s NRZ and 11 Gbit/s PAM-4 fulfilling the 6.25 % overhead hard-decision forward error correction threshold, limited only by the low signal-to-noise ratio of our detector.

  • 13.
    Deng, Qiuzhuo
    et al.
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China..
    Zhang, Lu
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 311121, Peoples R China..
    Zhang, Hongqi
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China..
    Yang, Zuomin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China..
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Bobrovs, Vjaceslavs
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Wu, Yixin
    Huawei Technol Co Ltd, Inst Strateg Res, Shenzhen 518055, Peoples R China..
    Yu, Xiongbin
    Huawei Technol Co Ltd, Inst Strateg Res, Shenzhen 518055, Peoples R China..
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden. ; Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Yu, Xianbin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 311121, Peoples R China..
    Quantum Noise Secured Terahertz Communications2023In: 2023 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION, OFC, Optica Publishing Group , 2023Conference paper (Refereed)
    Abstract [en]

    The quantum noise based terahertz signal encryption scheme is proposed, a 16 Gbits(-1) secure terahertz communication system at 300 GHz with the optical communication realms is demonstrated, taking a significant step toward high-security wireless communications.

  • 14. Derksen, R. H.
    et al.
    Wang, K.
    Networking and Transmission Laboratory, Acreo AB, Electrum 236, Kista, SE-164 40, Sweden;Royal Institute of Technology, Electrum 229, Kista, SE-164 40, Sweden; Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing, 100081, China.
    Li, J.
    Djupsjöbacka, A.
    Jacobsen, G.
    Chacinski, Marek
    KTH.
    Westergren, Urban
    KTH.
    Popov, Sergei
    KTH.
    Hurm, V.
    Makon, R. E.
    Driad, R.
    Walcher, H.
    Rosenzweig, J.
    Steffan, A. G.
    Mekonnen, G. G.
    Bach, H. -G
    Schubert, C.
    Setting the stage for 100GbE serial standard - The HECTO project2010In: World Telecommunications Congress 2010, WTC 2010, VDE Verlag GmbH , 2010, p. 118-123Conference paper (Refereed)
    Abstract [en]

    The standard for 100GbE will be adopted in 2010, defining transmission via 4 x 25 Gbit/s. A solution employing 1 x 100 Gbit/s would be cheaper - if the appropriate integrated components were available. These components now have been developed in the project HECTO. The project is shortly described and the main results are presented: the achieved performance of the components itself and the achieved system performance in a field trial. The complete ETDM system with monolithically integrated transmitter and receiver modules featured BER performance below standard FEC threshold (2 - 10 -3 ) in a field-link transmission with 112 Gbit/s over 42 km standard single-mode fibre.

  • 15.
    Ding, Jiazheng
    et al.
    Tianjin Univ, Sch Precis Instruments & Optoelect Engn, Tianjin 300072, Peoples R China..
    Liu, Tiegen
    Tianjin Univ, Sch Precis Instruments & Optoelect Engn, Tianjin 300072, Peoples R China..
    Xu, Tongyang
    Newcastle Univ, Sch Engn, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England.;UCL, Dept Elect & Elect Engn, London W E 7JE, England.;Tianjin Univ, Tianjin 300072, Peoples R China.;UCL, London W E 6BT, England..
    Hu, Wenxiu
    Univ Warwick, Sch Engn, Coventry CV4 7AL, W Midlands, England..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Leeson, Mark S.
    Univ Warwick, Sch Engn, Coventry CV4 7AL, W Midlands, England..
    Zhao, Jian
    Tianjin Univ, Sch Precis Instruments & Optoelect Engn, Tianjin 300072, Peoples R China..
    Xu, Tianhua
    Univ Warwick, Sch Engn, Coventry CV4 7AL, W Midlands, England..
    Intra-Channel Nonlinearity Mitigation in Optical Fiber Transmission Systems Using Perturbation-Based Neural Network2022In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 40, no 21, p. 7106-7116Article in journal (Refereed)
    Abstract [en]

    In this work, a perturbation-based neural network (P-NN) scheme with an embedded bidirectional long short-term memory (biLSTM) layer is investigated to compensate for the Kerr fiber nonlinearity in optical fiber communication systems. Numerical simulations have been carried out in a 32-Gbaud dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM) transmission system. It is shown that this P-NN equalizer can achieve signal-to-noise ratio improvements of similar to 1.37 dB and similar to 0.80 dB, compared to the use of a linear equalizer and a single step per span (StPS) digital back propagation (DBP) scheme, respectively. The P-NN equalizer requires lower computational complexity and can effectively compensate for intra-channel nonlinearity. Meanwhile, the performance of P-NN is more robust to the distortion caused by equalization enhanced phase noise (EEPN). Furthermore, it is also found that there exists a tradeoff between the choice of modulation format and the nonlinear equalization schemes for a given transmission distance.

  • 16.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Zhejiang University, China.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Influence of nanoparticles concentration on fluorescence quenching in gold/rhodamine 6G nanoassemblies2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, Optical Society of America, 2009, p. 5377045-Conference paper (Refereed)
    Abstract [en]

    Fluorescence enhancement of dye solution doped with gold nanoparticles is a well-known effect. However, depending on size and concentration, nanoparticles can also deteriorate dye lasing properties due to increased quenching of the excited molecules. Here we report experimental results on such dependence of fluorescence degradation on the nanoparticle concentration.

  • 17.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Iyer, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    3D fabrication of waveguide and grating coupler in SU-8 by optimized gray scale electron beam lithography2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 2010, p. 542-543Conference paper (Refereed)
    Abstract [en]

    Gray scale electron beam lithography is optimized for simple and accurate prototyping of 3D waveguides and grating output couplers in SU-8. Gratings with complex profiles and free of lag effect can be realized with this technique.

  • 18.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Iyer, Srinivasan
    KTH, School of Information and Communication Technology (ICT).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT).
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT). Aalto University, Finland.
    Gray scale E-beam lithography to fabricate 3D microsized waveguide and grating coupler in SU-82010In: Frontiers in Optics, 2010Conference paper (Refereed)
    Abstract [en]

    Gray scale electron beam lithography is applied to prototype 3D waveguides and grating output couplers in SU-8 with simple and accurate method. The lag effect in reactive ion etching of Silicon-on-insulator gratings is avoided here.

  • 19.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Measurement of radiative lifetime in CdSe/CdS core/shell structured quantum dots2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, p. 5377385-Conference paper (Refereed)
    Abstract [en]

    Radiative lifetime of chemically synthesized colloidal CdSe/CdS core/shell quantum dots is measured. Influence of the core size on the electron-hole pair separation is analyzed. A long radiative lifetime and the existence of electron-hole pair separation suggest high potential of these dots as gain material to achieve lasing under continuous-wave excitation.

  • 20.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    One-step fabrication of polymer components for microphotonics by gray scale electron beam lithography2011In: Journal of the European Optical Society-Rapid Publications, E-ISSN 1990-2573, Vol. 6, p. 11010-Article in journal (Refereed)
    Abstract [en]

    We demonstrate an application of gray scale electron beam lithography (EBL) for the fabrication of polymer waveguides and grating output couplers with depth variable features, using the SU-8 resist. The technique is mainly applicable for multi-level binary profile, where groove depths of the structure are controlled by choosing a proper exposure dose. Unlike reactive ion etching which is limited by the lag effect, the gray scale EBL allows free combination of groove widths and depths. Shrinking effect which is critical in polymer couplers' writing is taken into account and can be compensated. For better fabrication feasibility, the grating couplers can be simultaneously produced with waveguides with no inter-step alignment required. Therefore, this is a promising technique in manufacturing grating output couplers for polymer based waveguides with high performance in terms of mode matching/confinement and coupling efficiency.

  • 21.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Sergeyev, Sergey
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Spatial light modulator as a reconfigurable intracavity dispersive element for tunable lasers2010In: Central European Journal of Physics, ISSN 1895-1082, E-ISSN 1644-3608, ISSN 1895-1082 print, Vol. 8, no 2, p. 228-234Article in journal (Refereed)
    Abstract [en]

    An improved approach for narrow-band wavelength selection in tunable lasers is described. To provide the tunability, a reconfigurable diffractive optical element (DOE) based on a programmable spatial light modulator (PSLM) is applied. With a proper choice of the phase transfer function of the PSLM, the device can be used as a dispersive intra-cavity component for precise tuning within the lasing spectral band of a solid-state dye laser. The suggested design allows avoiding the mechanical movement of any cavity components. The tunability performance and simulation are demonstrated using the Fourier optics method.

  • 22.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Sugunan, Abhilash
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhou, Sicheng
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Photoluminescence from quasi-type-II spherical CdSe-CdS core-shell quantum dots2013In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 52, no 1, p. 105-109Article in journal (Refereed)
    Abstract [en]

    Spherical CdSe-CdS core-shell quantum dots (QDs) are found to be flexible in the transition between the type-I regime and the type-II regime with different core/shell dimensions. The quasi-type-II feature of the colloidal dots is confirmed with time-resolved photoluminescence (PL) measurements. Two recombination paths of the excitons with significantly different decay rates are observed and analyzed. The spherical CdSe-CdS core-shell QDs are numerically simulated to investigate the carrier separation. A relatively long radiative lifetime and high degree of spatial carrier separation provide good potential to achieve lasing under continuous-wave excitation. Amplified spontaneous emission at room temperature is detected from the QDs embedded in the polymer matrix. It is shown that a larger shell thickness results in a lower pumping threshold, while a smaller shell thickness leads to higher PL efficiency.

  • 23.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Liuolia, Vytautas
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Lasing From Water Solution of Rhodamine 6G/Gold Nanoparticles: Impact of SiO2-Coating on Metal Surface2012In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 48, no 9, p. 1220-1226Article in journal (Refereed)
    Abstract [en]

    Gold nanoparticles embedded in an optical gain material, particularly in a water solution of Rhodamine 6G, used in dye lasers can both increase and damp dye flourescence, thus changing the laser output intensity. Simultaneously, such nanoparticles influence the gain material's resistance against photobleaching. In this paper, we report our study on the impact of the SiO2 coating of nanoparticles on the enhancement or quenching and photobleaching of the fluorescence. The investigation demonstrates a noticeable improvement of the gain material's photostability compared to uncoated gold nanoparticles when silicon dioxide coating is implemented.

  • 24.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Enhanced photostability of aqueous solution of Rhodamine 6G with gold nanoparticles in lasing process by silica coating2012In: 2012 Conference on Lasers and Electro-Optics, CLEO 2012, IEEE , 2012, p. 6325399-Conference paper (Refereed)
    Abstract [en]

    Gold nanoparticles are mixed in aqueous solution of Rhodamine 6G to modify the lasing output intensity. The photostability deterioration of the gain medium by gold nanoparticles is successfully compensated by silica coating on the nanoparticles.

  • 25.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Chughtai, Adnan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Photostability of lasing process from water solution of Rhodamine 6G with gold nanoparticles2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 1, p. 34-36Article in journal (Refereed)
    Abstract [en]

    We report the lasing performance and photobleaching of gain material containing a water solution of Rhodamine 6G dye and gold nanoparticles (NPs). In comparison to a pure dye solution, the investigated material demonstrated both enhancement and quenching of the lasing output, depending on the relative concentration of the gold NPs. Although the presence of NPs with an optimized concentration looks preferable in terms of the lasing output enhancement, such additives deteriorate the operational resource of the gain material; i.e., the photobleaching rate speeds up.

  • 26.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Ye, Fei
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Hu, Jun
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fluorescence quenching and photobleaching in Au/Rh6G nanoassemblies: impact of competition between radiative and non-radiative decay2011In: Journal of the European Optical Society-Rapid Publications, E-ISSN 1990-2573, Vol. 6, p. 11019-Article in journal (Refereed)
    Abstract [en]

    We report the study of fluorescence quenching from nanoassemblies formed by Rhodamine 6G and gold nanoparticles (Au NPs) of 2.6 nm radius. The presence of Au NPs induces long-term degradation of the photostability (photobleaching) of Rhodamine 6G used as a gain medium in a Fabry-Perot laser cavity. We found that the degradation gets profound when the Au NPs concentration is significantly increased. Calculation of the radiative rate and direct time-resolved measurement of the fluorescence decay indicates that both the decrease of radiative decay rate and increase of non-radiative decay rate are responsible for the fluorescence quenching and photostability degradation. An energy transfer from the dye molecules to gold nanoparticles is dominating within small distance between them and suppresses the quantum efficiency of Rhodamine 6G drastically. In a long time scale, the photobleaching rate was slowing down, and the laser output intensity reached a stabilized level which depends on the gold nanoparticles concentration.

  • 27.
    Dyakov, S. A.
    et al.
    Skolkovo Inst Sci & Technol, Photon & Quantum Mat Ctr, Moscow 143025, Russia..
    Zhigunov, D. M.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia..
    Marinins, A.
    KTH, School of Electrical Engineering (EES).
    Shalygina, O. A.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia..
    Vabishchevich, P. P.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia..
    Shcherbakov, M. R.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia..
    Presnov, D. E.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia.;Skobeltsyn Inst Nucl Phys, Moscow 119991, Russia..
    Fedyanin, A. A.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia..
    Kashkarov, P. K.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia.;Natl Res Ctr Inst, Moscow 123182, Russia..
    Popov, Sergei
    KTH, School of Electrical Engineering (EES).
    Gippius, N. A.
    Skolkovo Inst Sci & Technol, Photon & Quantum Mat Ctr, Moscow 143025, Russia..
    Tikhodeev, S. G.
    Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia.;AM Prokhorov Gen Phys Inst, Moscow 119991, Russia..
    Plasmon induced modification of silicon nanocrystals photoluminescence in presence of gold nanostripes2018In: Scientific Reports, E-ISSN 2045-2322, Vol. 8, article id 4911Article in journal (Refereed)
    Abstract [en]

    We report on the results of theoretical and experimental studies of photoluminescense of silicon nanocrystals in the proximity to plasmonic modes of different types. In the studied samples, the type of plasmonic mode is determined by the filling ratio of a one-dimensional array of gold stripes which covers the thin film with silicon nanocrystals on a quartz substrate. We analyze the extinction, photoluminesce spectra and decay kinetics of silicon nanocrystals and show that the incident and emitted light is coupled to the corresponding plasmonic mode. We demonstrate the modification of the extinction and photoluminesce spectra under the transition from wide to narrow gold stripes. The experimental extinction and photoluminescense spectra are in good agreement with theoretical calculations performed by the rigorous coupled wave analysis. We study the contribution of individual silicon nanocrystals to the overall photoluminescense intensity, depending on their spacial position inside the structure.

  • 28.
    Dyakov, Sergey
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Skolkovo Institute of Science and Technology, Russia.
    Zhigunov, D. M.
    Marinins, Aleksandrs
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Shcherbakov, M. R.
    Fedyanin, A. A.
    Vorontsov, A. S.
    Kashkarov, P. K.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO. Zhejiang University, China.
    Zacharias, M.
    Tikhodeev, S. G.
    Gippius, N. A.
    Optical properties of silicon nanocrystals covered by periodic array of gold nanowires2016In: Physical Review B, ISSN 2469-9950, Vol. 93, no 20, article id 205413Article in journal (Refereed)
    Abstract [en]

    Extinction and photoluminescence spectra are experimentally and theoretically studied for a periodic array of gold nanowires deposited on top of a dielectric substrate containing silicon nanocrystals. Quasiguided modes are observed in the substrate resulting in modification of optical properties of silicon nanocrystals. Our calculations of extinction and photoluminescence spectra are in good agreement with experimental results. The periodicity provides a powerful tool for achieving a high photoluminescence outcoupling efficiency of silicon nanocrystals.

  • 29. El-Taher, A.
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sergeyev, S.
    Noise characterization and transmission evaluation of unrepeated Raman amplified DP-16QAM link2015In: Optical Fiber Communication Conference, OFC 2015, The Optical Society , 2015Conference paper (Refereed)
    Abstract [en]

    Impairments characterization and performance evaluation of Raman amplified unrepeated DP-16QAM transmissions are conducted. Experimental results indicate that small gain in forward direction enhance the system signal-to-noise ratio for longer reach without introducing noticeable penalty.

  • 30. El-Taher, Atalla
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Sergeyev, Sergey
    Noise characterization and transmission evaluation of unrepeated Raman amplified DP-16QAM link2015In: Optical Fiber Communication Conference, Institute of Electrical and Electronics Engineers Inc. , 2015Conference paper (Refereed)
    Abstract [en]

    Impairments characterization and performance evaluation of Raman amplified unrepeated DP-16QAM transmissions arc conducted, Experimental results indicate that small gain in forward direction enhance the system signal-to-noise ratio for longer reach without introducing noticeable penalty.

  • 31.
    Estaran, Jose Manuel
    et al.
    Nokia Bell Labs, F-91620 Nozay, France..
    Mardoyan, Haik
    Nokia Bell Labs, F-91620 Nozay, France..
    Jorge, Filipe
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, S-16425 Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, S-16425 Kista, Sweden..
    Konczykowska, Agnieszka
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Riet, Muriel
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Duval, Bernadette
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Nodjiadjim, Virginie
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Dupuy, Jean-Yves
    Joint Lab Nokia Bell Labs Thales Res & Technol, Lab 3 5, F-91767 Palaiseau, France.;CEA Leti, F-91767 Palaiseau, France..
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Bigo, Sebastien
    Nokia Bell Labs, F-91620 Nozay, France..
    140/180/204-Gbaud OOK Transceiver for Inter- and Intra-Data Center Connectivity2019In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 37, no 1, p. 178-187Article in journal (Refereed)
    Abstract [en]

    We report on an ON OFF keying intensity-modulation and direct-detection C-band optical transceiver capable of addressing all datacenter interconnect environments at well beyond 100 Gbaud. For this, the transmitter makes the use of two key InP technologies: a 2:1 double heterojunction bipolar transistor selector multiplexer and a monolithically integrated distributed feedback laser traveling-wave electro-absorption modulator, both exceeding 100-GHz of 3-dB analog bandwidth. A preamplified 110-Gaz PIN photodiode prior to a 100-CHs analog-to-digital converter complete the ultrahigh bandwidth transceiver module; the device under study. In the experimental work, which discriminates between intra- and inter-data center scenarios (dispersion unmanaged 120, 560, and 960 m; and dispersion-managed 10 and 80 km of standard single-mode fiber), we evaluate the bit-error rate evolution against the received optical power at 140, 180, and 204 Gbaud ON OFF keying for different equalization configurations (adaptive linear filter with and without the help of short-memory sequence estimation) and forward error correction schemes (hard-decision codes with 7% and 20% overhead); drawing conclusions from the observed system-level limitations of the respective environments at this ultrahigh baudrate, as well as from the operation margins and sensitivity metrics. From the demonstration, we highlight three results: successful operation with >6-dB sensitivity margin below the 7% error-correction at 140 Gbaud over the entire 100 m-80 km range with only linear feed-forward equalization. Then, the transmission of a 180-Gbaud ON OFF keying carrier over 80 km considering 20% error-correction overhead. Finally, a 10-km communication at 204 (Maud ON OFF keying with up to 6 dB sensitivity margin, and regular 7% overhead error-correction.

  • 32.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI).
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI).
    Udalcovs, A.
    Natalino, C.
    Zhang, L.
    Spolitis, S.
    Bobrovs, V.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI).
    Yu, X.
    Furdek, M.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI).
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI).
    EVM Estimation for Performance Monitoring in Coherent Optical Systems: An Approach of Linear Regression2022In: 2022 Conference on Lasers and Electro-Optics, CLEO 2022 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2022Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate the effectiveness of a simple linear regression scheme for optical performance monitoring when applied after modulation format identification. It outperforms the FFNN-based benchmark scheme providing 0.2% mean absolute error for EVM estimation.

  • 33.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    RISE Research Institutes of Sweden, Kista, 164 40, Sweden.
    Natalino, Carlos
    Chalmers University of Technology, Department of Electrical Engineering, Gothenburg, 412 96, Sweden.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Furdek, Marija
    Chalmers University of Technology, Department of Electrical Engineering, Gothenburg, 412 96, Sweden.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Laser Linewidth Tolerant EVM Estimation Approach for Intelligent Signal Quality Monitoring Relying on Feedforward Neural Networks2021In: 2021 European Conference on Optical Communication, ECOC 2021, Institute of Electrical and Electronics Engineers (IEEE) , 2021Conference paper (Refereed)
    Abstract [en]

    Robustness against the large linewidth semiconductor laser-induced impairments in coherent systems is experimentally demonstrated for a feedforward neural network-enabled EVM estimation scheme. A mean error of 0.4% is achieved for 28 Gbaud square and circular QAM signals and linewidths up to 12.3 MHz. 

  • 34.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    Udalcovs, Aleksejs
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Natalino, Carlos
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Bobrovs, Vjaceslavs
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    Furdek, Marija
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Feedforward Neural Network-based EVM Estimation: Impairment Tolerance in Coherent Optical Systems2022In: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, p. 1-1Article in journal (Refereed)
    Abstract [en]

    Error vector magnitude (EVM) is commonly used for evaluating the quality of m-ary quadrature amplitude modulation (mQAM) signals. Recently proposed deep learning techniques for EVM estimation extend the functionality of conventional optical performance monitoring (OPM). In this article, we evaluate the tolerance of our developed EVM estimation scheme against various impairments in coherent optical systems. In particular, we analyze the signal quality monitoring capabilities in the presence of residual in-phase/quadrature (IQ) imbalance, fiber nonlinearity, and laser phase noise. We use feedforward neural networks (FFNNs) to extract the EVM information from amplitude histograms of 100 symbols per IQ cluster signal sequence captured before carrier phase recovery. We perform simulations of the considered impairments, along with an experimental investigation of the impact of laser phase noise. To investigate the tolerance of the EVM estimation scheme to each impairment type, we compare the accuracy for three training methods: 1) training without impairment, 2) training one model for all impairments, and 3) training an independent model for each impairment. Results indicate a good generalization of the proposed EVM estimation scheme, thus providing a valuable reference for developing next-generation intelligent OPM systems.

  • 35.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. School oRISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Udalcovs, Aleksejs
    RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Natalino, Carlos
    Department of Electrical Engineering, Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg, Sweden, Chalmersplatsen 4.
    Zhang, Lu
    College of Information Science and Electronic Engineering, Zhejiang University, China.
    Spolitis, Sandis
    Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    Bobrovs, Vjaceslavs
    Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    College of Information Science and Electronic Engineering, Zhejiang University, China.
    Furdek, Marija
    Department of Electrical Engineering, Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg, Sweden, Chalmersplatsen 4.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22; Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    A Comparison of Linear Regression and Deep Learning Model for EVM Estimation in Coherent Optical Systems2022In: 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE) , 2022Conference paper (Refereed)
    Abstract [en]

    We experimentally investigate EVM estimation approaches based on linear regression and deep learning for 28 Gbaud coherent optical systems. We show that the estimation performances are comparable when the modulation format is known.

  • 36.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    Natalino, Carlos
    CTH.
    Zhang, Lu
    Zhejiang University.
    Spolitis, Sandis
    Riga Technical University.
    Bobrovs, Vjaceslavs
    Riga Technical University.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    Zhejiang University.
    Furdek, Marija
    CTH.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    A Comparison of Linear Regression and Deep LearningModel for EVM Estimation in Coherent Optical Systems2022Conference paper (Refereed)
  • 37.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Udalcovs, Aleksejs
    RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22.
    Natalino, Carlos
    Department of Electrical Engineering, Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg, Sweden, Chalmersplatsen 4.
    Zhang, Lu
    College of Information Science and Electronic Engineering, Zhejiang University, China.
    Spolitis, Sandis
    Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    Bobrovs, Vjaceslavs
    Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    College of Information Science and Electronic Engineering, Zhejiang University, China.
    Furdek, Marija
    Department of Electrical Engineering, Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg, Sweden, Chalmersplatsen 4.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics. RISE Research Institutes of Sweden, Isafjordsgatan 22, 164 40 Kista, Sweden, Isafjordsgatan 22; Institute of Telecommunications, Riga Technical University, 1048 Riga, Latvia.
    EVM Estimation for Performance Monitoring in Coherent Optical Systems: An Approach of Linear Regression2022In: Optics InfoBase Conference Papers, Optica Publishing Group (formerly OSA) , 2022, article id SW4E.8Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate the effectiveness of a simple linear regression scheme for optical performance monitoring when applied after modulation format identification. It outperforms the FFNN-based benchmark scheme providing 0.2% mean absolute error for EVM estimation.

  • 38.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Natalino, Carlos
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS, Optical Network Laboratory (ON Lab). CTH.
    Zhang, Lu
    Zhejiang University.
    Spolitis, Sandis
    Riga Technical University.
    Bobrovs, Vjaceslavs
    Riga Technical University.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    Zhejiang University.
    Furdek, Marija
    CTH.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    EVM Estimation for Performance Monitoring in Coherent Optical Systems: An Approach of Linear Regression2022Conference paper (Refereed)
  • 39.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics. RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Natalino, Carlos
    Chalmers Univ Technol, Elect Engn Dept, S-41296 Gothenburg, Sweden..
    Zhang, Lu
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 310000, Peoples R China..
    Spolitis, Sandis
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Bobrovs, Vjaceslavs
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Yu, Xianbin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 310000, Peoples R China..
    Furdek, Marija
    Chalmers Univ Technol, Elect Engn Dept, S-41296 Gothenburg, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden.;Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Linear Regression vs. Deep Learning for Signal Quality Monitoring in Coherent Optical Systems2022In: IEEE Photonics Journal, E-ISSN 1943-0655, Vol. 14, no 4, article id 8643108Article in journal (Refereed)
    Abstract [en]

    Error vector magnitude (EVM) is a metric for assessing the quality of m-ary quadrature amplitude modulation (mQAM) signals. Recently proposed deep learning techniques, e.g., feedforward neural networks (FFNNs) -based EVM estimation scheme leverage fast signal quality monitoring in coherent optical communication systems. Such a scheme estimates EVM from amplitude histograms (AHs) of short signal sequences captured before carrier phase recovery (CPR). In this work, we explore further complexity reduction by proposing a simple linear regression (LR) -based EVM monitoring method. We systematically compare the performance of the proposed method with the FFNN-based scheme and demonstrate its capability to infer EVM from an AH when the modulation format information is known in advance. We perform both simulation and experiment to show that the LR-based EVM estimation method achieves a comparable accuracy as the FFNN-based scheme. The technique can be embedded with modulation format identification modules to provide comprehensive signal information. Therefore, this work paves the way to design a fast-learning scheme with parsimony as a future intelligent OPM enabler.

  • 40.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    RISE Research Institutes of Sweden.
    Natalino, Carlos
    Chalmers University of Technology.
    Zhang, Lu
    Zhejiang University.
    Spolitis, Sandis
    Riga Technical University.
    Bobrovs, Vjaceslavs
    Riga Technical University.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    Zhejiang University.
    Furdek, Marija
    Chalmers University of Technology.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Linear Regression vs. Deep Learning for Signal Quality Monitoring in CoherentOptical SystemsManuscript (preprint) (Other academic)
  • 41.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Udalcovs, A.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Natalino, C.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Furdek, M.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Deep learning assisted pre-carrier phase recovery EVM estimation for coherent transmission systems2021In: Optics InfoBase Conference Papers, The Optical Society , 2021Conference paper (Refereed)
    Abstract [en]

    We exploit deep supervised learning and amplitude histograms of coherent optical signals captured before carrier phase recovery (CPR) to perform time-sensitive and accurate error vector magnitude (EVM) estimation for 32 Gbaud mQAM signal monitoring purposes. 

  • 42.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, A.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Natalino, C.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Furdek, M.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Deep Learning Assisted Pre-Carrier Phase Recovery EVM Estimation for Coherent Transmission Systems2021In: 2021 Conference on Lasers and Electro-Optics, CLEO 2021 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2021Conference paper (Refereed)
    Abstract [en]

    We exploit deep supervised learning and amplitude histograms of coherent optical signals captured before carrier phase recovery (CPR) to perform time-sensitive and accurate error vector magnitude (EVM) estimation for 32 Gbaud mQAM signal monitoring purposes. 

  • 43.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE .
    Udalcovs, Aleksejs
    RISE Res Inst Sweden, Isatjordsgatan 22, S-16440 Kista, Sweden..
    Natalino, Carlos
    Chalmers Univ Technol, Dept Elect Engn, Chalmersplatsen 4, S-41296 Gothenburg, Sweden..
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS, Optical Network Laboratory (ON Lab). KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Furdek, Marija
    Chalmers Univ Technol, Dept Elect Engn, Chalmersplatsen 4, S-41296 Gothenburg, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, Isatjordsgatan 22, S-16440 Kista, Sweden..
    Experimental validation of CNNs versus FFNNs for time- and energy-efficient EVM estimation in coherent optical systems2021In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 13, no 10, p. E63-E71Article in journal (Refereed)
    Abstract [en]

    Error vector magnitude (EVM) has proven to be one of the optical performance monitoring metrics providing the quantitative estimation of error statistics. However, the EVM estimation efficiency has not been fully exploited in terms of complexity and energy consumption. Therefore, in this paper, we explore two deep-learning-based EVM estimation schemes. The first scheme exploits convolutional neural networks (CNNs) to extract EVM information from images of the constellation diagram in the in-phase/quadrature (IQ) complex plane or amplitude histograms (AHs). The second scheme relies on feedforward neural networks (FFNNs) extracting features from a vectorized representation of AHs. In both cases, we use short sequences of 32 Gbaud m-ary quadrature amplitude modulation (mQAM) signals captured before or after a carrier phase recovery. The impacts of the sequence length, neural network structure, and data set representation on the EVM estimation accuracy as well as the model training time are thoroughly studied. Furthermore, we validate the performance of the proposed schemes using the experimental implementation of 28 Gbaud 64QAM signals. We achieve a mean absolute estimation error below 0.15%, with short signals consisting of only 100 symbols per IQ cluster. Considering the estimation accuracy, the implementation complexity, and the potential energy savings, the proposed CNN- and FFNN-based schemes can be used to perform time-sensitive and accurate EVM estimation for mQAM signal quality monitoring purposes.

  • 44.
    Fan, Yuchuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Udalcovs, Aleksejs
    RISE Res Inst Sweden, Isafjordsgatan 22, S-16440 Kista, Sweden..
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, Isafjordsgatan 22, S-16440 Kista, Sweden..
    Natalino, Carlos
    Chalmers Univ Technol, Dept Elect Engn, Chalmersplatsen 4, S-41296 Gothenburg, Sweden..
    Furdek, Marija
    Chalmers Univ Technol, Dept Elect Engn, Chalmersplatsen 4, S-41296 Gothenburg, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Fast signal quality monitoring for coherent communications enabled by CNN-based EVM estimation2021In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 13, no 4, p. B12-B20Article in journal (Refereed)
    Abstract [en]

    We propose a fast and accurate signal quality monitoring scheme that uses convolutional neural networks for error vector magnitude (EVM) estimation in coherent optical communications. We build a regression model to extract EVM information from complex signal constellation diagrams using a small number of received symbols. For the additive-white-Gaussian-noise-impaired channel, the proposed EVM estimation scheme shows a normalized mean absolute estimation error of 3.7% for quadrature phase-shift keying, 2.2% for 16-ary quadrature amplitude modulation (16QAM), and 1.1% for 64QAM signals, requiring only 100 symbols per constellation cluster in each observation period. Therefore, it can be used as a low-complexity alternative to conventional biterror-rate estimation, enabling solutions for intelligent optical performance monitoring.

  • 45. Favier, Maxime
    et al.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Tailored polarization eigenstates of liquid crystal SLM to generate Laguerre-Gaussian beams2014In: Proceedings - 2014 International Conference Laser Optics, LO 2014, 2014Conference paper (Refereed)
    Abstract [en]

    We use an SLM to generate laser beams of variable orbital angular momentum, also referred as Laguerre-Gaussian beams. Input beam polarization should match local birefringence of each pixel of the SLM. We identify the beam polarization eigenstates allowing generate L-G beams of different order owing to matching variable birefringence of separate pixels. Experimental results demonstrate an excellent agreement with simulations.

  • 46.
    Gaiarin, Simone
    et al.
    DTU Fotonik, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark.
    Pang, Xiaodan
    Acreo Swedish ICT AB, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Ozolins, Oskars
    Acreo Swedish ICT AB, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Jones, Rasmus T
    DTU Fotonik, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark.
    Da Silva, Edson Porto
    DTU Fotonik, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark.
    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.
    Jacobsen, Gunnar
    Acreo Swedish ICT AB, Isafjordsgatan 22, Kista, 164 40, Sweden.
    Zibar, Darko
    DTU Fotonik, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark.
    High speed PAM-8 optical interconnects with digital equalization based on neural network2016In: Asia Communications and Photonics Conference, Optical Society of America, 2016Conference paper (Refereed)
    Abstract [en]

    We experimentally evaluate a high-speed optical interconnection link with neural network equalization. Enhanced equalization performances are shown comparing to standard linear FFE for an EML-based 32 GBd PAM-8 signal after 4-km SMF transmission.

  • 47.
    Gyger, Samuel
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Zeuner, Katharina D.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jöns, Klaus D.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Elshaari, Ali W.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Paul, Matthias
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Reuterskiöld Hedlund, Carl
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Hammar, Mattias
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics. Rise AB, NETLAB, Isafjordsgatan 22, S-16440 Kista, Sweden.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Reconfigurable frequency coding of triggered single photons in the telecom C-band2019In: Optics Express, E-ISSN 1094-4087, Vol. 27, no 10, p. 14400-14406Article in journal (Refereed)
    Abstract [en]

    In this work, we demonstrate reconfigurable frequency manipulation of quantum states of light in the telecom C-band. Triggered single photons are encoded in a superposition state of three channels using sidebands up to 53 GHz created by an off-the-shelf phase modulator. The single photons are emitted by an InAs/GaAs quantum dot grown by metal-organic vapor-phase epitaxy within the transparency window of the backbone fiber optical network. A cross-correlation measurement of the sidebands demonstrates the preservation of the single photon nature; an important prerequisite for future quantum technology applications using the existing telecommunication fiber network.

  • 48.
    Han, Mengyao
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Beijing Jiaotong Univ, Inst Lightwave Technol, Key Lab All Opt Network, Adv Telecommun Network, Beijing 100044, Peoples R China..
    Joharifar, Mahdieh
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Wang, Muguang
    Beijing Jiaotong Univ, Inst Lightwave Technol, Key Lab All Opt Network, Adv Telecommun Network, Beijing 100044, Peoples R China..
    Fan, Yuchuan
    RISE Res Inst Sweden, Kista, Sweden..
    Maisons, Gregory
    mirSense, Palaiseau, France..
    Abautret, Johan
    mirSense, Palaiseau, France..
    Sun, Yan-Ting
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Teissier, Roland
    mirSense, Palaiseau, France..
    Zhang, Lu
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou, Peoples R China..
    Bobrovs, Vjaceslavs
    Riga Tech Univ, Inst Telecommun, Riga, Latvia..
    Yu, Xianbin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou, Peoples R China..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Long-Wave Infrared Discrete Multitone Free-Space Transmission Using a 9.15-μm Quantum Cascade Laser2023In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 35, no 9, p. 489-492Article in journal (Refereed)
    Abstract [en]

    A free-space optical (FSO) transmission system is experimentally demonstrated in the long-wave infrared (LWIR, 9.15 mu m) using a directly modulated quantum cascade laser (DM-QCL) and a commercial mercury-cadmium-telluride infrared photovoltaic detector. At room temperature, the DMQCL is current-modulated by discrete multitone signals pre-processed with bit-/power-loading. Up to 5.1 Gbit/s data rate is achieved with bit error rate performance below the 6.25% overhead hard-decision forward error correction limit of 4.5 x 10(-3), enabled by a frequency domain equalizer. The stability study of the FSO system is also performed at multiple temperature values. This study can provide a valuable reference for future terrestrial and space communications.

  • 49.
    Han, Mengyao
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Beijing Jiaotong Univ, Inst Lightwave Technol, Key Lab All Opt Network & Adv Telecommun Network, Minist Educ, Beijing 100044, Peoples R China..
    Joharifar, Mahdieh
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Wang, Muguang
    Beijing Jiaotong Univ, Inst Lightwave Technol, Key Lab All Opt Network & Adv Telecommun Network, Minist Educ, Beijing 100044, Peoples R China..
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Puerta, Rafael
    KTH, School of Engineering Sciences (SCI), Applied Physics. Ericsson AB, Ericsson Res, S-16483 Stockholm, Sweden..
    Sun, Yan-Ting
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Fan, Yuchuan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden..
    Maisons, Gregory
    mirSense, F-91120 Palaiseau, France..
    Abautret, Johan
    mirSense, F-91120 Palaiseau, France..
    Teissier, Roland
    mirSense, F-91120 Palaiseau, France..
    Zhang, Lu
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 310027, Peoples R China..
    Spolitis, Sandis
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Bobrovs, Vjaceslavs
    Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Lourdudoss, Sebastian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Yu, Xianbin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Peoples R China.;Zhejiang Lab, Hangzhou 310027, Peoples R China..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden.;Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Res Inst Sweden, S-16440 Kista, Sweden.;Riga Tech Univ, Inst Telecommun, LV-1048 Riga, Latvia..
    High Spectral Efficiency Long-Wave Infrared Free-Space Optical Transmission With Multilevel Signals2023In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 41, no 20, p. 6514-6520Article in journal (Refereed)
    Abstract [en]

    This study explores the potential of long-wave infrared free-space optical (FSO) transmission that leverages multilevel signals to attain high spectral efficiency. The FSO transmission system consists of a directly modulated-quantum cascade laser (DM-QCL) operating at 9.15 mu m and a mercury cadmium telluride (MCT) detector. To fully understand the system, we conduct measurements on the DM-QCL chip and MCT detector and assess the overall amplitude response of the DM-QCL, MCT detector, and all electrical components. We apply various signals, including on-off keying (OOK), 4-level pulse amplitude modulation (PAM4), 6-level PAM (PAM6), and 8-level PAM (PAM8) to maximize the bit rate and spectral efficiency of the FSO transmission. Through a two-dimensional sweeping of the laser bias current and MCT detector photovoltage, we optimize the transmission performance. At the optimal operation point, the FSO system achieved impressive results which are up to 6 Gbaud OOK, 3.5 Gbaud PAM4, 3 Gbaud PAM6, and 2.7 Gbaud PAM8 signal transmissions, with a bit error rate performance below 6.25% overhead hard decision-forward error correction limit when the DM-QCL operates at 10 degrees C. We also evaluate the eye diagrams and stability of the system to showcase its remarkable transmission performance. Our findings suggest that the DM-QCL and MCT detector-based FSO transceivers offer a highly competitive solution for the next generation of optical wireless communication systems.

  • 50.
    Han, Mengyao
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. Institute of Lightwave Technology, Key Lab of All Optical Network & Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
    Wang, Muguang
    Institute of Lightwave Technology, Key Lab of All Optical Network & Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
    Fan, Yuchuan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, 164 40 Kista, Sweden.
    Cai, Shiyi
    Institute of Lightwave Technology, Key Lab of All Optical Network & Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
    Guo, Yuxiao
    Institute of Lightwave Technology, Key Lab of All Optical Network & Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
    Zhang, Naihan
    Institute of Lightwave Technology, Key Lab of All Optical Network & Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Ozolins, Oskars
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, 164 40 Kista, Sweden.
    Pang, Xiaodan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics. RISE Research Institutes of Sweden, 164 40 Kista, Sweden.
    Simultaneous modulation format identification and OSNR monitoring based on optoelectronic reservoir computing2022In: Optics Express, E-ISSN 1094-4087, Vol. 30, no 26, p. 47515-47527Article in journal (Refereed)
    Abstract [en]

    An approach for simultaneous modulation format identification (MFI) and optical signal-to-noise ratio (OSNR) monitoring in digital coherent optical communications is proposed based on optoelectronic reservoir computing (RC) and the signal’s amplitude histograms (AHs) obtained after the adaptive post-equalization. The optoelectronic RC is implemented using a Mach-Zehnder modulator and optoelectronic delay feedback loop. We investigate the performance of the proposed model with the number of symbols, bins of AHs and the hyperparameters of optoelectronic RC. The results show that 100% MFI accuracy can be achieved simultaneously with accurate OSNR estimation for different modulation formats under study. The lowest achievable OSNR estimation mean absolute errors for the dual-polarization (DP)-quadrature phase-shift keying signal, the DP-16-ary quadrature amplitude modulation (16QAM) signal, and the DP-64QAM signal are 0.2 dB, 0.32 dB and 0.53 dB, respectively. The robustness of the proposed scheme is also evaluated when the optoelectronic RC is in presence of additive white Gaussian noises. Then, a proof of concept experiment is demonstrated to further verify our proposed method. The proposed approach offers a potential solution for next-generation intelligent optical performance monitoring in the physical layer.

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