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  • 1. Abbas, Syed Sohail
    et al.
    Popov, Sergei Yu
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    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, E-ISSN 2070-3740, 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, Fotonik och mikrovågsteknik, FMI.
    Pang, Xiaodan
    RISE ACREO AB.
    Ozolins, O.
    Jacobsen, Gunnar
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Fotonik och mikrovågsteknik, 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%). © 2015 OSA.

  • 3. 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. 

  • 4. 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.

  • 5. 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.

  • 6.
    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.

  • 7. Da Ros, F.
    et al.
    Cristofori, V.
    Ozolins, O.
    Chaibi, M. E.
    Pang, Xiaodan
    RISE ACREO AB.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Galili, M.
    Oxenløwe, L. K.
    Peucheret, C.
    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.

  • 8. 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, ISSN 1097-5764, 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.

  • 9.
    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.

  • 10.
    Dong, Lin
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Iyer, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    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.

  • 11.
    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.

  • 12.
    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.

  • 13.
    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: J EUR OPT SOC-RAPID PUBL, 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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    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.

  • 17.
    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.

  • 18.
    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.

  • 19.
    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, 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.

  • 20.
    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, S.
    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, ISSN 2045-2322, 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.

  • 21.
    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.

  • 22. 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, 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.

  • 23. 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.

  • 24. Gaiarin, S.
    et al.
    Pang, X.
    Ozolins, O.
    Jones, R. T.
    Da Silva, E. P.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Jacobsen, G.
    Zibar, D.
    High speed PAM-8 optical interconnects with digital equalization based on neural network2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference 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.

  • 25.
    Hassinen, Timo
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Friberg, Ari T.
    Setala, Tero
    Generation of nearly 3D-unpolarized evanescent optical near fields using total internal reflection2016In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 41, no 13, p. 2942-2945Article in journal (Refereed)
    Abstract [en]

    We analyze the time-domain partial polarization of optical fields composed of two evanescent waves created in total internal reflection by random electromagnetic beams with orthogonal planes of incidence. We show that such a two-beam configuration enables to generate nearly unpolarized, genuine three-component (3D) near fields. This result complements earlier studies on spectral polarization, which state that at least three symmetrically propagating beams are required to produce a 3D-unpolarized near field. The degree of polarization of the near field can be controlled by adjusting the polarization states and mutual correlation of the incident beams.

  • 26.
    Hong, Xuezhi
    et al.
    KTH, School of Information and Communication Technology (ICT). South China Normal University, China.
    Ozolins, O.
    Guo, C.
    Pang, X.
    Zhang, J.
    Navarro, J. R.
    Kakkar, Aditya
    KTH, School of Information and Communication Technology (ICT).
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal University, China.
    1.55-jnm EML-based DMT transmission with nonlinearity-aware time domain super-nyquist image induced aliasing2017In: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a DMT transmission system with 1.55-μm EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by ∼16.8%(33.1%) with proposed method for 4(40) km transmission.

  • 27.
    Hong, Xuezhi
    et al.
    KTH, School of Information and Communication Technology (ICT). South China Normal Univ, Peoples R China.
    Ozolins, O.
    Guo, C.
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, J.
    Navarro, J. R.
    Kakkar, Aditya
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal Univ, Peoples R China.
    1.55-μm EML-based DMT transmission with nonlinearity- aware time domain super-nyquist image induced aliasing2017In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a DMT transmission system with 1.55-μm EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by ~16.8%(33.1%) with proposed method for 4(40) km transmission.

  • 28.
    Hong, Xuezhi
    et al.
    KTH, School of Information and Communication Technology (ICT). South China Normal Univ, Peoples R China.
    Ozolins, Oskars
    Guo, Changjian
    Pang, Xiaodan
    Zhang, Junwei
    Navarro, Jaime Rodrigo
    Kakkar, Aditya
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal Univ, Peoples R China.
    1.55-mu m EML-based DMT Transmission with Nonlinearity-Aware Time Domain Super-Nyquist Image Induced Aliasing2017In: 2017 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a DMT transmission system with 1.55-mu m EML using nonlinearity-aware time domain super-Nyquist image induced aliasing. Compared with linear equalization, the capacity is improved by similar to 16.8%(33.1%) with proposed method for 4(40) km transmission.

  • 29.
    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.

  • 30.
    Iglesias Olmedo, Miguel
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO. Technical University of Denmark (DTU), Denmark .
    Pang, Xiaodan
    RISE ACREO AB.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zibar, D.
    Tafur Monroy, I.
    Jacobsen, Gunnar
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO. Acreo AB, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Digital signal processing approaches for semiconductor phase noise tolerant coherent transmission systems2015In: Proceedings of SPIE - The International Society for Optical Engineering, 2015Conference paper (Refereed)
    Abstract [en]

    We discuss about digital signal processing approaches that can enable coherent links based on semiconductor lasers. A state-of-the art analysis on different carrier-phase recovery (CPR) techniques is presented. We show that these techniques are based on the assumption of lorentzian linewidth, which does not hold for monolithically integrated semiconductor lasers. We investigate the impact of such lineshape on both 3 and 20 dB linewidth and experimentally conduct a systematic study for 56-GBaud DP-QPSK and 28-GBaud DP-16QAM systems using a decision directed phase look loop algorithm. We show how carrier induced frequency noise has no impact on linewidth but a significant impact on system performance; which rises the question on whether 3-dB linewidth should be used as performance estimator for semiconductor lasers.

  • 31.
    Iglesias Olmedo, Miguel
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zuo, Tianjian
    Jensen, Jesper Bevensee
    Zhong, Qiwen
    Xu, Xiaogeng
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Monroy, Idelfonso Tafur
    Multiband Carrierless Amplitude Phase Modulation for High Capacity Optical Data Links2014In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 32, no 4, p. 798-804Article in journal (Refereed)
    Abstract [en]

    Short range optical data links are experiencing bandwidth limitations making it very challenging to cope with the growing data transmission capacity demands. Parallel optics appears as a valid short-term solution. It is, however, not a viable solution in the long-term because of its complex optical packaging. Therefore, increasing effort is now put into the possibility of exploiting higher order modulation formats with increased spectral efficiency and reduced optical transceiver complexity. As these type of links are based on intensity modulation and direct detection, modulation formats relying on optical coherent detection can not be straight forwardly employed. As an alternative and more viable solution, this paper proposes the use of carrierless amplitude phase (CAP) in a novel multiband approach (MultiCAP) that achieves record spectral efficiency, increases tolerance towards dispersion and bandwidth limitations, and reduces the complexity of the transceiver. We report on numerical simulations and experimental demonstrations with capacity beyond 100 Gb/s transmission using a single externally modulated laser. In addition, an extensive comparison with conventional CAP is also provided. The reported experiment uses MultiCAP to achieve 102.4 Gb/s transmission, corresponding to a data payload of 95.2 Gb/s error free transmission by using a 7% forward error correction code. The signal is successfully recovered after 15 km of standard single mode fiber in a system limited by a 3 dB bandwidth of 14GHz.

  • 32.
    Innocenti, Nicolas
    et al.
    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.
    Sergeyev, Sergey
    Waterford Institute of Technology.
    Friberg, Ari
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    External field enhancement in coupled polymer microcavities - New options for integrated photonic components2009In: European Conference on Lasers and Electro-Optics 2009 and the European Quantum Electronics Conference. CLEO Europe - EQEC 2009, 2009Conference paper (Other academic)
    Abstract [en]

    Microcavities are key components for integrated optical devices and systems. In this paper, enhancement of the resonance electric field outside a pair of coupled polymeric microcavities of hexagonal shape is investigated. Using numerical simulation, enhancement of outside-cavity field has been demonstrated in different sections of the coupled cavity system depending on particular design. Resonance frequencies are in visible part of electromagnetic spectrum. In reported simulations rigorous models based on solving Maxwell equations for propagating electromagnetic field in polymeric materials commonly used in nano-imprinting lithography is demonstrated.

  • 33.
    Iyer, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Dong, Lin
    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.
    Physical reason behind far-field transmission resonances from U-shaped metallic structures2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 2010, p. 326-327Conference paper (Refereed)
    Abstract [en]

    The far-field transmission spectrum of crescent-like metallic nanostructures on a glass substrate at normal incidence is studied numerically. The interpretation of transmission resonances arising from a periodic subwavelength U-shaped metal nanostructure in terms of plasmonic eigen modes is revisited.

  • 34.
    Iyer, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Dong, Lin
    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. Aalto University, Finland .
    Refractive index sensor performance based on enhanced transmission of light through perforated metallic films2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 2010, p. 328-329Conference paper (Refereed)
    Abstract [en]

    The transmission of light through a thin Au film with periodic subwavelength double nanoholes at normal incidence is analyzed numerically and compared to other conventional hole shapes. The performance of such perforated metallic films as a potential refractive index sensor is discussed.

  • 35.
    Iyer, Srinivasan
    et al.
    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. Aalto University, Finland.
    Double nanoholes in a metal film as refractive index sensors2010In: Frontiers in Optics, FiO 2010, 2010Conference paper (Refereed)
    Abstract [en]

    The transmission of light through a thin Au film with subwavelength double nanoholes is modeled using vectorial three-dimensional finite element method. The performance of such perforated films as a potential refractive index sensor is discussed.

  • 36.
    Iyer, Srinivasan
    et al.
    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.
    Effective tunability and realistic estimates of group index in plasmonic metamaterials exhibiting electromagnetically induced transparency2011In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 50, no 21, p. 3958-3961Article in journal (Refereed)
    Abstract [en]

    We study the phenomenon of the electromagnetically induced transparency in planar and stacked plasmonic metamaterials (MMs) using the finite integration time domain and finite element methods. For such structures, the dependence of the tunability of the inherent structural resonances on geometry design is clarified. We also analyze the performance of recently demonstrated MM designs in terms of the achievable group refractive index and losses, which are of great interest for slowing light applications.

  • 37.
    Iyer, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT).
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT). Aalto University, Finland.
    Extraordinary transmission resonance due to near-field effect in periodic U-shaped metal nanostructures2010In: Frontiers in Optics 2010/Laser Science XXVI, 2010Conference paper (Refereed)
    Abstract [en]

    The far-field transmission spectrum of crescent-like metallic nanostructures on a glass substrate at normal incidence is studied numerically. The interpretation of transmission resonances arising from a periodic subwavelength U-shaped metal nanostructure is revisited.

  • 38.
    Iyer, Srinivasan
    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 T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Impact of apexes on the resonance shift in double hole nanocavities2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, no 1, p. 193-203Article in journal (Refereed)
    Abstract [en]

    The transmission of light through metallic films with periodic double nanoholes is studied using vectorial three-dimensional finite element method. Special emphasis is given on understanding different transmission resonances arising in gold and silver films with periodic sub-wavelength holes of different shapes. The spectral shift of the hole-shape resonance resulting from a variation of the hole refractive index is analyzed for a double nanohole geometry in the transmission mode using numerical simulations. Specifically, the role of field enhancement at the apexes of the double nanohole in the sensing of medium within the hole cavity is pointed out and discussed. The presence of sharp apexes within the double nanoholes significantly improves the resonance sensitivity as compared to rectangular holes of comparable area. Impact of possible manufacturing errors on the overall sensitivity is also characterized. Robustness and a relatively simple fabrication procedure make these kinds of refractive index sensors practically attractive.

  • 39.
    Iyer, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Friberg, Ari. T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Interpreting the dipolar plasmon resonance of rectangular metallic nanoantennasIn: Plasmonics, ISSN 1557-1955, E-ISSN 1557-1963Article in journal (Other academic)
  • 40.
    Iyer, Srinivasan
    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. T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Linear birefringence in split-ring resonators2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 11, p. 2043-2045Article in journal (Refereed)
    Abstract [en]

    We study polarization-dependent transmission of light through arrays of single-slit split-ring resonator (SSRR) based systems at normal incidence using finite integration time domain (FITD) and finite element methods (FEM). It is found that a conventional planar array of SSRRs acts as an effective optical wave plate at certain polarizations of incident light. The effect is attributed to the intrinsic linear birefringence of individual SSRRs. A comparison is made with other split-ring resonator-based systems exhibiting wave-plate-like properties due to inter-SSRR coupling.

  • 41.
    Iyer, Srinivasan
    et al.
    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.
    Transmission resonances in periodic U-shaped metallic nanostructures2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, no 17, p. 17719-17728Article in journal (Refereed)
    Abstract [en]

    The spectral response of crescent-like metallic nanostructures, a sub-class of U-shaped split-ring resonators, on a glass substrate at normal incidence is studied numerically. Also, the interpretation of transmission resonances arising from periodic conventional standard split-ring resonators with rectangular edges (SSRR) at normal incidence is revisited. In particular, we focus on one specific transmission resonance which is present for nano-crescents (NC) but absent in the case of SSRRs used for metamaterials. It is proposed that for a U-shaped metallic structure of arbitrary geometry, coupling of plasmonic eigen modes at all the surfaces of the three-dimensional structure is essential to be considered. The manner in which the coupling takes place between plasmonic modes at all the surfaces of the three-dimensional structure is what completely characterizes transmission resonances, and it is unique for each given resonance. (C) 2010 Optical Society of America

  • 42.
    Iyer, Srinivasan Shankararaman
    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.
    Loss optimization in double fishnet metamaterials at telecommunication wavelengths2011In: JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS, ISSN 1990-2573, Vol. 6, p. 11008-Article in journal (Refereed)
    Abstract [en]

    A hole shape optimization study was made for a double fishnet metamaterial producing a negative index of refraction within 1.4 - 1.5 mu m. It is found that within these wavelengths, elliptical holes offer lower losses as compared to rectangular ones and theoretically produce the best figure of merit (FOM) of approximately 6.

  • 43. Jacobsen, G.
    et al.
    Xu, T.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Sergeyev, S.
    Phase noise influence in coherent optical DnPSK systems with DSP based dispersion compensation2014In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 35, no 1, p. 57-61Article in journal (Refereed)
    Abstract [en]

    We present a comparative study of the influence of dispersion induced phase noise for n-level PSK systems. From the analysis, we conclude that the phase noise influence for classical homodyne/heterodyne PSK systems is entirely determined by the modulation complexity (expressed in terms of constellation diagram) and the analogue demodulation format. On the other hand, the use of digital signal processing (DSP) in homodyne/intradyne systems renders a fiber length dependence originating from the generation of equalization enhanced phase noise. For future high capacity systems, high constellations must be used in order to lower the symbol rate to practically manageable speeds, and this fact puts severe requirements to the signal and local oscillator (LO) linewidths. Our results for the bit-error-rate (BER) floor caused by the phase noise influence in the case of QPSK, 16PSK and 64PSK systems outline tolerance limitations for the LO performance: 5 MHz linewidth (at 3-dB level) for 100 Gbit/s QPSK; 1 MHz for 400 Gbit/s QPSK; 0.1 MHz for 400 Gbit/s 16PSK and 1 Tbit/s 64PSK systems. This defines design constrains for the phase noise impact in distributed-feed-back (DFB) or distributed-Bragg-reflector (DBR) semiconductor lasers, that would allow moving the system capacity from 100 Gbit/s system capacity to 400 Gbit/s in 3 years (1 Tbit/s in 5 years). It is imperative at the same time to increase the analogue to digital conversion (ADC) speed such that the single quadrature symbol rate goes from today's 25 GS/s to 100 GS/s (using two samples per symbol).

  • 44. Jacobsen, G.
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Li, J.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Zhang, Y.
    Phase noise influence in coherent optical OFDM systems with RF pilot tone: Digital IFFT multiplexing and FFT demodulation2012In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 33, no 3, p. 217-226Article in journal (Refereed)
    Abstract [en]

    We present a comparative study of the influence of dispersion induced phase noise for CO-OFDM systems using Tx channel multiplexing and Rx matched filter (analogue hardware based); and digital FFT multiplexing/ IFFT demultiplexing techniques (software based). An RF carrier pilot tone is used to mitigate the phase noise influence. From the analysis, it appears that the phase noise influence for the two OFDM implementations is very similar. The software based system provides a method for a rigorous evaluation of the phase noise variance caused by Common Phase Error (CPE) and Inter-Carrier Interference (ICI) and this, in turns, leads to a BER specification. Numerical results focus on a CO-OFDM system with 1 GS/s QPSK channel modulation. Worst case BER results are evaluated and compared to the BER of a QPSK system with the same capacity as the OFDM implementation. Results are evaluated as a function of transmission distance, and for the QPSK system the influence of equalization enhanced phase noise (EEPN) is included. For both types of systems, the phase noise variance increases significantly with increasing transmission distance. An important and novel observation is that the two types of systems have very closely the same BER as a function of transmission distance for the same capacity. For the high capacity QPSK implementation, the increase in BER is due to EEPN, whereas for the OFDM approach it is due to the dispersion caused walk-off of the RF pilot tone relative to the OFDM signal channels. For a total capacity of 400 Gbit/s, the transmission distance to have the BER &lt; 10-4 is less than 277 km. For an RF pilot located in the center of the OFDM band in a CO-OFDM implementation with n-level PSK channel modulation the current results suggest that the walk-off effect is equivalent to the EEPN impact in a single channel n-level PSK system with the same capacity. This observation is important for future design of coherent long-range systems since it shows that there is a free choice between CO-OFDM and a high capacity nPSK implementation at least as long as the phase noise influence is concerned.

  • 45. Jacobsen, G.
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Sergeyev, S.
    Zhang, Y.
    Phase noise influence in long-range coherent optical OFDM systems with delay detection, IFFT multiplexing and FFT demodulation2012In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 33, no 4, p. 289-295Article in journal (Refereed)
    Abstract [en]

    We present a study of the influence of dispersion induced phase noise for CO-OFDM systems using FFT multiplexing/IFFT demultiplexing techniques (software based). The software based system provides a method for a rigorous evaluation of the phase noise variance caused by Common Phase Error (CPE) and Inter-Carrier Interference (ICI) including - for the first time to our knowledge - in explicit form the effect of equalization enhanced phase noise (EEPN). This, in turns, leads to an analytic BER specification. Numerical results focus on a CO-OFDM system with 10-25 GS/s QPSK channel modulation. A worst case constellation configuration is identified for the phase noise influence and the resulting BER is compared to the BER of a conventional single channel QPSK system with the same capacity as the CO-OFDM implementation. Results are evaluated as a function of transmission distance. For both types of systems, the phase noise variance increases significantly with increasing transmission distance. For a total capacity of 400 (1000) Gbit/s, the transmission distance to have the BER &lt; 10-2 for the worst case CO-OFDM design is less than 800 and 460 km, respectively, whereas for a single channel QPSK system it is less than 1400 and 560 km.

  • 46.
    Jacobsen, Gunnar
    et al.
    Acreo AB, Electrum 236, Kista, Sweden.
    Kazovsky, L. G.
    Stanford University, USA.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Zhang, Y.
    Tianjin University, China.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Phase noise influence in optical OFDM systems employing RF pilot tone for noise cancellation2011In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, no 2Article in journal (Refereed)
    Abstract [en]

    For coherent and direct-detection Orthogonal Frequency Division Multiplexed (OFDM) systems employing radio frequency (RF) pilot tone phase noise cancellation the influence of laser phase noise is evaluated. Novel analytical results for the common phase error and for the (modulation dependent) inter carrier interference are evaluated based upon Gaussian statistics for the laser phase noise. In the evaluation it is accounted for that the laser phase noise is filtered in the correlation signal detection. Numerical results are presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud rate of 1 GS/s. It is found that about 225 km transmission is feasible for the coherent 4PSKOFDM system over normal (G.652) fiber.

  • 47. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    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.
    Li, Jie
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    EEPN and CD study for coherent optical nPSK and nQAM systems with RF pilot based phase noise compensation2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 8, p. 8862-8870Article in journal (Refereed)
    Abstract [en]

    A radio frequency (RF) carrier can be used to mitigate the phase noise impact in n-level PSK and QAM systems. The systems performance is influenced by the use of an RF pilot carrier to accomplish phase noise compensation through complex multiplication in combination with discrete filters to compensate for the chromatic dispersion (CD). We perform a detailed study comparing two filters for the CD compensation namely the fixed frequency domain equalizer (FDE) filter and the adaptive least-mean-square (LMS) filter. The study provides important novel physical insight into the equalization enhanced phase noise (EEPN) influence on the system bit-error-rate (BER) versus optical signal-to-noise-ratio (OSNR) performance. Important results of the analysis are that the FDE filter position relative to the RF carrier phase noise compensation module provides a possibility for choosing whether the EEPN from the Tx or the LO laser influences the system quality. The LMS filter works very inefficiently when placed prior to the RF phase noise compensation stage of the Rx whereas it works much more efficiently and gives almost the same performance as the FDE filter when placed after the RF phase noise compensation stage.

  • 48. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    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.
    Li, Jie
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Receiver implemented RF pilot tone phase noise mitigation in coherent optical nPSK and nQAM systems2011In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, no 15, p. 14487-14494Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel method for extracting an RF pilot carrier signal in the coherent receiver is presented. The RF carrier is used to mitigate the phase noise influence in n-level PSK and QAM systems. The performance is compared to the use of an (ideal) optically transmitted RF pilot tone. As expected an electronically generated RF carrier provides less efficient phase noise mitigation than the optical RF. However, the electronically generated RF carrier still improves the phase noise tolerance by about one order of magnitude in bit error rate (BER) compared to using no RF pilot tone. It is also found, as a novel study result, that equalization enhanced phase noise - which appears as correlated pure phase noise, amplitude noise and time jitter - cannot be efficiently mitigated by the use of an (optically or electrically generated) RF pilot tone.

  • 49. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    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.
    Li, Jie
    Zhang, Yimo
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Error-rate floors in differential n-level phase-shift-keying coherent receivers employing electronic dispersion equalisation2011In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, p. 191-193Article in journal (Refereed)
    Abstract [en]

    A model for the phase noise influence in differential n-level phase shift keying (nPSK) systems and 2nlevel quadrature amplitude modulated (2nQAM) systems employing electronic dispersion equalization and quadruple carrier phase extraction is presented. The model includes the dispersion equalization enhanced local oscillator phase noise influence. Numerical results for phase noise error-rate floors are given for dual polarization (DQPSK, Dl6PSK and D64PSK) system configurations with basic baud-rate of 25 GS/s. The transmission distance in excess of 1000 km requires local oscillator lasers with sub-MHz linewidth.

  • 50. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Sergeyev, Sergey
    Study of EEPN mitigation using modified RF pilot and Viterbi-Viterbi based phase noise compensation2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 10, p. 12351-12362Article in journal (Refereed)
    Abstract [en]

    We propose - as a modification of the optical (RF) pilot scheme - a balanced phase modulation between two polarizations of the optical signal in order to generate correlated equalization enhanced phase noise (EEPN) contributions in the two polarizations. The method is applicable for n-level PSK system. The EEPN can be compensated, the carrier phase extracted and the nPSK signal regenerated by complex conjugation and multiplication in the receiver. The method is tested by system simulations in a single channel QPSK system at 56 Gb/s system rate. It is found that the conjugation and multiplication scheme in the Rx can mitigate the EEPN to within 1/2 orders of magnitude. Results are compared to using the Viterbi-Viterbi algorithm to mitigate the EEPN. The latter method improves the sensitivity more than two orders of magnitude. Important novel insight into the statistical properties of EEPN is identified and discussed in the paper.

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