Ändra sökning
Avgränsa sökresultatet
2627282930 1401 - 1450 av 1481
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1401.
    Yu, Xia
    et al.
    Singapore Institute of Manufacturing Technology, Singapore.
    Yan, Min
    Technical University of Denmark.
    Ren, Guobin
    Tong, Weijun
    Cheng, Xueping
    Zhou, Junqiang
    Shum, Perry Ping
    Ngo, Nam Quoc
    Nanostructure core fiber with enhanced performances: Design, fabrication and devices2009Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 27, nr 11, s. 1548-1555Artikel i tidskrift (Refereegranskat)
  • 1402. Yu, Xianbin
    et al.
    Jia, Shi
    Pang, Xiaodan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). RISE ACREO AB.
    Morioka, Toshio
    Oxenloewe, Leif K.
    Beyond 100 Gbit/s wireless connectivity enabled by THz photonics2017Ingår i: Transparent Optical Networks (ICTON), 2017 19th International Conference on, IEEE Computer Society, 2017, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    Beyond 100Gbit/s wireless connectivity is appreciated in many scenarios, such as big data wireless cloud, ultrafast wireless download, large volume data transfer, etc. In this paper, we will present our recent achievements on beyond 100Gbit/s ultrafast terahertz (THz) wireless links enabled by THz photonics.

  • 1403. Yu, Xianbin
    et al.
    Zhao, Ying
    Deng, Lei
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Tafur Monroy, Idelfonso
    Existing PON Infrastructure Supported Hybrid Fiber-Wireless Sensor Networks2012Ingår i: National Fiber Optic Engineers Conference, NFOEC 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a hybrid fiber wireless sensor network based on the existing PON infrastructure. The feasibility of remote sensing and PON convergence is experimentally proven by transmitting direct-sequence spread-spectrum wireless sensing and 2.5Gbps GPON signals.

  • 1404.
    Yu, Yichuan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Karlsson, Stefan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Liu, C. P.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Kjebon, Olle
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Chuang, C. H.
    He, Sailing
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Seeds, A. J.
    Krysa, A. B.
    Roberts, J. S.
    Intermodulation Distortion Suppression in a Full-Duplex Radio-over-Fibre System Employing Asymmetric Fabry-Perot Modulator/Detector2006Ingår i: 2006 European Conference on Optical Communications Proceedings, ECOC 2006, 2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    The property of intermodulation distortion in a full-duplex radio-over-fibre system with Asymmetric Fabry-Perot Modulator/Detector was investigated. By employing the balanced RF input powers, intermodulation distortion was suppressed and a SFDR of 99dB. Hz2/3 has been achieved.

  • 1405.
    Yu, Zhangwei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Knape, Harald
    Tarasenko, Olesandr
    Koch, Ralf
    Margulis, Walter
    All-fiber single-pulse selection and nanosecond gating2009Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 34, nr 7, s. 1024-1026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two functions normally attributed to Pockels cells are performed with internal-electrode microstructured fiber components. Single-pulse selection out of a 100 MHz mode-locked pulse train is demonstrated using all-fiber nanosecond polarization rotation. Additionally, off-on-off gating with duration similar to 13 ns is achieved with a polarization rotator made out of a four-hole silicate fiber.

  • 1406.
    Yu, Zhangwei
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Malmström, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Sterner, C.
    Tarasenko, O.
    Margulis, Walther
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fonjallaz, P. -Y
    Dynamics of long-period gratings tuned with internal fiber electrodes2011Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 36, nr 5, s. 633-635Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The physics of electrically switched long-period grating in a twin-hole fiber with internal electrodes is studied. Dynamic measurements for the two polarizations show how the grating spectra shift in time due to the mechanical stress and heat transfer in the core and the cladding.

  • 1407.
    Yu, Zhangwei
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Malmström, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Tarasenko, O.
    Margulis, Walter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Actively Q-switched all-fiber laser with an electrically controlled microstructured fiber2010Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, nr 11, s. 11052-11057Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Actively Q-switching of an all-fiber laser system is demonstrated. The active element is a polarization switch with nanosecond risetime based on a microstructured fiber with electrically driven internal electrodes. Optical feedback between two 100% reflectors is inhibited until a nanosecond current pulse Q-switches the laser. After a short optical pulse develops several roundtrips later, the fiber switch is turned off, removing the short optical pulse from the cavity through a polarization splitter. Pulses of 50 W peak power and similar to 12 ns duration are obtained with 400 mW pump power at 100 Hz. (C) 2010 Optical Society of America

  • 1408.
    Yu, Zhangwei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Margulis, Walter
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Fonjallaz, Pierre-Yves
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Tarasenko, Oleksandr V.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Physics of electricity switched fiber Bragg gratings2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    The physics of electrically switched FBGs was studied in fibers with internal electrodes. Wavelength shifts due to mechanical effects (nanoseconds) and heat (milliseconds) depend quadratically on the electrical pulse voltage and linearly on pulse duration.

  • 1409.
    Yu, Zhangwei
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. Acreo AB, Kista, Sweden .
    Margulis, Walter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. Acreo AB, Kista, Sweden .
    Malmström, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. Acreo AB, Kista, Sweden .
    Tarasenko, O.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. Acreo AB, Kista, Sweden .
    Q-switching a fiber laser with an electrically controlled microstructured fiber2010Ingår i: Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, 2010, s. 5500945-Konferensbidrag (Refereegranskat)
    Abstract [en]

    A monolithic fiber laser incorporating an electrically driven microstructured fiber is Q-switched exploiting nanosecond polarization rotation and multi-pass amplification. All components are in-fiber, simplifying fabrication and improving robustness.

  • 1410.
    Yu, Zhangwei
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Margulis, Walter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Tarasenko, O.
    Malmström, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    All-fiber laser cavity dumping2009Ingår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS, IEEE , 2009, s. 463-464Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cavity dumping of a fiber laser is demonstrated. A microstructured fiber with an electrically driven internal electrode is used for intracavity polarization rotation with nanosecond risetime. The optical flux can be dumped within one roundtrip.

  • 1411.
    Yu, Zhenhua
    et al.
    Niels Bohr Inst, Copenhagen O, Denmark ; Ohio State Univ, Columbus, OH USA ; Tsinghua Univ, Beijing, Peoples R China .
    Pethick, Christopher J.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Induced interactions in dilute atomic gases and liquid helium mixtures2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 6, s. 063616-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In dilute mixtures of two atomic gases, interactions between two minority atoms acquire a contribution due to interaction with the majority component. Using thermodynamic arguments, we derive expressions for this induced interaction for both fermions and bosons for arbitrary strength of the interaction between the two components. Implications of the work for the theory of dilute solutions of He-3 in liquid He-4 are discussed.

  • 1412. Yurkin, Yu.T.
    et al.
    Carlson, Per
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Gillard, William
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wu, Yueshi
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Zverev, V. G.
    et al.,
    Trapped antiprotons in the Earth inner radiation belt in PAMELA experiment2011Ingår i: Bulletin of the Russian Academy of Sciences: Physics, ISSN 1062-8738, Vol. 75, nr 6, s. 854-856Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The existence of trapped antiprotons in the Earth's inner radiation belt has been theoretically predicted, but not observed. We present a procedure for antiproton selection and the observation results from the PAMELA space experiment measurements. The PAMELA magnetic spectrometer ensures reliable identification of particles and charge signs, value determination, and energy measurement, thus enabling us to experimentally establish the existence of antiprotons trapped in the Earth's inner radiation belt.

  • 1413.
    Zafra, Sebastian Ortega
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT AB, Sweden.
    Pang, Xiaodan
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Sergeyev, Sergey
    Phase noise tolerance study in coherent optical circular QAM transmissions with Viterbi-Viterbi carrier phase estimation2014Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, nr 25, s. 30579-30585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a performance evaluation of a non-conventional approach to implement phase noise tolerant optical systems with multilevel modulation formats. The performance of normalized Viterbi-Viterbi carrier phase estimation (V-V CPE) is investigated in detail for circular m-level quadrature amplitude modulation (C-mQAM) signals. The intrinsic property of C-mQAM constellation points with a uniform phase separation allows a straightforward employment of V-V CPE without the need to adapt constellation. Compared with conventional feed-forward CPE for square QAM signals, the simulated results show an enhanced tolerance of linewidth symbol duration product (Delta vT(s)) at a low sensitivity penalty by using feed-forward CPE structure with C-mQAM. This scheme can be easily upgraded to higher order modulations without inducing considerable complexity.

  • 1414.
    Zakomirnyi, Vadim
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Siberian Federal University, Krasnoyarsk, Russian Federation.
    Rasskazov, I. L.
    Gerasimov, V. S.
    Ershov, A. E.
    Polyutov, S. P.
    Karpov, S. V.
    Ågren, Hans
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Siberian Federal University, Krasnoyarsk, Russian Federation.
    Titanium nitride nanoparticles as an alternative platform for plasmonic waveguides in the visible and telecommunication wavelength ranges2018Ingår i: Photonics and Nanostructures - Fundamentals and Applications, ISSN 1569-4410, Vol. 30, s. 50-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose to utilize titanium nitride (TiN) as an alternative material for linear periodic chains (LPCs) of nanoparticles (NPs) which support surface plasmon polariton (SPP) propagation. Dispersion and transmission properties of LPCs have been examined within the framework of the dipole approximation for NPs with various shapes: spheres, prolate and oblate spheroids. It is shown that LPCs of TiN NPs support high-Q eigenmodes for an SPP attenuation that is comparable with LPCs from conventional plasmonic materials such as Au or Ag, with the advantage that the refractory properties and cheap fabrication of TiN nanostructures are more preferable in practical implementations compared to Au and Ag. We show that the SPP decay in TiN LPCs remains almost the same even at extremely high temperatures which is impossible to reach with conventional plasmonic materials. Finally, we show that the bandwidth of TiN LPCs from non-spherical particles can be tuned from the visible to the telecommunication wavelength range by switching the SPP polarization, which is an attractive feature for integrating these structures into modern photonic devices.

  • 1415.
    Zeil, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Tailored fiber lasers and their use in nonlinear optics2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The objective of this thesis work was to develop tailored fiber lasers, which meet the pump requirement for efficient continuous-wave (cw) frequency conversion to the visible and the mid-infrared wavelength regimes: a stable, high-power, wavelength-tunable, narrow-linewidth output in a single polarization. As a first step, the prospect of tuning ytterbium fiber lasers over an unprecedented wavelength range, from 980nm to 1100nm, was investigated. The results further substantiate the enormous potential of fiber lasers to act as widely tunable pump sources for nonlinear frequency conversion schemes, allowing the design of coherent light sources in large parts of the optical spectrum. Subsequently, a method of flexible wavelength-tuning and -locking for high-power fiber oscillators was demonstrated, incorporating the use of a highly reflective transversely-chirped volume Bragg grating as cavity mirror. Through a simple lateral translation of the grating, continuous wavelength-tuning over 2.5 THz was achieved without sacrificing efficiency, spectral or spatial beam quality. As the latter free-space laser architecture relied on an intra-cavity polarization filter to ensure a linearly polarized output state, the filtered orthogonal polarization state was available for a secondary laser oscillation. Following this basic design idea, a high-power dual-wavelength laser with a tunable wavelength separation of up to 2 THz was demonstrated. With both signals separated in wavelength and polarization, gain competition was effectively suppressed and the presented source possessed the necessary stability for potential use in power-demanding applications such as difference frequency generation of cw THz radiation. After establishing a flexible and reliable fiber pump source, continuous-wave, quasi-phase matched, second harmonic generation experiments were performed on several crystals from the KTiOPO4 family. The power scaling limitations of these materials, when generating high-power signals in the visible spectral range were studied. Although, a conclusive identication of the optimal KTiOPO4 isomorph for this process was hindered due to varying crystal quality from different vendors, comparative transmission studies suggest that the arsenate isomorph, KTiOAsO4, could be best suited by virtue of its low linear absorption in the visible region. Finally, a singly-resonant optical parametric oscillator, pumped by the above narrowband fiber laser source, efficiently generated 11W of mid-infrared radiation at 3.4 µm and 19W single-frequency radiation at 1.55 µm. Stable, high-power operation of this parametric source was facilitated by a novel method of controlling the intra-cavity signal power using a volume Bragg grating with variable reectivity.

  • 1416.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Volume Bragg grating controlled fiber lasers2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In recent years, rare earth doped fiber lasers have experienced remarkable progress in terms of power scaling, warranting their use in numerous research and industry applications. Especially, the rapid rise in output powers an be attributed to the fact that the fiber laser design naturally promotes good thermal handling capabilities, over-all efficiency and exceptional spatial beam qualities. Moreover, the broad fluorescence spectra of the used rare earth gain media allow great flexibility in operating wavelength. However, proper restriction and stabilization of the spectral properties has to keep up with the rapid increase in power levels, without sacrificing the advantages of fiber lasers. In our work, we demonstrate how the implementation of volume-Bragg grating can cater for that demand. We show how this generic technology can be applied to increase the spectral brightness and to permit flexible wavelength-tuning and discuss its advantages and limitations with respect to other approaches.

  • 1417.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Efficient spectral control and tuning of a high-power narrow-linewidth Yb-doped fiber laser using a transversally chirped volume-Bragg grating (TCVBG)2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we present a high-power (>100 W) tunable Yb-berlaser oscillator. Facile tuning over 2.5 THz of the narrow-band (10GHz) signal was achieved by translating a transversally chirpedvolume-Bragg grating whilst maintaining constant output powerand the polarization.

  • 1418.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Tunable, high-power, continuous-wave dual-polarization Yb-fiber oscillator2015Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, nr 13, s. 17450-17455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate a high-power, dual-polarization Yb-fiber oscillator, by separately locking the two linear polarization states defined by slow and fast axis of a polarization-maintaining gain fiber with volume Bragg gratings. Dual-line lasing is achieved with a tunable wavelength separation from 0.03 to 2 THz, while exceeding output powers of 78 W over the entire tuning range, maintaining a high beam-quality with M-2<1.2. With this laser configuration we achieve a peak-to-peak power variation of <1% for the dual-line signal and <3% for the individual signals.

  • 1419.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Eciency-optimized, 30W continuous-waveOPO employing a variable re ectivity volume Bragg grating2015Konferensbidrag (Refereegranskat)
  • 1420.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High-power, single-frequency, continuous-waveoptical parametric oscillator employing avariable reflectivity volume Bragg grating2014Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, nr 24, s. 29907-29913Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A continuous-wave singly-resonant optical parametric oscillator (SRO) with an optimum extraction efficiency, that can be adjusted independent of the pump power, is demonstrated. The scheme employs a variable-reflectivity volume Bragg grating (VBG) as the output coupler of a ring cavity, omitting any additional intra-cavity elements. In this configuration, we obtained a 75%-efficient SRO with a combined signal (19 W @ 1.55 mu m) and idler (11 W @ 3.4 mu m) output power of 30 W.

  • 1421.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pump threshold optimization of a continuous-wave optical parametric oscillator using avariable-reflectivity volume Bragg grating2014Konferensbidrag (Refereegranskat)
  • 1422.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Zukauskas, Andrius
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Frequency doubling in Rb:PPKTP of a high-power, continuous-wave, VBG-locked fiber laser2012Konferensbidrag (Refereegranskat)
  • 1423.
    Zeil, Peter
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Zukauskas, Andrius
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High-power Continuous-wave Frequency-doubling in KTiOAsO42013Ingår i: Advanced Solid-State Lasers Congress: OSA Technical Digest 2013 / [ed] G. Huber and P. Moulton, Optical Society of America, 2013, s. AM3A.4-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present efficient single-pass second harmonic generation at 533 nm by frequency doubling a high-power continuous wave fiber laser in KTiOAsO4 (KTA). The scheme provided 11.4 W of green power at a conversion efficiency of 25 %.

  • 1424. Zhan, Qiuqiang
    et al.
    Liu, Haichun
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wang, Baoju
    Wu, Qiusheng
    Pu, Rui
    Zhou, Chao
    Huang, Bingru
    Peng, Xingyun
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. South China Normal University, China.
    Achieving high-efficiency emission depletion nanoscopy by employing cross relaxation in upconversion nanoparticles2017Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, nr 1, artikel-id 1058Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stimulated emission depletion microscopy provides a powerful sub-diffraction imaging modality for life science studies. Conventionally, stimulated emission depletion requires a relatively high light intensity to obtain an adequate depletion efficiency through only light–matter interaction. Here we show efficient emission depletion for a class of lanthanide-doped upconversion nanoparticles with the assistance of interionic cross relaxation, which significantly lowers the laser intensity requirements of optical depletion. We demonstrate two-color super-resolution imaging using upconversion nanoparticles (resolution ~ 66 nm) with a single pair of excitation/depletion beams. In addition, we show super-resolution imaging of immunostained cytoskeleton structures of fixed cells (resolution ~ 82 nm) using upconversion nanoparticles. These achievements provide a new perspective for the development of photoswitchable luminescent probes and will broaden the applications of lanthanide-doped nanoparticles for sub-diffraction microscopic imaging.

  • 1425.
    Zhang, Feng
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Ai, Yue-Jie
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fang, Wei-Hai
    Nonadiabatic histidine dissociation of hexacoordinate heme in neuroglobin protein2010Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, density functional theory and canonical nonadiabatic Monte Carlo transition state theory have been used to investigate histidine dissociation process from the hexacoordinate heme in Ngb protein. The potential energy surfaces (PES) of the lowest singlet, triplet, and quintet states are calculated by stepwise optimization along with the histidine dissociation pathway. Based on the calculated two-dimensional PES, the histidine dissociation rates for the spin-forbidden processes via singlet to triplet and singlet to quintet transitions have been calculated by the nonadiabatic Monte Carlo transition state theory in canonical ensemble. The present study provides a quantitative description on spin-forbidden histidine dissociation processes.

  • 1426.
    Zhang, Igor Ying
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Wu, Jianming
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Xu, Xin
    Trends in R-X Bond Dissociation Energies (R-center dot = Me, Et, i-Pr, t-Bu, X-center dot = H, Me, Cl, OH)2010Ingår i: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 6, nr 5, s. 1462-1469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Trends for R X bond dissociation energies have been examined with density functional methods of B3LYP, BMK, M06-2X, MC3MPW, B2PLYP, MCG3-MPW, and XYG3, as well as 03, MCG3/3, G3X, and 04 theories as functions of alkylation (i.e., IT = Me, Et, i-Pr, (-Bu) and X' substitution (i.e., X' = H, Me, Cl, OH). The results highlight the physical origin of success or failure of each method and demonstrate the good agreement with experimental results for G4, MCG3-MPW, and XYG3. The last holds great promise as a reliable method that is applicable to larger systems.

  • 1427.
    Zhang, Liyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    The effect of transformation order on the invisibility performance of a practical cylindrical cloak2008Ingår i: Journal of Optics. A, Pure and applied optics, ISSN 1464-4258, E-ISSN 1741-3567, Vol. 10, nr 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A class of polynomial coordinate transformation functions with an arbitrary order number is used to design cylindrical invisibility cloaks. Since an ideal cylindrical cloak is inevitably unphysical at its inner boundary, our investigation involves the replacement of a thin layer of material at the cloak's inner surface by a homogeneous material layer. This approach effectively avoids the infinities in the material parameters, and at the same time produces practical near-ideal invisibility cloaks. The cloaks obtained are perfectly matched in impedance at the outer boundary. We quantitatively show the effect of the transformation order on the proposed cloak's scattering coefficients.

  • 1428.
    Zhang, Lu
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, O.
    Lin, Rui
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Djupsjobacka, A.
    Martensson, J.
    Westergren, Urban
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Tang, M.
    Fu, S.
    Liu, D.
    Tong, W.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Jacobsen, G.
    Hu, W.
    Xiao, S.
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Kernel Adaptive Filtering for Nonlinearity-Tolerant Optical Direct Detection Systems2018Ingår i: European Conference on Optical Communication, ECOC, Institute of Electrical and Electronics Engineers Inc. , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Kernel adaptive filtering (KAF) is proposed for nonlinearity-tolerant optical direct detection. for 7× 128 Gbit/s PAM4 transmission over 33.6km 7-core-fiber, KAF only needs 10 equalizer taps to reach KP4-FEC limit (BER@2.2e-4), whereas decision-feedback-equalizer needs 43 equalizer taps to reach HD-FEC limit (BER@3.8e-3).

  • 1429.
    Zhang, Lu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). State Key Laboratory of Advanced Optical Communication System and Networks, Shanghai Jiao Tong University, Shanghai, China.
    Pang, Xiaodan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). Networking and Transmission Laboratory, RISE Acreo AB, Kista, Sweden.
    Ozolins, Oskars
    Udalcovs, Aleksejs
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI).
    Westergren, Urban
    KTH, Skolan för teknikvetenskap (SCI).
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI).
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Xiao, Shilin
    Hu, Weisheng
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Digital mobile fronthaul employing differential pulse code modulation with suppressed quantization noise2017Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, nr 25, s. 31921-31936Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A differential pulse code modulation (DPCM) based digital mobile fronthaul architecture is proposed and experimentally demonstrated. By using a linear predictor in the DPCM encoding process, the quantization noise can be effectively suppressed and a prediction gain of 7 similar to 8 dB can be obtained. Experimental validation is carried out with a 20 km 15-Gbaud/lambda 4-level pulse amplitude modulation (PAM4) intensity modulation and direct detection system. The results verify the feasibility of supporting 163, 122, 98, 81 20-MHz 4, 16, 64, 256 QAM based antenna-carrier (AxC) containers with only 3, 4, 5, 6 quantization bits at a sampling rate of 30.72MSa/s in LTE-A environment. Further increasing the number of quantization bits to 8 and 9, 1024 quadrature amplitude modulation (1024 QAM) and 4096 QAM transmission can be realized with error vector magnitude (EVM) lower than 1% and 0.5%, respectively. The supported number of AxCs in the proposed DPCM-based fronthaul is increased and the EVM is greatly reduced compared to the common public radio interface (CPRI) based fronthaul that uses pulse code modulation. Besides, the DPCM-based fronthaul is also experimentally demonstrated to support universal filtered multicarrier signal that is one candidate waveform for the 5th generation mobile systems.

  • 1430.
    Zhang, Pu
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Lobet, Michael
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Carpet cloaking on a dielectric half-space2010Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, nr 17, s. 18158-18163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carpet cloaking is proposed to hide an object on a dielectric half-space from electromagnetic (EM) detection. A two-dimensional conformal transformation specified by an analytic function is utilized for the design. Only one nonsingular material parameter distribution suffices for the characterization. The cloaking cover situates on the dielectric half-space, and consists of a lossless upper part for EM wave redirection and an absorbing bottom layer for inducing correct reflection coefficient and absorbing transmission. Numerical simulations with Gaussian beam incidence are performed for verification. The broadband behavior of the carpet cloaking is also illustrated.

  • 1431. Zhang, Qun
    et al.
    Lin, Ke
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Laser-launched evanescent surface plasmon polariton field utilized as a direct coherent pumping source to generate emitted nonlinear four-wave mixing radiation2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 6, s. 4991-5001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We develop a concept of surface plasmon polaritons (SPPs) based four-wave mixing (4WM), in which a laser-launched evanescent SPP field is utilized as a coherent pumping source to involve directly in a nonlinear 4WM process at the dielectric/metal interface. Conversion efficiency of the resulting 4WM radiation is expected to be dramatically increased due to the local-field enhancement effect. Feasibility of implementing this concept at the air/gold film and graphene flake/gold film interfaces is further examined by numerical simulations. The concept shows intriguing promise for applications in newly emerging nanophotonics, optoelectronics, and active plasmonics.

  • 1432. Zhang, Song Bin
    et al.
    Kimberg, Victor
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Rohringer, Nina
    Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme2016Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 94, nr 6, artikel-id 06413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present paper we propose nonlinear femtosecond x-ray pump-probe spectroscopy to study the vibrational dynamics of a core-excited molecular state and discuss numerical results in CO. A femtosecond pump resonantly excites the carbon core-excited 1s-1π∗ state of the CO molecule. A second strong probe (control) pulse is applied at variable delay and is resonantly coupled to a valence excited state of the molecule. The strong nonlinear coupling of the control pulse induces Rabi flopping between the two electronic states. During this process, a vibrational wave packet in the core-excited state is created, which can be effectively manipulated by changing the time delay between pump and control pulses. We present an analysis of the resonant Auger electron spectrum and the transient absorption or emission spectrum on the pump transition and discuss their information content for reconstruction of the vibrational wave packet.

  • 1433. Zhang, Xu
    et al.
    Othman, Maisara B
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Jensen, Jesper B
    Monroy, Idelfonso Tafur
    Bi-directional multi dimension CAP transmission for smart grid communication services2012Ingår i: Communications and Photonics Conference (ACP), 2012 Asia, Optical Society of America, 2012, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency.

  • 1434. Zhang, Xu
    et al.
    Pang, Xiaodan
    Technical University of Denmark, Denmark.
    Deng, Lei
    Zibar, Darko
    Monroy, Idelfonso Tafur
    Younce, Richard
    High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems2012Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, nr 18, s. 19990-19995Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs) with approximate 300 MHz linewidth are used as transmitters and local oscillators for coherent detection of optical DP-QPSK signals. The proposed system, with central wavelength at 1540.68 nm, operates at 40 Gb/s over 80 km single mode fiber (SMF) as part of a passive optical network (PON). The deployment of pilot-tone-aided PNC algorithm guarantees a bit error rate (BER) performance below the forward error correction (FEC) threshold. Moreover, we also evaluate a novel digital signal processing (DSP) algorithm for adaptive pilot tone detection.

  • 1435. Zhang, Xu
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Dogadaev, Anton K
    Monroy, Idelfonso Tafur
    Zibar, Darko
    Younce, Richard C
    High spectrum narrowing tolerant 112 Gb/s dual polarization QPSK optical communication systems using digital adaptive channel estimation2012Ingår i: 2012 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    We experimentally demonstrate high spectrum narrowing tolerant 112-Gb/s QPSK polarization multiplex system based on digital adaptive channel estimation method. The proposed algorithm is able to detect severe spectrum-narrowed signal even with 20GHz 3dB bandwidth.

  • 1436. Zhang, Y.
    et al.
    Xiao, S.
    Yu, Y.
    Chen, C.
    Bi, M.
    Liu, L.
    Zhang, Lu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). Shanghai Jiao Tong Univ, Peoples R China.
    Hu, W.
    Experimental study of wideband in-band full-duplex communication based on optical self-interference cancellation2016Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 24, nr 26, s. 30139-30148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we experimentally demonstrate and study a wideband in-band fullduplex (IBFD) wireless communication system based on optical self-interference cancellation (SIC). The optical SIC performances based on antennas for broadband IBFD are firstly evaluated within high frequency bands (&gt; 10GHz). In this system, two electro-absorptionmodulated lasers (EMLs) and a balanced photo-detector (BPD) are employed to remove the wideband self-interference within received wireless signal. By theoretical derivation and experimental verification, the impact factors of SIC are analyzed, especially for non-flatness wireless channel case. Experimental results show more than 30-dB cancellation depth in 100-MHz bandwidth with employment of horn antennas. Besides, IBFD transmission performance based on OFDM signals for different bandwidth with 11.15-GHz center frequency is also demonstrated, and ∼52.2-dB•Hz2/3 spurious-free dynamic range (SFDR) is obtained.

  • 1437.
    Zhang, Ziyang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Silicon-based Photonic Devices: Design, Fabrication and Characterization2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The field of Information and Communication Technologies is witnessing a development speed unprecedented in history. Moore’s law proves that the processor speed and memory size are roughly doubling each 18 months, which is expected to continue in the next decade. If photonics is going to play a substantial role in the ICT market, it will have to follow the same dynamics. There are mainly two groups of components that need to be integrated. The active components, including light sources, electro-optic modulators, and detectors, are mostly fabricated in III-V semiconductors. The passive components, such as waveguides, resonators, couplers and splitters, need no power supply and can be realized in silicon-related semiconductors. The prospects of silicon photonics are particularly promising, the fabrication is mostly compatible with standard CMOS technology and the on-chip optical interconnects are expected to increase the speed of microprocessors to the next generation.

    This thesis starts with designs of various silicon-based devices using finite-difference time-domain simulations. Parallel computation is a powerful tool in the modeling of large-scale photonic circuits. High Q cavities and resonant channel drop filters are designed in photonic crystal platform. Different methods to couple light from a single mode fiber to silicon waveguides are studied by coupled-mode theory and verified using parallel simulations. The performance of waveguide grating coupler for vertical radiation is also studied.

    The fabrication of silicon-based photonic devices involves material deposition, E-beam or optical lithography for pattern defining, and plasma/wet-chemistry etching for pattern transfer. For nanometer-scaled structures, E-beam lithography is the most critical process. Depending on the structures of the devices, both positive resist (ZEP520A) and negative resist (maN2405) are used. The proximity and stitch issues are addressed by careful dose correction and patches exposure. Some examples are given including photonic crystal surface mode filter, micro-ring resonators and gold grating couplers. In particular, high Q (2.6×105), deep notch (40 dB) and resonance-splitting phenomenon are demonstrated for silicon ring resonators.

    It is challenging to couple light into photonic integrated circuits directly from a single-mode fiber. The butt-coupled light-injecting method usually causes large insertion loss due to small overlap of the mode profiles and large index mismatch. Practically it is not easy to cleave silicon sample with smooth facet where the waveguide exposes. By adding gold gratings to the waveguides, light can be injected and collected vertically from single-mode fiber. The coupling efficiency is much higher. There is no need to cleave the sample. The access waveguides are much shortened and the stitch problem in E-beam lithography is avoided.

    In summary, this thesis introduces parallel simulations for the design of modern large-scale photonic devices, addresses various issues with Si-based fabrication, and analyses the data from the characterization. Several novel devices using silicon nanowire waveguides and 2D photonic crystal structures have been demonstrated for the first time.

  • 1438.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, Ulf
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC. KTH, Skolan för datavetenskap och kommunikation (CSC).
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Subwavelength-diameter Silica Wire and Photonic Crystal Waveguide Slow Light Coupling2007Ingår i: Active and Passive Electronic Components, ISSN 0882-7516, E-ISSN 1563-5031, Vol. 2007, s. 78602-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Counter-directional coupling between subwavelength-diameter silica wire and single-line-defect two-dimensional photonic crystal slab waveguide is studied numerically using parallel three-dimensional finite-different time-domain method. By modifying silica wire properties or engineering photonic crystal waveguide dispersion band, the coupling central wavelength can be moved to the slow light region and the coupling efficiency improves simultaneously. One design gives 82 peak power transmission from silica wire to photonic crystal waveguide over an interacting distance of 50 lattice constants. The group velocity is estimated as 1/35 of light speed in vacuum.

  • 1439.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Dainese, Matteo
    Replisaurus AB.
    Chacinski, Marek
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    High-quality-factor micro-ring resonator in amorphous-silicon on insulator structure2008Ingår i: ECIO'08 Eindhoven - Proceedings of the 14th European Conference on Integrated Optics and Technical Exhibition, Contributed and Invited Papers, 2008, s. 329-332Konferensbidrag (Refereegranskat)
    Abstract [en]

    Micro-ring resonators have been fabricated in hydrogenated amorphous silicon on silica structure. The intrinsic quality factor is estimated as 56,000 and the notch depth is ̃ 30dB. The intrinsic loss per unit length is 15.3dB/cm, comparable to 9.16dB/cm in the single-crystalline silicon ring of the same geometry.

  • 1440.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Dainese, Matteo
    Replisaurus AB.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Resonance-splitting and enhanced notch depth in SOI ring resonators with mutual mode coupling2008Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 16, nr 7, s. 4621-4630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Resonance-splitting and enhanced notch depth are experimentally demonstrated in micro-ring resonators on SOI platform as a result of the mutual mode coupling. This coupling can be generated either by the nanometer-scaled gratings along the ring sidewalls or by evanescent directional coupling between two concentric rings. The transmission spectra are fitted using the time-domain coupled mode analysis. Split-wavelength separation of 0.68 nm for the 5-mu m-radius ring, notch depth of 40 dB for the 10-mu m-radius ring, and intrinsic Q factor of 2.6 x 10(5) for the 20-mu m-radius ring are demonstrated. Notch depth improvement larger than 25dB has been reached in the 40-39-mu m-radius double-ring structure. The enhanced notch depth and increased modal area for the concentric rings might be promising advantages for bio-sensing applications.

  • 1441.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Dainese, Matteo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Xiao, Sanshui
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Swillo, Marcin
    PhoXtal Communications AB.
    Andersson, Ulf
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC. KTH, Skolan för datavetenskap och kommunikation (CSC).
    Optical filter based on two-dimensional photonic crystal surface-mode cavity in amorphous silicon-on-silica structure2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, nr 4, s. 041108-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An optical filter based on side coupling between silicon wire waveguide and two-dimensional photonic crystal surface-mode cavity is presented. The design is optimized numerically by parallel three-dimensional finite-different time-domain simulations. The device is then fabricated on amorphous silicon-on-silica structure. The drop wavelength is observed around 1580 nm. The extinction ratio of the filter is larger than 10 dB and the intrinsic quality factor of the surface-mode cavity is approximately 2000.

  • 1442.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Compact in-plane channel drop filter design using a single cavity with two degenerate modes in 2D photonic crystal slabs2005Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 13, nr 7, s. 2596-2604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A compact in-plane channel drop filter design in 2D hexagonal lattice photonic crystal slabs is presented in this paper. The system consists of two photonic crystal waveguides and a single cavity with two degenerate modes. Both modes are able to confine light strongly in the vertical dimension and prove to couple equally into the waveguides. Three dimensional finite difference time domain simulations show that the quality factor is around 3,000. At resonance, power transferred to the drop waveguide is 78% and only 1.6% remains in the bus waveguide. We also show that by carefully tuning the drop waveguide boundary, light remaining in the bus can be further reduced to below 0.4% and thus the channel isolation is larger than 22dB.

  • 1443.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Coupled mode analysis of in-plane channel drop filters with resonant mirrors2005Ingår i: Photonics and Nanostructures-Fundamentals and Applications, ISSN 1569-4410, Vol. 3, nr 2-3, s. 84-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A channel drop filter system that consists of two waveguides and three cavities is studied. One cavity couples with both waveguides, while the other two work as resonant mirrors to reflect the selected channel back into the system. The operation of this configuration is analyzed, using coupled mode theory. The conditions to achieve 100% in-plane channel transfer are derived. A method to suppress the side lobes of reflection and backward drop is also proposed. The direct coupling between the cavities is not required. The analysis is verified by two-dimensional finite difference time domain simulations in 2D hexagonal photonic crystals.

  • 1444.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Fabrication tolerance tests on high-Q microcavities in 2D photonic crystal slabs2005Ingår i: Conference on Lasers and Electro-Optics Europe: Technical Digest, 2005Konferensbidrag (Refereegranskat)
  • 1445.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Influence of structural variations on high-Q microcavities in two-dimensional photonic crystal slabs2005Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, nr 13, s. 1713-1715Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of some critical structural variations in high-Q microcavities in two-dimensional photonic crystal slabs is investigated. All the cavities studied maintain a high Q in a wide range of structural variations, while the resonant frequencies shift on a relatively large scale when the structural variations are comparable to the physical sizes of the cavities.

  • 1446.
    Zhang, Ziyang
    et al.
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Qiu, Min
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Small-volume waveguide-section high Q microcavities in 2D photonic crystal slabs2004Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 12, nr 17, s. 3988-3995Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of microcavities in 2D hexagonal lattice photonic crystal slabs are studied in this paper. The microcavities are small sections of a photonic crystal waveguide. Finite difference time domain simulations show that these cavities preserve high Q modes with similar geometrical parameters and field profile. Effective modal volume is reduced gradually in this series of microcavity modes while maintaining high quality factor. Vertical Q value larger than 106 is obtained for one of these cavity modes with effective modal volume around 5.40 cubic half wavelengths [(lambda/2n(slab))(3)]. Another cavity mode provides even smaller modal volume around 2.30 cubic half wavelengths, with vertical Q value exceeding 10(5).

  • 1447.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, Ulf
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC. KTH, Skolan för datavetenskap och kommunikation (CSC).
    Tong, Limin
    Department of Optical Engineering, Zhejiang University.
    Subwavelength-diameter Silica Wire for Light In-coupling to Silicon-based Waveguide2007Ingår i: Chinese optics letters, ISSN 1671-7694, Vol. 5, nr 10, s. 577-579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coupling between subwavelength-diameter silica wires and silicon-based waveguides is studied using the parallel three-dimensional (3D) finite-different time-domain method. Conventional butt-coupling to a silica-substrated silicon wire waveguide gives above 40% transmission at the wavelength range from 1300 to 1750 nm with good robustness against axial misalignments. Slow light can be generated by counter-directional coupling between a silica wire and a two-dimensional (2D) silicon photonic crystal slab waveguide. Through dispersion-band engineering, 82% transmission is achieved over a coupling distance of 50 lattice constants. The group velocity is estimated as 1/35 of the light speed in vacuum.

  • 1448.
    Zhang, Ziyang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qui, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Coupled-mode analysis of a resonant channel drop filter using waveguides with mirror boundaries2006Ingår i: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 23, nr 1, s. 104-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The operation of resonant channel drop filters is analyzed using coupled-mode theory. The resonator is chosen to support a single standing-wave mode, and, in the ideal case, one can realize 100% in-plane channel transfer by properly applying mirror boundaries to the waveguides. The presence of the mirrors causes the resonant frequency to shift, and the system Q factor also changes accordingly. The two variables are related by a closed curve depending on the phase introduced by the reflection and wave propagation between the two ports. When one works on different regions of the curve, the system can be tuned to work at different resonant frequencies with minimum Q-factor variations or vice versa. The mirror can be frequency selective. The same single-mode cavity can be used as a resonant mirror to terminate the waveguide. The combined system is analyzed, and we find the conditions to achieve 100% channel transfer as well as to maintain a simple Lorentzian line shape of the transmission spectra. The analysis is verified by two-dimensional (2D) finite-difference time-domain simulations in 2D hexagonal photonic crystals.

  • 1449. Zhao, D.
    et al.
    Liu, S.
    Yang, H.
    Ma, Z.
    Reuterskiöld-Hedlund, C.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zhou, W.
    Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report here an optically pumped hybrid III-V/Si photoic crystal surface emitting laser (PCSEL), consisting of a heterogeneously integrated III-V InGaAsP quantum well heterostructure gain medium, printed on a patterned defect-free Si photonic crystal (PC) bandedge cavity. Single mode lasing was achieved for a large area laser, with a side-mode suppression ratio of 28 dB, for lasing operation temperature ∼200 K. Two types of lasers were demonstrated operating at different temperatures. Detailed modal analysis reveals the lasing mode matches with the estimated lasing gain threshold conditions. Our demonstration promises a hybrid laser sources on Si towards three-dimensional (3D) integrated Si photonics for on-chip wavelength-division multiplex (3D WDM) systems for a wide range of volume photonic/electronic applications in computing, communication, sensing, imaging, etc.

  • 1450. Zhao, Deyin
    et al.
    Liu, Shihchia
    Yang, Hongjun
    Ma, Zhenqiang
    Reuterskiöld-Hedlund, Carl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zhou, Weidong
    Design and Characterization of Photonic Crystal Bandedge Surface-emitting Lasers on Silicon2015Ingår i: 2015 PHOTONICS CONFERENCE (IPC), IEEE conference proceedings, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report the detailed design and experimental realization of single mode photonic crystal bandedge surface-emitting lasers on silicon based on a transfer process. By improving the coupling efficiency, the single mode operation regime can be shifted to higher temperatures.

2627282930 1401 - 1450 av 1481
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf