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  • 451.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Swillo, Marcin
    Phoxtal Communications AB.
    Dainese, Matteo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Group delay-compensated Bragg grating filters for high speed DWDM systems2006In: Integrated Optics, Silicon Photonics, and Photonic Integrated Circuits / [ed] Righini, GC, BELLINGHAM, WA: SPIE-INT SOC OPTICAL ENGINEERING , 2006, Vol. 6183, p. S1831-S1831Conference paper (Refereed)
    Abstract [en]

    We present a novel practical method for group delay compensation of Bragg gratings imprinted in planar waveguides for high speed DWDM systems. Although Bragg grating-based wavelength selective devices in optical fibers have reached their maturity, similar components built on the basis of planar technology are still the research issue. We analyze an integrated Mach-Zehnder interferometer-based Add-Drop multiplexer equipped with two pairs of gratings, one designed as a wavelength selective filter and the other one as a group delay compensator.

  • 452.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Integrated silicon nanophotonics: a solution for computer interconnects2011In: 2011 13th International Conference on Transparent Optical Networks, ICTON 2011, IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    To solve the processors performance limitations, new chip-to-chip and on-chip communication needs to be introduced. Optical technology will play here a crucial role. Optical links will move into the chip multiprocessors connecting tens or even hundreds of processing elements and forming a photonic network for communication between them. In this talk we will present our solutions of silicon-based CMOS-compatible optical components for the main building blocks in application to computer interconnects.

  • 453.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Silicon-based Devices for Computer Interconnects2010In: 2010 IEEE 4th International Symposium on Advanced Networks and Telecommunication Systems, ANTS 2010, IEEE Communications Society, 2010, p. 7-9Conference paper (Refereed)
    Abstract [en]

    Similarly to optical telecommunication, optical fibers interconnect today computer systems performing very fast communication between servers and supercomputers or between racks in modern data centers. In the near future optical links will move into the chip multiprocessors connecting tens or even hundreds of processing elements and forming a photonic network for communication between them. For these applications novel, highly integrated and CMOS compatible devices need to be developed. In this talk we will present some of our recent silicon-based CMOS-compatible optical components for application in computer chip-to-chip and on-chip communication

  • 454.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Wang, Zhechao
    Lou, Fei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Dai, Daoxin
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Advanced silicon device technologies for optical interconnects2012In: Optoelectronic Integrated Circuits XIV / [ed] Louay A. Eldada, El-Hang Lee, SPIE - International Society for Optical Engineering, 2012, p. 826506-Conference paper (Refereed)
    Abstract [en]

    Silicon photonics is an emerging technology offering novel solutions in different areas requiring highly integrated communication systems for optical networking, sensing, bio-applications and computer interconnects. Silicon photonicsbased communication has many advantages over electric wires for multiprocessor and multicore macro-chip architectures including high bandwidth data transmission, high speed and low power consumption. Following the INTEL's concept to "siliconize" photonics, silicon device technologies should be able to solve the fabrication problems for six main building blocks for realization of optical interconnects: light generation, guiding of light including wavelength selectivity, light modulation for signal encoding, detection, low cost assembly including optical connecting of the devices to the real world and finally the electronic control systems.

  • 455.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Tang, Yongbo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Coupling of silicon nanophotonic circuits to optical fibers2010In: Asia Communications and Photonics Conference and Exhibition, ACP 2010, IEEE Communications Society, 2010, p. 421-422Conference paper (Refereed)
    Abstract [en]

    Silicon-based nanophotonic waveguides and components fabricated in silicon-on-insulator technology build a platform for high density photonic integrated circuits, where active III-V devices can be incorporated using evanescent field coupling. These circuits can be fabricated with standard CMOS technology processing, allowing for low cost mass production in applications such as optical networks, computer interconnects and sensing. Connecting of these integrated structures to the real world of optical fibers appears is an important problem to be solved. In this paper we discuss some solutions and present some of fabricated devices including a grating coupler-polarization splitter with over 50% efficiency for both polarizations and a nonuniform grating coupler with 68% efficiency for single polarization. To the best of our knowledge, they are the highest coupling efficiencies obtained by regular SOI grating couplers for both, single polarization and polarization splitting.

  • 456.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Tang, Yongbo
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Interfacing of Silicon-on-insulator nanophotonic circuits to the real world2010In: 2010 12th International Conference on Transparent Optical Networks (ICTON), IEEE Communications Society, 2010, p. 5549268-Conference paper (Refereed)
    Abstract [en]

    Silicon-on-insulator material structure allows for very high light confinement in the silicon core due to its high refractive index. The advantages of this technology include the possibility to miniaturize devices and integrate different functions on a single chip, reduction of optical loss and power consumption and potential perspectives for low cost mass production in CMOS technology line. Together with these advantages some new problems appear in comparison to weakly guided light in silica-on-silicon components, causing additional challenges for researchers to be solved. Besides much higher demands for fabrication accuracy, high refractive index contrast introduces additional optical input/output coupling problems as well as much higher polarization sensitivity of nanophotonic structures. Here we will propose some solutions for these problems and illustrate them with designed and fabricated components

  • 457.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Zhu, Ning
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Silicon-Based Integrated Multiplexers for WDM Systems2009In: ICTON: 2009 11TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, NEW YORK: IEEE , 2009, p. 1267-1270Conference paper (Refereed)
    Abstract [en]

    Wavelength Division Multiplexing systems use multiplexers and demultiplexers to increase network capacity by allowing several information channels to be placed into one fiber. Depending on the application multiplexers and demultiplexers can have wide, coarse or dense channel spacing as well as different number of channels that they process. There are many techniques available today for realization of these passive, wavelength selective components including: thin film filters, Bragg gratings, arrayed waveguide gratings and echelle gratings. The last two solutions appear to be most suitable for wafer scale mass production. Silicon-based technology additionally allows for a high level of integration and compatibility with CMOS processing. Here we discuss issues related to different solutions and fabrication technologies and compare two of them based on planar lightwave circuits. We will illustrate with designed and fabricated components for different applications.

  • 458.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Zhu, Ning
    Liu, Liu
    Photonic crystals for polarization splitting, filtering and sensing2010In: 2010 OSA-IEEE-COS Advances in Optoelectronics and Micro/Nano-Optics, AOM 2010, IEEE Communications Society, 2010Conference paper (Refereed)
    Abstract [en]

    In this paper we discuss different unconventional nanophotonic solutions using photonic crystal-based components including filters, sensors and polarization splitter, which utilizes positive and negative refracted beams. We illustrate them with design, technology and fabricated devices.

  • 459.
    Wosinski, Lech
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Zhu, Ning
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wang, Zhechao
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Wavelength Selective Devices for WDM Communication Systems2009In: 2009 IEEE 3RD INTERNATIONAL SYMPOSIUM ON ADVANCED NETWORKS AND TELECOMMUNICATION SYSTEMS (ANTS 2009), NEW YORK: IEEE , 2009, p. 49-51Conference paper (Refereed)
    Abstract [en]

    Depending on the application in optical communication systems different wavelength division multiplexing devices are used to increase network capacity by allowing several wavelength channels to be transmitted by one fiber, to add or drop different wavelength channels or to separate or put together channels carrying different services. Depending on the application such devices can have wide, coarse or dense channel spacing. Furthermore they can handle different number of channels. In this paper we present some of such devices, their functionality, structures and fabrication technologies.

  • 460. Wu, Jing
    et al.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Jin, Yaohui
    Araki, Soichiro
    Special Issue on Optical Network Architectures and Management2011In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 8, no 4, p. 225-225Article in journal (Other academic)
  • 461.
    Wyrowski, Frank
    et al.
    University of Jena, Germany.
    Popov, SergeiKTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.Jaroszewicz, ZbigniewInst. of Applied Optics, Warsaw, Poland.
    Optical Security Systems2005Conference proceedings (editor) (Other academic)
  • 462. Xu, Tao
    et al.
    Zhu, Ning
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Xu, Michelle Y. C.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Aitchison, J. Stewart
    Ruda, H. E.
    Pillar-array based optical sensor2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 6, p. 5420-5425Article in journal (Refereed)
    Abstract [en]

    An optical microcavity based on pillar arrays has been fabricated in Si/SiO2 material system. Transmission measurement was taken and a quality factor as high as 27,600 was observed. This cavity was tested for sensing applications by immersing into optical fluids with accurate refractive indices. For refractive index change of 0.01, a resonance peak wavelength shift of 3.5 nm was measured. We also compare cavities consisting of pillars with different aspect ratios.

  • 463.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Digital Dispersion Equalization and Carrier Phase Estimation in 112-Gbit/s Coherent Optical Fiber Transmission System2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Coherent detection employing multilevel modulation format has become one of the most promising technologies for next generation high speed transmission system due to the high power and spectral efficiencies. With the powerful digital signal processing (DSP), coherent optical receivers allow the significant equalization of chromatic dispersion (CD), polarization mode dispersion (PMD), phase noise (PN) and nonlinear effects in the electrical domain. Recently, the realizations of these DSP algorithms for mitigating the channel distortions in the transmission system are the most attractive investigations. 

    The CD equalization can be performed by the digital filters developed in the time and the frequency domain, which can suppress the fiber dispersion effectively. The PMD compensation is usually performed in the time domain with the adaptive least mean square (LMS) and constant modulus algorithms (CMA) equalization. Feed-forward and feed-back carrier phase estimation algorithms are employed to mitigate the phase noise from the transmitter and local oscillator lasers. The fiber nonlinearities are compensated by using the digital backward propagation methods based on solving the nolinear Schrodinger (NLS) equation and the Manakov equation. 

    In this dissertation, we present a comparative analysis of three digital filters for chromatic dispersion compensation, an analytical evaluation of carrier phase estimation with digital equalization enhanced phase noise and a brief discussion for PMD adaptive equalization. To implement these investigations, a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent transmission system is realized in the VPI simulation platform. With the coherent transmission system, these CD equalizers have been compared by evaluating their applicability for different fiber lengths, their usability for dispersion perturbations and their computational complexity. Meanwhile, the bit-error-rate (BER) floor in carrier phase estimation using a one-tap normalized LMS filter is evaluated analytically, and the numerical results are compared to a differential QPSK detection system.

    Download full text (pdf)
    KTH Licentiate_Tianhua Xu
  • 464.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    DSP based Chromatic Dispersion Equalization and Carrier Phase Estimation in High Speed Coherent Optical Transmission Systems2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Coherent detection employing multilevel modulation formats has become one of the most promising technologies for next generation high speed transmission systems due to the high power and spectral efficiencies. Using the powerful digital signal processing (DSP), coherent optical receivers allow the significant equalization of chromatic dispersion (CD), polarization mode dispersion (PMD), phase noise (PN) and nonlinear effects in the electrical domain. Recently, the realizations of these DSP algorithms for mitigating the channel distortions in the coherent transmission systems are the most attractive investigations.

    The CD equalization can be performed by the digital filters developed in the time and the frequency domain, which can suppress the fiber dispersion effectively. The PMD compensation is usually performed in the time domain with the adaptive least mean square (LMS) and constant modulus algorithms (CMA) equalization. Feed-forward and feed-back carrier phase estimation (CPE) algorithms are employed to mitigate the phase noise (PN) from the transmitter (TX) and the local oscillator (LO) lasers. The fiber nonlinearities are compensated by using the digital backward propagation methods based on solving the nonlinear Schrödinger (NLS) equation and the Manakov equation.

    In this dissertation, we present a comparative analysis of three digital filters for chromatic dispersion compensation, a comparative evaluation of different carrier phase estimation methods considering digital equalization enhanced phase noise (EEPN) and a brief discussion for PMD adaptive equalization. To implement these investigations, a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent transmission system with post-compensation of dispersion is realized in the VPI simulation platform. In the coherent transmission system, these CD equalizers have been compared by evaluating their applicability for different fiber lengths, their usability for dispersion perturbations and their computational complexity. The carrier phase estimation using the one-tap normalized LMS (NLMS) filter, the differential detection, the block-average (BA) algorithm and the Viterbi-Viterbi (VV) algorithm is evaluated, and the analytical predictions are compared to the numerical simulations. Meanwhile, the phase noise mitigation using the radio frequency (RF) pilot tone is also investigated in a 56-Gbit/s NRZ single polarization QPSK (NRZ-SP-QPSK) coherent transmission system with post-compensation of chromatic dispersion. Besides, a 56-Gbit/s NRZ-SP-QPSK coherent transmission system with CD pre-distortion is also implemented to analyze the influence of equalization enhanced phase noise in more detail.

    Download full text (pdf)
    fulltext
  • 465.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Li, J.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Variable-step-size LMS adaptive filter for digital chromatic dispersion compensation in PDM-QPSK coherent transmission system2009In: 2009 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments, SPIE - International Society for Optical Engineering, 2009, p. 75062I-Conference paper (Refereed)
    Abstract [en]

    High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Digital filters in coherent optical receivers can be used to mitigate the chromatic dispersion entirely in the optical transmission system. In this paper, the least mean square adaptive filter has been developed for chromatic equalization in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent optical transmission system established on the VPIphotonics simulation platform. It is found that the chromatic dispersion equalization shows a better performance when a smaller step size is used. However, the smaller step size in least mean square filter will lead to a slower iterative operation to achieve the guaranteed convergence. In order to solve this contradiction, an adaptive filter employing variable-step-size least mean square algorithm is proposed to compensate the chromatic dispersion in the 112-Gbit/s coherent communication system. The variable-step-size least mean square filter could make a compromise and optimization between the chromatic dispersion equalization performance and the algorithm converging speed. Meanwhile, the required tap number and the converged tap weights distribution of the variable-step-size least mean square filter for a certain fiber chromatic dispersion are analyzed and discussed in the investigation of the filter feature.

  • 466.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Forzati, M.
    Acreo AB, Electrum 236, Kista, Sweden.
    Mårtensson, J.
    Acreo AB, Electrum 236, Kista, Sweden.
    Mussolin, M.
    University of Padova, Italy.
    Li, J.
    Acreo AB, Electrum 236, Kista, Sweden.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Y.
    Tianjin University, Tianjin, China.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Frequency-domain chromatic dispersion equalization using overlap-add methods in coherent optical system2011In: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 27, no 2Article in journal (Refereed)
    Abstract [en]

    The frequency domain equalizers (FDEs) employing two types of overlap-add zero-padding (OLA-ZP) methods are applied to compensate the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent optical transmission system. Simulation results demonstrate that the OLA-ZP methods can achieve the same acceptable performance as the overlap-save method. The required minimum overlap (or zero-padding) in the FDE is derived, and the optimum fast Fourier transform length to minimize the computational complexity is also analyzed.

     

  • 467.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB.
    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.
    Li, Jie
    Acreo AB.
    Zhang, Yimo
    Phase noise mitigation in coherent transmission system using a pilot carrier2011In: Optical Transmission Systems, Subsystems, and Technologies IX / [ed] Xiang Liu, SPIE - International Society for Optical Engineering, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the phase noise elimination employing an optical pilot carrier in the high speed coherent transmission system considering the equalization enhanced phase noise (EEPN). The numerical simulations are performed in a 28-Gsymbol/s quadrature phase shift keying (QPSK) coherent system with a polarization multiplexed pilot carrier. The carrier phase estimation is implemented by the one-tap normalized least mean square (NLMS) filter and the differential phase detection, respectively. Simulation results demonstrate that the application of the optical pilot carrier is very effective for the intrinsic laser phase noise cancellation, while is less efficient for the EEPN mitigation.

  • 468.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics. Acreo AB, Sweden.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, J.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics. Acreo AB, Sweden.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Digital compensation of chromatic dispersion in 112-Gbit/s PDM-QPSK system2009In: Optical Transmission Systems, Switching, and Subsystems VII, SPIE - International Society for Optical Engineering, 2009, p. 763202-Conference paper (Refereed)
    Abstract [en]

    High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bitor-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters.

  • 469.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Tianjin University, China.
    Analytical estimation of phase noise influence in coherent transmission system with digital dispersion equalization2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 8, p. 7756-7768Article in journal (Refereed)
    Abstract [en]

    We present a novel investigation on the enhancement of phase noise in coherent optical transmission system due to electronic chromatic dispersion compensation. Two types of equalizers, including a time domain fiber dispersion finite impulse response (FD-FIR) filter and a frequency domain blind look-up (BLU) filter are applied to mitigate the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying (PDM-QPSK) transmission system. The bit-error-rate (BER) floor in phase estimation using an optimized one-tap normalized least-mean-square (NLMS) filter, and considering the equalization enhanced phase noise (EEPN) is evaluated analytically including the correlation effects. The numerical simulations are implemented and compared with the performance of differential QPSK demodulation system. (C) 2011 Optical Society of America

  • 470.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Li, Jie
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Zhang, Yimo
    Carrier phase estimation methods in coherent transmission systems influenced by equalization enhanced phase noise2013In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 293, p. 54-60Article in journal (Refereed)
    Abstract [en]

    We present a comparative study on three carrier phase estimation algorithms, including a one-tap normalized least mean square (NLMS) method, a block-average method, and a Viterbi-Viterbi method in the n-level phase shift keying coherent transmission systems considering the equalization enhanced phase noise (EEPN). In these carrier phase estimation methods, the theoretical bit-error-rate floors based on traditional leading-order Taylor expansion are compared to the practical simulation results, and the tolerable total effective linewidths (involving the transmitter, the local oscillator lasers and the EEPN) for a fixed bit-error-rate floor are evaluated with different block sizes, when the fiber nonlinearities are neglected. The complexity of the three carrier phase estimation methods is also discussed. We find that the carrier phase estimation methods in practical systems should be analyzed based on the simulation results rather than the traditional theoretical predictions, when large EEPN is involved. The one-tap NLMS method can always show an acceptable behavior, while the step size is complicated to optimize. The block-average method is efficient to implement, but it behaves unsatisfactorily when using a large block size. The Viterbi-Viterbi method can show a small improvement compared to the block-average method, while it requires more computational complexity.

  • 471.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Tianjin University, China.
    Digital chromatic dispersion compensation in coherent transmission system using a time-domain filter2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, Shanghai, 2010, p. 132-133Conference paper (Refereed)
    Abstract [en]

    We demonstrate the chromatic dispersion equalization employing a time-domain filter in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent system. The required tap number of the filter is analyzed from anti-aliasing and pulse broadening. The dynamic range of the filter is evaluated by using different number of taps.

  • 472.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Vanin, Evgeny
    Acreo AB, Electrum 236, Kista, Sweden.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Zhang, Yimo
    Tianjin University, China.
    Chromatic dispersion compensation in coherent transmission system using digital filters2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 15, p. 16243-16257Article in journal (Refereed)
    Abstract [en]

    We present a comparative analysis of three popular digital filters for chromatic dispersion compensation: a time-domain least mean square adaptive filter, a time-domain fiber dispersion finite impulse response filter, and a frequency-domain blind look-up filter. The filters are applied to equalize the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying transmission system. The characteristics of these filters are compared by evaluating their applicability for different fiber lengths, their usability for dispersion perturbations, and their computational complexity. In addition, the phase noise tolerance of these filters is also analyzed. (C) 2010 Optical Society of America

  • 473.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics. KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Wang, Ke
    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.
    Digital compensation of chromatic dispersion in 112-Gbit/s PDM-QPSK system2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, p. 5377275-Conference paper (Refereed)
    Abstract [en]

    Coherent optical receivers with digital filters can mitigate the impairments in optical transmission system. In this paper, an adaptive filter employing NLMS algorithm is developed for chromatic dispersion compensation in a 112-Gbit/s PDM-QPSK coherent communication system. The performance of the adaptive filter is analyzed by comparing with present digital filters .

  • 474.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jacobsen, Gunnar
    Acreo AB, Electrum 236, Kista, Sweden.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Wang, Ke
    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.
    Normalized LMS digital filter for chromatic dispersion equalization in 112-Gbit/s PDM-QPSK coherent optical transmission system2010In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, no 6, p. 963-967Article in journal (Refereed)
    Abstract [en]

    High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI Simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bit-error-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters.

  • 475.
    Yan, Chunsheng
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
      Experimental study of the optical waveguides by scanning near-field optical microscopy (NSOM)2011In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 53, no 7, p. 1658-1663Article in journal (Refereed)
    Abstract [en]

    In this article, the ordinary optical waveguides are investigated by the near field optical microscopy (NSOM). Three kinds of experimental systems are set up and the corresponding operation modes of NSOM (illumination mode, illumination-collection mode and collection mode) are realized and analyzed.

  • 476.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Metal–insulator–metal light absorber: a continuous structure2013In: Journal of Optics, ISSN 2040-8978, E-ISSN 2040-8986, Vol. 15, no 2, p. 025006-025006Article in journal (Refereed)
    Abstract [en]

    A type of light absorber made of continuous layers of metal and dielectric films is studied. The metal films can have thicknesses close to their skin depths in the wavelength range concerned, which allows for both light transmission and reflection. Resonances induced by multiple reflections in the structure, when combined with the inherent lossy nature of metals, result in strong absorption spectral features. An eigen-mode analysis is carried out for the plasmonic multilayer nanostructures which provides a generic understanding of the absorption features. Experimentally, the calculation is verified by a reflection measurement with a representative structure. Such an absorber is simple to fabricate. The highly efficient absorption characteristics can be potentially deployed for optical filter designs, sensors, accurate photothermal temperature control in a micro-environment and even for backscattering reduction of small particles, etc.

  • 477.
    Yan, Min
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Mortensen, Niels Asger
    Metamaterial reflector for hollow-core infrared fiber design2010In: Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010Conference paper (Refereed)
    Abstract [en]

    The metal-wire based metamaterial is found to be able to reflect TM-polarized light with a higher efficiency compared to plain metal. The prospect of such medium for designing a hollow-core infrared fiber is investigated.

  • 478.
    Yan, Min
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Thylen, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Layered metal-dielectric waveguide: subwavelength guidance, leveraged modulation sensitivity in mode index, and reversed mode ordering2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 4, p. 3818-3824Article in journal (Refereed)
    Abstract [en]

    We describe a layered metal-dielectric waveguide, whose fundamental mode has an effective index as high as 7.35 at 1.55 mu m, enabling subwavelength spatial confinement. The loss is found to be reasonable in relation to the confinement. The indefinite dielectric tensor of the stratified metamaterial core generally leads to multimode operation of the waveguide, exhibiting a "reversed" mode ordering contrary to conventional waveguides. The waveguide features a strong leveraging in modal index change subject to a change of index in the dielectric layers, opening the design possibilities of very compact active electro-optic devices.

  • 479.
    Yan, Min
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yan, Wei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Cylindrical superlens by a coordinate transformation2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 12, p. 125113-Article in journal (Refereed)
    Abstract [en]

    Cylinder-shaped perfect lens deduced from the coordinate transformation method is proposed. The previously reported perfect slab lens is noticed to be a limiting form of the cylindrical lens when the inner radius approaches infinity with respect to the lens thickness. Connaturality between a cylindrical lens and a slab lens is affirmed by comparing their eigenfield transfer functions. We numerically confirm the subwavelength focusing capability of such a cylindrical lens with consideration of material imperfection. Compared to a slab lens, a cylindrical lens has several advantages, including finiteness in cross section and ability in lensing with magnification or demagnification. Immediate applications of such a cylindrical lens can be in high-resolution imaging and lithography technologies. In addition, its invisibility property suggests that it may be valuable for noninvasive electromagnetic probing.

  • 480.
    Yan, Min
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Yan, Wei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Invisibility Cloaking by Coordinate Transformation2009In: Progress in optics, ISSN 0079-6638, Vol. 52, p. 261-304Article, review/survey (Refereed)
  • 481.
    Ye, Fei
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Brismar, Torkel
    Shi, Jingwen
    Lin, Dong
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Sayed, Ramy El
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Gold nanorod/mesoporoussilica/gadolinium oxide carbonate hydrate core/shell nanoparticles: A multimodalcontrast agent for MRI, CT and fluorescence imaging2012Manuscript (preprint) (Other academic)
  • 482. Yu, Y. C.
    et al.
    Karlsson, S.
    Liu, C. P.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Chuang, C. H.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Krysa, A. B.
    Roberts, J. S.
    Seeds, A. J.
    Enhanced linear dynamic range of asymmetric Fabry-Perot modulator/detector2006In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, no 12-sep, p. 1040-1042Article in journal (Refereed)
    Abstract [en]

    An InGaAsP multiple-quantum-well asymmetric Fabry-Wrot modulator/detector has been developed for radio-over-fiber systems. The measured bandwidth is more than 6 GHz and the total insertion loss is 7.1 dB. The property of nonlinearity and spurious-free dynamic range (SFDR) has been studied theoretically. By optimizing the operation optical wavelength and bias voltage based on the numerical simulation, fifth-order nonlinearity dominates the intermodulation distortion and an SFDR of 101 dB center dot Hz(4/5) has been achieved experimentally.

  • 483. Yu, Y. C.
    et al.
    Karlsson, S.
    Liu, C. P.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Chuang, C. H.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Krysa, A. B.
    Roberts, J. S.
    Seeds, A. J.
    Enhanced linear dynamic range of asymmetric Fabry-Perot modulator/detector2006In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, no 08-maj, p. 770-772Article in journal (Refereed)
    Abstract [en]

    An InGaAsP multiple-quantum-well asymmetric Fabry-Perot modulator/detector has been developed for radioover-fiber systems. The measured bandwidth is more than 6 GHz and the total insertion loss is 7.1 dB. The property of nonlinearity and spurious-free dynamic range (SFDR) has been studied theoretically. By optimizing the operation optical wavelength and bias voltage based on the numerical simulation, fifth-order nonlinearity dominates the intermodulation distortion and an SFDR of 101 dB. Hz(4/5) has been achieved experimentally.

  • 484. Yu, Y.
    et al.
    Lewen, R.
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Irmscher, S.
    Eriksson, U.
    Temperature-dependent effects in highspeed travelling-wave electroabsorption modulators2005In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 41, no 4, p. 209-211Article in journal (Refereed)
    Abstract [en]

    The temperature-dependent effects in a segmented travelling-wave electroabsorption modulator are demonstrated and analysed. Optimum operation voltages with the highest modulation efficiency at different temperatures are identified. This can ensure the modulator working at 50 Gbit/s with RF extinction ratio > 8.4 dB between 10-50degreesC at lambda = 1540 nm.

  • 485.
    Zhang, Andy Zhenzhong
    et al.
    Acreo, Sweden .
    Wang, Qin
    Karlsson, Stefan
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. Kista Photonics Resarch Center, Sweden.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. Kista Photonics Resarch Center, Sweden.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. Kista Photonics Resarch Center, Sweden.
    Fonjallaz, Pierre-Yves
    Almqvist, Susanne
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Thylen, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics. Kista Photonics Resarch Center, Sweden.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Honecker, Joerg
    Steffan, Andreas
    Fabrication of an electro-absorption transceiver with a monolithically integrated optical amplifier for fiber transmission of 40-60 GHz radio signals2011In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 26, no 1, p. 014042-Article in journal (Refereed)
    Abstract [en]

    We report on the fabrication of a monolithically integrated semiconductor optical amplifier (SOA) and a reflective electro-absorption transceiver (EAT) for 40-60 GHz radio-over-fiber applications. The EAT can either function as a transmitter (reflective modulator) or as a receiver (photodetector) depending on operation mode. The SOA and the EAT sections are based on different InGaAsP multiple quantum-well active layers connected by a butt joint. Benzocyclobutene is used to reduce the capacitance beside the ridge mesa. Devices are designed to have a peaked response at the operating frequency through the design of microwave waveguides on top of the devices. The packaged device exhibits at 0.1 mW optical input power an amplified DC responsivity of 18.5 mA mW(-1) and a modulation efficiency of 0.67 mW V-1. The estimated radio frequency loss at 40 GHz of an optical link consisting of two SOA-EAT devices was 23 dB using an unmodulated optical input carrier to the transmitter of 0.94 mW.

  • 486. Zhang, Hongxia
    et al.
    Chen, Xinwei
    Ye, Wenting
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Jia, Dagong
    Zhang, Yimo
    Mitigation of the birefringence dispersion on the polarization coupling measurement in a long-distance high-birefringence fiber2012In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 23, no 2, p. 025203-Article in journal (Refereed)
    Abstract [en]

    Due to the birefringence dispersion, the polarization coupling parameter measurement in high-birefringence fiber decreases obviously with the fiber length, especially for long-distance fibers. In this paper, two methods for mitigating the birefringence dispersion in a long-distance fiber are proposed. The first method is a spectral-domain measurement method. The experimental setup and results are described in detail. The other method is a time-domain numerical dispersion compensation algorithm to amend the coupling strength calculation equation. It is based on the fact that the interferogram envelope area is constant even with the existence of birefringence dispersion. The experimental result shows that the time-domain algorithm has high accuracy, and the absolute deviation is less than 1%. The two methods are validated to mitigate the birefringence dispersion in the long-distance high-birefringence fiber effectively.

  • 487. Zhang, Hongxia
    et al.
    Xu, Tianhua
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Jia, Dagong
    Jing, Wencai
    Liu, Kun
    Zhang, Yimo
    Effects of angular misalignment in interferometric detection of distributed polarization coupling2009In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 20, no 9, p. 095112-Article in journal (Refereed)
    Abstract [en]

    White light interferometry is used to measure the distributed polarization coupling (DPC) in polarization-maintaining fibers (PMFs). By using a scanning Michelson interferometer to compensate the optical path difference (OPD) induced by the modal birefringence of PMFs, both the coupling strength and positions of the coupling points can be acquired. In ideal DPC measurement, the two reflective mirrors on the fixed and scanning arms of the Michelson interferometer are normal to each other. But in practice, the movable reflective mirror cannot be aligned normally to the fixed mirror exactly, which leads to an angular misalignment. The angular misalignment causes a variation of the OPD, which will reduce the fringe visibility. The theoretical simulation is investigated correspondingly. Consequently, the angular error leads to the miscalculation of the polarization coupling intensity. Based on the experimental results, a revised coupling strength calculation equation is proposed to minimize the influence of angular misalignment.

  • 488. Zhang, Rui
    et al.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Ricciardi, Sebastien
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Sergeyev, Sergey
    DISTORTION TOLERANCE AGAINST GEOMETRY IMPERFECTIONS IN POLYMERIC MICROCAVITY DYE LASER2008In: Journal of nonlinear optical physics and materials, ISSN 0218-8635, Vol. 17, no 4, p. 367-375Article in journal (Refereed)
    Abstract [en]

    A polymeric solid-state microcavity dye laser of the size comparable to a lasing wavelength is modeled by means of the finite element method (FEM). Lasing modes are calculated taking into account the gain material properties, such as absorption, dispersion and fluorescence. Study of the microcavity tolerance against possible geometrical imperfections demonstrates good robustness of the chosen shape and stability of the operation under possible cavity distortions.

  • 489. Zheng, Xueyan
    et al.
    Mahgerefteh, D.
    Matsui, Y.
    Ye, Xiong
    Bu, V.
    McCallion, K.
    Xu, Haitao
    Deutsch, M.
    Ereifej, H.
    Lewén, R.
    Wesström, J. -O
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Rigole, P. -J
    Generation of RZ-AMI using a widely tuneable modulated grating Y-branch chirp managed laser2010In: 2010 Conference on Optical Fiber Communication, Collocated National Fiber Optic Engineers Conference, OFC/NFOEC 2010, 2010, p. 5465413-Conference paper (Refereed)
    Abstract [en]

    A 10 Gb/s RZ-AMI format is generated using a 45 nm tunable Modulated-Grating Y-branch Chirp Managed Laser (CML) with an optical delay line interferometer (DLI), achieving +/- 800 ps/nm dispersion tolerance window.

  • 490. Zhou, G.
    et al.
    Zhang, L.
    Li, F.
    Hu, X.
    Wang, T.
    Li, Qiang
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Su, Y.
    All-optical temporal differentiation of ultra-high-speed picosecond pulses based on compact silicon microring resonator2011In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 47, no 14, p. 814-U104Article in journal (Refereed)
    Abstract [en]

    A high-speed all-optical temporal differentiator based on a compact silicon microring resonator with a radius of 20 mm is demonstrated. 80 Gbit/s signal differentiation is experimentally realised.

  • 491.
    Zhu, Ning
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Song, Jun
    KTH, School of Information and Communication Technology (ICT), Centres, Kista Photonics Research Center, KPRC.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Experimental demonstration of a cross-order echelle grating triplexer based on an amorphous silicon nanowire platform2009In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 34, no 3, p. 383-385Article in journal (Refereed)
    Abstract [en]

    We present the design, fabrication, and characterization of an ultracompact silicon-on-insulator-based echelle grating triplexer. It is based on the cross-order design, which utilizes different diffraction orders to cover a large spectral range from 1.3 to 1.5 mu m with three channels located at 1310, 1490, and 1550 nm and with a footprint of 150 mu m X 130 mu m.

  • 492. Zibar, Darko
    et al.
    Sambaraju, Rakesh
    Caballero, Antonio
    Herrera, Javier
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Walber, Achim
    Jensen, Jesper Beevense
    Marti, Javier
    Monroy, Idelfonso Tafur
    High-Capacity Wireless Signal Generation and Demodulation in 75-to 110-GHz Band Employing All-Optical OFDM2011In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 23, no 12, p. 810-812Article in journal (Refereed)
    Abstract [en]

    We present a radio-frequency (RF) and bit-rate scalable technique for multigigabit wireless signal generation based on all-optical orthogonal frequency-division multiplexing (OFDM) and photonic up-conversion. Coherent detection supported by digital signal processing is used for signal demodulation and data recovery. In order to demonstrate the RF frequency scalability and bit-rate transparency, the system is tested at 60 GHz and in the 75- to 110-GHz band at the baud rates of 5 and 10 Gbaud. In terms of the bit rate, the proposed system is experimentally tested up to 40 Gb/s for wireless signal generation and demodulation. The wireless transmission is not considered in this letter. Additionally, a novel digital carrier phase/frequency recovery structure is employed to enable robust phase and frequency tracking between the beating lasers.

  • 493. Zientkiewicz, Jacek K.
    et al.
    Lach, Zbigniew T.
    Grabiec, Piotr
    Driessen, Alfred
    Jaskorzynska, Bozena
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    A roadmap to a technological platform for integrating nanophotonic structures with micromechanical systems in silicon-on-insulator2005In: Integrated Optics: Theory and Applications / [ed] Pustelny T., Lambeck P.V., Gorecki C., SPIE - International Society for Optical Engineering, 2005, p. 59560H-Conference paper (Refereed)
    Abstract [en]

    On the foundation of joint experience acquired by several research centres there was defined the roadmap to the desired single technological platform for fabrication of a specific class of photonic integrated circuits, which are controlled by mechanical means. In the paper the challenges of fabrication of such photonic circuits are discussed. The main arguments in favour of the Silicon-on-Insulator materials system as the basis for the platform are presented. Options for the mechanics-to-optics arrangement, materials and processes are described and illustrated with the current achievements from the authors' labs. In the roadmap the preference is given to the vertical arrangement in which, the mechanical part is stacked above the waveguiding layer. A flexible trimming routine is designed to complement the process flow if the technologies developed cannot provide the required reproducibility.

78910 451 - 493 of 493
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