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  • 51.
    Jacobsen, Gunnar
    et al.
    Acreo AB, Electrum 236, Kista, Sweden.
    Kazovsky, L. G.
    Stanford University, USA.
    Xu, Tianhua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Optik (Stängd 20120101).
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Optik (Stängd 20120101).
    Li, Jie
    Acreo AB, Electrum 236, Kista, Sweden.
    Zhang, Y.
    Tianjin University, China.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Optik (Stängd 20120101).
    Phase noise influence in optical OFDM systems employing RF pilot tone for noise cancellation2011Ingår i: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 52. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Li, Jie
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Zhang, Yimo
    EEPN and CD study for coherent optical nPSK and nQAM systems with RF pilot based phase noise compensation2012Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, nr 8, s. 8862-8870Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 53. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Li, Jie
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Zhang, Yimo
    Receiver implemented RF pilot tone phase noise mitigation in coherent optical nPSK and nQAM systems2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 15, s. 14487-14494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 54. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Li, Jie
    Zhang, Yimo
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Error-rate floors in differential n-level phase-shift-keying coherent receivers employing electronic dispersion equalisation2011Ingår i: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 32, s. 191-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 55. Jacobsen, Gunnar
    et al.
    Xu, Tianhua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Sergeyev, Sergey
    Study of EEPN mitigation using modified RF pilot and Viterbi-Viterbi based phase noise compensation2013Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, nr 10, s. 12351-12362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 56. Jaroszewicz, Zbigniew
    et al.
    Adamkiewicz, Grazyna
    Duran-Bosch, Vicente
    Friberg, Ari
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Kolodziejczyk, Andrzej
    Kowalik, Andrzej
    Lancis, Jesus
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Optik.
    Kinoform apodization by using of programmable diffractive optical elements2004Ingår i: Proceedings of SPIE - The International Society for Optical Engineering: Volume 5456, 2004 / [ed] Frank Wyrowski, SPIE - International Society for Optical Engineering, 2004, s. 153-156Konferensbidrag (Refereegranskat)
    Abstract [en]

    The apodizationof diffractiveopticalelementscan be realized by a local change of their diffraction efficiency. In the case of lithographic elementswith step-like structure of the period, the variable diffraction efficiency can be achieved by a gradual transformation of the 2m stepkinoform into its conjugate counterpart across theapodization region. In the present contribution we show experimental results confirming this idea, which until no was verified only by simulations. The apodized quaternary grating with locally varying diffraction efficiency was obtained on a SLM device as aprogrammablediffractiveopticalelement by changing gradually the period's profile. Knowledge of the phase heights of the SLM's pixels is required for successful implementation of theapodization function. It was determined from Fresnel images of the binary phase gratings with different phase step height programmed on the SLM. The Fresnel images become then binary and their visibility depends on the phase height of the grating in a known way, what makes possible to calibrate the SLM.

  • 57. Jia, Shi
    et al.
    Pang, Xiaodan
    KTH, Skolan för informations- och kommunikationsteknik (ICT). RISE Acreo AB, NETLAB, SE-16425 Kista, Sweden.
    Ozolins, Oskars
    Yu, Xianbin
    Hu, Hao
    Yu, Jinlong
    Guan, Pengyu
    Da Ros, Francesco
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Jacobsen, Gunnar
    Galili, Michael
    Morioka, Toshio
    Zibar, Darko
    Oxenlowe, Leif K.
    0.4 THz Photonic-Wireless Link With 106 Gb/s Single Channel Bitrate2018Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 36, nr 2, s. 610-616Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To accommodate the demand of exponentially increased global wireless data traffic, the prospective data rates for wireless communication in the market place will soon reach 100 Gb/s and beyond. In the lab environment, wireless transmission throughput has been elevated to the level of over 100 Gb/s attributed to the development of photonic-assisted millimeter wave and terahertz (THz) technologies. However, most of recent demonstrations with over 100 Gb/s data rates are based on spatial or frequency division multiplexing techniques, resulting in increased system's complexity and energy consumption. Here, we experimentally demonstrate a single channel 0.4 THz photonic-wireless link achieving a net data rate of beyond 100 Gb/s by using a single pair of THz emitter and receiver, without employing any spatial/frequency division multiplexing techniques. The high throughput up to 106 Gb/s within a single THz channel is enabled by combining spectrally efficient modulation format, ultrabroadband THz transceiver and advanced digital signal processing routine. Besides that, our demonstration from system-wide implementation viewpoint also features high transmission stability, and hence shows its great potential to not only decrease the system's complexity, butalsomeet the requirements of prospective data rates for bandwidth-hungryshort-range wireless applications.

  • 58.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Navarro, J. R.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Louchet, H.
    Pang, Xiaodan
    RISE ACREO AB.
    Ozolins, O.
    Jacobsen, G.
    Popov, Sergei Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Comprehensive study of equalization-enhanced phase noise in coherent optical systems2015Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 33, nr 23, s. 4834-4841, artikel-id 7299252Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A thorough analysis of equalization-enhanced phase noise (EEPN) and its impact on the coherent optical system is presented. We show with a time-domain analysis that EEPN is caused due to the interference of multiple delayed versions of the dispersed signal, generated by intermixing of the received dispersed signal, and the noise side bands of the local oscillator (LO) in the photodetectors. We derive statistical properties such as the mean, variance, and error vector magnitude of the received signal influenced with EEPN. We show that in coherent optical systems utilizing electronic dispersion compensation, this noise corresponds to multipath fading in wireless communication systems. Closed-form expressions of necessary LO linewidth and/or mitigation bandwidth for a general system configuration and specified OSNR penalty are given. The expressions for system design parameters, validated with system simulations, show that higher order modulation formats, such as 16-quadrature amplitude modulation and beyond, put stringent demands on the LO linewidth unless a mitigation technique is used.

  • 59.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Navarro, Jaime Rodrigo
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Pang, Xiaodan
    Ozolins, Oskars
    Louchet, Hadrien
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Equalization Enhanced Phase Noise in Coherent Optical Systems with Digital Pre- and Post-Processing2016Ingår i: PHOTONICS, ISSN 2304-6732, Vol. 3, nr 2, artikel-id 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an extensive study of equalization enhanced phase noise (EEPN) in coherent optical system for all practical electronic dispersion compensation configurations. It is shown that there are only eight practicable all-electronic impairment mitigation configurations. The non-linear and time variant analysis reveals that the existence and the cause of EEPN depend on the digital signal processing (DSP) schemes. There are three schemes that in principle do not cause EEPN. Analysis further reveals the statistical equivalence of the remaining five system configurations resulting in EEPN. In three of them, EEPN is due to phase noise of the transmitting laser, while in the remaining two, EEPN is caused by the local oscillator. We provide a simple look-up table for the system designer to make an informative decision regarding practicable configuration choice and design.

  • 60.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Navarro, Jaime Rodrigo
    Acreo Swedish ICT AB, Network & Transmiss Lab, S-16425 Kista, Sweden..
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Pang, Xiaodan
    Acreo Swedish ICT AB, Network & Transmiss Lab, S-16425 Kista, Sweden..
    Ozolins, Oskars
    Acreo Swedish ICT AB, Network & Transmiss Lab, S-16425 Kista, Sweden..
    Louchet, Hadrien
    VPI Photon GmBH, D-10587 Berlin, Germany..
    Jacobsen, Gunnar
    Acreo Swedish ICT AB, Network & Transmiss Lab, S-16425 Kista, Sweden..
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Mitigation of EEPN in Coherent Optical Systems With Low-Speed Digital Coherence Enhancement2015Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 18, s. 1942-1945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method for mitigating local oscillator (LO) phase noise-induced impairment, also known as equalization-enhanced phase noise, in coherent optical systems is discussed. The method is suitable for real-time implementation and requires hardware with a bandwidth much lower than the signal baud rate, even for a system utilizing conventional semiconductor laser as LO. We evaluate the required parameters like interpolation technique, electrical signal-to-noise ratio at digital coherence enhancement (DCE) front end, for long haul transmission links having quadrature phase shift keying and 16-quadrature amplitude modulation formats. We show that the method can be implemented using a low-speed DCE front end and a simple digital linear interpolator with small (<1 dB) implementation penalty even in cases that would otherwise result in error floor.

  • 61.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Navarro, Jaime Rodrigo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Networking and Transmission Laboratory (NETLAB), Acreo Swedish ICT, AB, SE-16425, Kista, Sweden.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Pang, Xiaodan
    Ozolins, Oskars
    Udalcovs, Aleksejs
    Louchet, Hadrien
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Jacobsen, Gunnar
    Laser Frequency Noise in Coherent Optical Systems: Spectral Regimes and Impairments2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 844Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coherent communication networks are based on the ability to use multiple dimensions of the lightwave together with electrical domain compensation of transmission impairments. Electrical-domain dispersion compensation (EDC) provides many advantages such as network flexibility and enhanced fiber nonlinearity tolerance, but makes the system more susceptible to laser frequency noise (FN), e.g. to the local oscillator FN in systems with post-reception EDC. Although this problem has been extensively studied, statistically, for links assuming lasers with white-FN, many questions remain unanswered. Particularly, the influence of a realistic non-white FN-spectrum due to e.g., the presence of 1/f-flicker and carrier induced noise remains elusive and a statistical analysis becomes insufficient. Here we provide an experimentally validated theory for coherent optical links with lasers having general non-white FN-spectrum and EDC. The fundamental reason of the increased susceptibility is shown to be FN-induced symbol displacement that causes timing jitter and/or inter/intra symbol interference. We establish that different regimes of the laser FN-spectrum cause a different set of impairments. The influence of the impairments due to some regimes can be reduced by optimizing the corresponding mitigation algorithms, while other regimes cause irretrievable impairments. Theoretical boundaries of these regimes and corresponding criteria applicable to system/laser design are provided.

  • 62.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Olmedo, Miguel Iglesias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Ozolins, Oskars
    Navarro, Jaime Rodrigo
    Pang, Xiaodan
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Louchet, Hadrien
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Overcoming EEPN in Coherent Transmission Systems2016Ingår i: 2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE conference proceedings, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    We for the first time experimentally demonstrate a simple technique to overcome EEPN. Performance recovery from above FEC to <1 dB penalty for 28 Gbd 16-QAM over 520 km with high LO linewidth is achieved.

  • 63.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Ozolins, O.
    Navarro, J. R.
    Pang, Xiaodan
    RISE ACREO AB.
    Olmedo, Miguel Iglesias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Louchet, H.
    Jacobsen, G.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Design of coherent optical systems impaired by EEPN2016Ingår i: 2016 Optical Fiber Communications Conference and Exhibition, OFC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present experimental validation of novel analytical expressions essential for the design of coherent optical systems impaired by EEPN. These expressions enable a simple and accurate EEPN analysis for any system specification. 

  • 64.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Pang, Xiaodan
    RISE ACREO AB.
    Ozolins, O.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Navarro, J. R.
    Louchet, H.
    Jacobsen, G.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    A path to use large linewidth LO in 28 Gbd 16-QAM metro links2015Ingår i: European Conference on Optical Communication, ECOC, IEEE , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    We experimentally investigate the possibility to mitigate local oscillator induced Equalization Enhanced Phase Noise penalty. The results pave the way for the use of even 10 MHz linewidth local oscillator lasers in 28 Gbd 16-QAM metro links.

  • 65.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT AB, Sweden.
    Rodrigo Navarro, Jaime
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT AB, Sweden.
    Pang, Xiaodan
    Ozolins, Oskars
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Low Complexity Timing Recovery Algorithm for PAM-8 in High Speed Direct Detection Short Range Links2017Ingår i: Optics InfoBase Conference Papers, Volume Part F40-OFC 2017, 2017, IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a low complexity timing algorithm for high order PAM. Experimental results demonstrate higher performance and lower complexity than conventional algorithms in a 32 Gbaud PAM-8 transmission over 4 kin SMF links.

  • 66.
    Kakkar, Aditya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Optik och Fotonik, OFO.
    Rodrigo Navarro, Jaime
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Optik och Fotonik, OFO.
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Optik och Fotonik, OFO.
    Pang, Xiaodan
    RISE ACREO AB.
    Ozolins, Oskars
    Nordwall, Fredrik
    Zibar, Darko
    Jacobsen, Gunnnar
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Optik och Fotonik, OFO.
    Influence of Lasers with Non-White Frequency Noise on the Design of Coherent Optical Links2017Ingår i: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings, 2017, artikel-id 7937006Konferensbidrag (Refereegranskat)
    Abstract [en]

    We experimentally demonstrate for a 28 Gbaud 64-QAM metro link that the LO frequency noise causes timing impairment. Results show the existence of LO frequency noise spectrum regimes where different design criteria apply.

  • 67.
    Kakkar, Aditya
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Pang, Xiaodan
    Navarro, Jaime Rodrigo
    Louchet, Hadrien
    Ozolins, Oskars
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Impact of local oscillator frequency noise on coherent optical systems with electronic dispersion compensation2015Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, nr 9, s. 11221-11226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A theoretical investigation of the equalization-enhanced phase noise (EEPN) and its mitigation is presented. We show with a frequency domain analysis that the EEPN results from the non-linear inter-mixing between the sidebands of the dispersed signal and the noise sidebands of the local oscillator. It is further shown and validated with system simulations that the transmission penalty is mainly due to the slow optical frequency fluctuations of the local oscillator. Hence, elimination of the frequency noise below a certain cut-off frequency significantly reduces the transmission penalty, even when frequency noise would otherwise cause an error floor. The required cut-off frequency increases linearly with the white frequency noise level and hence the linewidth of the local oscillator laser, but is virtually independent of the symbol rate and the accumulated dispersion.

  • 68. Kalashnikov, Vladimir
    et al.
    Sergeyev, Sergey V.
    Jacobsen, Gunnar
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Turitsyn, Sergei K.
    Multi-scale polarisation phenomena2016Ingår i: LIGHT-SCIENCE & APPLICATIONS, ISSN 2047-7538, Vol. 5, artikel-id e16011Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multi-scale methods that separate different time or spatial scales are among the most powerful techniques in physics, especially in applications that study nonlinear systems with noise. When the time scales (noise and perturbation) are of the same order, the scales separation becomes impossible. Thus, the multi-scale approach has to be modified to characterise a variety of noise-induced phenomena. Here, based on stochastic modelling and analytical study, we demonstrate in terms of the fluctuation-induced phenomena and Hurst R/S analysis metrics that the matching scales of random birefringence and pump-signal states of polarisation interaction in a fibre Raman amplifier results in a new random birefringence-mediated phenomenon, which is similar to stochastic anti-resonance. The observed phenomenon, apart from the fundamental interest, provides a base for advancing multi-scale methods with application to different coupled nonlinear systems ranging from lasers (multimode, mode-locked, random, etc.) to nanostructures (light-mediated conformation of molecules and chemical reactions, Brownian motors, etc.).

  • 69.
    Khachatourian, Malek Adrine
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. Iran University of Science and Technology, Iran.
    Golestani-Fard, F.
    Sarpoolaky, H.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vasileva, Elena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Mensi, Mounir
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties2016Ingår i: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 169, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Red fluorescent emitting monodispersed spherical Y<inf>2</inf>O<inf>3</inf> nanophosphors with different Eu3+ doping concentrations (0-13 mol%) are synthesized by a novel microwave assisted urea precipitation, which is recognized as a green, fast and reproducible synthesis method. The effect of Eu3+ doping and calcination temperature on the structural characteristics and luminescence properties of particles is investigated in detail. The as prepared powders have (Y,Eu)(OH)(CO<inf>3</inf>) structure which converts to Y<inf>2</inf>O<inf>3</inf>:Eu3+ from 500 °C and become crystalline at higher temperatures. The crystallite size of nanophosphors increased from 15 nm to 25 nm as the calcination temperature increased from 700 °C to 1050 °C. The efficient incorporation of Eu3+ ions in cubic Y<inf>2</inf>O<inf>3</inf> host matrix is confirmed by the calculated X-ray Powder diffraction (XRPD) structural parameters. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show that the as obtained and calcined particles are spherical, monodispersed and non-agglomerated. The overall size of particles increases from 61±8 nm to 86±9 nm by increasing Eu3+ concentration from 0 mol% to 13 mol%. High resolution TEM revealed polycrystalline nature of calcined particles. The particles exhibit a strong red emission under ultraviolet (UV) excitation. The photoluminescence (PL) intensity of the peaks increases proportionally with Eu3+ concentration and the calcination temperature with no luminescence quenching phenomenon observed even for Y<inf>2</inf>O<inf>3</inf>:13%Eu3+. The fluorescent emission properties combined with the monodispersity and narrow size distribution characteristics make the Y<inf>2</inf>O<inf>3</inf>:Eu3+ heavy metal free nanophosphors applicable in fluorescence cell imaging and as fluorescence biolabels.

  • 70.
    Koivurova, Matias
    et al.
    Univ Eastern Finland, Inst Photon, POB 111, FI-80101 Joensuu, Finland..
    Vasileva, Elena
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Li, Yuanyuan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Complete spatial coherence characterization of quasi-random laser emission from dye doped transparent wood2018Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, nr 10, s. 13474-13482Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 71.
    Lavrinovica, Ingrida
    et al.
    Riga Tech Univ, Inst Telecommun, Azenes St 12, LV-1048 Riga, Latvia..
    Supe, Andis
    Riga Tech Univ, Inst Telecommun, Azenes St 12, LV-1048 Riga, Latvia..
    Udalcovs, Aleksejs
    RISE Acreo AB, Isafjordsgatan 22, S-16440 Kista, Sweden..
    Ozolins, Oskars
    RISE Acreo AB, Isafjordsgatan 22, S-16440 Kista, Sweden..
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Porins, Jurgis
    Riga Tech Univ, Inst Telecommun, Azenes St 12, LV-1048 Riga, Latvia..
    Exploration of Optical Amplifiers Based on Erbium (Er3+) and Ytterbium (Yb3+) Doped Fiber Segments and Its Emerging Applications2018Ingår i: 2018 Progress in Electromagnetics Research Symposium (PIERS-TOYAMA) / [ed] Chew, WC He, S, IEEE, 2018, s. 237-240, artikel-id 8598244Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes the improvement of EDFA amplifier properties by adding additional segments of Yb3+ doped fiber. Experimental demonstration of a combined erbium ytterbium doped fiber amplifier (EYDFA) performance using 5m long erbium-doped fiber (EDF) and 5 m long ytterbium-doped fiber (YDF) is presented.

  • 72.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT, Stockholm, Sweden .
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Sergeyev, S.
    Receiver sensitivity in optical and microwave, heterodyne and homodyne systems2014Ingår i: Journal of optical communications, ISSN 0173-4911, E-ISSN 2191-6322, Vol. 35, nr 3, s. 221-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we analyze the sensitivities of coherent optical receivers and microwave receivers. We derive theoretical limits of signal-to-noise ratio and bit error rate. By applying a generic approach to a broad range of receivers, we can compare their performance directly. Other publications have considered some of these receivers. However, their diverse nature obscures the big picture. Using our results as a unifying platform, previous publications can be compared and discrepancies between them identified.

  • 73.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT AB, Sweden .
    Larsen, K. J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT AB, Sweden .
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zibar, D.
    Sergeyev, S.
    Novel BCH code design for mitigation of phase noise induced cycle slips in DQPSK systems2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    We show that by proper code design, phase noise induced cycle slips causing an error floor can be mitigated for 28 Gbaud DQPSK systems. Performance of BCH codes are investigated in terms of required overhead.

  • 74.
    Leong, Miu yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT, Sweden.
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Acreo Swedish ICT, Sweden.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zibar, Darko
    Sergeyev, S.
    Dimensioning RS codes for mitigation of phase noise induced cycle slips in DQPSK systems2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a semi-analytical method for dimensioning Reed-Solomon codes for coherent DQPSK systems with laser phase noise and cycle slips. We evaluate the accuracy of our method for a 28 Gbaud system using numerical simulations.

  • 75.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zibar, Darko
    Sergeyev, Sergey
    Dimensioning BCH Codes for Coherent DQPSK Systems With Laser Phase Noise and Cycle Slips2014Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 32, nr 21, s. 4048-4052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN. This changes the error statistics and impacts FEC performance. In this paper, we propose a novel semianalytical method for dimensioning binary Bose-Chaudhuri-Hocquenghem (BCH) codes for systems with PN. Our method involves extracting statistics from pre-FEC bit error rate (BER) simulations. We use these statistics to parameterize a bivariate binomial model that describes the distribution of bit errors. In this way, we relate pre-FEC statistics to post-FEC BER and BCHcodes. Our method is applicable to pre-FEC BER around 10(-3) and any post-FEC BER. Using numerical simulations, we evaluate the accuracy of our approach for a target post-FEC BER of 10(-5). Codes dimensioned with our bivariate binomial model meet the target within 0.2-dB signal-to-noise ratio.

  • 76.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Technical University of Denmark, Denmark .
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. Technical University of Denmark, Denmark .
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zibar, Darko
    Sergeyev, Sergey
    Interleavers and BCH Codes for Coherent DQPSK Systems With Laser Phase Noise2015Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 7, s. 685-688Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The relatively high phase noise of coherent optical systems poses unique challenges for forward error correction (FEC). In this letter, we propose a novel semianalytical method for selecting combinations of interleaver lengths and binary Bose-Chaudhuri-Hocquenghem (BCH) codes that meet a target post-FEC bit error rate (BER). Our method requires only short pre-FEC simulations, based on which we design interleavers and codes analytically. It is applicable to pre-FEC BER similar to 10(-3), and any post-FEC BER. In addition, we show that there is a tradeoff between code overhead and interleaver delay. Finally, for a target of 10(-5), numerical simulations show that interleaver-code combinations selected using our method have post-FEC BER around 2x target. The target BER is achieved with 0.1 dB extra signal-to-noise ratio.

  • 77.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. ACREO Swedish, Sweden.
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. ACREO Swedish, Sweden.
    Zibar, Darko
    Sergeyev, Sergey
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    BCH codes for coherent star DQAM systems with laser phase noiseManuskript (preprint) (Övrigt vetenskapligt)
  • 78.
    Leong, Miu Yoong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. ACREO Swedish, Sweden.
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO. ACREO Swedish, Sweden.
    Zibar, Darko
    Sergeyev, Sergey
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Low complexity BCH codes with optimized interleavers for DQPSK systems with laser phase noiseManuskript (preprint) (Övrigt vetenskapligt)
  • 79.
    Leong, Miu Yoong
    et al.
    KTH. Acreo.
    Larsen, Knud J.
    Jacobsen, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Zibar, Darko
    Sergeyev, Sergey
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Low-complexity BCH codes with optimized interleavers for DQPSK systems with laser phase noise2017Ingår i: Photonic network communications, ISSN 1387-974X, E-ISSN 1572-8188, Vol. 33, nr 3, s. 328-333Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The presence of high phase noise in addition to additive white Gaussian noise in coherent optical systems affects the performance of forward error correction (FEC) schemes. In this paper, we propose a simple scheme for such systems, using block interleavers and binary Bose-Chaudhuri-Hocquenghem (BCH) codes. The block interleavers are specifically optimized for differential quadrature phase shift keying modulation. We propose a method for selecting BCH codes that, together with the interleavers, achieve a target post-FEC bit error rate (BER). This combination of interleavers and BCH codes has very low implementation complexity. In addition, our approach is straightforward, requiring only short pre-FEC simulations to parameterize a model, based on which we select codes analytically. We aim to correct a pre-FEC BER of around . We evaluate the accuracy of our approach using numerical simulations. For a target post-FEC BER of , codes selected using our method result in BERs around 3 target and achieve the target with around 0.2 dB extra signal-to-noise ratio.

  • 80.
    Li, Yanlu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Rigorous modeling and physical interpretation of terahertz near-field imaging using SNOM techniques2009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Apertureless scanning near-field optical microscopy (SNOM) operating with terahertz (THz) laser pulses is a subject of great research interest. The Mie scattering theory is commonly used to explain the features of the optical waves produced by field interactions with SNOM tips and microstructures. However, since Mie scattering fails with SNOMs at submillimeter wavelengths, a rigorous model and analysis are desirable to assess the feasibility of the THz tip-enhanced scanning near-field techniques. In this paper, we present a numerical simulation of an apertureless SNOM imaging system in the THz band. A 2-dimensional model based on the finite element method (FEM) is investigated and discussed. The modeling results are in good agreement with the experimental data obtained for this system at 2 THz radiation [8]. Additionally, a physical interpretation using the antenna theory is successfully confirmed by the simulation results. [DOI: 10.2971/jeos.2009.09007]

  • 81.
    Li, Yuanyuan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Vasileva, Elena
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Sychugov, Ilya
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Optically Transparent Wood: Recent Progress, Opportunities, and Challenges2018Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, nr 14, artikel-id 1800059Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Transparent wood is an emerging load-bearing material reinvented from natural wood scaffolds with added light management functionalities. Such material shows promising properties for buildings and related structural applications, including its renewable and abundant origin, interesting optical properties, outstanding mechanical performance, low density, low thermal conductivity, and great potential for multifunctionalization. In this study, a detailed summary of recent progress on the transparent wood research topic is presented. Remaining questions and challenges related to transparent wood preparation, optical property measurements, and transparent wood modification and applications are discussed.

  • 82.
    Lin, Rui
    et al.
    KTH.
    Kerrebrouck, J. V.
    Pang, Xiaodan
    KTH.
    Verplaetse, M.
    Ozolins, O.
    Udalcovs, A.
    Zhang, Lu
    KTH.
    Gan, L.
    Tang, M.
    Fu, S.
    Schatz, Richard
    KTH.
    Westergren, Urban
    KTH.
    Popov, Sergei
    KTH.
    Liu, D.
    Tong, W.
    Keulenaer, T. D. E.
    Torfs, G.
    Bauwelinck, J.
    Yin, X.
    Chen, Jiajia
    KTH.
    Real-time 100 Gbps/λ/core NRZ and EDB IM/DD transmission over multicore fiber for intra-datacenter communication networks2018Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, nr 8, s. 10519-10526Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A BiCMOS chip-based real-time intensity modulation/direct detection spatial division multiplexing system is experimentally demonstrated for both optical interconnects. 100 Gbps/λ/core electrical duobinary (EDB) transmission over 1 km 7-core multicore fiber (MCF) is carried out, achieving KP4 forward error correction (FEC) limit (BER < 2E-4). Using optical dispersion compensation, 7 × 100 Gbps/λ/core transmission of both non-return-to-zero (NRZ) and EDB signals over 10 km MCF transmission is achieved with BER lower than 7% overhead hard-decision FEC limit (BER < 3.8E-3). The integrated low complexity transceiver IC and analog signal processing approach make such a system highly attractive for the high-speed intra-datacenter interconnects.

  • 83.
    Lin, Rui
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Lu, Yang
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Cheng, Yuxin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Tang, Ming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Liu, Deming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    First Experimental Demonstration of Physical-Layer Network Coding in PAM4 System for Passive Optical Interconnects2017Ingår i: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 84.
    Lin, Rui
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Pang, X.
    Ozolins, O.
    Feng, Z.
    Djupsjobacka, A.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Jacobsen, G.
    Tang, M.
    Fu, S.
    Liu, D.
    Popov, Sergei Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Performance evaluation of PAM and DMT for short-range optical transmission with high speed InGaAsP DFB-TWEAM2016Ingår i: 2016 Optical Fiber Communications Conference and Exhibition, OFC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on experimental results of 56-Gb/s OOK, PAM4 and 25-Gb/s DMT transmission with a high speed InGaAsP based monolithically integrated DFB-TWEAM, and evaluate different digital equalization implementations.

  • 85.
    Lin, Rui
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. Huazhong University of Science and Technology, China.
    Pang, Xiaodan
    Ozolins, Oskars
    Feng, Zhenhua
    Djupsjöbacka, Anders
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Jacobsen, Gunnar
    Tang, Ming
    Fu, Songnian
    Liu, Deming
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Experimental Validation of Scalability Improvement for Passive Optical Interconnect by Implementing Digital Equalization2016Konferensbidrag (Refereegranskat)
  • 86.
    Lin, Rui
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Belgium.
    Verplaetse, M.
    Belgium.
    Ozolins, O.
    Udalcovs, A.
    Zhang, Lu
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    China.
    Tang, M.
    China.
    Fu, S.
    China.
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Westergren, Urban
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Liu, D.
    China.
    Tong, W.
    China.
    De Keulenaer, T.
    Belgium.
    Torfs, G.
    Belgium.
    Bauwelinck, J.
    Belgium.
    Yin, X.
    Belgium.
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Real-time 100 Gbps/λ/core NRZ and EDB IM/DD transmission over 10 km multicore fiber2018Ingår i: Optics InfoBase Conference Papers, Optical Society of America, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 87.
    Lin, Rui
    et al.
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China.;KTH Royal Inst Technol, Electrum 229, Kista, Sweden..
    Pang, Xiaodan
    KTH.
    Van Kerrebrouck, Joris
    Univ Ghent, IMEC, Dept Informat Technol INTEC, IDLab, Ghent, Belgium..
    Verplaetse, Michiel
    Univ Ghent, IMEC, Dept Informat Technol INTEC, IDLab, Ghent, Belgium..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Zhang, Lu
    KTH.
    Gan, Lin
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tang, Ming
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Fu, Songnian
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Schatz, Richard
    KTH.
    Westergren, Urban
    KTH.
    Popov, Sergei
    KTH.
    Liu, Deming
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tong, Weijun
    Yangtze Opt Fiber & Cable Joint Stock Ltd Co YOFC, Wuhan, Hubei, Peoples R China..
    De Keulenaer, Timothy
    Univ Ghent, IMEC, Spin Off IDLab, BiFAST, Ghent, Belgium..
    Torfs, Guy
    Univ Ghent, IMEC, Dept Informat Technol INTEC, IDLab, Ghent, Belgium..
    Bauwelinck, Johan
    Univ Ghent, IMEC, Dept Informat Technol INTEC, IDLab, Ghent, Belgium..
    Yin, Xin
    Univ Ghent, IMEC, Dept Informat Technol INTEC, IDLab, Ghent, Belgium..
    Chen, Jiajia
    KTH.
    Real-time 100 Gbps/lambda/core NRZ and EDB IM/DD Transmission over 10 km Multicore Fiber2018Ingår i: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 88.
    Lin, Rui
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, A.
    Ozolins, O.
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    Shen, L.
    Tang, M.
    Fu, S.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Yang, C.
    Tong, W.
    Liu, D.
    Da Silva, T. F.
    Xavier, G. B.
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Telecom Compatibility Validation of Quantum Key Distribution Co-Existing with 112 Gbps/λ/core Data Transmission in Non-Trench and Trench-Assistant Multicore Fibers2018Ingår i: European Conference on Optical Communication, ECOC, Institute of Electrical and Electronics Engineers Inc. , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    We experimentally characterize photon leakage from 112Gb/s data channels in both non-trench and trench-assistant 7-core fibers, demonstrating telecom compatibility for QKD co-existing with high-speed data transmission when a proper core/wavelength allocation is carried out.

  • 89.
    Lin, Rui
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Van Kerrebrouck, Joris
    Univ Ghent, Imec, IDLab, Dept Informat Technol, Ghent, Belgium..
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Verplaetse, Michiel
    Univ Ghent, Imec, IDLab, Dept Informat Technol, Ghent, Belgium..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Zhang, Lu
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Gan, Lin
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tang, Ming
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Fu, Songnian
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Westergren, Urban
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Liu, Deming
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tong, Weijun
    Yangtze Opt Fiber & Cable Joint Stock Ltd Co YOFC, Wuhan, Hubei, Peoples R China..
    De Keulenaer, Timothy
    Univ Ghent, Imec, Spin Off IDLab, BiFAST, Ghent, Belgium..
    Torfs, Guy
    Univ Ghent, Imec, IDLab, Dept Informat Technol, Ghent, Belgium..
    Bauwelinck, Johan
    Univ Ghent, Imec, IDLab, Dept Informat Technol, Ghent, Belgium..
    Yin, Xin
    Univ Ghent, Imec, IDLab, Dept Informat Technol, Ghent, Belgium..
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Spatial Division Multiplexing for Optical Data Center Networks2018Ingår i: 22ND INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING (ONDM 2018) / [ed] Ruffini, M Tzanakaki, A Casellas, R Autenrieth, A MarquezBarja, JM, IEEE , 2018, s. 239-241Konferensbidrag (Refereegranskat)
    Abstract [en]

    Emerging mobile and cloud applications drive everincreasing capacity demands, particularly for short-reach optical communications, where low-cost and low-power solutions are highly required. Spatial division multiplexing (SDM) techniques provide a promising way to scale up the lane count per fiber, while reducing the number of fiber connections and patch cords, and hence simplifying cabling complexity. This talk will address challenges on both system and network levels, and report our recent development on SDM techniques for optical data center networks.

  • 90.
    Lobov, G. S.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Marinins, A.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Etcheverry, S.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Vasileva, Elena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Sugunan, A.
    Laurell, F.
    Thylén, Lars
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wosinski, L.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Toprak, M. S.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component2017Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, nr 1, s. 52-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

  • 91.
    Lobov, Gleb
    et al.
    KTH, Skolan för teknikvetenskap (SCI).
    Marinins, Aleksandrs
    KTH, Skolan för teknikvetenskap (SCI).
    Shafagh, R. Zandi
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Zhao, Y
    KTH, Skolan för teknikvetenskap (SCI).
    van der Wijngaart, W.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Wosinski, L.
    KTH, Skolan för teknikvetenskap (SCI).
    Thylen, L
    KTH, Skolan för bioteknologi (BIO).
    Toprak, M. S.
    KTH, Skolan för teknikvetenskap (SCI).
    Haraldsson, T.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Östling, M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Popov, S.
    KTH, Skolan för teknikvetenskap (SCI).
    Electro-optical effects of high aspect ratio P3HT nanofibers colloid in polymer micro-fluid cells2017Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 42, nr 11, s. 2157-2160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This Letter reports the electro-optical (EO) effect of Poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofibers colloid in a polymer micro-fluidic EO cell. P3HT nanofibers are high aspect ratio semiconducting nanostructures, and can be collectively aligned by an external alternating electric field. Optical transmission modulated by the electric field is a manifestation of the electro-optical effect due to high inner crystallinity of P3HT nanofibers. According to our results, the degree of alignment reaches a maximum at 0.6 V/μm of electric field strength, implying a big polarizability value due to geometry and electrical properties of P3HT nanofibers. We believe that one-dimensional crystalline organic nanostructures have a large potential in EO devices due to their significant anisotropy, wide variety of properties, low actuation voltages, and opportunity to be tailored via adjustment of the fabrication process.

  • 92.
    Lobov, Gleb S.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Marinins, Aleksandrs
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Sugunan, Abhilash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Thylen, Lars
    KTH, Skolan för bioteknologi (BIO).
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Ostling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Size Impact of Ordered P3HT Nanofibers on Optical Anisotropy2016Ingår i: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 217, nr 9, s. 1089-1095Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline structures with semiconductor properties. When P3HT nanofi bers are dispersed in nonconducting solvent, they react to external alternate electric field by aligning along the field lines. This can be used to create layers of ordered nanofi bers and is referred to as alternating current poling method. P3HT nanofi bers with three different size distributions are fabricated, using self-assembly mechanism in marginal solvents, and used for the alignment studies. Anisotropic absorption of oriented 2 mu m long nanofi bers exponentially increases with the magnitude of applied field to a certain asymptotic limit at 0.8 V mu m(-1), while 100-500 nm long nanofi bers respond to electric field negligibly. Effective optical birefringence of oriented 2 mu m long nanofi bers is calculated, based on the phase shift at 633 nm and the average layer thickness, to be 0.41. These results combined with further studies on real-time control over orientation of P3HT nanofi bers in liquid solution or host system are promising in terms of exploiting them in electroabsorptive and electrorefractive applications.

  • 93.
    Lobov, Gleb S.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Marinins, Aleksandrs
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Li, Jiantong
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Sugunan, A.
    Thylén, Lars
    KTH, Skolan för bioteknologi (BIO). Hewlett-Packard Laboratories, United States.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution2015Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 5, nr 11, s. 2642-2647Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nanofiber morphology of regioregular Poly-3- hexylthiophene (P3HT) is a 1D crystalline structure organized by π - π stacking of the backbone chains. In this study, we report the impact of electric field on the orientation and optical properties of P3HT nanofibers dispersed in liquid solution. We demonstrate that alternating electric field aligns nanofibers, whereas static electric field forces them to migrate towards the cathode. The alignment of nanofibers introduces anisotropic optical properties, which can be dynamically manipulated until the solvent has evaporated. Time resolved spectroscopic measurements revealed that the electro-optical response time decreases significantly with the magnitude of applied electric field. Thus, for electric field 1.3 V ·μm-1 the response time was measured as low as 20 ms, while for 0.65 V ·μm-1 it was 110-150 ms. Observed phenomenon is the first mention of P3HT supramolecules associated with electrooptical effect. Proposed method provides real time control over the orientation of nanofibers, which is a starting point for a novel practical implementation. With further development P3HT nanofibers can be used individually as an anisotropic solution or as an active component in a guest-host system.

  • 94.
    Lobov, Gleb S.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Marinins, Aleksandrs
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Sugunan, A.
    Thylen, Lars
    KTH, Skolan för bioteknologi (BIO).
    Wosinski, L.ech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Popov, Sergei Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Electro-optical response of P3HT nanofibers in liquid solution2015Ingår i: Asia Communications and Photonics Conference, ACPC 2015, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals. © 2015 OSA.

  • 95.
    Lobov, Gleb
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Marinins, Aleksandrs
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Sugunan, A.
    Thylén, Lars
    KTH, Skolan för bioteknologi (BIO). Hewlett-Packard Laboratories, United States.
    Wosinski, L.ech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Fotonik och mikrovågsteknik, FMI.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Dynamic Manipulation of Optical Anisotropy of Suspended Poly-3-hexylthiophene Nanofibers2016Ingår i: Advanced Optical Materials, ISSN 2195-1071, Vol. 4, nr 10, s. 1651-1656Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​

  • 96.
    Lobov, Gleb
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Marinins, Aleksandrs
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Yan, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Sugunan, A.
    Thylén, Lars
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Optik och Fotonik, OFO.
    Optical birefringence from P3HT nanofibers in alternating electric field2014Ingår i: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    AC poling allowing to control the orientation of P3HT nanofibers, result in strong optical birefringence with promising implementation in a novel type of optical modulator, without necessary embedding into any hosting matrix, e.g. liquid crystal.

  • 97. Loiko, P.
    et al.
    Serres, J. M.
    Delekta, S. S.
    Kifle, E.
    Mateos, X.
    Baranov, A.
    Aguiló, M.
    Díaz, F.
    Griebner, U.
    Petrov, V.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Inkjet-printing of graphene saturable absorbers for ~2 μm bulk and waveguide lasers2017Ingår i: Optics InfoBase Conference Papers, Optical Society of America, 2017, Vol. Part F41Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on inkjet-printing of graphene saturable absorbers (SAs) suitable for passive Qswitching of ~2-μm bulk and waveguide lasers. Using graphene-SA in a microchip Tm:KLu(WO4)2 laser, 1.2 μJ/136 ns pulses are generated at 1917 nm.

  • 98.
    Loiko, Pavel
    et al.
    ITMO Univ, Kronverkskiy Pr 49, St Petersburg 197101, Russia..
    Maria Serres, Josep
    URV, Dept Quim Fis & Inorgan, Fis & Cristal Lografia Mat & Nanomat FiCMA FiCNA, EMaS, E-43007 Tarragona, Spain..
    Delekta, Szymon Sollami
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Kifle, Esrom
    URV, Dept Quim Fis & Inorgan, Fis & Cristal Lografia Mat & Nanomat FiCMA FiCNA, EMaS, E-43007 Tarragona, Spain..
    Boguslawski, Jakub
    Wroclaw Univ Sci & Technol, Fac Elect, Laser & Fiber Elect Grp, Wybrzeze S Wyspianskiego 27, PL-50370 Wroclaw, Poland.;Polish Acad Sci, Inst Phys Chem, Kasprzaka 44-52, PL-01224 Warsaw, Poland..
    Kowalczyk, Maciej
    Wroclaw Univ Sci & Technol, Fac Elect, Laser & Fiber Elect Grp, Wybrzeze S Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Sotor, Jaroslaw
    Wroclaw Univ Sci & Technol, Fac Elect, Laser & Fiber Elect Grp, Wybrzeze S Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Aguilo, Magdalena
    URV, Dept Quim Fis & Inorgan, Fis & Cristal Lografia Mat & Nanomat FiCMA FiCNA, EMaS, E-43007 Tarragona, Spain..
    Diaz, Francesc
    URV, Dept Quim Fis & Inorgan, Fis & Cristal Lografia Mat & Nanomat FiCMA FiCNA, EMaS, E-43007 Tarragona, Spain..
    Griebner, Uwe
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2a, D-12489 Berlin, Germany..
    Petrov, Valentin
    Max Born Inst Nonlinear Opt & Short Pulse Spect, Max Born Str 2a, D-12489 Berlin, Germany..
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Li, Jiantong
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Mateos, Xavier
    URV, Dept Quim Fis & Inorgan, Fis & Cristal Lografia Mat & Nanomat FiCMA FiCNA, EMaS, E-43007 Tarragona, Spain..
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Inkjet-printing of graphene saturable absorbers for similar to 2 mu m bulk and waveguide lasers2018Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 8, nr 9, s. 2803-2814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A technique for inkjet-printing of graphene saturable absorbers (SAs) for similar to 2-mu m bulk and waveguide lasers is presented. Based on distillation-assisted solvent exchange to fabricate high-concentration graphene inks, this technique is capable of producing few-layer graphene films of arbitrary shape. Absorption saturation of graphene printed on glass is demonstrated at similar to 1.56 mu m for picosecond and femtosecond pulses indicating a large fraction of the saturable losses. Inkjet-printed transmission-type graphene SAs are applied in passively Q-switched nanosecond thulium (Tm) microchip and planar waveguide lasers. The Tm microchip laser generates 136 ns / 1.2 mu J pulses at 1917 nm with a repetition rate of 0.37 MHz with a Q-switching conversion efficiency reaching 65%. The planar waveguide laser generates 98 ns / 21 nJ pulses at 1834 nm at a repetition rate in the MHz-range. The inkjet-printing technique is promising for production of patterned SAs for waveguide lasers.

  • 99.
    Loiko, Pavel
    et al.
    ITMO Univ, 49 Kronverkskiy Pr, St Petersburg 197101, Russia..
    Maria Serres, Josep
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Delekta, Szymon Sollami
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Kifle, Esrom
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Mateos, Xavier
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain.;Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Baranov, Alexander
    ITMO Univ, 49 Kronverkskiy Pr, St Petersburg 197101, Russia..
    Aguilo, Magdalena
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Diaz, Francesc
    Univ Rovira & Virgili, Fis & Cristallog Mat & Nanomat FiCMA FiCNA, Campus Sescelades,C Marcelli Domingo S-N, E-43007 Tarragona, Spain..
    Griebner, Uwe
    Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Petrov, Valentin
    Max Born Inst Nonlinear Opt & Short Pulse Spect, 2A Max Born Str, D-12489 Berlin, Germany..
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Li, Jiantong
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Inkjet-Printing of Graphene Saturable Absorbers for similar to 2 mu m Bulk and Waveguide Lasers2017Ingår i: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 100.
    Lu, Xingyuan
    et al.
    Soochow Univ, Sch Phys Sci & Technol, Suzhou 215006, Peoples R China..
    Zhao, Chengliang
    Soochow Univ, Sch Phys Sci & Technol, Suzhou 215006, Peoples R China..
    Shao, Yifeng
    Delft Univ Technol, Opt Res Grp, NL-2628 CH Delft, Netherlands..
    Zeng, Jun
    Soochow Univ, Sch Phys Sci & Technol, Suzhou 215006, Peoples R China..
    Konijnenberg, Sander
    Delft Univ Technol, Opt Res Grp, NL-2628 CH Delft, Netherlands..
    Zhu, Xinlei
    Soochow Univ, Sch Phys Sci & Technol, Suzhou 215006, Peoples R China..
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Urbach, H. Paul
    Delft Univ Technol, Opt Res Grp, NL-2628 CH Delft, Netherlands..
    Cai, Yangjian
    Soochow Univ, Sch Phys Sci & Technol, Suzhou 215006, Peoples R China.;Shandong Normal Univ, Sch Phys & Elect, Shandong Prov Engn & Tech Ctr Light Manipulat, Jinan 250014, Shandong, Peoples R China.;Shandong Normal Univ, Sch Phys & Elect, Shandong Prov Key Lab Opt & Photon Device, Jinan 250014, Shandong, Peoples R China..
    Phase detection of coherence singularities and determination of the topological charge of a partially coherent vortex beam2019Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 114, nr 20, artikel-id 201106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the theory of partial coherence, coherence singularities can occur in the spectral degree of coherence (SDOC): in case the fields at two different points are completely uncorrelated, the phase of the SDOC is undefined. For a partially coherent vortex beam, the detection of coherence singularities is linked to the measurement of topological charge, whose magnitude equals the number of ring dislocations in its far field amplitude. However, the phase distribution of coherence singularities is rarely mentioned in the literature and the amplitude distribution can hardly reflect the sign of topological charge. In this letter, we present a phase-analysis method for measuring the coherence singularities by introducing a movable perturbation at a certain point in an illumination window of a finite size. Using the proposed method, we measure experimentally the coherence singularities of a partially coherent vortex beam in the focal plane. From the results, the magnitude and sign of the topological charge can be determined simultaneously from the phase distribution of the coherence singularities. Our results can find application in information transmission.

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