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  • 1.
    Akram, Nadeem
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Schatz, Richard
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Kjebon, Olle
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Influence of electrical parasitics and drive impedance on the laser modulation response2004Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 16, nr 1, s. 21-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this letter, we analyze the effects of electrical parasitics and drive impedance on the laser modulation response. It is found that for lasers with small active-region volume, e.g., vertical-cavity surface-emitting lasers, the finite drive impedance and/or the laser parasitic capacitance can significantly enhance the damping of the laser resonance peak at low bias. This is due to the voltage fluctuations across the laser diode active layer during modulation. It is also shown that the real pole of the small-signal response transfer function corresponding to the laser parasitic cutoff frequency is not fixed but decreases with the increased bias level.

  • 2. Baek, J. H.
    et al.
    Soares, F. M.
    Seo, S. W.
    Jiang, W.
    Fontaine, N. K.
    Broeke, R. G.
    Cao, J.
    Olsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Halvledarmaterial, HMA (Stängd 20120101).
    Yoo, S. J. B.
    10-GHz and 20-GHz channel spacing high-resolution AWGs on InP2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 5, s. 298-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter reports on 10-GHz and 20-GHz channel-spacing arrayed waveguide gratings (AWGs) based on InP technology. The dimensions of the AWGs are 6.8 × 8.2 mm2 and 5.0 × 6.0 mm2, respectively, and the devices show crosstalk levels of 12 dB for the 10-GHz and 17 dB for the 20-GHz AWG without any compensation for the phase errors in the arrayed waveguides. The root-mean-square phase errors for the center arrayed waveguides were characterized by using an optical vector network analyzer, and are 18° for the 10-GHz AWG and 28° for the 10-GHz AWG.

  • 3. Bandelow, U.
    et al.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wunsche, H. -J
    A correct single-mode photon rate equation for multisection lasers1996Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 8, s. 614-616Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown that not the photon number but photon number divided by the square root of the excess factor of spontaneous emission must be used in the photon rate equation for single-mode lasers when the longitudinal field distribution changes with time. The importance of using the correct dynamic quantity is illustrated with two examples.

  • 4.
    Blomqvist, Mats
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Khartsev, Sergiy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Grishin, Alexander M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Electrooptic ferroelectric Na0.5K0.5NbO3 films2005Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, nr 8, s. 1638-1640Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on waveguiding and electrooptic properties of epitaxial Na0.5K0.5NbO3 films grown by radio-frequency magnetron sputtering on Al2O3 (1102) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.

  • 5.
    Cao, Jing
    et al.
    Department of Electrical and Computer Engineering, University of California.
    Broeke, R. G.
    Department of Electrical and Computer Engineering, University of California.
    Fontaine, N. K.
    Department of Electrical and Computer Engineering, University of California.
    Ji, C.
    Department of Electrical and Computer Engineering, University of California.
    Du, Y.
    Department of Electrical and Computer Engineering, University of California.
    Chubun, N.
    Department of Electrical and Computer Engineering, University of California.
    Aihara, K.
    Department of Electrical and Computer Engineering, University of California.
    Pham, Anh-Wu
    Department of Electrical and Computer Engineering, University of California.
    Olsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Yoo, S. J. Ben
    Department of Electrical and Computer Engineering, University of California.
    Demonstration of Spectral Phase O-CDMA Encoding and Decoding in Monolithically Integrated Arrayed-Waveguide-Grating-Based Encoder2006Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 21-24, s. 2602-2604Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on successful spectral phase encoding and decoding operation in a pair of monolithically integrated InP encoder chips, each consisting of an arrayed waveguide grating (AWG) pair and an eight-channel electrooptic phase shifter array. The monolithic fabrication process includes anisotropic reactive ion etching and planarizing hydride-vapor-phase-epitaxy lateral regrowth to realize buried hetero-waveguide structures in AWGs and phase shifters. Electrooptical modulation in the phase shifter arrays in the encoder chip achieved Walsh-code-based optical code-division multiple access (O-CDMA) encoding and decoding. The matched-code encoding-decoding operation resulted in error-free performance in the presence of an interferer, indicating good potential for O-CDMA network applications.

  • 6.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Isaksson, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Schatz, Johan Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    High-speed direct Modulation of widely tunable MG-Y laser2005Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, nr 6, s. 1157-1159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic performance of the modulated-grating Y-branch laser is presented. In order to reach over 40-nm tuning range, the devices utilize an additive Vernier effect and relative tuning of two reflecting gratings. The device shows high (> 13 dBrn ex-facet) and uniform (< 1.2-dB variation) steady state output power over the tuning range, and sidemode suppression ratio > d40 dB. The laser behavior under small- and large-signal operation conditions is investigated. The laser exhibits a resonance frequency of 7.4-8.8 GHz at 80-mA bias. A 10-Gb/s eye diagram measurement showed, high extinction ratio and signal-to-noise ratio.

  • 7.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Stoltz, Björn
    Rosenzweig, Josef
    Driad, Rachid
    Makon, Robert E.
    Li, Jie
    Steffan, Andreas
    ETDM Transmitter Module for 100-Gb/s Ethernet2010Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 22, nr 2, s. 70-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Performance of a packaged distributed-feedback travelling-wave electroabsorption modulator module for data transmission at 100 Gb/s is presented for the first time. Clearly open eye diagrams at 80 Gb/s with an extinction ratio ( ER) of 4.9 dB and 100 Gb/s with ER 4.2 dB ( limited by measurement setup) are demonstrated together with data transmission over 100-m-long standard single-mode fiber and over dispersion-compensated 10-km fiber link.

  • 8. Chang, Qingjiang
    et al.
    Li, Qiang
    Zhang, Ziyang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ye, Tong
    Su, Yikai
    A Tunable Broadband Photonic RF Phase Shifter Based on a Silicon Microring Resonator2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 1-4, s. 60-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose and demonstrate a tunable broadband photonic radio frequency (RF) phase shifter based on a silicon microring resonator. This scheme utilizes the thermal nonlinear effect of the silicon microring to change the electrical phase of the RF signal with a wide tuning range. A prototype of the phase shifter is experimentally demonstrated for a 40-GHz signal with a 0-4.6-rad tuning range.

  • 9.
    Chen, Daru
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Shen, Linfang
    Ultrahigh bireffingent photonic crystal fiber with ultralow confinement loss2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 2-4, s. 185-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A photonic crystal fiber (PCF) with circular air holes in the fiber cladding and elliptical air holes in the fiber core is proposed. According to calculation, both ultrahigh birefringence (larger than 0.01) and ultralow confinement loss (less than 0.001 dB/km) can be achieved simultaneously over a large wavelength range for a PCF with only four rings of circular air holes in the fiber cladding. The confinement loss in this PCF can be effectively reduced while the birefringence almost remains the same. The proposed design of the PCF is a solution to the tradeoff between the birefringence and the confinement loss for the originally reported highly birefringent elliptical-hole PCF. Moreover, an approach to modify the effective index of fiber core is also suggested in this letter.

  • 10.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    High utilization of wavelengths and simple interconnection between users in a protection scheme for passive optical networks2008Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 5-8, s. 389-391Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel protection architecture for passive optical networks (PONs) is presented and evaluated. It is based on the cyclic property of arrayed waveguide gratings (AWGs) and the interconnection between two adjacent optical network units. The proposed scheme is compatible with both wavelength-division-multiplexing (WDM) PONs and hybrid WDM/time-division-multiplexing PONs. It is compared with two existing schemes and shown to have several advantages: 1) 50% less wavelengths is needed; 2) the fiber interconnections are simplified; 3) the connection availability is improved by one order of magnitude.

  • 11. Chen, X.
    et al.
    Lin, R.
    Cui, J.
    Gan, L.
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Ozolins, O.
    Udalcovs, A.
    Jiang, T.
    Schatz, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Popov, Sergei
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Fotonik.
    Chen, Jiajia
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Fu, S.
    Liu, D.
    TDHQ Enabling Fine-Granularity Adaptive Loading for SSB-DMT Systems2018Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 30, nr 19, s. 1687-1690, artikkel-id 8443443Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this letter, we introduce time domain hybrid quadrature amplitude modulation (TDHQ) for the single sideband discrete multi-tone systems. The experimental results reveal that with a single precoding set and the proposed adaptive loading algorithm, the TDHQ scheme can achieve finer granularity and therefore smoother continuous growth of data rate than that with the conventional quadrature amplitude modulation. Besides, thanks to the frame construction and the tailored mapping rule, the scheme with TDHQ has an obviously better peak to an average power ratio. 

  • 12. Cristofori, Valentina
    et al.
    Da Ros, Francesco
    Ozolins, Oskars
    Chaibi, Mohamed E.
    Bramerie, Laurent
    Ding, Yunhong
    Pang, Xiaodan
    Shen, Alexandre
    Gallet, Antonin
    Duan, Guang-Hua
    Hassan, Karim
    Olivier, Segolene
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Jacobsen, Gunnar
    Oxenlowe, Leif K.
    Peucheret, Christophe
    25-Gb/s Transmission Over 2.5-km SSMF by Silicon MRR Enhanced 1.55-mu m III-V/SOI DML2017Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 29, nr 12, s. 960-963Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 13. Dai, D. X.
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Proposal for diminishment of the polarization-dependency in a Si-nanowire multimode interference (MMI) coupler by tapering the MMI section2008Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 5-8, s. 599-601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter presents a design for diminishing the polarization-dependency of a Si nanowire-based multimode interference (MMI) coupler by using a tapered MMI section. The entrance width and waist width of the tapered MMI section are optimized to obtain a polarization-insensitive MMI length for N-fold self-imaging. The MMI section with a diminished polarization-dependency has a relatively large entrance width, which is beneficial to the separation of adjacent access waveguides for minimizing the coupling between them. One can tune the power splitting ratio of a 2 x 2 Si-nanowire MMI coupler by adjusting the entrance and the waist width of the tapered MMI section.

  • 14. Dai, Daoxin
    et al.
    He, Sailing
    Optimization of ultracompact polarization-insensitive multimode interference couplers based on Si nanowire waveguides2006Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 17-20, s. 2017-2019Artikkel i tidsskrift (Fagfellevurdert)
  • 15. Dai, Daoxin
    et al.
    He, Sailing
    Proposal of a Coupled-Microring-Based Wavelength-Selective 1 x N Power Splitter2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 21, s. 1630-1632Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel wavelength-selective 1 x N power splitter, which consists of a microring and N + 1 couplers, is presented. One coupler is for coupling the light signal from the input port into the microring and the other couplers are for coupling the signal light from the microring to the output ports. The channels with the resonant wavelength of the microring are dropped and split into output ports. The critical coupling condition to achieve a high extinction ratio is also given. By appropriately choosing the coupling coefficients for the input/output couplers, it is flexible to have a uniform or nonuniform power splitting as desired.

  • 16. Dai, Daoxin
    et al.
    Hu, Rui
    He, Sailing
    A minimized SiO2 waveguide with an antiresonant reflecting structure for large-scale optical integrations2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 09-12, s. 759-761Artikkel i tidsskrift (Fagfellevurdert)
  • 17. Dai, Daoxin
    et al.
    Yang, Bo
    Yang, Liu
    Sheng, Z.
    He, Sailing
    Compact Microracetrack Resonator Devices Based on Small SU-8 Polymer Strip Waveguides2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 1-4, s. 254-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n similar to 1.573), a SiO2 buffer (n similar to 1.445), and an air cladding. The fabricate straight waveguide has a low propagation loss of about 0.1. dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (similar to 150 mu m) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.

  • 18. Ding, J. F.
    et al.
    Zhang, A. P.
    Shao, L. Y.
    Yan, J. H.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Fiber-taper seeded long-period grating pair as a highly sensitive refractive-index sensor2005Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, nr 6, s. 1247-1249Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Dong, Hui
    et al.
    Nanyang Techbological University, Singapore.
    Shum, Ping
    Nanyang Techbological University, Singapore.
    Gong, Yandong
    Yan, Min
    Nanyang Techbological University, Singapore.
    Zhou, Junqiang
    Wu, Chongqing
    Virtual generalized Mueller matrix method for measurement of complex polarization-mode dispersion vector in optical fibers2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 1, s. 27-29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A virtual generalized Mueller matrix method (VGMMM) is proposed to measure the complex polarization-mode dispersion (PMD) vector in a fiber system with polarization-dependent loss or gain. VGMMM can attain the low-noise high-resolution PMD data using a relatively large frequency step, without the knowledge of input polarization states. VGMMM combines the advantages of both matrix-based methods and differentiation-based methods and overcomes their shortcomings. Experimental results on a fiber system confirm the validity and accuracy of VGMMM.

  • 20.
    Eriksson, Tobias A.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Puttnam, Benjamin J.
    Rademacher, Georg
    Luis, Ruben S.
    Fujiwara, Mikio
    Takeoka, Masahiro
    Awaji, Yoshinari
    Sasaki, Masahide
    Wada, Naoya
    Crosstalk Impact on Continuous Variable Quantum Key Distribution in lticore Fiber Transmission2019Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 31, nr 6, s. 467-470Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the excess noise induced by crosstalk in a trench-assisted homogeneous 19-core fiber for a continuous variable quantum key distribution (CV-QKD) receiver. Crosstalk is studied for both 30 wavelength division multiplexing channels of 24.5-Gbaud PM-16QAM with 100-GHz channel spacing and for an amplified spontaneous emission signal with 37.5-GHz bandwidth. We show that in-band crosstalk from neighboring cores prohibits secret key generation. However, it is possible to place CV-QKD channels at wavelengths not used by the classical channels even though wideband amplified spontaneous emission noise is present. The excess noise induced by crosstalk from a neighboring core is shown to be time-dependent.

  • 21.
    Fei, Chao
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Zhejiang, Peoples R China.
    Hong, Xiaojian
    Zhang, Guowu
    Ji, Du
    Wang, Yuan
    He, Sailing
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Zhejiang, Peoples R China.
    Improving the Performance of Long Reach UOWC With Multiband DFT-Spread2019Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 31, nr 16, s. 1315-1318Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this letter, a multiband discrete-Fourier-transform spread (DFT-spread) is introduced to reduce the peak-to-average-power ratio (PAPR) of discrete multitone (DMT)-based underwater optical wireless communication (UOWC) system. The performance of different multiband DFT-spread DMT schemes in a wide underwater transmission range (from 5 to 55 m at a fixed transmission data rate of 5.6 Gb/s) is experimentally investigated. The measured results show that the 1-band DFT-spread and 2-band DFT-spread DMT can significantly improve the system performance compared with the conventional clipping DMT, while the 1-band DFT-spread gives the best performance. Due to the single carrier frequency domain equalization-like characteristic, the 1-band DFT-spread exhibits a relatively uniform signal-to-noise ratio (SNR) profile, which shows the robustness to high frequency fading in the band-limited UOWC system. These intrinsic advantages could jointly ease the bit error rate (BER) deterioration in a long reach UOWC system. Furthermore, the measured data rate-distance product has reached 308 Gb/s*m (i.e., 55-m * 5.6 Gb/s), which to the best of our knowledge is the largest for the single modulation format.

  • 22. Feng, Zhenhua
    et al.
    Tang, Ming
    Fu, Songnian
    Deng, Lei
    Wu, Qiong
    Lin, Rui
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Wang, Ruoxu
    Shum, Ping
    Liu, Deming
    Performance-Enhanced Direct Detection Optical OFDM Transmission With CAZAC Equalization2015Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 14, s. 1507-1510Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) transmission with constant amplitude zero autocorrelation (CAZAC) sequence equalization is proposed and experimentally demonstrated. Simulation results show that more than 2-dB peak-to-average power ratio (PAPR) reduction can be realized using CAZAC equalization, and 50-km standard single mode fiber (SSMF) transmission of 4.11-Gb/s QPSK-OFDM can be achieved with bit-error rate (BER) under forward error correction limit. Transmission performance of QPSK-based DDO-OFDM system is analyzed in both OB2B configuration and fiber link with and without CAZAC equalization. More than 2.5-dB optical receiver sensitivity improvements can be obtained thanks to the PAPR reduction enjoyed by CAZAC equalization. Signal-to-noise ratio for every subcarrier derived from error vector magnitude is estimated and its flatness is confirmed to be much improved with CAZAC equalization. The performance improvements brought by CAZAC equalization can be extended to other modulation formats, and 8.22-Gb/s 16-quadratic-amplitude modulation-OFDM signals transmission using CAZAC equalization is demonstrated with over 1.5 dB enhancement in receiver sensitivity.

  • 23. Fu, H. Y.
    et al.
    Zhou, K. M.
    Saffari, P.
    Mou, C. B.
    Zhang, L.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Bennion, I.
    Microchanneled Chirped Fiber Bragg Grating Formed by Femtosecond Laser-Aided Chemical Etching for Refractive Index and Temperature Measurements2008Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 17-20, s. 1609-1611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a microchanneled chirped fiber Bragg grating (MCFBG) is proposed and fabricated through the femtosecond laser-assisted chemical etching. The microchannel (similar to 550 mu m) gives access to the external index liquid, thus inducing refractive index (RI) sensitivity to the structure. In the experiment, the transmission bands induced by the reduced effective index in the microchannel region were used to sense the surrounding RI and temperature changes. The experimental results show good agreement with the theoretical analysis. The proposed MCFBG offers enhanced RI sensitivity without degrading the robustness of the device showing good application potential as bio-chemical sensors.

  • 24. Fu, Hongyan
    et al.
    Shu, X. W.
    Mou, C. B.
    Zhang, L.
    He, Sailing
    Bennion, I.
    Transversal Loading Sensor Based on Tunable Beat Frequency of a Dual-Wavelength Fiber Laser2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 14, s. 987-989Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microwave signal generation by using the photonic beating from a phase-shift fiber Bragg grating (PS-FBG)-based dual-wavelength laser is proposed and experimentally demonstrated. The dual-wavelength laser is formed by a linear cavity, in which a PS-FBG is used as a dual-wavelength selective component. Transversal loading on the PS-FBG enhances the birefringence of the optical fiber and consequently makes the transmission peak of the PS-FBG splitting into two sharp transmission peaks of orthogonal polarizations. The wavelength spacing between the two transmission peaks increases with the transversal loading on the PS-FBG, thus making the polarization beating frequency increase. This property is exploited in a transversal loading sensor.

  • 25. Fu, Hongyan
    et al.
    Zhang, W.
    Mou, C. B.
    Shu, X. W.
    Zhang, L.
    He, Sailing
    Bennion, I.
    High-Frequency Fiber Bragg Grating Sensing Interrogation System Using Sagnac-Loop-Based Microwave Photonic Filtering2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 8, s. 519-521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel high-frequency fiber Bragg grating (FBG) sensing interrogation system by using fiber Sagnac-loop-based microwave photonic filtering is proposed and experimentally demonstrated. By adopting the microwave photonic filtering, the wavelength shift of sensing FBG can be converted into amplitude variation of the modulated electronic radio-frequency (RF) signal. In the experiment, the strain applied onto the sensing FBG has been demodulated by measuring the intensity of the recovered RF signal, and by modulating the RF signal with different frequencies, different interrogation sensitivities can be achieved.

  • 26. Guan, Z. G.
    et al.
    Zhang, A. P.
    Jiang, M.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Low-coherence interrogation scheme for multiplexed sensors based on long-period-grating Mach-Zehnder interferometers2006Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 05-8, s. 832-834Artikkel i tidsskrift (Fagfellevurdert)
  • 27. Guan, Zu-Guang
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Coherence multiplexing system based on asymmetric mach-zehnder interferometers for Faraday sensors2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 21-24, s. 1907-1909Artikkel i tidsskrift (Fagfellevurdert)
  • 28. Guan, Zu-Guang
    et al.
    Zhou, Bin
    Liu, Guorong
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Quasi-distributed absorption sensing system based on a coherent multiplexing technique2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 09-12, s. 792-794Artikkel i tidsskrift (Fagfellevurdert)
  • 29. Guo, C. J.
    et al.
    Hong, X. Z.
    He, Sailing
    Elimination of Multiple Access Interference in Ultrashort Pulse OCDMA Through Nonlinear Polarization Rotation2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 20, s. 1484-1486Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multiple access interference elimination scheme based on nonlinear polarization rotation (NPR) is proposed for ultrashort pulse optical code-division multiple access (OCDMA). This scheme is experimentally investigated in a four-user and 2.5-Gb/s coherent OCDMA system encoded/decoded by 127-chip superstructured fiber Bragg gratings. The measured bit-error-rate results of the NPR-based thresholder are also compared with those of a conventional supercontinuum-based thresholder in both the back-to-back and 20-km transmission cases. Our proposed scheme has the advantage of colorless operation over C-band.

  • 30. Guo, Changjian
    et al.
    Huang, Lingchen
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Demonstration of 1 Gb/s x 15-User CDM Over WDM-PON Using Electrical Spatial Coding and Subcarrier Multiplexing2011Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 23, nr 14, s. 953-955Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The downlink transmission of a 1 Gb/s x 15-user code-division multiplexing (CDM) over wavelength-division-multiplexing passive optical network (WDM-PON) based on electrical spatial coding and subcarrier multiplexing is experimentally demonstrated. Two wavelengths with 100-GHz spacing are used to carry the 15 spatial encoded subcarriers generated by an arbitrary waveform generator. Our results show that error-free operation can be achieved after 20-km standard single-mode fiber (SSMF) transmission when 15 simultaneous users are present assuming that forward-error correction coding is used.

  • 31. Han, Zhanghua
    et al.
    Forsberg, Erik
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Surface plasmon Bragg gratings formed in metal-insulator-metal waveguides2007Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 02-4, s. 91-93Artikkel i tidsskrift (Fagfellevurdert)
  • 32.
    Huang, Meng
    et al.
    Huazhong Univ Sci & Technol, Wuhan Natl Lab Optoelect, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Ren, Haonan
    Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England..
    Aktas, Ozan
    Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England..
    Shen, Li
    Huazhong Univ Sci & Technol, Wuhan Natl Lab Optoelect, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China.;Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England..
    Wang, Jian
    Huazhong Univ Sci & Technol, Wuhan Natl Lab Optoelect, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Hawkins, Thomas W.
    Clemson Univ, Ctr Opt Mat Sci & Engn Technol, Dept Mat Sci & Engn, Clemson, SC 29634 USA..
    Ballato, John
    Clemson Univ, Ctr Opt Mat Sci & Engn Technol, Dept Mat Sci & Engn, Clemson, SC 29634 USA..
    Gibson, Ursula J.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Norwegian Univ Sci & Technol, Dept Phys & Porelabs, N-7491 Trondheim, Norway..
    Peacock, Anna C.
    Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England..
    Fiber Integrated Wavelength Converter Based on a Silicon Core Fiber With a Nano-Spike Coupler2019Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 31, nr 19, s. 1561-1564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An all-fiber integrated nonlinear silicon photonic wavelength converter has been proposed and fabricated using the silicon core fiber platform. The silicon fiber was spliced directly to a conventional single mode fiber, facilitated via an inverse tapered nano-spike that helped to reduce the mode mismatch between the different core materials. Four-wave mixing-based wavelength conversion with an efficiency as high as -22.1 dB has been achieved for selected wavelengths across the C-band in a device length of only similar to 1 cm. Successful conversion of quadrature phase-shift keying signals at a 20-Gb/s bitrate, with a 1 to 2 dB penalty level at the bit error ratio (BER) = 3.8 x 10(-3), was used to demonstrate the suitability of the silicon fiber device for the construction of ultra-compact, all-fiber-based optical signal processing systems.

  • 33. Huang, Qiangsheng
    et al.
    Ma, Keqi
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Experimental Demonstration of Single Mode-Splitting in Microring With Bragg Gratings2015Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 13, s. 1402-1405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate single mode-splitting in two types of microring resonators with Bragg gratings. In the first device type, gratings are periodically embedded to the inner wall of the microring resonator. By adjusting the reflection coefficient of the grating and the self-coupling coefficient between the waveguide and microring, experimental results show that the distance between the splitting dips can vary from 0 to more than 1 nm. In the second device type, Bragg gratings break into two identical parts with a pi phase shift between them. The center peak in the mode-splitting spectrum has a full-width at half-maximum of 0.1 nm. The spectra can also be a Fano-type transmission, when the phase shift deviates from pi.

  • 34. Jiang, Meng
    et al.
    Chen, Daru
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Multiplexing Scheme of Long-Period Grating Sensors Based on a Modified Optical Frequency Domain Reflectometry2008Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 21-24, s. 1962-1964Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a novel quasi-real-time sensing scheme by employing a modified optical frequency domain reflectometry technique to multiplex long-period grating (LPG) sensors of transmission mode. Different sensing signals are demodulated by different beat signals through presetting different values for the optical path differences between the measuring arms and a static reference arm. The amplitude of each beat signal is associated with the transmissivity of a sensing LPG. The present multiplexing scheme has the advantages of real-time, high speed, high sensitivity, large capacity, and high resolution over an intermediate length. A measurement of fiber bending curvature is demonstrated to verify good performances of the present LPG sensing system.

  • 35. Jiao, Y. Q.
    et al.
    Dai, Daoxin
    Shi, Yaocheng
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Shortened Polarization Beam Splitters With Two Cascaded Multimode Interference Sections2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 20, s. 1538-1540Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter presents a design for shortening the length of a polarization beam splitter (PBS) by using two cascaded multimode interference (MMI) sections with different widths. By optimizing the MMI parameters, a short PBS of good performance is achieved. The total length of the PBS is reduced to about 1/28 of that of a conventional design.

  • 36.
    Junique, Stephane
    et al.
    Industrial Nano- and Micro-technologies Department, Kista.
    Ågren, Daniel
    Industrial Nano- and Micro-technologies Department, Kista.
    Wang, Qin
    Industrial Nano- and Micro-technologies Department, Kista.
    Almqvist, S.
    Industrial Nano- and Micro-technologies Department, Kista.
    Noharet, Bertrand
    Industrial Nano- and Micro-technologies Department, Kista.
    Andersson, Jan Y.
    IEEE.
    A Modulating retro-reflector for free-space optical communication2006Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 1, s. 85-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present modeling of a modulating retro-reflector for free-space optical communication, composed of a reflective resonant-cavity modulator and a corner cube. Although resonant-cavity modulators are sensitive to the angle of incidence of the light beam, we show that with the right geometrical arrangement, the field of view can be more than ten-fold that of the modulator. The modeling is validated by experimental data using a corner cube and a 14 x 14 mm(2) multiple quantum-well modulator.

  • 37.
    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 Enhancement2015Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 18, s. 1942-1945Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 38.
    Karlsson, A.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Bjork, G.
    On the modulation bandwidth of semiconductor microcavity lasers1994Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 6, s. 1312-1314Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The small signal injection current modulation bandwidth of vertical cavity microlasers in the conventional macroscopic regime and in the microscopic regime of "controlled spontaneous emission" is investigated. A microlaser, under constraint of nonlinear gain or current density limitations, is found to have the same intrinsic modulation bandwidth as conventional edge-emitting lasers with the same cavity losses and photon density.<>

  • 39. Lang, T. T.
    et al.
    He, J. J.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Cross-order arrayed waveguide grating design for triplexers in fiber access networks2006Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 01-4, s. 232-234Artikkel i tidsskrift (Fagfellevurdert)
  • 40.
    Laurell, Fredrik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Webjörn, J.
    Arvidsson, G.
    Bluelight generated by frequency doubling of laser diode light in a lithium niobatechannel waveguide1989Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    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 Noise2015Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 7, s. 685-688Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 42. Li, Shuo
    et al.
    Wang, Meiqian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Overby, Harald
    Wong, Eric W. M.
    Zukerman, Moshe
    Performance Evaluation of a Bufferless OBS/OPS Network With 1+1 Path Protection2015Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 27, nr 20, s. 2115-2118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In optical burst/packet switched (OBS/OPS) networks, bursts/packets may be dropped because of equipment failures. A widely used mechanism to protect a connection from a single-trunk-failure event is 1 + 1 path protection. We consider a bufferless OBS/OPS network with two types of users: 1) premium (that receive 1 + 1 protection service) and 2) regular (that do not receive such a service). We propose a fast and accurate approximation to evaluate the performance of such OBS/OPS network. The accuracy and scalability of the approximation and the effect of the proportion of the premium users in the network are discussed.

  • 43. Li, Shuo
    et al.
    Wang, Meiqian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wong, Eric W. M.
    Overby, Harald
    Zukerman, Moshe
    Evaluation of Burst/Packet Loss Ratio in a Bufferless OBS/OPS Network With 1+X Path Protection2016Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 28, nr 15, s. 1688-1691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The importance of avoiding burst/packet loss because of equipment failures, especially for critical-mission services, gives rise to a method known as 1 + X path protection in optical networks. This method provides additional protection for premium (including emergency) services than the more common 1 + 1 path protection. In this letter, we consider a bufferless optical burst switched (OBS)/optical packet switched (OPS) network with two types of users: premium (that receive 1 + X protection service) and regular (that do not receive such a service). We propose an analytical method based on Erlang fixed-point approximation to evaluate the burst/packet loss of such OBS/OPS network. We demonstrate numerically the accuracy of the approximation, and also the effect and implications of the proportion of the premium traffic as X increases.

  • 44. Lindberg, H
    et al.
    Strassner, Martin
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Bengtsson, J
    Larsson, A
    High-power optically pumped 1550-nm VECSEL with a bonded silicon heat spreader2004Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 16, nr 5, s. 1233-1235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an optically pumped 1550-nm vertical-external-cavity surface-emitting laser with improved output power and operating temperature using a bonded heat spreader. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Heat transport is enhanced by a Si heat spreader bonded to the InGaAsP surface by liquid capillary bonding. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 250 mW was obtained under multitransverse mode operation at 240 K. Under operation in the fundamental near-Gaussian mode, we obtained a maximum power of 230 mW with a beam quality factor (M-2) of 1.22. At room temperature, the output power was limited to 12 mW.

  • 45. Lindberg, H
    et al.
    Strassner, Martin
    KTH, Tidigare Institutioner, Halvledarlaboratoriet.
    Bengtsson, J
    Larsson, A
    InP-based optically pumped VECSEL operating CW at 1550 nm2004Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 16, nr 2, s. 362-364Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a vertical external-cavity surface-emitting laser operating at 1550 run. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 70 mW was obtained under multitransverse mode operation at 233 K. Under single-mode operation, we obtained a maximum power of 60 mW with a beam quality factor M-2 less than 1.1.

  • 46. Lindberg, H
    et al.
    Strassner, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Larsson, A
    Improved spectral properties of an optically pumped semiconductor disk laser using a thin diamond heat spreader as an intracavity filter2005Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, nr 7, s. 1363-1365Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter describes an optically pumped high-power InP-based semiconductor disk laser with a thin (50 mu m) diamond heat spreader bonded to the surface of the gain chip. The diamond heat spreader performs the multiple functions of heat removal, spectral filtering, and wavelength stabilization by utilizing the high thermal conductivity and the low thermooptic coefficient of diamond, along with the large free-spectral range of a thin intracavity etalon. A pump-power-limited output power of 680 mW at 1.55 mu m is demonstrated at a heat sink temperature of -30 degrees C, and 140 mW at room temperature. The spectral width was measured to be less than 0.08 nm and the spectral drift with temperature and pump power as low as 0.03 nm/degrees C and 0.14 nm/W, respectively.

  • 47.
    Lindgren, Stefan
    et al.
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Åhlfeldt, Henrik
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Bäcklin, Lennart
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Forssén, Lili
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Vieider, Christian
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Elderstig, Håkan
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Svensson, Magnus
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Granlund, Lennart
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Andersson, Lars
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Kerzar, Boris
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Broberg, Björn
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Kjebon, Olle
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Forzelius, Elisabeth
    KTH, Tidigare Institutioner, Elektronik.
    Nilsson, Stefan
    KTH, Tidigare Institutioner, Elektronik.
    24-GHz modulation bandwidth and passive alignment of flip-chip mounted DFB laser diodes1997Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 9, nr 3, s. 306-308Artikkel i tidsskrift (Fagfellevurdert)
  • 48. Liu, J.
    et al.
    Lu, Y.
    Guo, C. J.
    Hong, X. Z.
    Xu, L.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Demonstration of Low-Cost Uplink Transmission in a Coherent OCDMA PON Using Gain-Switched Fabry-Perot Lasers With External Injection2010Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 22, nr 8, s. 583-585Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose and demonstrate a simple and low-cost uplink transmission scheme for coherent optical code-division multiple access (OCDMA) passive optical networks (PONs), using gain-switched Fabry-Perot (GS-FP) lasers with external injection as local light sources at optical network units. Experimental results based on the two-user 1.25-Gb/s OCDMA system confirm the feasibility of this scheme. The system performance is compared with that of the OCDMA system using a conventional mode-locked laser (MLL). The auto-correlation peak to the maximum wing level (P/W) ratio is also given as the central wavelength of the GS-FP laser varies. The present low-cost scheme is highly preferable for OCDMA PON applications.

  • 49.
    Liu, Kexin
    et al.
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Jia, Shi
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Wang, Shiwei
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Pang, Xiaodan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Li, Wei
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Zheng, Shilie
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Chi, Hao
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Jin, Xiaofeng
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Zhang, Xianmin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    Yu, Xianbin
    Zhejiang Univ, Coll Informat Sci & Elect Engn, Hangzhou 310027, Zhejiang, Peoples R China..
    100 Gbit/s THz Photonic Wireless Transmission in the 350-GHz Band With Extended Reach2018Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 30, nr 11, s. 1064-1067Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this letter, we experimentally demonstrate terahertz (THz) photonic wireless transmission of high-speed quadrature-phase-shift-keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) signals in the 350-GHz band, with an effort to extend the wireless reach of ultrafast 100 Gbit/s. In the experiment, a narrowband unitraveling-carrier photodiode (UTC-PD) is used for heterodyne generation of THz communication signals, which is transparent to optical modulation formats. Experimental results show that 30 GBd/s QPSK (60 Gbit/s) and 25 GBd/s 16-QAM signals (100 Gbit/s) are successfully transmitted over a 350-GHz wireless link with an extended distance of 2 m. This enhancement is enabled by combining the techniques of employing cutting-edge narrowband UTC-PD as the photomixing THz emitter, spectrally efficient modulation format and advanced digital signal processing algorithms. The achievement makes 100 Gbit/s THz wireless communication systems promising for future smart wireless services.

  • 50. Liu, Sheng
    et al.
    Lee, Kwang Jo
    Parmigiani, Francesca
    Gallo, Katia
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    Petropoulos, Periklis
    Richardson, David J.
    Retiming of Short Pulses Using Quadratic Cascading in a Periodically Poled Lithium Niobate Waveguide2011Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 23, nr 2, s. 94-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate an all-optical technique for the mitigation of timing jitter in short pulse transmission systems. The technique relies on pulse preshaping followed by optical switching in a periodically poled lithium niobate waveguide via cascaded second harmonic and difference frequency generation. The original data pulses are shaped into flat-top pulses to avoid conversion of their timing jitter into pulse amplitude noise at the output of the waveguide. Pulse retiming is confirmed by temporal measurements, while bit-error-rate measurements confirm good noise performance for the system.

123 1 - 50 of 119
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