Hark Yoo

Electronics and Telecommunications Research Institute, Sŏul, Seoul, South Korea

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Publications (8)12.25 Total impact

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    ABSTRACT: We suggest an immediate allocation with colorless grant (IACG) method for dynamic bandwidth allocation of a gigabit passive optical network (GPON) system. The suggested method is based on the GigaPON Access Network (GIANT) media access control (MAC) method. The IACG method can assign the transmission bandwidth regardless of the value of a scheduling counter, whereas the GIANT MAC method can assign the transmission bandwidth only when the scheduling counter has a value of 1. Also, unlike the GIANT MAC method, the IACG method utilizes the unallocated remainder of the transmission bandwidth. At the end of scheduling, the IACG MAC method assigns the unallocated remainder to each optical network unit (ONU) with an equal share. Using computer simulations with the self-similar traffic model, we show that the IACG method dramatically outperforms the GIANT MAC method in mean delay and frame-loss rate.
    Journal of Optical Networking 07/2008; 7(8):783-795. DOI:10.1364/JON.7.000783 · 1.08 Impact Factor
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    ABSTRACT: We demonstrate optical burst add-drop multiplexing as a practical application of the optical burst switching technology in a wavelength-division-multiplexed ring network. To control optical bursts in the network, a burst identifier (BI) for delivering control information, and a BI processor for handling the BI, were designed. Optical bursts of 10- to 100-mus in length were optically multiplexed or demultiplexed in an intermediate node of the ring network. The demonstration shows that the optical burst add-drop multiplexing technique provides sub-wavelength granularity to a ring network.
    Optics Express 11/2007; 15(20):13256-65. DOI:10.1364/OE.15.013256 · 3.53 Impact Factor
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    ABSTRACT: A novel all-optical flip-flop is proposed and demonstrated experimentally. The flip-flop consists of a conventional multi-mode Fabry-Perot laser diode (FP-LD) and a specially designed master FP-LD which has a built-in external cavity and operates in single longitudinal mode oscillation. The triggering pulses were generated by external modulators with non-return-to-zero pulse pattern generators. The rising and falling times of the output signal in on-off operation of the flip-flop were about 50 ps. The required powers of both set and reset pulses were less than -9 dBm.
    Proceedings of SPIE - The International Society for Optical Engineering 10/2006; DOI:10.1117/12.691467 · 0.20 Impact Factor
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    ABSTRACT: We demonstrate the operation of a novel all-optical flip-flop. The flip-flop consists of a slave Fabry-Perot laser diode (FP-LD) and a specially designed master FP-LD which has a built-in external cavity and operates in single longitudinal mode oscillation. The set and reset pulses were generated by external modulators at 1 Gbit/s. The rising and falling times of the output signal in on-off operation of the flip-flop were about 50 ps. The required powers of both set and reset pulses were less than -9 dBm.
    Optics Express 06/2006; 14(9):4058-63. DOI:10.1364/OE.14.004058 · 3.53 Impact Factor
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    ABSTRACT: An wideband and efficient wavelength conversion based on the absorption modulation of a Fabry-Perot laser diode is proposed. The experimental results show an 50 nm wavelength conversion range with more than 10 dB extinction ratios.
    Lasers and Electro-Optics, 2004. (CLEO). Conference on; 06/2004
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    ABSTRACT: A novel all-optical wavelength converter based on the transverse-magnetic (TM)-mode absorption modulation of a Fabry-Perot laser diode (FP-LD) is proposed and demonstrated. An FP-LD shows absorption nulls for TM mode probe beam, which are red-shifted by an additional optical pump injection. Using this, the transmission of the continuous-wave probe beam can be optically controlled and wavelength conversion is, thus, achieved. The proposed scheme is simple and cost-effective, and can be used for very wide-range wavelength conversion. Bit-error-rate measurements at 2.5 Gb/s were performed, and the power penalties of 2 and 6 dB were observed, respectively, for noninverted and inverted wavelength conversion.
    IEEE Photonics Technology Letters 03/2004; 16(2-16):536 - 538. DOI:10.1109/LPT.2003.823090 · 2.18 Impact Factor
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    ABSTRACT: A novel tunable encoding/decoding scheme based on an arrayed waveguide grating (AWG) and optical switches for time–wavelength hybrid (TWH) optical code division multiple-access (CDMA) systems is proposed. The scheme uses optical switches and fixed delay lines instead of tunable delay lines (TDLs) and utilizes the structure of the TWH optical signature sequences. The advantages of the scheme are that it can be implemented using fewer elements and that the encoded signal suffers lower loss than in those using TDLs. A TWH optical CDMA system for local area network (LAN) applications using the proposed tunable encoder and a simple fixed decoder is examined and its feasibility is experimentally verified.
    Optics Communications 02/2003; 216(4):335-342. DOI:10.1016/S0030-4018(02)02338-6 · 1.54 Impact Factor
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    ABSTRACT: We propose and simulate a novel optical label swapping scheme using a frequency-doubled subcarrier multiplexed (SCM) signal processing technique. This method can support a dispersion-insensitive and polarization-independent transmission and extraction of an SCM optical label using a standard fiber Bragg Grating (FBG) filter and an optical circulator without a conventional SCM coherent detection circuitry. Simulation results show that our method is applicable to an FBG filter with wide reflection bandwidth (BW), and relieves the restriction of an optical FBG filter, satisfying the wavelength tolerance of the dense WDM sources and FBGí»s center wavelength . Driving an external Mach-Zehnder (MZ) modulator over the full switching voltage improves the receiver sensitivity, compared to the previous standard double-sideband (DSB) SCM header processing technique.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2002; DOI:10.1117/12.482287 · 0.20 Impact Factor