A.S. Xu

Peking University, Peping, Beijing, China

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Publications (6)5.35 Total impact

  • Source
    L. Wu · M. Li · F. Zhang · Z.Y. Chen · L.-K. Chen · A.S. Xu
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    ABSTRACT: Fibre nonlinearity mitigation of non-return-to-zero on-off keying (NRZ-OOK) signals with diverse-vestigial-sideband (DVSB) filtering maximum likelihood sequence estimation (MLSE) is demonstrated by experiments and simulations, in which DVSB filtering is realised with a Mach-Zehnder (MZ) filter. In a 10.709-Gbit/s NRZ-OOK system, experimental results show that, at a fixed optical signal-to-noise ratio, the Q -factor is improved significantly with DVSB-MLSE compared to that with conventional MLSE. Simulations reveal that the performance of DVSB-MLSE can be further improved by optimising the parameters of DVSB filters for different launch powers.
    Electronics Letters 06/2010; 46(11-46):780 - 781. DOI:10.1049/el.2010.0361 · 1.07 Impact Factor
  • M. Li · C. Hong · D. Liu · L. Li · Z.R. Zhang · L.X. Zhu · F. Zhang · Z.Y. Chen · A.S. Xu
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    ABSTRACT: Chromatic dispersion compensation of non-return-to-zero on-off keying (NRZ-OOK) signals with a diverse-vestigial-sideband-filtering feed forward equaliser and a decision feedback equaliser (DVSB-FFE-DFE) is presented, in which diverse vestigial sideband (VSB) filtering is realised with a Mach-Zehnder (MZ) filter. In a 10.709 Gbit/s NRZ-OOK system, experiment results show that the standard singlemode fibre transmission distance at 3 dB optical signal-to-noise ratio penalty with DVSB-FFE-DFE is doubled, compared to that with conventional FFE-DFE.
    Electronics Letters 08/2009; 45(14-45):751 - 752. DOI:10.1049/el.2009.1057 · 1.07 Impact Factor
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    ABSTRACT: We report on a novel micro torsion mirror actuated by a compound electrostatic driving structure. The compound driving structure is made up of a planar plate drive and a vertical comb drive. The device is fabricated in SOI substrate by using a bulk-and-surface mixed silicon micromachining process. As demonstrated by experiment, the novel driving structure can actuate the mirror to achieve large-range continuous rotation as well as spontaneous 90° rotation induced by the pull-in effect in a voltage control fashion. The continuous rotating range of the micro torsion mirror is increased to about 46° at an increased threshold voltage. The measured threshold voltage ranges of the mirrors with torsion springs of 1 μm and 0.5 μm in thickness are 390–410 V and 140–160 V, respectively. Theoretical modeling is carried out to compare with the experiment. The optical insertion loss has also been measured to be −1.98 dB when the mirrors serve as digital optical switches in a 2 × 2 array form.
    Sensors and Actuators A Physical 04/2007; 135(2-135):758-764. DOI:10.1016/j.sna.2006.08.007 · 1.94 Impact Factor
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    ABSTRACT: A 42.8 Gbit/s NRZ transmitter based on electro-absorption modulation (EAM) is demonstrated experimentally in a transmission system over 1200 km standard singlemode fibre. The combined effect of positive chirp in the EAM transmitter and the second-order dispersion compresses the pulse after transmission, which leads to better performance
    Electronics Letters 02/2007; 43(4-43):237 - 239. DOI:10.1049/el:20073654 · 1.07 Impact Factor
  • W.G. Wu · Q.H. Chen · G.Z. Yan · Y.L. Hao · D.Q. Yin · Z Y Chen · A.S. Xu
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    ABSTRACT: A novel hybrid electrostatic actuator made up of a planar plate drive and a vertical comb drive is developed for actuating torsional micromirror. The device consisting of the actuator and an into-plane tiltable mirror is fabricated in SOI substrate based on bulk-and-surface mixed silicon micromachining. As demonstrated by experiment, the novel actuator can drive the mirror to achieve large-range continuous tilting as well as spontaneous 90° tilting induced by the pull-in effect in a voltage control fashion. The continuous tilting range of the micromirror is increased to about 46°. Both theoretical modeling and experimental observations indicate that, accompanying the increase in the continuous tilting range, the yielding voltage increases. The device has also been used as a mirror switch in an optical system, and the optical insertion loss is measured to be -1.98 dB.
    Sensors, 2005 IEEE; 01/2005
  • Y Zhang · T Tong · AS Xu · DM Wu
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    ABSTRACT: Multi-granularity switching in optical layer has gain significant importance due to the reduction of size and cost of the optical cross-connect. In this paper, we propose a novel structure of MG-OXC, named two-layer MG-OXC, and also give a new graph model for describing the function of the all kinds of MG-OXC. The network states can be represented completely through our auxiliary graph. In such an auxiliary graph, the optical tunnel allocation in multi-granularity switching network is reduced to the min-cost path rind problem, and different traffic grooming policies can be archived simultaneously. We compare the performance of the two-layer MG-OXC to the normal three-layer MG-OXC and single-layer MG-OXC by the algorithm we proposed through simulation, and conclude that the novel MG-OXC can get very close performance to three-layer MG-OXC but smaller size of switching matrix. The simulation also proved the algorithms we proposed performs better than traditional RWA algorithms dealing the routing and wavelength sub problems separately.
    Conference on Architectures, Management, and Applications III; 01/2005