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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; · 0.96 Impact Factor
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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; · 0.96 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; · 0.96 Impact Factor
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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 optimis-ing the parameters of DVSB filters for different launch powers. Introduction: As electronic equalisation techniques have proven to be powerful tools for the compensation of signal distortions in optical com-munication systems, maximum likelihood sequence estimation (MLSE) has emerged as one of the most effective compensation technologies. It has shown to be effective in compensating for linear impairments such as chromatic dispersion (CD) and polarisation-mode dispersion [1, 2], as well as self-phase modulation (SPM) in the presence of large residual CD values [3]. However, the MLSE receiver shows little improvement in nonlinear tolerance compared to the standard receiver for small residual CD [3]. One of the approaches that can enhance the perform-ance of MLSE is diverse-vestigial-sideband (DVSB) filtering and joint equalisation, which has proven to be effective through simulations in our previous works [4, 5]. In this Letter, we experimentally investigate the nonlinear mitigation capability of diverse-vestigial-sideband-filter-ing MLSE (DVSB-MLSE), in which DVSB filtering is realised with a Mach-Zehnder (MZ) filter. We also investigate the performance of DVSB-MLSE with optimal DVSB filters for different launch powers by simulation. Configuration of DVSB-MLSE: Fig. 1 shows the configuration of DVSB-MLSE. The input optical signal is first split into two branches. The signals in the two branches are then filtered with optical bandpass filters (OBPFs) to upper and lower vestigial sideband (VSB) signals and optically-electrically (O/E) converted, respectively. Finally, the converted electrical signals are sampled by analogue-to-digital conver-ters (ADCs) for joint MLSE equalisation. Since the inter-symbol inter-ference brought about by fibre nonlinearity behaves differently in the upper and the lower VSB filtered signals, through jointly equalising them the nonlinearity can be better mitigated.
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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;
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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.
