The Square Kilometre Array (SKA) will be the world's largest and most sensitive radio telescope. It will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the big bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. This project envisages the construction of 133 15-m antennas in South Africa and 131,072 log-periodic antennas in Australia, together with the associated infrastructure in the two desert sites. In addition, the SKA is an exemplar Big Data project, with data rates of over 10 Tbps being transported from the telescope to HPC/HTC facilities.

Authors demonstrate that a combination of feed-back control, feed-forward control, optical delay line and saturating channel can obtain the effective suppression of the transient effect in EDFA-based optical burst switched systems.

This paper studies the performance of RZ-DPSK at 10, 20 and 40 Gb/s for application on NZDSF based submarine systems. It compares the upgraded performance with respect to the original RZ-ASK modulation and bit rate. OCIS codes: (060.2330) fibre optics communications; (060.5060) phase modulation IntroductionRecent research on higher line rates for undersea transmission systems has mainly focussed on 40 Gb/s transmission, driven by the gaining popularity of OC-768/STM-256 in other segments of the network. Initial work assumed "green field" installations, where systems are built using new line elements such as dispersion managed fibres with low polarisation mode dispersion (PMD) or Raman assisted amplification [1]. Upgrades of existing systems using N×40 Gb/s RZ-DPSK over non-slope matched fibres have also been studied. Even with slope compensating devices at the receiver they did not achieve an increase in total capacity compared to N×10 Gb/s ASK [2,3]. In addition it was found that performance fluctuations were excessive at transoceanic distances, indicating that system power budget requirements would be very hard to meet. By using 40 Gb/s RZ-DQPSK instead of RZ-DPSK the magnitude of the time varying effects was reduced [4], but the mean performance was found to be worse. By polarisation/phase modulating the DQPSK signals the overall system margin was improved, but no significant spectral efficiency improvement was evident.In recent years legacy systems, originally designed for single channel or N×2.5 Gb/s WDM operation, have been successfully upgraded by increasing the bit rate and/or by adding channels. In this paper we address whether and how this can be done for more recent systems designed for N×10 Gb/s. Recent work has shown that 20 Gb/s RZ-DPSK is a promising candidate to perform cost effective overlay upgrades where some of the existing 10 Gb/s ASK channels are left in place [5]. In a continuation of this work we report here further results of our investigations into overlays and whether this bit rate is also suitable for dark fibre upgrades, i.e., where there are no pre-existing channels, and how it compares with 10 Gb/s RZ-DPSK.

For radio telescope array applications, the precise time and frequency reference predominantly determines the quality of the observation. In this paper, we demonstrate an integrated dissemination system which can achieve ultra-stable frequency dissemination, time synchronization and data transfer simultaneously over a single optical fiber link. The test of this integrated system was carried out on the 48-km fiber link, which consisted of 28-km buried fibers, and 20-km fiber spool in laboratory. It has been experimentally demonstrated that the frequency transfer stability is 2.6 × 10 −14 / and 3.0 × 10 −16 /10 4. The time synchronization with 100-ps accuracy and the error bit ratio of data transfer at the level of 10-8 are also demonstrated.

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