Optical fibre measurement for clock tones in telescope networks

Astronomy dates back to the early man’s impression of the heavens with little information recorded including some drawings of comets, eclipse and supernovas[1]. Major progress has been made in the field of Astronomy since then. Scientific curiosity to probe the universe in attempt to answer questions such as the origin of the universe, the matter it is made of, the formation of stars, planets and galaxies, and tracking life in other solar systems has brought about the need for more advanced tools capable of detailed observations. In 1608 H. Lippershey developed the first refracting telescope[2], [3]. A year later Galileo used a similar telescope pointing skywards discovering mountains and craters on the earth’s moon, the moons of Jupiter and the phases of Venus. Over the years telescopes have been developed with advancements from the optical telescope towards much larger and more sensitive radio telescopes. The first radio signal from space was detected by Karl Jansky and ever since then astronomers have been using radio telescopes to explore the universe by detecting radio waves emitted by cosmic objects[4]. The ability of radio telescopes to detect weak signals is related to the signal capture surface. As the demand for sensitivity, transmission bandwidth and data rate increases, so does the need for telescopes with a large field of view and capability to observe different parts of the sky at once[5]. This is possible with radio telescope array, with the data from the antennas combined electronically to produce a high resolution image of the sky. The South African MeerKAT radio telescope is an array of 64 interlinked antennas each transmitting up to 160 Gbps of data to the central processing site over optical fibre which is ideal for carrying large volumes of data at high speeds. The MeerKAT telescope is a precursor to the Square kilometer Array which will have up to 50 times the sensitivity and 10000 times the survey speed than the best telescope[6]

Generation and optimization of picosecond optical pulses for use in hybrid WDM/OTDM networks

The burgeoning demand for broadband services such as database queries, home shopping, video-on-demand, remote education, telemedicine and videoconferencing will push the existing networks to their limits. This demand was mainly fueled by the brisk proliferation of Personal Computers (PC) together with the exceptional increases in their storage capacity and processing capabilities and the widespread availability of the internet. Hence the necessity, to develop high-speed optical technologies in order to construct large capacity networks, arises. Two of the most popular multiplexing techniques available in the optical domain that are used in the building of such high capacity networks, are Wavelength Division Multiplexing (WDM) and Optical Time Division Multiplexing (OTDM). However merging these two techniques to form very high-speed hybrid WDM/OTDM networks brings about the merits of both multiplexing technologies. This thesis examines the development of one of the key components (picosecond optical pulses) associated to such high-speed systems. Recent analysis has shown that RZ format is superior to conventional NRZ systems as it is easier to compensate for dispersion and nonlinear effects in the fibre by employing soliton-like propagation. In addition to this development, the use of wavelength tunability for dynamic provisioning is another area that is actively researched on. Self-seeding of a gain switched Fabry Perot laser is shown to one of the simplest and cost effective methods of generating, transform limited optical pulses that are wavelength tunable over very wide ranges. One of the vital characteristics of the above mentioned pulse sources, is their Side Mode Suppression Ratio (SMSR). This thesis examines in detail how the pulse SMSR affects the performance of high-speed WDM/OTDM systems that employ self-seeded gain-switched pulse sources

Optics in Our Time

Optics, Lasers, Photonics, Optical Devices; Quantum Optics; Popular Science in Physics; History and Philosophical Foundations of Physic

ReSCon '12, Research Student Conference: Book of Abstracts

The fifth SED Research Student Conference (ReSCon2012) was hosted over three days, 18-20 June 2012, in the Hamilton Centre at Brunel University. The conference consisted of 130 oral and 70 poster presentations, based on the high quality and diverse research being conducted within the School of Engineering and Design by postgraduate research students. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Particle Physics Reference Library

This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the “Particle Physics Reference Library” provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A,B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium