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School of Physical, Environmental and Mathematical Sciences |
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Research Interests:
Optimization, Optics and Photonics, Science Education
Current Research
Design of large area mode fibres (Dr Isaac Towers & Zlatko Jovanoski)
Single-moded optical fibres are preferred for optical communication and for high power applications. The small core of a conventional single-mode fibre leads to high power densities and gives rise to significant unwanted nonlinear optical effects. Nonlinear effects in a fibre can distort the pulses at high bit rate and can produce crosstalk among the closely spaced wavelengths. However, the use of large-core conventional fibres to overcome nonlinear effects is not advisable as the large number of modes in such a fibre reduces the data transfer rate in an optical communication system and affects the beam quality in fibre lasers. It is therefore preferred to use a fibre with a large core yet supporting a single guided mode. The goal of this project is to investigate designs for optical fibres which maximise mode area but allow only a single mode to propagate a meaningful distance.
Recent Research
Nonlinear bent waveguides (Dr Zlatko Jovanoski, Dr Isaac Towers & Prof. Rowland Sammut)
With the continuing development of optical communication, fibre sensors and optical integrated circuits it is fundamentally important to understand how optical signals with intensities in the nonlinear regime are affected by bends in the waveguide. Once this behaviour is understood, the potential exists to exploit the polarization and pulse propagation properties of nonlinear light beams in curved structures to design optical devices for use in future all-optical communication systems. The aim of this project is to perform a detailed theoretical study of nonlinear effects in curved optical waveguides via numerical modelling and solution of the equations describing the propagation of light in such waveguides.
Nonlinear superposition (Dr Zlatko Jovanoski, Prof. Rowland Sammut & Dr Isaac Towers)
The dynamics of nonlinear systems are much richer than those of linear systems. (For example chaos is one consequence of nonlinearity.) But this interesting and complex behaviour is accompanied by an increase in the difficulty of solving the relevant equations. One of the reasons for this is that the principle of superposition -- which allows us to combine simple solutions to solve more complex problems -- is invalid for nonlinear problems. However Jacobi elliptic functions can be combined because of some remarkable identities they have. This project proposes to find solutions of some important nonlinear equations as linear combinations of elliptic functions.
Variational analysis of beam propagation (Dr Zlatko Jovanoski, Prof. Rowland Sammut & Dr Isaac Towers)
Solitary waves have been known to exist in a variety of nonlinear, dispersive media for many years. They have attracted a great deal of practical interest, as solitons in optical fibres offer the potential for very high- capacity communications. While most analyses of soliton propagation rely on numerical simulations, the aim of this project is to use an analytical model to examine the effect on the dynamics of pulse propagation resulting from non-ideal conditions such as attenuation and saturation of the nonlinearity.
PhD Opportunities and Scholarships available within the Optics and Photonics Research Group
If you are interested in PhD research in Optics and Photonics contact Dr Isaac Towers or Dr Zlatko Jovanoski for further information.
Recent Publications
Journal – refereed
Jovanoski, Z. , Ansari, N. A., Towers, I. N. & Sammut, R. A., 2008, Exact domain-wall solitons, Physics Letters A , 372(5), 610-612.
Ansari, N. A., Towers, I. N ., Jovanoski, Z. & Sidhu, H. S., 2007, A semi-classical approach to two-frequency solitons in a three-level cascade atomic system, Optics Communications , 274(1), 66-73.
Ansari, N .A., Jovanoski, Z. , Sidhu, H.S. & Towers, I. N. , 2006, Non-linear interaction of two intense fields with a three-level atomic system, Journal of Nonlinear Optical Physics & Materials , 15(4), 401-413.
Sidhu, H. S., Mercer, G. N., Sexton, M. J., Ansari, N. A. & Jovanoski, Z. , 2006, Optimal path trajectories in a threat environment, Journal of Battlefield Technology, 9(3), 1-7.