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Projects
Integrated Microwave Photonics
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  This project aims to develop photonic integration technologies enabling microwave photonic (MWP) functions on a chip. Integration platforms such as InP, Silicon on Insulator (SOI), and Silicon Nitride (Si3N4-SiO2) have reached the required degree of maturity to be considered as viable options for the implementation of MWP functions. The aim is to offer the required MWP technologies in the form of stable, cost-effective and scalable photonic integrated circuits.



Optoelectronic sensing technology
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  There is an increasing demand for real time monitoring and detection in biomedical, environmental and industrial applications using optoelectronic sensors. The photonic based sensing technology offers sensors with relative immunity to electromagnetic interference, weight savings and safety improvement. This project aims to develop highly sensitive and robust sensors for hazard detection, health and fitness monitoring, and biomarker discovery.



Bragg grating solitons
Staff             Internal Research Member
A/Prof Javid Atai
Description  The aim of this project is to analyze and characterize the formation and dynamics of Bragg grating solitons in various structures such as nonuniform and coupled Bragg gratings and photonic crystals. Bragg grating solitons can be utilized to design optical buffers and logic gates.



Design of novel Bragg gratings for filtering and data format conversion
Staff             Internal Research Member
A/Prof Javid Atai
Support  Researchers from Foshan University, Huazhong University of Science and Technology and Wuhan National Laboratory for Optoelectronics
Description  This is a collaborative project with researchers from Foshan University and Huazhong University of Science and Technology and Wuhan National Laboratory for Optoelectronics. The aim of this project to design novel Bragg gratings that can be used for optical data format conversion (e.g. RZ-DPSK to NRZ-DPSK and vice versa).



Localization of capsule endoscope
Staff             Internal Research Member
A/Prof Javid Atai
Support  Researchers from Harvard University, University of Southern Denmark, and Worcester Polytechnic Institute.
Description  The aim of this project is to develop novel adaptive algorithms to accurately determine the location of the capsule endoscope in the body.



Photonic Signal Processing
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  This project aims to develop new photonic signal processing structures that can manipulate broadband signals. An important aspect of the work is to explore techniques to make the processors adaptive and tunable so that the characteristics can be controlled for information processing. Optical signal processing is expected to effectively handle high-speed, broadband signals in advanced optical communications systems and information processing. This can provide direct interfacing of fibre processing with high-speed systems.

Photonic signal processors can overcome limitations imposed by conventional electrical signal processors at sampling speeds above 1 GHz. In addition photonic processors are compatible with fire-optic transmission systems and can process signals in the optical domain directly. Research is aimed at deriving new structures that can perform high speed processing tasks on the signals that are contained within the fibre.

Applications both in the frequency domain and time domain include microwave filtering, interference suppressors, channel selectors, fast signal correlation, matched filtering and programmable delay lines.

The structures being researched are based on discrete time signal processors using Bragg grating sampling elements and multiple wavelength techniques. The objectives are to investigate new structures that can realise high-resolution optical filters for microwave signals. An additional objective is to investigate techniques to make these processors widely tunable and adaptive, to enable high-resolution microwave optical signal processing with high time-bandwidth operation.



Dispersion managed solitons
Staff             Internal Research Member
A/Prof Javid Atai
Description  The aim of this project is to study the propagation of optical pulses in dispersion managed links particularly in the presence of optical filtering. One of the goals this project is to find better ways of suppressing Gordon-Haus jitter.



Nonlinear pulse propagation in periodic media
Staff             Internal Research Member
A/Prof Javid Atai
Support  Boris Malomed
Description  In this project we have studied the stability of Bragg grating solitons in media where the sign of nonlinearity is periodically changing ("nonlinearity management"). We have found that the stability diagram in this model is a universal one inthat it is not dependent on the soliton's power



Optically-controlled Phased Arrays
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  This project aims to derive new architectures of optical phased arrays that realise high capacity phased array antennas that can generate high-resolution steerable beams and which can operate with wide bandwidth. Future radar and communication systems will require phased array antennas that can achieve true-time delay beam-forming and which can synthesises a large number of beams. The important advantages of wideband and squint-free operation motivate the use of optical beamforming techniques.

The aim is to investigate new photonic-based beamforming architecture that can realise a true-time delay beam steering in wide-band phased array antennas. This is based on fibre Bragg grating true time delay elements and multiple wavelength WDM techniques. This exploits the wavelength selectivity of gratings to realise a highly parallel delay processing function, which perform the complex signal delay processing equalisation on a large number of array elements simultaneously within the fibre. Our new architecture uses wavelength mapping to the array elements and partitioning concepts. Another objective is to investigate new direction finding techniques using photonics-based techniques that solve the accuracy and wideband operation requirements of these systems. The aim is to open the way to the realization of high-functionality arrays for high-resolution multiple-beam antennas with wideband operation.



WDM photonic downconverter
Staff             Internal Research Member
Prof Robert Minasian
Description  Photonic mixing has several advantages over the conventional approach of direct detection of the optical carrier followed by electronic mixing. This includes a higher conversion efficiency and dynamic range. In addition, photonic mixing has inherent high isolation due to the optical interaction process in mixing, immunity of EMI and crosstalk, and the ability of operating over very wide bandwidths.
This project aims to derive new techniques that provide linearisation as well as wideband mixing capability. The objective is to use WDM techniques to simultaneously frequency convert multiple carriers. Another objective is to increase the dynamic range characteristics. Investigations involve optimum optoelectronic device structures for increasing the spurious free dynamic range, and for reducing the noise figure. The aim is to obtain new topologies that overcome existing limitations of mixers, and to increase the dynamic range, which is a fundamental requirement of receiver systems.



Solitons in dual-core optical waveguides
Staff             Internal Research Member
A/Prof Javid Atai
Support  Boris Malomed
Description  In this project stability and interactions of spatial solitons in a model of two linearly coupled nonlinear optical waveguides with a phase-velocity difference between them are investigated. By means of systematic numerical simulations, conjectures about stability of different branches of solitons in this system are verified. Additionally, a stable branch into which unstable solitons evolve is identified. It is also shown that the outcome of interaction depends on the initial separation and asymmetry parameter.



Microwave Photonics
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  There is currently investigation of possible applications of photonics applicable to the development of radar and microwave signal conditioning systems. This includes optimum optical modulation formats and structures for programmable photonic delay lines. The project also aims to develop new photonic-based tunable filters to provide signal conditioning in receivers. Future receiver systems will utilise the benefits of fibre optics and it is useful to implement as much signal conditioning as possible in the fibre. The objective of this project is to investigate new structures for signal conditioning of RF signals using optical fibre and widely tunable filters implemented in the fibre.



Optical Fibre Transmission and Interference Mitigation Filters
Staff             Internal Research Members
Prof Robert Minasian, Prof Xiaoke Yi
Description  Two critical aspects of research relating to next-generation antenna arrays relate to the transmission of broadband (>1GHz) signals over the array network and the removal of interfering signals. The objective of this project is to investigate new fibre-based filter structures that can suppress interference and which are compatible with fibre-optic transmission systems.



Wavelength division multiplexing in a stabilized Ginzburg-Landau system
Staff             Internal Research Member
A/Prof Javid Atai
Support  B.A. Malomed, D.J. Frantzeskakis, K. Hizanidis
Description  We have studied the stability and interactions of chirped solitary pulses in a system of nonlinearly coupled cubic Ginzburg-Landau (CGL) equations with a group-velocity mismatch between them, where each CGL equation is stabilized by linearly coupling it to an additional linear dissipative equation. In the context of nonlinear fiber optics, the model describes transmission and collisions of pulses at different wavelengths in a dual-core fiber, in which the active core is furnished with bandwidth-limited gain, while the other, passive (lossy) one is necessary for stabilization of the solitary pulses. It is demonstrated that the model may readily support fully stable pulses whose collisions are quasielastic, provided that the group-velocity difference between the two channels exceeds a critical value. In the case of quasielastic collisions, the temporal shift of pulses, predicted by the analytical approach, is in semi-quantitative agreement with direct numerical results in the case of anomalous dispersion. We also consider a simultaneous collision between pulses in three channels. It is found that this collision remains quasielastic, and the pulses remain completely stable.



THz Imaging and Phased Array Techniques
Staff             Internal Research Member
Prof Robert Minasian
Support  Trevor Bird (CSIRO)
Description  Terahertz waves lie in the electromagnetic spectrum between infrared light and microwaves. The term terahertz is generally accepted as referring to the submillimetre wave energy with wavelengths between 1000mm and 100mm (frequencies between 300GHz and 3THz). Today, the terahertz region remains one of the least utilised regions of the electromagnetic spectrum, with potential applications in imaging, medicine, radio astronomy and short-range radar and communications. This research project will explore the use of sensor arrays for performing terahertz imaging. It is a collaborative research project between the CSIRO’s Electromagnetics and Antennas group and The University of Sydney’s Fibre-Optics & Photonics Group. This research has potential applications relating to medical imaging, security, communications and spectroscopy.



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