Professor Azizur Rahman

Overview

Professor B. M. Azizur Rahman received BSc Eng and MSc Eng degrees in Electrical Engineering with distinctions from Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh, in 1976 and 1979, respectively. He also received two gold medals for being the best undergraduate and graduate student of the University in 1976 and 1979, respectively. He received his PhD degree in Electronic Engineering from University College, London in 1982. From 1976 to 1979, he was a Lecturer at the Electrical Engineering Department, BUET. After completing his PhD he joined University College London as a Post-doctoral Research Fellow and continued his research work on the finite element modelling of optical waveguide until 1988. In 1988, he joined the Electrical, Electronic and Information Engineering Department of City University, London, as a Lecturer, where he is now a Professor. Prof. Rahman is a Member of the Institute of Engineering Technology (formerly IEE), England, Fellow of the Optical Society of America, and a Senior Member of the Institute of Electrical and Electronic Engineers (USA).

Qualifications

• PhD Electronics, University College London, United Kingdom, 1982
• MSc Electronics, Bangladesh University of Engineering and Technology, Bangladesh, 1979
• BEng Electrical Engineering, Bangladesh University of Engineering and Technology, Bangladesh, 1976

Employment

• Professor, City, University of London, Jun 2000 – present
• Reader, City, University of London, Oct 1994 – May 2000
• Lecturer, City, University of London, May 1988 – Sep 1994
• Postdoctoral Research Fellow, University College London, Oct 1982 – Apr 1988
• Lecturer, Bangladesh University of Engineering and Technology, Oct 1976 – Sep 1979

Memberships of professional organisations

• Senior Member, IEEE, 1980 – present
• Member, IET, 1980 – present
• Fellow, Optical Societey of America, 1980 – present
• Member, SPIE (Photonics Society), 1980 – present

Teaching

EE2402 Communication Systems

2nd year module

EE3519 Wireless and Optical Communications

3rd year module

EPM911Laser and Optoelectronics

MSc module

EPM759 Signal and Information theory

MSc module

EPM756 Wireless Communications

MSc module

Research interests

At City University, he leads the research group on Photonics Modelling, specialised in the development and use of the rigorous and full-vectorial numerical approaches, frequency domain modal solution approach, the beam propagation method, and time-domain approach, primarily based on the numerically efficient finite element method. He has published more than 450 journals and conference papers, in the areas of optical waveguides, integrated optics, single polarisation guides, photonic devices, such as high-speed modulators and switches, power splitters, compact bend designs, polarisation splitters, polarisation rotators, polarisation controllers, spot-size converters, optical amplifiers, narrow-band optical filters, nonlinear optical devices, optical structures supporting surface-plasmon modes, photonic crystal fibres, and THz waveguides. His journal papers have been cited more than 1900 times. He has received more than £6 million on research grants from the EPSRC, EU, British Council and industries.

Development of Numerical Methods for Photonics

Practical optical waveguides can have complex shapes, such as microstructures features, slanted side walls and complex materials profiles, such as anisotropic, electrooptic, nonlinear material properties, with complex refractive indices to account for the modal leakage, loss or gain and graded or diffused index profiles. Prof. Rahman has been working for more than 35 years on the development of rigorous and full vectorial finite element method (FEM) based numerical approaches for the modal solution of such practical waveguides in GaAs, InP, silicon, silica, plasmonic, lithium niobate or polymers. Besides the modal solution package, which may be the best in the world, PRG has also developed beam propagation method (BPM) based on the FEM to study light propagation through uniform, tapered or bent optical waveguides. Both standard BPM and also Imaginary distance BPM have been developed to study spot-size converters, polarization rotators, and bent waveguides. More recently, to study time domain phenomenon, a new time-domain approach, but based on the computationally efficient FEM has been developed, partly funded by US Army Microwave Research. This approach is being developed to study photonic crystals, metamaterials, and pulse propagation through optoelectronic systems with strong discontinuities and reflections. Besides these optical methods, the PRG has also developed FEM based electronic, stress, thermal, electric field, and acoustic models to study optical interactions with other physical models to study active, passive, linear, nonlinear, elasto-optic, thermo-optic, electro-optic and acousto-optic photonic devices. These methods form the basis of the tools a wide range of photonic devices and optoelectronic systems described below.

Polarization issues in Photonics

Polarization issues, such as polarization mode dispersion and polarization crosstalk are the limiting factors for high-speed and long-distance communication systems. Earlier, we have worked on the EPSRC funded project on the development of highly birefringent polarization maintaining 'Panda' or 'Bow-tie' optical fibres. More recently, we have been working on the development of polarization maintaining PCFs. We have also studied polarization cross-talk in high-index contrast optical waveguides and also in high-speed modulators. We have designed optical polarizers using metal clad or layered core optical waveguides. We have also developed single-polarization optical waveguides using layers core for which QinetiQ applied for a patent. We have also developed various compact optical polarizers using single section optical waveguide with slanted side wall or using cascaded bent waveguides. Some of these projects were funded by Bookham. Novel polarization rotators, using multiple section design, single section design, bent guides, slanted side walls, asymmetric design, in InP, Silicon based devices have been carried out. We have also developed concept of a novel polarization controller using asymmetric loading and QinetiQ has applied for its patent.

Microstructured Optical Fibres

These new type of microstructured optical fibres, also known as photonic crystal fibres (PCF) or holey fibres is showing a range of novel and useful properties for their applications in optical communications and sensing applications. We have received EU support for the Marie Curie Fellow, Dr Kejalakshmy to study single mode and single polarization studies of such fibres. Dr Kabir also researched on the modal solutions of such exotic optical fibres. Dr Uthman has researched on the bending issues related to PCFs. By being inspired by the optimisation process in nature, Dr Arti Agrawal has developed a new approach to design PCF, called equiangular spiral. We have received an UKIERI Major research grant linking with the key research institutes, such as IIT Delhi, IIT Roorkee and Malavia National Institute of Technology, Jaipur, India. Besides our partners in India, we have research collaborations with ORC at Southampton University, Nottingham University, Heriot Watt University, and Strathclyde University in UK, to develop function specific novel PCFs. New types of microstructured fibres, with spiral air-holes and segmented claddings are also being studied.

THz waveguides and devices

Compared to microwave and optical technologies, the intermediate frequency THz range has largely being not developed. PRG is working with the Rutgers University, USA to develop low-loss metal-clad THz waveguides, which has been fabricated at the Bell Labs, USA. We also have active collaboration with Dr Themistos from Cyprus to study surface Plasmon modes in optical and THz waveguides. Recently the Royal Society is also funding the fellowship of Prof. Chattapadhyay from Visva Bharati University, India to develop THz generators. British Council is funding one ongoing project with collaboration from University of Rochester and IIT Delhi to develop low-loss waveguides and devices. We have a long running collaboration with Frederick University in Cyprus on the design optimization of THz waveguides and devices. We also have research collaboration with City University Hong Kong to develop polymer based THz waveguides.

High-speed modulators

PRG has worked extensively on the development of microwave solver, electro-optic models and their application to design lithium niobate, GaAs, InP and polymer-based high-speed modulators. Improvement of phase matching between the optical and modulation RF waves, impedance matching and reduction of both conductive and dielectric losses have been undertaken to improve the data rates of these modulators. Dr Wongcharoen, Dr Anwar, Dr Haxha and Dr Obayya have worked to the various aspects of these devices. Nortel and QinetiQ and Nortel have directly funded to improve the deeply-etched GaAs modulators, particularly to reduce the unexpected polarization rotation in high-speed GaAs modulators.

Research students

1^st supervisor

• Souvik Ghosh

Publications by category