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Newton Advanced Fellowship for City photonics specialist

Professor B.M. Azizur Rahman and Professor Linjie Zhou of Shanghai Jiao Tong University (SJTU) have been awarded a prestigious Newton Advanced Fellowship.
by John Stevenson (Senior Communications Officer)

City University London’s Professor of Photonics, Professor B.M. Azizur Rahman and Professor Linjie Zhou of Shanghai Jiao Tong University (SJTU) have been awarded a prestigious Royal Society Newton Advanced Fellowship scheme.

Portrait of Azizur Rahman The scheme provides established international researchers with an opportunity to develop the strengths and capabilities of their research group through training, collaboration and reciprocal visits with a partner in the UK. The skills and knowledge gained should lead to changes in the well-being of communities and increased economic benefits.

Three orders of magnitude

Professors Rahman and Zhou have proposed research and development on a novel silicon optical modulator based on a hybrid slot waveguide composed of a vertical polysilicon-VO2-SiO2-silicon stack.

Similar to graphene, the VO2 material also changes from the insulating to the metal phase when a high electrical field is applied, thus allowing for a significant change in its complex refractive index. Following the insulator-to-metal transition of the VO2 material, the waveguide effective index experiences a large change, which is three orders of magnitude higher than other commonly used approaches. This translates into a dramatic loss change in an ultra-short device, which could be utilized to realize intensity modulation of the guiding light.

Nano photonicsProfessor Rahman’s City research group has developed the most powerful finite element method (FEM) modelling based computer codes to analyse such photonic devices with nanometer scale dimensions and complex refractive indices.

Evaluation of devices

Working in collaboration with SJTU - one of the leading universities in China - and utilising its state-of-the-art fabrication facilities, the two academics will produce these devices. Following their fabrication at SJTU, the optical and high-speed ratio frequency (RF) responses of these devices will also be evaluated.

The Si-VO2 hybrid modulator has wide potential for applications in long-haul optical telecommunications or short-reach interconnections for data centres and supercomputers. Its main function is to realize signal conversion from the electrical domain to the optical domain. It is one of the key components in the transmitter module for an optical link. It could be used as a discrete component in an optical system or be integrated in an optoelectronic chip.  

This may eventually allow the implementation of a novel Si-VO2 hybrid modulator with superior performance, where the outcome of the research may allow innovative products to be developed, offering economic benefits to both UK and China and to its consumers.

Definition
Finite Element Modelling

Finite Element Modelling, or FEM, is an approximation method for studying continuous physical systems, used in structural mechanics, electrical field theory and fluid mechanics. The system is broken down into discrete elements interconnected at discrete node points.

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