Smart Materials and Transformation Optics

We have a long tradition of studying different numerical techniques to solve the Maxwell's Equations. We started it with the development of FDTD algorithm in the nonorthogonal coordinate system. We also developed some novel techniques to tackle both frequency and spatial dispersion of metamaterials. We developed the first time domain simulation of invisibility cloak, where superluminal behaviour of wave propagation can be visualised.

While commercial modelling tools are becoming more and more powerful, we have now turned our attention to the modelling of novel materials and devices. For example, we have developed FDTD algorithms to understand the nonlinearity and THz responses of graphene under DC magnetic fields. We have also stretched our knowledge to include the Monte Carlo technique to model electron transport in graphene and other 2D materials. This has helped us to develop accurate transistor models, which can be used in the design of novel active devices and metamaterials. More recently, we have implemented a coupled nonlinear model to study tunable metamaterials containing ferroelectrics and accurately predict their effective properties as a function of an external applied voltage, taking into account the localized electric field enhancement in the unit cell.

Materials by design has always been perceived as a scientific fiction and now with the rapid advance of machine-learning, and fast modelling tools, it has become viable to tailor-make materials ranging from nanocomposites, graphene and 2D materials, metamaterials. This allows us to look into the possibility of developing new devices and systems across different length scales. One of examples is that, based on the dipole moment technique, we are now able to model up to 30,000 nanoparticles inside a Luneburg lens. We have also developed topology optimisation algorithms to design metamaterials with complex geometries according to performance objectives and manufacturing constraints, and applied them to invisibility cloaks and illusion devices. This will no doubt provide us the opportunity to apply different optimisation techniques to modify our designs according to industrial requirements.