Prof. Shuang Zhang
School of Physics & Astronomy, University of Birmingham, UK
Abstract: Metamaterials have become one of the most exciting fields in optics due to their exotic optical properties and important applications that are not attainable from naturally occurring materials. In particular, broken symmetry in metamaterials can lead to extremely strong effects of anisotropy (broken rotational symmetry), chirality and bianisotropy (broken mirror symmetry), which go far beyond the properties of nature materials. In this talk, I will show that by combining chirality with strong anisotropy, new topological order emerges in metamaterials leading topologically protected photonic surface states that are immune from scattering by defects and sharp edges. In addition, I will talk about our recent works on optical metasurfaces, a new type of structured surfaces showing well controlled abrupt phase discontinuities for circularly polarized incident light arising from Berry phase. I will give a number of examples of device applications based on metasurfaces: a dual polarity metalens that can functions either as a convex or a concave lens, a helicity switchable unidirectional surface plasmon polariton coupler, and high definition three dimensional holograms. Finally, I will show that extending the concept of Berry phase to harmonic generations can lead to continuous phase control over the local nonlinear polarizability, which goes beyond the conventional poling technique.
Prof Zhang' s research includes metamaterials and transformation optics. Prof . Zhang has pioneered on optical metamaterials with entirely different designs from that of the microwave frequencies. He has authored 1 book chapter and over 60 refereed publications in journals including Nature, Nat. Mater., Nat. Nanotechnology, Nat. Physics, Nat. Comm., PRL, and Nano Letters, with total ISI citations over 4600. His experimental work on macroscopic invisibility cloak was selected as the top ten breakthroughs by Physics World. He has received research grants from ERC, EPSRC, Leverhulme and Marie Curie Foundation.