题目：Edge States and Quasi-Solitons in Polariton Topological Insulators
报告人：Prof. Yaroslav Kartashov
主持人：黄国翔教授
时间：2017年11月14日 16:00
地点：理科大楼A510 报告厅
报告人简介：
Prof. Y. V. Kartashov works in the field of nonlinear optics. His research interests include nonlinear phenomena, in general, and soliton formation, in particular, in inhomogeneous optical materials with various types of nonlinearity; nonlinear waves in Bose-Einstein condensates; theory of nondiffracting beams, waves in parity-time symmetric systems, nonlinear topological insulators, and many others. He currently holds a position of Leading Researcher in the Institute of Spectroscopy of the Russian Academy of Sciences, located in Troitsk, Russia, and he works simultaneously as a Visiting Professor at ICFO – The Institute of Photonic Sciences in Barcelona, Spain. In addition to the PhD degree, which he obtained from the Physics Faculty of Moscow State University in 2002, Prof. Kartashov defended the degree of Doctor of physical and mathematical sciences at the Institute of Spectroscopy of the Russian Academy of Sciences in 2012. Prof. Kartashov presently serves as an expert reviewer for more than 30 leading international journals publishing research on optics, including journals from the Nature family, the Physical Review family of journals published by the American Physical Society, most of the journals of the Optical Society of America, as well as physical and optical journals published by Elsevier and IOP – Institute of Physics. He also serves as a topical editor of the premiere OSA journal – Optics Letters. He is co-author of more than 260 papers in leading peer-review journals. Prof. Kartashov made considerable contribution to the development of the theory of light propagation in waveguide arrays and optically induced lattices, the theory of nonlinear optical surface waves at the interface of different optical materials; he is co-author of experimental papers reporting on first observation of two-dimensional surface solitons and light bullets in waveguide arrays. He developed theory of solitons in optical lattices in BEC with spin-orbit coupling and presently he actively works on nonlinear topological insulators in systems with spin-orbit coupling.
报告内容简介：
Optical microcavities supporting exciton-polariton quasi-particles offer one of the most powerful platforms for investigation of rapidly developing area of topological photonics in general, and of photonic topological insulators in particular. Energy bands of the arrays of microcavity pillars of various geometries are readily controlled by magnetic field and influenced by the spin-orbit coupling effects, a combination leading to formation of linear unidirectional edge states in polariton topological insulators as predicted very recently. In this presentation I will depart from the linear limit of non-interacting polaritons and discuss instabilities of the nonlinear topological edge states resulting in the formation of the localized topological polariton quasi-solitons, which are exceptionally robust and immune to backscattering wavepackets propagating along the edge of honeycomb lattice of microcavity pillars. I will also discuss topological effects and polaritonic edge states in Lieb lattices of microcavity pillars. Nonlinear polariton edge states are characterized by the enhanced robustness in such structures, a property that allows to nest in them edge dark solitons propagating along the lattice edge without broadening over huge time intervals. Finally, I will consider topological effects with exciton-polaritons in the presence of losses and external pump. I will show that external pump leads to resonant excitation of topological edge states and bistability. Such settings admit existence of truly stable nonlinear edge states. Our results provide a background for experimental studies of nonlinear polariton topological insulators and can influence other subareas of photonics and condensed matter physics, where nonlinearities and spin-orbit effects are often important and utilized for applications.