报告时间：10:00-11:00,2016.8.9

报告地点：D223

Abstract: Photonic graphene, namely an honeycomb array of optical waveguide, has attracted much interest in the optics community. In recent experiments it was shown that introducing edges and suitable waveguides in the direction of propagation, unidirectional edge wave propagation at optical frequencies occurs in photonic graphene. The system is described analytically by the lattice nonlinear Schrodinger (NLS) equation with a honeycomb potential and a pseudo-magnetic field. In certain parameter regimes, these edge waves were found to be nearly immune to backscattering, and thus exhibit the hallmarks of (Floquet) topological insulators.

This talk addresses the linear and nonlinear dynamics of traveling edge waves in photonic graphene, using a tight-binding model derived from the lattice NLS equation. Two different asymptotic regimes are discussed, in which the pseudo-magnetic field is respectively assumed to vary rapidly and slowly. In the presence of nonlinearity, nonlinear edge solitons can exist due to the balance between dispersion and nonlinearity; these edge solitons appear to be immune to backscattering when the dispersion relation is topologically nontrivial. A remarkable effect of topology in bounded photonic graphene will also be demonstrated: the edge modes are found to exhibit strong transmission (reflection) around sharp corners when the dispersion relation is topologically nontrivial (trivial).

报告人简介：

      马一平：加州大学伯克利分校硕博连读博士，美国西北大学，芝加哥大学博士后，香港理工大学本科。目前主要研究方向为非线性波，斑图行程及气候动力学等，先后在SIAM. J. Appl. Dyn. Sytems, Physica D, Chaos等期刊发表论文20余篇。