The Photonics Institute The Photonics Institute Student Seminar Date: 10th June 2015 (Wed) Venue: Executive Seminar Room ( S2.2-B2-53) Time: 2.30pm – 4pm Light refreshments will be provided after the seminar Register Here Power coupling to fiber based whispering gallery mode resonators Zhou Yanyan (COFT) Presentation Abstract Whispering gallery mode (WGM) resonators create a peculiar class of optical cavities that are closed without the help of reflecting mirrors. The WGM resonators are monolithic and rely on total internal reflection to guide light in a circulating loop. Because of this closed feature, the WGM cavities generally have very high Q-factors and small modal volumes, enabling efficient optical confinement. In this talk, a series of power coupling methods to WGM resonators are first reviewed. The pros and cons of each methods are discussed. Then a new method, based on the metallic diffraction grating, as well as some of the exciting new functions that it enables are explained. Measurement of a topological edge invariant in a microwave network Hu Wenchao (CDPT) Presentation Abstract We map a well-known condensed-matter “thought experiment”, the topological pump, to a classical microwave network, and  hence measure a topological edge invariant in the form of the winding number of scattering matrix eigenvalues. Non-zero winding of the eigenvalues is observed, implying the existence of a topological band structure.