---

17.12.2015 | Thursday | 11:00 | Building 8 Seminar Room 424

---

Lecture: Professor Mikael Rechtsman (Pennsylvania State University)

Abstract: The professor will present the first observation of the topological protection of light, specifically, a photonic Floquet topological insulator. Topological insulators (TIs) are solid-state materials that are insulators in the bulk, but conduct electricity along their surfaces and are intrinsically robust to disorder. In particular, when a surface electron in a TI encounters a defect, it simply goes around it without scattering, always exhibiting – quite strikingly – perfect transmission. The structure is an array of coupled helical waveguides (the helicity generates a fictitious circularly-polarized electric field that leads to the TI behavior), and light propagating through it is ‘topologically protected’ from scattering. Topological protection therefore has the potential to endow photonic devices (e.g., delay lines, isolators, directional couplers, resonators) with quantum Hall-like robustness.