Experimental Observation of Topological Fano Resonances for Audible Sound

The Fano resonance is a widespread wave scattering phenomenon observed in many different systems, from cold atom physics, to electromagnetics, electronic circuits, and acoustics. It is characterized by a very sharp and asymmetric scattering cross-section spectrum that switches from a zero to a maximum value for two close by frequencies. Such extraordinary feature has established Fano resonances as the basic principle for many applications including efficient sources and emitters [1], switches [2], interferometers, or supersensitive sensors [3]. Yet, these resonances are difficult to achieve in practice, as they require tight geometrical tolerances and large fabrication precision to guarantee their occurrence in the desired frequency range, and the absence of parasitic peaks. In this talk, we will discuss a route for leveraging one-dimensional topological insulators to generate a novel form of sturdy Fano resonances, and experimentally demonstrate their robustness for audible sound waves [4]. Extension to other physical systems will be briefly discussed. 1. K. Nozaki, et al. Optics express 21.10 (2013): 11877-11888.2. S. Chua, et al. Optics express 19.2 (2011): 1539-1562.3. C. Wu, et al. Nature materials 11.1 (2012): 69.4. F. Zangeneh-Nejad, and R. Fleury, Physical review letters. 122 (2019): 014301