Moving media have recently attracted attention for their ability to break reciprocity without magnetic materials. By spinning air in an acoustic cavity, it was recently shown that it is possible to realize an acoustic circulator [R. Fleury, D. Sounas, A. Alù, Science 343, 516 (2014)], with applications for sonars and medical imaging devices. Similarly, by effectively imparting angular momentum to microwave and optical resonators through spatiotemporal modulation, it is possible to induce strong non-reciprocity, with groundbreaking applications in the design of full-duplex communication systems [N. Estep, D. Sounas, J. Soric, A. Alù, Nature Physics 10, 923 (2014)]. Here we show that the non-relativistic Fresnel-Fizeau effect at the basis of these mechanisms can be boosted in epsilon-near-zero (ENZ) media, due to their small intrinsic refractive index. This is a different scenario than resonant structures, where the Fresnel-Fizeau effect is boosted by the effectively large wave-matter interaction distance, even for large intrinsic refractive index for the moving medium. Our results open a new venue to use zero-index metamaterials, and can become practically important in the realization of non-reciprocal imaging systems with built-in isolation and protection from reflections.
Andrea Alù, Dimitrios Sounas, and Li Quan, "Non-reciprocal wave propagation in zero-index materials (Conference Presentation)," Proc. SPIE 10112, Photonic and Phononic Properties of Engineered Nanostructures VII, 1011207 (Presented at SPIE OPTO: January 30, 2017; Published: 28 April 2017); https://doi.org/10.1117/12.2257797.5395679920001.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations.