STU-GTIIT光学论坛（No.25）
报告地点：at Room 202 in the building of college of science, STU
报告时间：2024年10月14日 13:00
报告题目: Fast Time-modulating Acoustic Metamaterials Meeting Exceptional Points（全英报告）
报 告 人：Xinghong Zhu（Hong Kong University of Science and Technology (HKUST)）
报告摘要:
Symmetry breaking is a route to generate new kinds of optical properties. Particularly, exceptional points (EP) are non-Hermitian singularities where both eigenvalues of eigenmodes of a system response matrix coalesce, that can be generated when we lower the symmetry of the metamaterial to a combined parity-time (PT) symmetry. In this talk, I will introduce the tool of transformation optics to generate systems with EP but will not possess PT-symmetry in the conventional sense. Furthermore, I explore the existence of EP in the airborne acoustic platform by coupling two resonances of the meta-atom without obeying any spatial-PT-symmetry. In addition, time modulation provides another degree of freedom for symmetry breaking. Specifically, I will introduce the airborne acoustic platform in which the modulation frequency of material parameters can be significantly greater than the signal frequency. It allows us to consider the concept of temporal effective medium. I experimentally verify the temporal effective medium formulas by scattering experiments. Leveraging the tunability of the modulation frequency of our meta-atom, I set the modulation frequency to match the frequency difference between two tailor-made resonance modes and demonstratethe phenomenon of unidirectional amplification in frequency conversion. I further demonstrate that when we time modulating a resonating system with an EP, such an EP can be modulated to other harmonic frequencies, which can be useful for sensing.
报告人简介：
Dr. Xinghong ZHU received his PhD degree in Physics in HKUST under the supervision of Prof. Jensen Li in 2024.He earned his B.S. degree from Xiamen University, China in 2019. He is currently the Postdoc at HKUST. He has research interests in time-varying metamaterials, non-Hermitian physics, and transformation optics.
欢迎全校师生参加！
理学院
2024年10月11日
