Park Jagang, Cho Hyukjoon, Lee Seojoo, Lee Kyungmin, Lee Kanghee, Park Hee Chul, Ryu Jung-Wan, Park Namkyoo, Jeon Sanggeun, Min Bumki
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon 34126, Republic of Korea.
Sci Adv. 2022 Oct 7;8(40):eabo6220. doi: 10.1126/sciadv.abo6220.
Periodically driven systems are ubiquitously found in both classical and quantum regimes. In the field of photonics, these Floquet systems have begun to provide insight into how time periodicity can extend the concept of spatially periodic photonic crystals and metamaterials to the time domain. However, despite the necessity arising from the presence of nonreciprocal coupling between states in a photonic Floquet medium, a unified non-Hermitian band structure description remains elusive. We experimentally reveal the unique Bloch-Floquet and non-Bloch band structures of a photonic Floquet medium emulated in the microwave regime with a one-dimensional array of time-periodically driven resonators. These non-Hermitian band structures are shown to be two measurable distinct subsets of complex eigenfrequency surfaces of the photonic Floquet medium defined in complex momentum space.
周期性驱动系统在经典和量子领域中都普遍存在。在光子学领域，这些弗洛凯系统已开始为研究时间周期性如何将空间周期性光子晶体和超材料的概念扩展到时间域提供见解。然而，尽管光子弗洛凯介质中态之间存在非互易耦合导致了这种必要性，但统一的非厄米能带结构描述仍然难以捉摸。我们通过由时间周期性驱动的谐振器的一维阵列在微波频段模拟的光子弗洛凯介质，实验揭示了其独特的布洛赫 - 弗洛凯和非布洛赫能带结构。这些非厄米能带结构被证明是在复动量空间中定义的光子弗洛凯介质的复本征频率表面的两个可测量的不同子集。
