Non-Hermitian flat bands in rhombic microring resonator arrays
Non-Hermitian flat bands in rhombic microring resonator arrays
复制标题
菱形微环谐振器阵列中的非厄米平带
DOI：
10.1364/oe.431038
复制
发表时间：
2021-07-19
期刊：
影响因子：
3.8
通讯作者：
Lu, Peixiang
中科院分区：
文献类型：
--
作者：
Ding, Lu;Lin, Zekun;Lu, Peixiang
We investigate the flat bands in a quasi-one-dimensional rhombic array composed of evanescently coupled microring resonators (MRRs) with non-Hermitian coupling. By changing the relative position of non-Hermitian coupling in each cell, we construct topologically trivial and nontrivial flat bands, where both the real and imaginary parts of energy bands become flat and coalesce into a single band. We show the nontrivial systems are able to support topological boundary modes isolated from the flat bulk bands although there is no band gap. The elusive topology of flat bands can be geometrically visualized by plotting the trajectories of their eigenvectors on Bloch sphere based on Majorana's stellar representation (MSR). Furthermore, we perform a full wave simulation and show the characteristics of flat bands, associated compact localized modes, and boundary modes are reflected from absorption spectra and field intensity profiles. The study may find potential applications in lasers, narrowband filters, and efficient light harvesting. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
