Extended SSH Model in Non-Hermitian Waveguides with Alternating Real and Imaginary Couplings
Extended SSH Model in Non-Hermitian Waveguides with Alternating Real and Imaginary Couplings
复制标题
DOI：
10.3390/app10103425
复制
发表时间：
2020-05-01
影响因子：
2.7
通讯作者：
Ke, Shaolin
中科院分区：
文献类型：
--
作者：
Fu, Ziwei;Fu, Nianzu;Ke, Shaolin
研究了由真实的和虚的交替耦合的二元波导阵列组成的扩展的Su-Schrieffer-Heeger（SSH）模型的拓扑性质。即使系统是非厄米特的，周期结构的拓扑不变量仍然是量子化的手征对称性。数值结果表明，当两种耦合的绝对值相等时，相变发生。当保持手征对称性时，系统在非平凡结构的边界处支持拓扑零模。通过增加现场增益和损耗来破坏手征对称性，拓扑模在所有虚能绝对值最大的超模中占主导地位。该研究丰富了SSH模型在非厄米特系统中的研究，并可能在光路由器和光交换机中得到应用。
We studied the topological properties of an extended Su-Schrieffer-Heeger (SSH) model composed of a binary waveguide array with alternating real and imaginary couplings. The topological invariant of the periodic structures remained quantized with chiral symmetry even though the system was non-Hermitian. The numerical results indicated that phase transition arose when the absolute values of the two couplings were equal. The system supported a topological zero mode at the boundary of nontrivial structures when chiral symmetry was preserved. By adding onsite gain and loss to break chiral symmetry, the topological modes dominated in all supermodes with maximum absolute value of imaginary energy. This study enriches research on the SSH model in non-Hermitian systems and may find applications in optical routers and switches.