On-chip experiment for chiral mode transfer without enclosing an exceptional point
On-chip experiment for chiral mode transfer without enclosing an exceptional point
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DOI：
10.1103/physreva.103.023531
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发表时间：
2021-02-25
影响因子：
2.9
通讯作者：
Wang, Bing
中科院分区：
文献类型：
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作者：
Liu, Qingjie;Liu, Jibing;Wang, Bing
绝热地包围二维参数空间中的异常点（EP）通常会导致瞬时本征态的翻转。然而，动态包围 EP 会引起手性模式转移。所获得的本征态由环绕方向决定。一旦 EP 被包含在环中，该效果对于参数空间中的环绕环的大小是鲁棒的。理论上有报道称，当环路不包围 EP 但保持适当的距离时，也可以观察到该效应。在这里，我们通过设计和制造基于绝缘体上硅的亚波长光栅波导结构来实验验证理论预测。手性模式转移是通过激发和检测电信波长周围的偶数和奇数模式来实现的。研究结果为研究非厄米系统的拓扑性质提供了一种更稳健的方法。
Adiabatically encircling an exceptional point (EP) in a two-dimensional parameter space usually leads to the flip of instantaneous eigenstates. However, encircling dynamically the EP will arouse chiral modes transfer. The obtained eigenstate is determined by the encircling direction. The effect is robust against the size of the encircling loop in the parameter space once the EP is enclosed in the loop. It has been reported theoretically that the effect can also be observed when the loop does not enclose EP but keeps it at a proper distance. Here we experimentally validate the theoretical prediction by designing and fabricating a silicon-on-insulator based subwavelength grating waveguides structure. The chiral modes transfer is achieved via motivating and detecting the even and odd modes around the telecommunication wavelength. The results provide a more robust way for studying the topological properties of the non-Hermitian system.