Qin Haoye, Shi Xiaodong, Ou Haiyan
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Laboratory of Wave Engineering, School of Electrical Engineering, EPFL, Lausanne, Switzerland.
Nanophotonics. 2022 Nov 14;11(21):4909-4917. doi: 10.1515/nanoph-2022-0420. eCollection 2022 Dec.
We propose the realization of exceptional points (EP) at bound states in the continuum (BIC), with two coupled strips, made of an electron-beam resist and patterned on the thin film photonic integrated platform, which makes possible etchless photonics integrated circuits (PIC). The loss rate of the EP can be significantly decreased through merging the BIC peaks in the dual-BIC scheme. The orthogonality of the eigenvectors is retrieved for evaluating the Hermitian orthogonal eigenvectors and the non-Hermitian EP features. We also find that engineering the dimension of the dual-BIC scheme enables a transition between the coalesced eigenvectors in the EP and the orthogonal eigenvectors in the Hermitian system. This work is of great significance for the exploration on BIC-based directional coupling with ultralow-loss phase matching conditions, special coupling conditions of EPs and BICs with coupled quasi-BIC systems, dynamical EP encircling, and EP topology, in PICs.
我们提出在连续谱束缚态（BIC）中实现例外点（EP），通过由电子束抗蚀剂制成并在薄膜光子集成平台上进行图案化的两个耦合条带来实现，这使得无蚀刻光子集成电路（PIC）成为可能。通过在双BIC方案中合并BIC峰，可以显著降低EP的损耗率。为了评估厄米正交特征向量和非厄米EP特征，恢复了特征向量的正交性。我们还发现，设计双BIC方案的尺寸能够实现EP中合并的特征向量与厄米系统中正交特征向量之间的转变。这项工作对于在PIC中探索基于BIC的具有超低损耗相位匹配条件的定向耦合、EP与BIC以及耦合准BIC系统的特殊耦合条件、动态EP环绕和EP拓扑结构具有重要意义。
