Light trapping and manipulation of quasibound states in continuum Ge 2 Sb 2 Se 4 Te metasurfaces

作者：Jing Huang, Bing Meng, Li Chen, Xingfeng Wang, Xiaoying Qu, Menghui Fan, Chaobiao Zhou · 发表于：Physical review. B./Physical review. B · 年份：2022 · DOI：10.1103/physrevb.106.045416 · 被引用次数：33 · 研究领域：Metamaterials and Metasurfaces Applications、Plasmonic and Surface Plasmon Research、Photonic Crystals and Applications

Actively tunable nanodevices play an important role in modern photonics systems. Metasurfaces based on phase-change materials (PCMs) provide a new way for the realization of such devices. At present, the PCM is usually integrated with the resonant metasurfaces with low $Q$ factor or as a resonator to achieve the optical switches. Note that less work has focused on the switching characteristics of strong light trapping of in high-$Q$-factor metasurfaces. The main reason is that PCM has a significant intrinsic loss. Recently, the PCM ${\text{Ge}}_{2}{\text{Sb}}_{2}{\text{Se}}_{4}{\text{Te}}_{1}$ (GSST) with ultralow loss has been proved by in experiment ($k\ensuremath{\approx}0$), which makes it is possible to achieve the active metasurfaces with high $Q$ factor. Moreover, the symmetry-protected bound states in the continuum (BICs) provides an effective method to achieve the high-$Q$-factor metasurface. The perturbation that breaks the in-plane inversion symmetry of a structure can transform such a BIC mode into a leaky quasi-BIC with high $Q$ factor. In this work, the BIC and the light trapping characteristics of quasi-BIC in PCM GSST metasurfaces are studied numerically. Through moving the relative position of nanobars, the structure symmetry of the amorphous GSST metasurface is disturbed, which makes an ideal BIC convert to a quasi-BIC with high $Q$ factor. The average field-enhancement factor (EF) of quasi-BIC is evaluated, which is proportional to the $Q$ factor of resonan...