Maleki Javad, Fathi Davood
Department of Electrical and Computer Engineering, Tarbiat Modares University (TMU), Tehran, Iran.
Sci Rep. 2024 Feb 19;14(1):4110. doi: 10.1038/s41598-024-54579-8.
For the first time, an all-dielectric metasurface ultra-sensitive refractive index (RI) sensor with very high quality factor (QF) and figure of merit (FOM), with Fano-magnetic toroidal quadrupole (MTQ) resonance enabled by bound state in continuum (BIC) in terahertz (THz) region was designed. Furthermore, the MTQ resonance in the THz due to a distortion of symmetry-protected bound states in the continuum in the designed structure was investigated. Also, to achieve the dark mode, a combination of three methods including (i) breaking the symmetry, (ii) design of complex structures, and (iii) changing the incident angle was utilized. The broken symmetry in the structure caused a new mode to be excited, which is suitable for sensing applications. The designed metasurface was able to sense a wide range of RI in MTQ resonance, where its properties were improved for the value of sensitivity (S) from 217 GHz/RIU to 625 GHz/RIU, for FOM from 197 RIU to 2.21 × 10 RIU and for QF from 872 to 5.7 × 10.
首次设计了一种全介质超表面超灵敏折射率（RI）传感器，其具有非常高的品质因数（QF）和优值（FOM），在太赫兹（THz）区域通过连续统中的束缚态（BIC）实现了法诺磁环四极子（MTQ）共振。此外，研究了由于所设计结构中连续统中对称保护束缚态的畸变而导致的太赫兹波段MTQ共振。而且，为了实现暗模式，采用了三种方法的组合，包括（i）打破对称性，（ii）设计复杂结构，以及（iii）改变入射角。结构中的对称性破缺激发了一种新模式，适用于传感应用。所设计的超表面能够在MTQ共振中感应宽范围的RI，在此其灵敏度（S）值从217 GHz/RIU提高到625 GHz/RIU，FOM从197 RIU提高到2.21×10 RIU，QF从872提高到5.7×10 。
