Xu Xiaofeng, Luo Xiao-Qing, Zhang Jingzhao, Zhu Weihua, Chen Zhiyong, Li Tie-Fu, Liu W M, Wang Xin-Lin
Opt Express. 2022 Feb 14;30(4):5879-5895. doi: 10.1364/OE.452134.
Plasmonic sensing that enables the detection of minute events, when the incident light field interacts with the nanostructure interface, has been widely applied to optical and biological detection. Implementation of the controllable plasmonic double Fano resonances (DFRs) offers a flexible and efficient way for plasmonic sensing. However, plasmonic sensing and digital metasurface induced by tailorable plasmonic DFRs require further study. In this work, we numerically and theoretically investigate the near-infrared plasmonic DFRs for plasmonic sensing and digital metasurface in a hybrid metasurface with concentric ϕ-shaped-hole and circular-ring-aperture unit cells. We show that a plasmonic Fano resonance, resulting from the interaction between a narrow and a wide effective dipolar modes, can be realized in the ϕ-shaped hybrid metasurface. In particular, we demonstrate that the tailoring plasmonic DFRs with distinct mechanisms of actions can be accomplished in three different ϕ-shaped hybrid metasurfaces. Moreover, the resonance mode-broadening and mode-shifting plasmonic sensing can be fulfilled by modulating the polarization orientation and the related geometric parameters of the unit cells in the near-infrared waveband, respectively. In addition, the plasmonic switch with a high ON/OFF ratio can not only be achieved but also be exploited to establish a single-bit digital metasurface, even empower to implement two- and three-bit digital metasurface characterized by the plasmonic DFRs in the telecom L-band. Our results offer a new perspective toward realizing polarization-sensitive optical sensing, passive optical switches, and programmable metasurface devices, which also broaden the landscape of subwavelength nanostructures for biosensors and optical communications.
当入射光场与纳米结构界面相互作用时，能够检测微小事件的表面等离激元传感已被广泛应用于光学和生物检测。可控表面等离激元双法诺共振（DFR）的实现为表面等离激元传感提供了一种灵活而有效的方法。然而，由可定制的表面等离激元DFR诱导的表面等离激元传感和数字超表面仍需进一步研究。在这项工作中，我们通过数值和理论方法研究了具有同心ϕ形孔和圆环孔径单元的混合超表面中用于表面等离激元传感和数字超表面的近红外表面等离激元DFR。我们表明，在ϕ形混合超表面中可以实现由窄和宽有效偶极模式之间的相互作用产生的表面等离激元法诺共振。特别是，我们证明了可以在三种不同的ϕ形混合超表面中实现具有不同作用机制的可定制表面等离激元DFR。此外，通过分别调制近红外波段中单元的偏振方向和相关几何参数，可以实现共振模式展宽和模式移动的表面等离激元传感。此外，不仅可以实现具有高开/关比的表面等离激元开关，还可以利用它来建立单比特数字超表面，甚至能够实现以电信L波段中的表面等离激元DFR为特征的两比特和三比特数字超表面。我们的结果为实现偏振敏感光学传感、无源光开关和可编程超表面器件提供了新的视角，这也拓宽了用于生物传感器和光通信的亚波长纳米结构的前景。
