Cao Tun, Zhang Lei
Department of Biomedical Engineering, Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, China.
Opt Express. 2013 Aug 12;21(16):19228-39. doi: 10.1364/OE.21.019228.
Fano resonance (FR) within the transmission spectrum is demonstrated in the near infrared (NIR) region using elliptical nanoholes array (ENA) embedding through metal-dielectric-metal (MDM) layers. For the symmetric MDM-ENA, it has been shown that a FR can be excited by the normally incident light. This FR response is attributed to the interplay between the bright modes and dark modes, where the bright modes originate from the electric resonance (localized surface plasmon resonance) caused by the ENA and the dark modes are due to the magnetic resonance (inductive-capacitive resonance) induced by the MDM multilayers. Displacement of the elliptical nanoholes from their centers breaks the structural symmetry to excite a double FR as a result of the coherent interaction of the electric resonance with two splitting sub-magnetic resonances at different wavelengths. Moreover,the degree of the asymmetry allows for the tuning of the amplitude and bandwidth of the double FR window. The sensitivity to the slight variations of the dielectric environment has been calculated and yields a figure-of-merit of 0.8RIU(-1) for the symmetric MDM-ENA and 3.0RIU(-1) for the asymmetric MDM-ENA.
利用嵌入金属-电介质-金属（MDM）层的椭圆纳米孔阵列（ENA）在近红外（NIR）区域的透射光谱中展示了法诺共振（FR）。对于对称的MDM-ENA，已经表明法诺共振可以由垂直入射光激发。这种法诺共振响应归因于亮模式和暗模式之间的相互作用，其中亮模式源自ENA引起的电共振（局域表面等离子体共振），而暗模式则是由MDM多层结构诱导的磁共振（电感-电容共振）所致。椭圆纳米孔偏离其中心位置会打破结构对称性，由于电共振与不同波长处的两个分裂子磁共振的相干相互作用，从而激发双法诺共振。此外，不对称程度允许对双法诺共振窗口的幅度和带宽进行调谐。已计算出对称MDM-ENA对介电环境微小变化的灵敏度，品质因数为0.8RIU⁻¹，不对称MDM-ENA的品质因数为3.0RIU⁻¹。
