Ultra Sharp Fano Resonances Induced by Coupling between Plasmonic Stub and Circular Cavity Resonators

作者：Yun Binfeng; Zhang Ruohu; Hu Guohua; Cui Yiping^*

来源：Plasmonics, 2016, 11(4): 1157-1162.

DOI：10.1007/s11468-015-0154-5

• Surface plasmons
• Fano resonance
• Slow light
• Refractive index sensing

A plasmonic waveguide system composed of metal-insulator-metal (MIM) stub coupled with circular cavity resonator was proposed to produce ultra sharp Fano resonances, which resulted from the coupling between the ultra narrow discrete resonances and the ultra broad spectrum of the plasmonic circular cavity and stub resonator, respectively. The spectral line shapes of the Fano resonances can be easily adjusted by changing the structure parameters. And the transmittance of the system can sharply decrease from peak ("on state") to valley ("off state") with wavelength shifts of only about 8 nm. Due to the sharp phase change of the ultra asymmetric Fano resonance, a maximum group index of about 180 can be realized. Also, the ultra sharp spectrum contributes to a highly efficient plasmonic refractive index sensor, which can yield a linear sensitivity of 1277 nm/RIU and figure of merit of about 2.1 x 10(4). The proposed structure may have potential applications in nanoscale filter, slow light, and refractive index sensor.

• 出版日期2016-8
• 单位东南大学