Double Fano resonances excited in a compact structure by introducing a defect

Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University - Changsha 410082, China

^(a) llwang@hnu.edu.cn

Received: 18 April 2016
Accepted: 14 June 2016

Abstract

In this letter, the plasmonic system composed of a defective silver nanostrip and a complete silver nanostrip is theoretically investigated to achieve two Fano resonances. A quadrupole mode cannot be directly excited on a complete nanostrip, while it can be fulfilled by introducing the defect. This defective silver nanostrip supports both of the superradiant dipole and quadrupole modes, which produce bright-dark coupling and detuning modes mechanisms and further result in two asymmetric Fano dips in the transmission spectrum. Moreover, the Fano resonance characteristics in the two nanostrips can be tuned by modulating the gap distance between the two nanostrips, the parameters of the defect, and the electric-field polarization angle. Our structure may have potential applications for nanosensor in highly integrated circuits.