title: High-Q exterior whispering-gallery modes in a metal-coated microresonator.
abstract: We propose a kind of plasmonic whispering-gallery mode highly localized on the exterior surface of a metal-coated microresonator. This exterior (EX) surface mode possesses high quality factors at room temperature, and can be efficiently excited by a tapered fiber. The EX mode can couple to an interior (IN) mode and this coupling produces a strong anticrossing behavior, which not only allows conversion of IN to EX modes, but also forms a long-lived antisymmetric mode. As a potential application, the EX mode could be used for a biosensor with a sensitivity high of up to 500 nm per refraction index unit, a large figure of merit, and a wide detection range.
authors.affiliation: State Key Lab for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, People's Republic of China. yfxiao@pku.edu.cn
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Xiao
authors.forename: Chang-Ling
authors.initials: CL
authors.lastname: Zou
authors.forename: Bei-Bei
authors.initials: BB
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Dong
authors.forename: Zheng-Fu
authors.initials: ZF
authors.lastname: Han
authors.forename: Qihuang
authors.initials: Q
authors.lastname: Gong