Mode characteristics of silver-coated inverted-wedge silica microdisks

• Published in: Science China. Physics, mechanics & astronomy Vol. 58; no. 11; pp. 40 - 44
• Main Authors: Bo, Fang, Wang, XiaoOu, Li, Ying, Gao, Feng, Zhang, GuoQuan, Xu, JingJun
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.11.2015; Springer Nature B.V
• Subjects: Astronomy; Classical and Continuum Physics; Dielectrics; Finite element method; Hybrid modes; Light intensity; Luminous intensity; Observations and Techniques; Physics; Physics and Astronomy; Polaritons; Q factors; Raman spectra; Resonators; Silica; Silicon dioxide; Silver; Thickness; Whispering gallery modes; 力学; 天文学; 物理学; 科学学; 科学知识; whispering gallery mode; microcavity; surface plasmonic polariton
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-015-5722-3

The characteristics of whispering gallery modes （WGM） in silver-coated inverted-wedge silica microdisks are theoretically in- vestigated by using finite element method. Dielectric TE mode always exists in silver-coated inverted-wedge resonators; die- lectric TM mode tends to couple with SPP modes; only pure interior surface plasmonic polariton （SPP） mode but not pure ex- terior SPP mode is observed in contrast to the metal-coated cylindrical and toroidal resonators. The dependence of quality fac- tor of different kinds of WGMs on the radius of the resonator and the thickness of the coated silver layer are systematically an- alyzed. We find that the quality factors of the hybrid WGMs associated with SPP mode can reach 104. The maximum light in- tensity enhancement in ambient for a hybrid mode consisting of a dielectric TM mode and an exterior SPP mode can be ob- tained when a silver film of thickness -40 nm is deposited. The silver-coated inverted-wedge silica resonators may be widely applied in sensing and surface enhanced Raman scattering.