High-Q microsphere integrated with a tapered fiber suitable for biosensing applications

摘要

We propose a novel whispering gallery mode (WGM) microsphere resonator integrated with a tapered optical fiber. In the proposed structure, the surface of the silica microsphere is coated with a thin layer of Hafnia (Hafnium dioxide). The results from analytical and numerical simulations indicated that the WGMs can be efficiently excited with quality factors, Q, up to 1.9 x 10(5) in a silica-coated microsphere with a diameter of 24.08 mu m, coupled to a tapered silica fiber with 1 mu m core radius. The sensitivity, S, and figure of merit, FOM, of the proposed structure were 69 nm/R.I.U (nanometers per refractive index unit) and 1.3 x 10(7), respectively. Integration of microspheres and coupling system with High-Q and Ultra-High-S can be used for various applications such as detection and biosensing.