摘要

A finite element analysis is made of the shifts of resonance frequencies of whispering-gallery-mode (WGM) for a fiber-microsphere coupling miniature sensor. The time-domain Maxwell's equations were adopted to describe the near-field radiation and solved by the In-plane TE waves application mode of the FEMLAB. The electromagnetic field as well as the radiation energy distribution can be easily obtained by the finite element analysis. The resonance intensity spectrum curves in the frequency range from 213 THz to 220 THz were studied under different biosensor conditions. Emphasis was put on the analysis of resonance shift sensitivity influenced by changes of the effective size of the sensor resonator (i.e., microsphere) and/or the refractive index of the medium surrounding the resonator. It is estimated that the WGM biosensor can distinguish molecular size change in the magnitude of ∼10⁻⁴ nm and refractive index change in the magnitude of ∼10⁻⁶ . Finally, the potential of the WGM miniature biosensor for monitoring peptide growth is investigated and a linear sensor curve is obtained.