Sensitivity enhancement of a whispering-gallery-mode microsphere resonance-shift sensor by coating of a high-refractive index (RI) layer is examined for TM polarization. The enhancement of sensitivity in response to particle adsorption or a RI change of the surroundings at the optimized layer thickness is greater for the TM mode compared with the TE mode, but the TM mode requires a thicker layer. A particular choice of the layer thickness allows the TE and TM shifts to match. Matching of the resonance frequency of the two modes is also examined.
© 2007 Optical Society of America
Original Manuscript: September 28, 2006
Manuscript Accepted: October 27, 2006
Published: February 15, 2007
Vol. 2, Iss. 4 Virtual Journal for Biomedical Optics
Iwao Teraoka and Stephen Arnold, "Whispering-gallery modes in a microsphere coated with a high-refractive index layer: polarization-dependent sensitivity enhancement of the resonance-shift sensor and TE-TM resonance matching," J. Opt. Soc. Am. B 24, 653-659 (2007)