Thermo-optic and reactive mechanisms for label-free sensing of bio-particles are compared theoretically for Whispering Gallery Mode (WGM) resonators (sphere, toroid) formed from silica and stimulated into a first order equatorial mode. Although it has been expected that a thermooptic mechanism should "greatly enhance" wavelength shift signals [A.M. Armani et al, Science 317, 783-787 (2007)] accompanying protein binding on a silica WGM cavity having high Q (108), for a combination of wavelength (680 nm), drive power (1 mW), and cavity size (43 μm radius), our calculations find no such enhancement. The possible reasons for this disparity are discussed.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics