ABSTRACT
The emission of light from whispering-gallery modes excited in microscopic spheres is examined. An evanescent wave is produced by total internal reflection of an optical beam at a planar glass-air interface. This evanescent wave is used to excite whispering-gallery modes in single microscopic spheres placed behind the glass-air interface. The intensity of light emitted into the air half-space from such spheres is measured as a function of scattering angle for both p- and s-polarized input beams. These data are compared with a simple theory for the emission from a point source above a planar glass substrate.
ABSTRACT
Scattering of light from single spheres placed behind a glass-air interface with light incident through the glass is examined. This scattering is investigated for both p- and s-polarized light incident at angles below the glass-air critical angle. The intensity of light scattered into the air half-space from each sphere is measured as a function of scattering angle, and this response is compared in situ with the background scatter produced by the planar substrate. A detailed comparison between data and established theory are thereby obtained. This system is of interest in the field of optical biosensing.
