Related Experiment Video
Updated: Jun 22, 2026

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents
Published on: May 1, 2012
The effects of inter-cavity separation on optical coupling in dielectric bispheres
Abstract:
The optical coupling between two size-mismatched spheres was studied by using one sphere as a local source of light with whispering gallery modes (WGMs) and detecting the intensity of the light scattered by a second sphere playing the part of a receiver of electromagnetic energy. We developed techniques to control inter-cavity gap sizes between microspheres with ~30nm accuracy. We demonstrate high efficiencies (up to 0.2-0.3) of coupling between two separated cavities with strongly detuned eigenstates. At small separations (<1 microm) between the spheres, the mechanism of coupling is interpreted in terms of the Fano resonance between discrete level (true WGMs excited in a source sphere) and a continuum of "quasi"-WGMs with distorted shape which can be induced in the receiving sphere. At larger separations the spectra detected from the receiving sphere originate from scattering of the radiative modes.
Related Concept Videos
Electrostatic Boundary Conditions in Dielectrics
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's permittivity.
Dielectric Polarization in a Capacitor
Capacitor With A Dielectric
Dielectrics are non-conducting materials with no free or loosely bound electrons. When a dielectric is...
Susceptibility, Permittivity and Dielectric Constant
Imaging Biological Samples with Optical Microscopy
In optical microscopy, the specimen to be viewed is placed on a glass slide and clipped on the stage...

