  We investigate the possibility of using dielectric microdisk resonators for
the optical detection of single atoms trapped and cooled in magnetic microtraps
near the surface of a substrate. The bound and evanescent fields of optical
whispering gallery modes are calculated and the coupling to straight waveguides
is investigated using finite-difference time domain solutions of Maxwell's
equations. Results are compared with semi-analytical solutions based on coupled
mode theory. We discuss atom detection efficiencies and the feasibility of
non-destructive measurements in such a system depending on key parameters such
as disk size, disk-waveguide coupling, and scattering losses.
