How to simulate the whispering-gallery modes of dielectric microresonators in FEMLAB/COMSOL

Abstract

It is explained how FEMLAB / COMSOL Multiphysics can be configured to calculate, the frequencies, electromagnetic-field patterns, mode volumes, filling factors, radiation losses ... of the whispering-gallery modes of axisymmetric microresonators. The method exploits COMSOL's ability to accept the definition of solutions to Maxwells equations in so-called 'weak form'. As no transverse approximation is imposed, it remains accurate even for so-called quasi-TM and -TE modes of low, finite azimuthal mode order, as are relevant to applications in non-linear/quantum optics. The method's utility is exemplified by simulating various microresonators in the form of dielectric toroids and disks.