Symmetric Interacting Whispering Gallery Modes in Coupled Dielectric Microdisks

We study the characteristics of quasi-eigenmodes in coupled dielectric microdisks. The positions in complex energy plane of the modes and the corresponding mode distribution in real space are strongly affected by the inter-disk distance. As far as two identical microdisks are concerned, it has been shown that the interaction between the modes with odd parity show unexpected behavior for the inter-disk distance less than their wavelengths so as to cause the directional emission. Their directions of emission especially with relatively higher value are determined from neither the inter-disk distance nor their wavelengths rather but from the index of refraction of microdisks. Such a directionality can be understood in terms of an effective boundary deformation in ray dynamical analysis.