Deformed 2.5D whispering gallery resonators – simulation analysis of mode distribution and far field

We investigate a specific type of deformed whispering gallery resonator (WGR), called short-egg resonator. Besides the 2D (quasi circular) shape, optimized lithographic fabrication enables the control of the 2.5D morphology of these microresonators through the etching of sidewalls with precisely defined sidewall angles. Diffraction based coupling into these resonators poses a promising alternative to conventional tapered optical fiber coupling. To ensure maximum coupling efficiency using this technique, we investigate the mode characteristics in such 2.5D resonators. In particular, the field distributions, i.e. the far-field emission pattern and the resonant mode field inside the microcavity, need to be analyzed experimentally as well as theoretically. In this work, short-egg resonators with various sidewall angles are simulated using the simulation tool COMSOL and their respective field distributions are investigated with respect to the fabrication parameters.