Whispering Gallery Resonators with diffractive coupling elements

Abstract:
We propose the concept of diffractive optical coupling elements (DOE) which can be monolithically integrated into whispering gallery mode (WGM) resonators. Electromagnetic simulations show the feasibility of the proposed idea. The morphology of the resonator plays an essential role in the confinement of modes to specific areas in the resonator volume. This opens a path to the minimization of the interaction of the resonant modes with the diffractive coupling elements. Thus the losses of the resonators can be kept low which guarantees high quality (Q) factors. We present investigations of fluorocarbon plasma-based etching processes to produce the desired 3D shape based on the morphology requirements. We demonstrate the possibility to create a quasi 3D shape using binary hard masks. The next step will be investigations into the integration of DOE and WGM, whose manufacturing processes must meet different requirements. For this reason, special emphasis will be placed on ensuring that there are no parasitic influences on the processes.