FIB engineered WGM resonators
We are applying microfabrication techniques to macroscopic mechanically-polished crystalline disc resonators in order to achieve uniquely tailored high-Q resonators. In our efforts to date, we’ve utilized focused ion beam (FIB) milling to precisely carve nano- and micro-scale structures directly into the optical resonators. We have created FIB engineered disc (FIBED) resonators with open structure, i.e. a milled notch creates a free space gap within the mode volume . The gap provides complete access to the internal fields of the resonator and therefore the full mode intensity. A typical whispering gallery mode (WGM) resonator is a closed system, with only a small portion of the mode volume, the evanescent field just outside the dielectric boundary, exposed for external coupling (optomechanical, atomic and molecular sensing applications). This novel cavity system facilitates interaction of external mechanisms, atoms, or molecules with the full extent of the resonant light field. The FIBED approach also opens the door for other functional features to be formed into WGM structures.
 David C. Aveline, Lukas Baumgartel, Byungmin Ahn, Nan Yu, “Focused ion beam engineered whispering gallery mode resonators with open cavity structure.” Optics Express, Vol. 20, Issue 16, 18091-18096 (2012)