Role of edge inclination in optical microdisk resonator for label-free   sensing
  In this paper we report on the measurement and modelling of enhanced optical refractometric sensors based on whispering-gallery-modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide. In our approach, these microresonators are vertically coupled to a buried waveguide with the aim of creating integrated and cost-effective devices. The optimization analysis is a delicate balance of resonance quality factor and evanescent field overlap with the sorrounding environment to analyze. By numerical simulations we show that the microdisk thickness is critical to yield high figure of merit for the sensor, while edge inclination is less important. We also show that figures of merit as high as 1600/RIU are feasible. 
Davide Gandolfi, Fernando Ramiro-Manzano, Francisco Aparicio Rebollo,   Mher Ghulinyan, Georg Pucker, Lorenzo Pavesi
physics.optics