Coupling evanescently low loss Silicon-on-insulator ridge waveguides including high Q nanocavities for light control

Summary form only given. In this work, we propose an innovative way to achieve an air-slotted nanocavities by coupling evanescently low loss Silicon-on-insulator (SOI) ridge waveguides(WGs) including high Q nanocavities exhibiting an ultrasmall modal volume V. We first show that coupling two WGs allows us to achieve a field confinement within the air slot as low as lambda/30 while preserving a high group index of the guided modes. Then we demonstrate that merging such coupled WGs with state-of-the-art high-Q/small V nanocavities is a robust way to achieve a single compact (1 µm × 3 µm) air-slotted resonator on substrate. Finally, we extend the concept to multiple air-slotted resonator systems and evaluate their potential of such structures to produce sub-wavelength field localisation and distribution on demand.