Figure 1.

(a) SEM micrographs of vertically-coupled monolithically-integrated disk and wedge microresonators. The buried waveguide can be barely seen below the surface. Note the difference in sidewall angle; (b) Model of the cross-section profile of the wedge WGM resonator. R, t and θ are, respectively, the radius, thickness and inclination angle; (c) AFM profile of the sidewall of a wedge resonator. The red line is the fitted logistic function (1). Note that the axes’ scales have been modified to properly show the small aspect-ratio of the structure.