Figure 1.

Optical resonant cavity. (a) An image of a microtoroid resonant cavity. (b) Finite element method simulation of the intensity of the optical field at 633 nm for a microtoroid cavity. As can be seen, the optical field is primarily confined inside the silica cavity, but a small portion evanesces into the environment. (c) The intensity profile of the optical field inside (blue) and outside (red) of the cavity. The black line indicates the air/silica interface. It can be clearly seen that the evanescent tail is approximately 100 nm.