  We fabricated polygonal silica toroidal microcavities to achieve stable
mechanical coupling with an evanescent coupler such as a tapered fiber. The
polygonal cavity was fabricated by using a combination of isotropic etching,
anisotropic etching and laser reflow. It offers both high and low coupling
efficiencies with the cavity mode even when the coupler is in contact with the
cavity, which offers the possibility of taking the device outside the
laboratory. A numerical simulation showed that an octagonal silica toroidal
microcavity had an optical quality factor of 8.8\times10^6.
