  We study the effect of dynamical tunneling on emission from ray-chaotic
microcavities by introducing a suitably designed deformed disk cavity. We focus
on its high quality factor modes strongly localized along a stable periodic ray
orbit confined by total internal reflection. It is shown that dominant emission
originates from the tunneling from the periodic ray orbit to chaotic ones; the
latter eventually escape from the cavity refractively, resulting in directional
emission that is unexpected from the geometry of the periodic orbit, but fully
explained by unstable manifolds of chaotic ray dynamics. Experimentally
performing selective excitation of those modes, we succeeded in observing the
directional emission in good agreement with theoretical prediction. This
provides decisive experimental evidence of dynamical tunneling in a ray-chaotic
microcavity.
