  A new type of intermittent behavior is described to occur near the boundary
of phase synchronization regime of coupled chaotic oscillators. This mechanism,
called ring intermittency, arises for sufficiently high initial mismatches in
the frequencies of the two coupled systems. The laws for both the distribution
and the mean length of the laminar phases versus the coupling strength are
analytically deduced. A very good agreement between the theoretical results and
the numerically calculated data is shown. We discuss how this mechanism is
expected to take place in other relevant physical circumstances.
