Fig. 7.

Dynamics of an initially planar wave propagating from left to right in a medium with a small-size FPR. The coupling strength $D$ is fixed to $D=1$ everywhere except the central circular region of the radius $R=51$, where $D=D_0=2$ within the left part (dense filling) and $D/D_0=2/3$ in the right part (rare filling). $A=1$ everywhere.