  Using a passive driven nonlinear optical fiber ring resonator, we report the
experimental realization of dissipative polarization domain walls. The domain
walls arise through a symmetry breaking bifurcation and consist of temporally
localized structures where the amplitudes of the two polarization modes of the
resonator interchange, segregating domains of orthogonal polarization states.
We show that dissipative polarization domain walls can persist in the resonator
without changing shape. We also demonstrate on-demand excitation, as well as
pinning of domain walls at specific positions for arbitrary long times. Our
results could prove useful for the analog simulation of ubiquitous domain-wall
related phenomena, and pave the way to an all-optical buffer adapted to the
transmission of topological bits.
