Formation of phase soliton complexes in an optically injected semiconductor laser

We show experimental and numerical results about attractive interactions between phase solitons
in a strongly multimode semiconductor laser with injected signal. The formation of soliton bound states, or
phase solitons with multiple chiral charge, is demonstrated and analyzed in terms of the (spatio-temporally
resolved) phase dynamics of the system. Propagation velocity of phase solitons in the longitudinal cavity
is studied, and a correlation is established with phase soliton size and total charge.