Topological singular chain reactions in dynamic speckle fields

摘要

Interactions of structured light and structured media belong to the topical trends of modern optics. Dynamic vector speckle fields induced by the feedback interaction with the dynamic “optical-damage” effect provide, for the first time, real possibilities to produce and investigate the topological regularities of structured photorefractive media and coherent structured light interactions [Proc. SPIE 6905, 690505 (2008)]. The experiments provide evidence that dynamic topological speckle fields form ergodic systems, which develop through loop and chain trajectories in accordance with paired nucleation and annihilation of optical singularities. The loop/chain trajectories are realized for even/odd numbers of involved singular C points. Each loop reaction starts from a nucleated pair of C points and occurs in the same speckle up to their annihilation. A chain reaction starts from one C point of a nucleated C-point pair. It leaves the starting speckle and moves through the speckle field to other C-point pairs and annihilates with one of these. The second C point moves through the varying speckle field to the next pair of C points and so on. The conserved topological charge is equal to +(1∕2) or –(1∕2) for L-type and S-type chain reactions, respectively. Loop trajectories with zero topological charges are short-lived in contrast with the chain reactions that are theoretically not limited in space and time. The chain reactions consist of long links with a standard topological structure. The results obtained are important for fundamentals and applications. This paper is the first study of the optical dynamic topology.