Optical binding of nanoparticles

Optical binding is a laser-induced inter-particle force that exists between two or more particles subjected to off-resonant light. It is one of the key tools in optical manipulation of particles. Distinct from the single-particle forces which operate in optical trapping and tweezing, it enables the light-induced self-assembly of non-contact multi-particle arrays and structures. Whilst optical binding at the microscale between microparticles is well-established, it is only within the last few years that the experimental difficulties of observing nanoscale optical binding between nanoparticles have been overcome. This hurdle surmounted, there has been a sudden proliferation in observations of nanoscale optical binding, where the corresponding theoretical understanding and predictions of the underlying nanophotonics have become ever more important. This article covers these new developments, giving an overview of the emergent field of nanoscale optical binding.