Plasmonic octamer objects: reversal of near-field optical binding force without the aid of backgrounds.

In recent years, the near-field optical binding force has gained a lot of interest in the field of optical manipulation. The reversal of the near-field binding force, a new, to the best of our knowledge, kind of optical manipulation, has so far been investigated mostly between dimers and in a very few cases among tetramers by utilizing the help of suitable substrates or backgrounds. Until now, no known way to control the near-field optical binding force among octamer configurations has been found, to our knowledge.