Fibre-optic trapping and manipulation at the nanoscale

With the initial design based on Ashkin’s pioneering work in 1970, optical trapping and manipulation of micron-size particles and cells has been extensively applied in the fields of physical science and technology as well as cellular and molecular biology. However, due to the fundamental diffraction limit of light, it is difficult to extend these techniques to the nanometre range that includes nanomaterials such as nanotubes, nanowires, nanoparticles and biomolecules, which are crucial for nanoscience and nanotechnology. Recently, several approaches based on optical fibre nanoprobes have been developed and demonstrated for trapping and manipulation of nanostructures. Here, starting from basic theories of optical forces, we review the state-of-the-art in fibre-optic trapping and manipulation of different nanostructures, with an emphasis on carbon nanotubes, silver and semiconductor nanowires, upconversion and polystyrene nanoparticles, and DNA molecules. Finally, we discuss the future p