Machined multicore optical fibres for on-chip optical manipulation

Optical Tweezing is a non-invasive technique that can enable a variety of single cell experiments or cell-cell communication experiments. To date, optical tweezers tend to be based on a high numerical aperture microscope objective to deliver the tweezing light and image the sample, which introduces restrictions in terms of flexibility. A single optical fibre-based probe able to manipulate microparticles independently from the imaging system is demonstrated. The working principle of the probe is based upon two crossed beams that can be used to trap a microparticle in the area where the two beams overlap. The two deflected beams are produced by incorporating fibre-end facet mirrors onto a multicore fibre using a Focused Ion Beam fabrication technique. The light from the two cores overlaps close to the end of the fibre and has been demonstrated to be capable of trapping particles in the area where the beams intersect. By using a multicore fibre instead of separate fibres glued together results in simplified probe manufacture and alignment and offers a smaller probe that is suitable for use in a wider range of applications, including on-chip manipulation.