Abstract

We proposed and demonstrated a microsphere-tip hollow annual core single optical fiber tweezers for low-index bio-cells trapping in high-index mediums. The output beam from the hollow annual core fiber was focused by a high refractive index silica microsphere. The focused annular beams provided a suitable intensity profile for baker’s yeast cells trapping along the horizontal direction. In the vertical direction, the bio-cells were trapped where the net force of the optical trapping force, buoyancy and gravity exerting on the bio-cells was zero. We performed a gravity-assisted 3-dimensional trap for low-index particles based on the single fiber probe. Controlling bio-cells in high refractive index condensed mediums had potential applications in wastewater treatment via bio-catalysis and bio-degradation. Additionally, the optical damages to bio-cells was minimized with such hollow annular beams.

© 2018 The Author(s)