3-dimensional dark traps for low refractive index bio-cells using a single optical fiber Bessel beam

We proposed and experimentally demonstrated a 3-dimension dark traps for low refractive index bio-cells using a single optical fiber Bessel beam. The Bessel beam was produced by concatenating single mode fiber and a step index multimode fiber, which was then focused by a high refractive index glass microsphere integrated on the fiber end facet. The focused Bessel beam provided multiple dark fields along the axial direction, where stable trapping of low refractive index bio-cell was realized in a high refractive index liquid bath. All-fiber and seamlessly integrated structure of the proposed scheme can find ample potentials as micro-optical probe in in-situ characterization and manipulation of multiple bio-cells with refractive indices lower than that of liquid bath.