A novel approach to fiber-optic tweezers: Numerical analysis of the trapping efficiency

We present a novel all-fiber optical tweezer (OT) for biological applications. The tweezer is based on a new approach relying on total internal reflection in an annular core fiber or into a fiber bundle. The proposed device, whose trapping efficacy has been recently demonstrated experimentally, is extremely promising, also because optical manipulation and analysis functions can be easily added to the tweezer basic structure, leading to the realization of a powerful biotool. In this paper, a detailed numerical analysis of the structure properties and of its efficiency is carried out in the Mie regime. Moreover, by defining a new parameter to evaluate the trapping efficiency, we perform a comparison between the proposed tweezer structure and a standard OT based on a strongly focused Gaussian beam.