Design and optimization of a reflection-based fiber-optic tweezers.

We present the numerical modelling of a novel all-fiber optical tweezers, whose efficacy has been recently demonstrated. The device, realized by properly shaping the end-face of a fiber bundle, exploits total internal reflection to enhance the trapping efficiency. In order to allow the optimization of the performance, the trapping efficiency is evaluated as a function of different geometrical parameters of the structure. Given the peculiar spatial and angular distribution of the optical field, a new figure of merit is adopted to assess tweezers performance.