Figure 4: Insensitivity of mode rotation to fibre bending.
(a) Schematic illustrating the experimental setup. An LP11 mode is coupled into a few-mode fibre and the output beam is monitored by a camera. The fibre is freely suspended over a 45-cm gap. Bending of the fibre can be induced by moving the fibre mounts closer together so that the fibre sags by different amounts, h, resulting in an approximate curvature of 1/R. (b) Images of the output beam profiles as the input is rotated through 160° in 20°-steps for three different amounts of fibre bending. Mode rotations remain largely unaffected even in the slightly and strongly bent fibre configurations (that is, sagging by 4 and 12 cm, respectively) and still provide sufficient trapping potential for cell rotation.
