Bend translation in multimode fiber imaging

Light propagation in multimode fibers is typically assumed to be extremely sensitive to changes in geometry. We study here a particular configuration where an S-shaped bend is translated between two sections of fiber. In this sliding bend configuration, we show that nearly constant propagation characteristics can be obtained in certain fibers. Several fibers were tested using a bend with a peak radius of curvature of 25 mm. We found large differences in bending behavior between fibers of varying core diameters and numerical apertures. Fibers with a large numerical aperture are found to be more stable. In several fibers, the bend can be translated over a distance of 25 mm with a limited impact on imaging performance. The experimental results are confirmed using simulations. Our findings shed a new light on bending sensitivity in multimode fibers, and open up more possibilities for their use as imaging devices. (C) 2017 Optical Society of America