Transverse radiation force in a tailored optical fiber

We show, by means of simple model calculations, how a weak laser beam sent though an optical fiber exerts a transverse radiation force if there is an azimuthal asymmetry present in the fiber such that one side has a slightly different refractive index than the other. The refractive index difference Delta n needs only to be very low, of order 10(-3), to produce an appreciable transverse displacement of order 10 mu m. We argue that the effect has probably already been seen in a recent experiment by W. She et al. [Phys. Rev. Lett. 101, 243601 ( 2008)], and we discuss the correspondence between these observations and the theory presented. The effect could be used to bend optical fibers in a predictable and controlled manner and we propose that it could be useful for micron-scale devices.