We show, by means of simple model calculations, how a weak laser beam sent
through 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 small, of order $10^{-3}$, in order to produce
an appreciable transverse displacement of order 10 microns. We argue that the
effect has probably already been seen in a recent experiment of She et al.
[Phys. Rev. Lett. 101, 243601 (2008)], and we discuss 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.Comment: 4 pages, 3 figures. Accepted for publication as Rapid Communication
in Phys. Rev.