Propagation of light in a cylindrical system of tunnel-coupled waveguides

Propagation of light in a cylindrical system of tunnel-coupled waveguides is studied. The waveguide system was constructed by layer-by-layer deposition of waveguides on the inner wall of a reference tube by the SPCVD technique developed for synthesising fibre preforms. It is shown that the waveguide light beam in such a system moves along a helical wave-like trajectory and is partially emitted outside at its 'crests'. The angular dependence of the trajectory period and of the number of oscillations along the trajectory is measured.