The self-reproduction effect, or Talbot effect, is usually observed for the light-wave incident at a normal to a rectangular grating with the same transverse periods. A natural example of a one-index set of modes for which the Talbot effect must be quite pronounced is a tubular waveguide. This effect of azimuthal self-reproduction may be an important component of nonlinear azimuthal interactions of optical waves in multimode fibers. The self-reproduction effect is sensitive to the wavelength of radiation and therefore may be used for an inexpensive device for azimuthal scrambling and unscrambling of analog data
