Experimental investigation of energy transfer between modes in a graded-index fiber waveguide with periodic microbending of the axis

An experimental investigation was made of energy transfer between the lowest axially symmetric modes in a multimode graded-index fiber waveguide as a function of the amplitude of periodic bending of its axis. Selective excitation and detection of given modes in a waveguide was induced with the aid of synthesized holograms. The experimental curves were in satisfactory agreement with the results of a theoretical calculation and confirmed that the sensitivity of a mode to bending of the axis of a graded-index waveguide increased on increase in the mode number.