Abstract

The maximum transmitted power in an optical monomode fiber is limited to the 10-W range.¹ Higher power can be transmitted if the beam is split and coupled into several fibers of a monomode fiber bundle. In this case dephasing of the beam components occurs due to different path lengths in the individual fibers. The coherence in the output of the fiber bundle can, however, be reestablishing by adjusting the phase in each individual fiber of the bundle by applying stress or strain.² In our work we study theoretically the possibility of phase adjustment leading to a focus. Focusing is achieved with suitable phase differences between the individual fibers that lead to constructive interference at the focal point. The calculation shows that it is possible to concentrate more than 50% of the fiber output energy in the central peak of the resulting diffraction pattern, if a very dense packed array of fibers is used. Dense fiber bundles with core separation as low as 10 µm are already commercially available.³

© 1989 Optical Society of America