Ultra-dense, laser-welded, multi-core fiber-optic interfaces.

The packing density of fiber-optic interfaces is ultimately limited by the cladding diameter. We investigate direct laser welding of multi-core fibers as a means for overcoming this limit in constructing arbitrary-pitch arrayed optical interfaces. We demonstrate that submicron-precision laser welding, previously shown for single-core fibers, can be used to construct multicore fiber interfaces while fully preserving the beam quality of each core. This report describes the application of the new technique to 4- and 7-core fibers and quantifies the resulting beam quality to confirm laser welding invariance with respect to the radial distribution of the cores.