Coupled-mode propagation in multicore fibers characterized by optical low-coherence reflectometry

A fiber-optical low-coherence reflectometer has been used to probe a multicore fiber locally at a wavelength of 1.3 mu m. This technique allows one to determine the group index of refraction of the modes in the multicore fiber with high accuracy. Light, propagation that is due to noncoherent coupling of energy from one fiber core to adjacent cores through cladding modes can be distinguished quantitatively from light propagating in coherently coupled modes. Intercore coupling constants in the range of 0.6-2 mm(-1) have been evaluated for the coupled modes. (C) 1996 Optical Society of America