A multi-core optical fiber apparatus is disclosed. The multi-core optical fiber apparatus includes a cladding comprising quartz and a plurality of cores embedded in the cladding. Each of the cores has a diameter (D) ranging from 1.3µm to 2.0µm, a numerical aperture (NA) from 0.35 to 0.45 and a refractive index profile factor (±) from 2.0 to 4.0. A center of each of the cores has a germanium content of 20wt% to 30wt%. An interval between adjacent cores is 3.0µm or more.
