Spatial Distribution of Data Capacity for the Reduction of Number of Repeaters in Ultra Long-Haul Links

We present a novel method to reduce the number of repeaters and amplifiers in trans-oceanic links by distributing a given data capacity in spatial channels. We analytically, numerically and experimentally demonstrate the principle and show that about 40% of the repeaters can be omitted compared to a recently deployed cable. The method predicts that a single-fiber transmission link with 50 km amplifier spacing would be better off, repeater-wise, if the targeted single-fiber capacity is distributed in two fibers, each with an amplifier spacing of 150 km. In this scenario, one would thus only require 2/3 of the original number of amplifiers, and only 1/3 of the number of repeaters, housing the amplifiers. To test the principle of the proposed method, we experimentally and numerically investigate a 6900-km long link with amplifier spacing of 50 and 150 km using a recirculating fiber transmission loop, and find that the result supports the analytical model and thus the proposed method. We then use this concept to analytically investigate a realistic 12-fiber pair cable, and find that the same capacity could be distributed in 18 fiber pairs requiring only about 58% of the original number of repeaters.