Abstract

High-order Raman amplification using ultra-long Raman fiber lasers (URFLs) has proven to be a promising solution for future long-haul and unrepeatered communication links, combining a simple design with low signal power variation (SPV) and superior optical signal to noise ratios (OSNRs) [1]. Unfortunately, the ultimate performance of URFL amplifiers, where symmetric pumping leads to the lowest SPV along the span, and hence to the best possible balance between ASE noise and nonlinear impairments, is limited by the increased relative intensity noise (RIN) transfer from pump to propagating signal related to high forward pump powers and front-end reflectivities, which may be detrimental for transmission performance [2-4].

© 2017 IEEE