Examination of Potential Terrestrial System Effects From Raman Pumps Below Cable Cutoff in G.654.E Fibers

ITU G.654.E was recently approved as a new optical fiber standard for terrestrial systems. While G.654-compliant fibers have been used extensively in undersea submarine networks for some time, the G.654.E standard is optimized for terrestrial systems and, in particular, it enables the use of large effective area fibers to extend the reach of new high data rate signals with multilevel modulation formats. The new G.654.E fiber standard increases the maximum cable cutoff wavelength specification to the lower edge of the C-band, 1530 nm. We analyze potential signal impairments that may arise from Raman amplification with pump wavelengths below cable cutoff. We study the case where Raman pump relative intensity noise (RIN) is caused only by Raman pump multipath interference and show that its effect is negligible compared to the contribution from inherent Raman pump RIN that is constant along a fiber propagation length. We find negligible effects are expected even under worst-case condition.