Crosstalk Noise in Bi-Directional Transmission on Multi-Core Fiber Link With Distributed Raman Amplifier

The crosstalk (XT) noise-to-signal ratio characteristics in a distributed Raman amplifier (DRA) used for bi-directional multi-core fiber (MCF) transmission are investigated. We propose a model for calculating XT noise by considering the noise contribution due to Rayleigh scattering. We verify the validity of our model both numerically and experimentally. Our model reveals that the XT noise-to-signal ratio (
XT
_r
) varies with the on-off gain. This feature is unique for bi-directional transmission, and it provides an on-off gain at which the
XT
_r
can be minimized, although the corresponding net gain is less than 0 dB. We also show that the minimum
XT
_r
is relatively sensitive to the attenuation coefficient at both signal and pump wavelengths. Our model is beneficial for discussing the signal-to-noise ratio property in DRA-based MCF bi-directional transmission, and further study for hybrid DRA and discrete amplifier systems is expected.