Performance Analysis of CDL-impaired Multi-Core Fiber Transmission

Abstract

Single-mode fibers have reached a critical point in terms of optical communication capacity. Space division multiplexing (SDM) is one of the most promising candidates for increasing optical fiber capacity. SDM allows the propagation of multiple spatial channels where the paths could be multiple cores in a multi-core fiber (MCF). The transmission performance of MCFs is impaired by a non-unitary effect known as Core Dependent Loss (CDL). Multiple-input multiple-output (MIMO) technology is an effective solution to improve the transmission performance of MCFs. However, it can increase the system cost. Several techniques, such as core scrambling and Space-Time (ST) coding, have been proposed to mitigate CDL. This paper focuses on the analysis of the MCF transmission performance of different schemes. Our analysis concerns the derivation of an upper bound of the error probability by applying Maximum Likelihood (ML) and Zero-Forcing (ZF) decoders at the receiver. We also evaluate the performance of both core scrambling and ST coding systems. We prove that the ZF decoder offers similar performance to the ML decoder and confirm this with simulation results. Finally, to consider the cost factor of applying MIMO techniques, low complexity solution is proposed by combining core scrambling and ST codes using the sub-optimal ZF decoder and show performance close to the Gaussian channel.