Inter-core crosstalk analysis of homogeneous 12-core weakly-coupled multi-core fiber layouts for short-reach bidirectional transmission

Abstract

The feasibility of 12-core layouts of standard cladding diameter homogeneous single-mode weakly-coupled multi-core fibers with bidirectional transmission is assessed, regarding the inter-core crosstalk (ICXT) level in bidirectional transmission short-reach links. Four layouts reported in the literature, namely the square, hexagonal, outer circle and inner square and the reference layout, are compared. The square layout is the best for bidirectional transmission with propagation-direction interleaving in the C-band, with a reduction of more than 18 dB in the total ICXT level when compared to unidirectional transmission, for fiber lengths up to 10 km. This square layout has an outer cladding thickness of 22.5 ?m, a core pitch of 25.3 ?m, and a low confinement loss of 0.0045 dB/km due to suitable choice of the core parameters. Achieving a bidirectional ICXT level of -47.8 dB and -34 dB at 1 km and 10 km, respectively, the square layout reaches the maximum allowable ICXT level, for an outage probability of 10−4 with 4-level pulse amplitude modulation intensity-modulation and direct-detection systems, of -23.6 dB at 37 km (a 35 km longer length than the one found in unidirectional transmission with the same layout).