228-Spatial-Channel Bi-Directional Data Communication System Enabled by 39-Core 3-Mode Fiber

We demonstrated simultaneous usage of 228 spatial channels (effectively) within a strand of fiber. We fabricated a 13-km 39-core 3-mode fiber and constructed a bi-directional space division multiplexing (SDM) transmission setup by using cascaded spatial multiplexers on both fiber ends. Aggregated intercore crosstalk and return loss of the system were below -35 and above 31 dB, respectively, over the C and L bands. The feasibility of using bi-directional SDM transmission was investigated using 10 GBaud, 37.38-Gb/s dual-polarization QPSK signals at 1550 nm and coherent detection with a 6 × 6 multi-input-multi-output equalizer. Excellent transmission properties were obtained for most spatial channels.