Single-wavelength bidirectional 4-core MCF self-homodyne coherent link

In this paper, we propose and demonstrate a single-wavelength bidirectional self-homodyne coherent (SHC) link over a 125 µm cladding diameter based multicore fiber (MCF). The 4-core MCF based link efficiently uses two cores for each direction of propagation. In either direction, one of the cores carries a dual-polarized 40 Gbaud 16-QAM signal, and the second core carries a 40 Gbaud 16-QAM signal in one of the polarizations with the carrier multiplexed in its orthogonal polarization. Thus, a 480 Gbps data transmission rate is achieved in either direction of propagation over the 12.8 km long 4-core MCF. The SHC link operates at the same wavelength for each of the directions and eliminates the need for reconfigurable transceivers. A low-cost DFB laser (linewidth = 1 MHz) is used to demonstrate the bidirectional link, and the bit error rates (BERs) of the received signals are <5.5×10^-4. With higher baud rates, this approach can meet the capacity requirements of future short-reach data center interconnects (DCIs).