Bending Loss and Cut-Off Wavelength Properties of Randomly Coupled Multi-Core Fiber

In this work, we numerically and experimentally investigated the bending loss and cut-off wavelength characteristics of randomly coupled multi-core fiber (RC-MCF). The numerical results showed that the bending loss of the RC-MCF is larger than that obtained with single-core design due to the coupled core effect. In addition, the cut-off wavelength property is affected by the coupled core effect and requires a different design approach from that of the SMF. The subsequent experimental results for the bending loss and the cut-off wavelength properties of RC-MCFs with 4–12 cores were in good agreement with the simulation results. We also numerically investigated the core design range of the 4- and 12-core RC-MCF and found that the core design range of the RC-MCF shifts to the high-$\Delta$ region. Our findings indicate that the standard cladding diameter RC-MCF with up to 12 cores can be designed to satisfy the bending loss, cut-off wavelength, and MFD values specified in ITU-T Recommendations G.652/654.