Spatial-division multiplexing self-homodyne coherent transmission over 19-/24-core fibers assisted by homemade fan-in/fan-out 3D photonic devices

The self-homodyne detection (SHD) is a promising solution to achieve low-cost and low-power-consumption fiber-optic communications. In this work, we propose and demonstrate a high-capacity spatial-division multiplexing (SDM) system with SHD technology by employing single-mode multi-core fibers (SM-MCFs), where the fan-in/fan-out (FIFO) 3D photonic devices are designed and fabricated based on the femtosecond laser direct writing technique, enabling high-efficiency coupling between single-mode fibers (SMFs) and SM-MCFs. The FIFO 3D photonic devices, serving as the SDM (de)multiplexer, facilitate superior performance of low insertion loss and low inter-channel crosstalk. Using a low-cost MHz linewidth distributed feedback (DFB) laser, we experimentally demonstrate the SDM-SHD transmission system of 102-Gbaud dual-polarization (DP) 16-ary quadrature amplitude modulation (16QAM) signals per channel over a 2.7-km 24-core SM-MCF and 22-Gbaud DP-64QAM signals per channel over a 1-km 19-core SM-MCF. Without using wavelength-division multiplexing (WDM), the total data rate per channel reaches 816 Gbit/s, with an aggregate data throughput of 18.7 Tbit/s. The obtained results indicate that, by extending SHD technology to SDM communication systems, one can achieve low-cost, low-power-consumption, and scalable high-capacity data transmission in next-generation fiber-optic communication networks.