SDM-WDM ROADM Based on Direct-Laser-Writing SDM Core Separator

Weakly-coupled space division multiplexing (SDM) techniques based on multi-core fibers (MCF) have attracted great attention for the capacity enhancement of optical interconnect systems and networks. In this paper, we propose a novel direct-laser-writing (DLW) core separator device and apply it in a reconfigurable optical add/drop multiplexer (ROADM) structure for two-dimensional SDM and wavelength division multiplexing (WDM) switching. The proposed core separator matching an 8-core MCF is fabricated. Then assisted with MCF rotators, independent adding and dropping functionalities for arbitrary core are experimentally demonstrated with slight power penalty for both core and wavelength dimensions. The influence of crosstalk for cascading core separators is also investigated and below 0.35-dB receiving sensitivity penalty is obtained when three cores are dropped one by one. The compact DLW core separators can reduce the complexity of SDM nodes and will be beneficial for high-speed optical interconnects.