High-splitting-ratio PON systems using a PLC-based funnel-shaped waveguide with dual-mode fiber [invited]

This paper increases the splitting ratio of 10 Gb/s-class passive optical network (PON) systems by using a novel low-loss optical splitter based on single-mode (SM) to multimode (MM) coupling. It consists of a planar lightwave circuit (PLC)-based funnel-shaped waveguide (FW) and a dual-mode fiber (DMF) that supports both SM and MM propagation through its dual core configuration. While conventional low-loss splitters based on a similar principle, called mode couplers or mode combiners (MCs), pass through only upstream signals, the proposed FW-DMF acts as a low-loss splitter for upstream and a conventional splitter for downstream despite its simple configuration. Compared to conventional MCs, it greatly reduces the number of optical components required for an optical line terminal. Considering the more efficient use of existing infrastructures, we develop two types of FW-DMFs with branching ratios of 4 and 16. Bit error rate measurements assuming 10 G-EPON systems show the ability of our prototypes to realize 128-split 10 Gb/s-class PON systems.