An alternative architecture for a PON OLT splitter-combiner integrated into an SFP transceiver module

A 1×N single-mode splitter made of (N-1) 2×2 couplers is simultaneously a low-loss N → 1 optical combiner when unused 2×2 coupler ports route to a mode-coupling receiver. A PIC-based SFP transceiver module providing four class-B+ GPON OLT ports is thus realized.