US Patent 11835767 Optical subassembly for bidirectional WDM application

Embodiment of present invention provide an optical subassembly that includes a first, a second, and a third band filter (BF) each having a common port (CP), a port-A (PA), and a port-B (PB). The PA of the second BF is connected to the PA of the third BF and the PB of the first BF is connected to the PB of the third BF. The optical subassembly is adapted to route a first optical signal of a blue band from the PA to the CP of the first BF; to route the first optical signal from the CP of the second BF to the CP of the third BF; to route a second optical signal of a red band from the CP of the third BF to the CP of the first BF; and to route the second optical signal from the CP to the PB of the second BF.