Highly efficient configuration of reflective fiber-optic active star couplers

Abstract In this paper, we present a highly efficient configuration by using the basic 4 × 4 active star coupler and the 2 × 2 3-dB fiber coupler as building blocks to construct larger reflective active N star couplers with the fewest erbium-doped fibers (EDFs) and pump lasers. This configuration saves about half the fibers and components used with the transmissive N × N active star. Moreover, this configuration provides advantages such as very low cost, high gain, and pump-wavelength independence for system applications.