AbstractIn this letter we propose a novel configuration by using the basic 4 × 4 active star coupler and the 2 × 2 fiber coupler as building blocks to construct a larger transmissive single‐mode fiber‐optic N × N coupler with gain using minimum erbium‐doped fibers and pump lasers. This configuration provides three main advantages, i.e., high cost effect, pump wavelength independence, and configuration flexibility. The 64 × 64 active star coupler with 4‐dB net gain using moderate pump power is also discussed. It is found that the saving of total cost of the proposed configuration can be more than 55% and 40% of those used previously [1], for 980‐ and 1480‐nm pump lasers, respectively.