S-band single-stage EDFA with 25-dB gain using distributed ASE suppression

We propose a novel compact design for a single-stage S-band erbium-doped fiber amplifier, wherein distributed suppression of C-band amplified spontaneous emission is provided by optimized bend loss in a coaxial core fiber. Simulations show that ∼25-dB unsaturated gain over 30-nm bandwidth (1495-1525) nm is achievable with the designed module, using a nominal pump power of 500 mW. The noise figure of the amplifier varies between 4.5 and 8 dB from 1495 to 1525 nm. By proper designing, we have also ensured that the gain ripple over the entire 30-nm bandwidth is <±3 dB. Tolerance toward accuracy in bend radius has also been calculated and it has been shown through simulations that the amplifier performance is maintained for ±1-mm variation in bend diameter.