Widely flatness gain bandwidth with double pass parallel hybrid fiber amplifier

A Widely flatness gainbandwidth with double pass parallel hybrid fiber amplifier is experimentally demonstrated in this study. The proposed design combines serial erbium–Raman one branch and Raman the second branch. Multiple pump units a maximum power of 800 mW (250 1410 nm, 225 1480 325 1495 nm) are utilized. Pump recycling technique applied to achieve acceptable pumping efficiency. gain bandwidth 80 nm (1525–1605 average level 22.5 dB obtained at small input signal $$-25$$ dBm optimum values. While, wider 90 (1520–1610 11.5 achieved large $$-5$$ dBm.