Novel flat-gain L-band Raman/Er-Yb co-doped fiber hybrid optical amplifier for high capacity DWDM system

A novel flat-gain L-band hybrid optical amplifier is demonstrated using a combination of Raman and Er-Yb co-doped fiber amplifier (EYDFA) for a high capacity 80 × 100 Gb/s dense wavelength division multiplexed (DWDM) system at 0.2 nm channel spacing. The parameters of the proposed Raman-EYDFA hybrid amplifier are optimized using numerical techniques based on genetic algorithms to achieve a flat gain of >22 dB, with a gain ripple of 0.89 dB. This is obtained over a wavelength range of 1571-1587 nm at 1 mW optimum input power per channel, without using any costly gain clamping technique. The obtained noise figure (NF) is less than 6 dB for the given wavelength range. The overall decrease in gain and increase in NF is observed with the increase in input power. The obtained high and flat gain, along with the low NF and good Q-factor and bit error rate, confirms the feasibility of proposed amplifier for applications in broad band long-haul DWDM systems.