Gain clamped L-band EDFA with forward–backward pumping scheme using fiber Bragg grating

The paper proposes a novel two stage L-band erbium doped fiber amplifier with forward–backward pumping scheme for transmission of 32 wavelength division multiplexed (WDM) channels. It is gain clamped with an in-line fiber Bragg grating (FBG) to provide flat gain over 45nm by restricting and reutilizing amplified spontaneous emission (ASE). We demonstrate that it provides an efficient small signal gain with minimum noise figure of over 20dB and 5.5dB, respectively, in the L-band region (1565–1610nm) by comparing with its forward and backward pumped counterparts with fixed Er3+ fiber length of 20m for −30dBm/channel input power. We also obtain the gain and noise figure dependence as a function of each of the Er3+ fiber lengths, pump power (both 1480 and 980nm), and temperature. Hence a 10nm region (1580–1590nm) has been acknowledged where temperature variations become constricted for 30°C variations (15–45°C).