Comparison of 1480 nm and 980 nm-pumped Gallium-Erbium fiber amplifier

Abstract

Background: One way to reduce the length of the gain medium in Erbium-Doped Fiber Amplifier (EDFA) is by doping the fiber core with a high concentration of Erbium. However, this method caused ion clustering effects, which limits the EDFA’s efficiency.  In this research, the use of Gallium as a new co-dopant in erbium-doped silica fiber is explored. Methods: The new fiber, namely Gallium co-doped Erbium fiber (Ga-EDF), is used as a gain medium in an optical fiber amplifier setup. A 2-meter length of the Ga-EDF fiber was used in a single pass configuration with a forward pumping scheme at 150 mW pump power. The Ga-EDF amplifier's gain and noise figure while pumping at 980 nm and 1480 nm were compared. The amplifier's performance was evaluated as the input signal power varied between -30 dBm to 3 dBm, over the wavelength range of 1520 nm to 1580 nm. Results: The 980 nm-pumped Ga-EDF amplifier achieved the maximum small-signal gain of 22.45 dB and the corresponding noise figure of 5.71 dB at the input signal wavelength of 1535 nm. Meanwhile, the 1480 nm-pumped Ga-EDF amplifier attained the maximum small-signal gain of 20.83 dB and the corresponding noise figure of 5.09 dB at the input signal wavelength of 1550 nm. At the input signal power below -20 dBm and the wavelength range 1520 nm to 1547 nm, the Ga-EDF performs better when pumped at 980 nm. Their performance is comparable at the input signal wavelength range between 1547 nm to 1580 nm. At the input signal power above -20 dBm, the 1480 nm-pumped Ga-EDF outperformed the 980 nm-pumped amplifier. Conclusions: The overall performance indicates that the gain saturation point of the 1480 nm-pumped amplifier is higher than the 980 nm-pumped.