Dynamic-gain-tilt-free S-band optical amplifiers employing silica-based phosphorous/alumina-codoped EDFs designed for multi-wavelength photonic networks

This paper presents S-band optical amplification using silica-based phosphorous (P)/alumina (Al)-codoped EDF. As a result of the glass composition examination, both the sufficiently high concentration of P and the slight concentration of Al have been shown to be desirable for effective S-band amplification. Employing the best EDF with P of 11 weight (wt)% and Al of less than 1 wt%, two types of S-band EDFAs have been demonstrated. In the four-stage configuration EDFA without gain flattening filters, a gain enhancement of about 9 dB has been achieved over the wavelength range of 1491-1502 in comparison with conventional Al-codoped EDF. In the gain-flattened eight-stage configuration, the power conversion efficiency of 11.5% has been achieved, which is about twice of that of the previous work using the Al codoped EDF. Moreover, the gain ripple over the wavelength range of 1495-1520 nm has consistently been less than 1.3 dBp-p over the 8-dB dynamic range under the automatic level control. Namely, the dynamic-gain-tilt-free operation without any active control scheme has been demonstrated for the first time to the best of our knowledge.