Phase-Separated Alumina–Silica Glass-Based Erbium-Doped Fibers for Optical Amplifier: Material and Optical Characterization along with Amplification Properties

Abstract

In this paper, we present phase-separated alumina–silica glass-based Er3+-doped optical fibers made by a modified chemical vapor deposition (MCVD) process in combination with a solution doping (SD) technique. The fibers exhibited better optical performance than other silica-based host glasses—both in terms of spectral broadening and flattening of the gain spectra in the C band (1530–1560 nm) region—as well as an improved lifetime. These phase-separated erbium-doped fibers (EDF) promoted longer Er–O bond lengths and also hexa- and penta-coordinated Al3+ ions instead of the fourfold coordination found in non-phase-separated EDF. It was observed that the higher coordination numbers of Er3+ and Al3+ ions in phase-separated glass hosts led to more homogeneous and inhomogeneous broadening, resulting in better flatness of the gain spectrum with 1.2 dB more gain compared to the non-phase-separated EDF.