“…Telluride glasses, though stable, have a high index of refraction and high thermal expansion, both of which complicate splicing into an all-optical system. The normal alumina-silica glass-based EDF with high Al codoping shows better flatness compared to other silica EDFs, such as those based on germanium-silica and phosphosilicate glasses [6]. Accordingly, fabrication of high Al-doped silica-based optical fiber has gained significant attention in recent years, and various techniques such as modified chemical vapor deposition coupled with solution doping (MCVD-SD), direct nanoparticle deposition (DND), sol-gel methods etc.…”