Optical fiber and method for making such fiber

摘要

According to one example of the invention an optical fiber comprises: (i) silica based, rare earth doped core having a first index of refraction n₁; (ii) at least one silica based cladding surrounding the core and having a second index of refraction n₂, such that n₁>n₂; wherein at least one of the core or cladding is doped with Al₂O₃, such that the ratio of max wt % to min wt % of Al₂O₃ concentration is less than 2:1