A new method of developing ultralow-loss glasses

A new and effective method for developing ultralow-loss glasses for long-distance optical fiber systems is presented. The idea is based on the observed strong effect of a very small amount of alkaline or alkaline-earth impurities on structural relaxation of “frozen-in” density fluctuations. Efficiency of this method is demonstrated in the case of silica glass with Na2O of less than 50 wt. ppm, where the light scattering loss was reduced by 13% by the addition of only 10 wt. ppm (≈1×10−3 mol %) Na2O. Various problems in developing ultralow-loss fiber materials in multicomponent glasses are avoidable in this method, since concentrations of dopants are very small.