Sapphire-derived all-glass optical fibres

As performance demands continue to grow, many optical fibre systems are operating at progressively higher power levels. However, Brillouin scattering restricts continued power scaling in narrow-linewidth systems. Optical fibres with engineered Brillouin properties that are manufactured using industry-accepted methods would be of great practical benefit. Here, we show all-glass optical fibres derived from sapphire that have alumina concentrations of up to ∼55 mol%, which is considerably greater than conventionally possible and enables a series of useful properties. Specifically, a Brillouin gain coefficient of 3.1× 10^-13 m W^-1, a value nearly 100 times lower than commercial fibre, was measured for a fibre with an average alumina concentration of 54 mol%. Furthermore, a fibre with ∼38 mol% alumina was found to be athermal, with a Brillouin frequency that was insensitive to changes in temperature. Such optical fibres may be beneficial in realizing enhanced telecommunication, sensor and high-energy laser systems.