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.

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Figure 1: Selected optical, compositional and dimensional properties of sapphire-derived fibres.
Figure 2: Measured attenuation of the sapphire-derived fibre using a cut-back method over a distance of 5 m.
Figure 3: Brillouin spectra for three segments of the sapphire-derived fibre corresponding to different alumina contents in the core.
Figure 4: Acoustic velocity and Brillouin linewidth as a function of alumina concentration in sapphire-derived optical fibres.
Figure 5: Absolute and normalized BGCs as a function of alumina concentration in sapphire-derived optical fibres.
Figure 6: Selected Brillouin properties of sapphire-derived optical fibres.


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The authors thank C. Dunn for technical support and A. Yablon for the refractive index profile measurements.

Author information




P.D. conducted experimental work, analysed data and wrote some of the manuscript. T.H., P.F. and S.M. synthesized the fibres and conducted experimental work. J.B. conceived the work, analysed data and wrote some of the manuscript.

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Correspondence to J. Ballato.

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Dragic, P., Hawkins, T., Foy, P. et al. Sapphire-derived all-glass optical fibres. Nature Photon 6, 627–633 (2012).

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