Modern optical fibres owe their success to the long-range signal transmission in tele­com­munications. The high purity achieved when producing silica preforms by the mCVD method, yields transmission losses as low as 0.18 dB/km at a wavelength of 1.5 mm. Allowing to transmit signals over hundreds of kilometres with virtually no losses.

However, in the eighties and nineties it was recognized, that there is much more to optical fibres than signal transmission: if loss requirements are relaxed and in the range of 0.1 dB per meter or higher, a wealth of new production methods and hence fibre types and applications are possible to achieve.

In the last 3 decades many new fibre production methods and fibre types have emerged, such as microstructured optical fibres, fibres with active cores and hollow core fibres, just to name a few. Further, with the application of powder-in-tube process, material compositions of core and cladding can be used, which are not suitable for mCVD based methods.

In this presentation it will be shown how the powder-in-tube technique is used for the fabrication of fibres with high aluminium contents.

The introduction of Sapphire or aluminium oxide (Al₂O₃) as core and with a mixture of silica and aluminium oxide powders in the cladding, yields to microstructured fibres that can be used at very high temperatures.

Potentially, the optical transmission range of sapphire from the UV to 5.5 mm makes these fibres interesting for medical applications such as dentistry or bone cutting.

The present work will depict the powder preparation and fibre drawing process, as well as the characterization of the special optical fibres produced, in order to confirm a higher transmission in the mid IR and resistance to elevated temperatures.