Regenerated femtosecond fibre Bragg gratings

We demonstrate the thermal regeneration of fibre Bragg gratings inscribed by direct writing using a femtosecond, infrared laser into standard SMF-28 and pure silica core fibres. Post-H₂ loading was used. The regeneration process is shown to extend the temperature operation of these gratings up to 1200°C. The temperature durability of regenerated 193nm-written gratings in SMF-28 fibre is presented for comparison. The ability to enhance the temperature durability of femtosecond inscribed index changes has significance beyond fibre Bragg gratings; for example, the micromachining of photonic components such as planar waveguides.