Thermal preparation of highly stable glass periodic changes with nano-scale resolution using a laser-inscribed hydrogen loaded seed template

Strong regenerated gratings with a maximum grating strength exceeding (40-50) dB are fabricated inside an optical fibre by bulk macro thermal processing ~900degC using a UV-laser seeded Bragg grating. Further annealing between 1000 and 1100degC leads to a stabilised grating ~18 dB in strength. This suffers no further degradation at 1100degC for the period monitored, over 4 hrs. To determine the potential resolution of this process, two regenerated complex profiles with no phase difference between seed and processed structures is reported. This opens the way for nano-engineering of materials using thermal processing and seed templates.