Bragg grating writing in acoustically excited optical fiber

Abstract

The inscription of Bragg gratings in optical fiber under acoustic excitation is proposed and demonstrated. A permanent change in the refractive index as the period of the grating is modulated with periodic acoustic excitation during UV grating writing leads to sampling of the structure and the production of spectral combs. A physical contribution to index change through stress profiling reveals a complicated picture of UV-induced index change, well beyond simple localized defect and structural changes. The method offers the potential for tuning and tailoring conventional uniform gratings during the writing process using adjustable acoustic wave functions, an approach to control the writing process.