Fibre Bragg grating characterization with ultraviolet-based interferometric side diffraction

The interferometric side diffraction method for fibre Bragg grating characterization is evaluated using a set-up with an ultraviolet interrogation beam. In its present configuration, the reproducibility errors are 2–5% for the index and typically 10°–20° for the phase profile. The reflection spectra of chirped test gratings have been successfully reproduced with the aid of the acquired phase and refractive index envelope data. It is verified that the power of the interrogating beam, within some limits, is unimportant as regards the phase reproducibility, and the importance of relating the analysis to the fabrication parameters of the grating under investigation is stressed.