Comparative study of long-period gratings written in a boron co-doped fiber by an electric arc and UV irradiation

• Published in: Measurement science & technology Vol. 21; no. 2; p. 025309
• Main Authors: Smietana, M, Bock, W J, Mikulic, P
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.02.2010
• Subjects: Arc discharges; Boron; Boron fibers; Diffraction gratings; Fibers; Gratings (spectra); Irradiation; LPG
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/21/2/025309

The paper presents for the first time a comparative study of long-period gratings (LPGs) written by point-by-point UV irradiation and by electrical arc discharges. These gratings were inscribed in a highly photosensitive boron co-doped fiber that can be considered as a suitable platform for LPG writing using either technology. The experimental transmission data for the manufactured LPG devices fit well when compared to the simulations we carried out in parallel. As a result of each of these writing processes, we were able to obtain a remarkably good quality of grating. Two reasons could explain the observed small differences between the spectra: a slight mismatch of the period of the gratings and an unintentional tapering of the fiber during the arc-based processes. We also found that the UV irradiation at Delta *l = 248 nm can cause clearly visible damage to the fiber's surface. As a result of the UV writing, a coupling to the asymmetrical cladding modes can take place. Moreover, the gratings written using the two technologies show a very similar refractive index and temperature-sensing properties. The only differences between them can come from a physical deformation of the fiber induced by the electric arc discharges.