Analysis of tuning of Bragg wavelength of photowritten fiber Bragg gratings during the inscription process using a biprism.

This paper presents an analysis of a simple biprism-based technique that enables inscription of multiple fiber Bragg gratings (FBGs), each with different Bragg wavelength, into a section of an optical fiber. The method offers a tuning range for Bragg wavelength that is comparable to that of the multiple mirror interferometer method. This has an additional advantage over multiple mirror interferometer methods, in that it does not require shifting of the fiber position perpendicular to the fiber axis, over a wide tuning range. Results of an analysis on how such tuning of Bragg wavelengths affects other important parameters of FBGs such as length, bandwidth, and reflectivity have been presented.