Two-frequency scanning of FBG with arbitrary reflection spectrum

Fiber Bragg gratings are the most important elements in different fiber optics devices and are widely used both in fiberoptic communications and fiber optic sensor applications. The paper considers the integral analysis of FBG reflection spectrum (the analysis of two-frequency signal envelope). Firstly this method was supposed for studying the abstract circuit. In this paper it has been developed to analyze FBG with arbitrary shape of reflection spectrum.