Modelling and record technologies of address fibre Bragg structures based on two identical ultra-narrow gratings with different central wavelengths

Abstract

Address fiber Bragg structures (AFBS) make it possible to effectively solve the problem of sensors interrogation and multiplexing in multi-sensor networks with microwave photonic processing of information. Based on the method of inverse Fourier transform, a mathematical model of the optical fiber refractive index profile was constructed to form 2λ-FBG AFBS with two FBG with identical spectral responses at separated wavelengths. As the initial parameters for the construction of the mathematical model, the desired spectral profile of 2λ-FBG AFBS was specified, including the reflection coefficient and the width of the transmission band of its two identical ultra-narrow-band gratings and the separation between them. On the basis of the study of the mathematical model, the possibility of selecting the necessary values of the refractive index and the laws of its modulation is shown, allowing the spectral profile of 2λ-FBG AFBS to be formed so that they can be used as a sensitive element, transforming information from optical range to radiofrequency one. The analysis of the formation and recording methods for 2λ-FBG AFBS was carried out. To implement given structures, the technology, using of an ultraviolet argon laser, the classic phase masks with sequential recording of several arrays with precise movement and strain of the fiber were chosen. Further paper deals with issues of interrogation of the developed structures and principles of measurement system construction on their basis.