Synthesis of combined address fiber Bragg structures

The main objective of this paper is to create scientifically based principles for design of two-component asymmetric address fiber Bragg structures (λ+λ/π)-AFBS of the combined type. As can be seen from the name of such a structure, it consists of two sequentially installed FBG and FBG with a phase shift, having different wavelengths spaced apart at the address frequency. Additional requirements for the structure of an asymmetric (λ+λ/π)-AFBS are defined as the same bandwidth of both FBGs, which will determine the difference in the power of radiation reflected from them without and with a transparency window. Wave FBG, λ-FBG, is an important part of fiber-optic sensors, which has many advantages, such as compact structure, the ability to organize quasi-distributed measurements, low transmission losses and resistance to electromagnetic interference. In addition, a conventional λ-FBG is practically insensitive to bending and the external refractive index. This makes measuring strain, temperature and other parameters more convenient and accurate. FBG with a phase shift, in particular with a phase shift of π, π-FBG, has attracted widespread attention. π-FBGs not only have the advantages of λ-FBGs, but also have many special sensory characteristics, which are determined by different quantities and methods of generating the phase shift. It should be noted that the presence of narrow-band transparency windows in the π-FBG makes it possible to increase the resolution of sensors compared to the λ-FBG by a number of times equal to the ratio of the transmission bands of the λ-FBG and the transparency window of the π-FBG. Therefore, they have high advanced applied value in various sensor systems. Two-component asymmetric (λ+λ/π)-AFBS of the combined type according to our evaluations should allow us to obtain a synergistic effect from their use in various systems, including intellectual energy systems built according to the Smart Grid Plus concept.