Synthesis of symmetrical wave and phase address fiber Bragg structures

The main objective of this paper is to create scientifically based principles for the development of two-component symmetrical wave address fiber Bragg structures with a phase π shift (2λ/π-AFBS) as new sensitive elements of microwave photonic sensor systems. As can be seen from the model of such a combined structure, it consists of two sequentially installed FBGs with a phase shift. Additional requirements for the structure of a symmetrical 2λ/π-AFBS are defined as the same bandwidth of both FBGs and the transparency windows in them. In asymmetrical 2λ/π-AFBS these values may differ from each other. Phase Nπ-AFBS and wave Nπ-AFBS have their advantages and disadvantages. The corresponding development and elimination of their shortcomings is aimed at the creation of 2λ/π-AFBS with a certain frequency difference between the Bragg frequencies of the first and second FBGs, which is called the main address frequency for transmission, and at which the central wavelengths of the transparency windows are located. The width of the transparency window at the level of maximum reflection of symmetrical FBG components allows the formation of an additional address frequency for reflection, which is one order of magnitude lower in frequency than the main one. In FBG components, transparency windows that are not identical in bandwidth can also be formed, and, accordingly, different additional address frequencies. Two-component symmetric 2λ/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.