R.V. Budaragin1, M.I. Kurzenkov2, A.A. Radionov3, Z.Yu. Salasenko4

1-4 Nizhny Novgorod State Technical University named after R.E. Alekseev (Nizhny Novgorod, Russia)

1 rbudaragin@mail.ru; 2 cheetah10@mail.ru; 3 radionow.aleck@yandex.ru; 4 zina.salasenko@mail.ru

Optical fibers with inserts of non-standard fibers include such structures as long-period fiber gratings (LPG) and their cascade connection. On their basis, frequency-separating devices are created, for example, fiber-optic filters. The report proposes an electrodynamic model of such a filter, an algorithm for calculating the structure and presents the results of the calculation.

During the calculation, it was assumed that each fiber junction is a connection of regular waveguide segments with constant parameters. Combining strict electrodynamic partial domain method and decomposition method, we solve the diffraction problem and find the coefficients of transmission and reflection of the structure. The approbation of the considered method was carried out by reducing the two-stage LPG model to a single one and comparing the results with the results obtained using other calculation methods. The obtained results coincided with an accuracy of up to 95%.

The use of the proposed method made it possible to confirm the frequency-selective properties of the structure based on a two-stage LPG. As a result of the simulation, it was found that the transmission spectrum of such a filter is multi-band, and the number of bands is determined by its geometry. The cascade LPG spectrum contains multiple resonances with an envelope coinciding with the transmission spectrum of a single LPG.

Budaragin R.V., Kurzenkov M.I., Radionov A.A., Salasenko Z.Yu. Optical filter based on cascaded long-period fiber arrays of the refractive index of the core. Radiotekhnika. 2023. V. 87. № 11. P. 192−201. DOI: https://doi.org/10.18127/j00338486-202311-24 (In Russian)

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