The calculation of a two-cascade long-period fiber grating of the refractive index

A method is proposed for calculating the spectral characteristics of cascade long-period fiber gratings refractive index core based on partial regions and decomposition. According to method, structure represented as a connection basic inhomogeneities, each which junction several optical fibers with different dielectric geometric parameters. Approbation was carried out by reducing single grating comparing results obtained using other calculation methods. The matched graphical accuracy. advantage possibility theoretically study effect parameters properties structure, well significantly save time resources. transmission spectra period T, length L, distance between Lf are presented.