Application of Standard Recurrent Formulas to the Calculation of Multilayer Systems with Light Absorption near the Layer Boundaries

摘要

The problem of numerical calculation of weakly absorbing multilayer dielectric coatings with loss concentrated near the layer boundaries, in interlayers of thickness h, which are considerably smaller than the wavelength λ, was solved. The application of standard recurrent formulas is often difficult because of the absence of exact information on h, the refractive indices of interlayers n, and their absorption coefficients χ. To overcome this obstacle, one can take certain fictitious values of h, n, and χ, which, when substituted into formulas, finally give the correct optical parameters of a multilayer as a whole. This statement was supported by numerical calculations made for a typical dielectric mirror for different angles of incidence and polarizations. The results obtained show that the simplest way of solving the problem is to assume that each interlayer has a purely ohmic conduction, i.e., set n = χ. It is reasonable to recommend the values h/λ = 10~(-6) or 10~(-7) and chose the product nxh/λ starting from the loss of a multilayer system as a whole.