Dependences of quantities ϕ₁, R₂₁, R₂₃, I ⁽¹⁾ on the main layer thickness d₂ for various materials of layers 1, 3. The values of parameters are: ε₁ = ε₃ = 2 + 10⁻³ i (a, c), 0.01 + 0.01i (b), −13 + 0.5i (d); d_1,3 = 250 nm (a, b), 13 nm (c, d); λ = 0.63 μm (a, b), 0.6 μm (c, d). Denotations of the curves in Figures b, d are given in Figures a, c. I ⁽¹⁾ = I ^TM (1) (z = d₁ + 0.5d₂) for all the graphs. Parameter d₂ is used as the abscissa axis for all the graphs.