Further observations on the variation with dielectric constant and thickness of the reflectance and phase change on reflection of films

摘要

Studies of the behaviour with epsilon(1), epsilon(2) and film thickness of the optical functions reflectance (R) and phase change on reflection (Phi(r)) have previously been made for both very thin and very thick films. Abeles [J. Opt. Sec. Amer. 47 (1957) 473] has formulated equations for very thin films where functions of epsilon(1) and epsilon(2) are the coefficients of a power series of the optical thickness, x(2 pi d/lambda) up to x(2), whilst in the case of very thick films (solids) the relationships between epsilon(1) and epsilon(2) can be represented in polar coordinates L and alpha by epsilon(1) = L cos alpha, epsilon(2) = L sin alpha where L-R = 2y(0)(2)W (2)(1 + cos alpha - 1/W (2)) [W = (1 + R)/(1-R)] and L-Phi r = 2(y(0)/ tan Phi(r))(2)(1 - cos alpha + tan (2)Phi(r)) [Ward, Opt. and Laser Tech. 27 (1995) 125]. The present study is concerned with films of intermediate optical thicknesses (1.0 < 2 pi d/lambda < solid) and has revealed that the polar-type relationships previously noted for solid materials are augmented by secondary structures of maxima and minima whose position and amplitude can be predicted by adapting the exact equations for R and Phi(r). (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 5]