Abstract

I am working with a computer program that models inhomogeneous layers as a series of up to 100 homogeneous steps per layer. With this program I have examined the behavior of reflectors containing graduated layers of various types such as straight-line ramps in log (index) and rugates. A rugate layer is defined for this purpose by an index, n, and a quarter wave optical thickness, x, such that where n_max is assumed to be the maximum n(x) at x = 1/σ. It is known that reflectors made up entirely of rugate layers should have a high reflectance at the design wavenumber σ and very little reflectance at 2σ, 3σ or any other integer multiple of σ. Such behavior is not obtained if n varies linearly, or log (n) varies linearly, or the sin² curve is in n itself rather than log (n). In all such cases reflectance bands will appear at odd harmonics, even harmonics or both.

© 1988 Optical Society of America