Antireflecting surface coatings with continuously varying complex refractive index

Nonreflecting coatings for absorbing materials, based on thin films with an inhomogeneous complex refractive index, are considered. The reflectivity of these coatings is determined as a function of the film thickness (in units of the radiation wave length), optical constants, and the radiation incidence angle. It is shown that properly selected absorbing materials can be used to obtain surfaces with extremely low reflection coefficients.