Can multilayers be optimized sequentially when radiation is partially polarized?

Abstract

For radiation-absorbing materials and nonnormal incidence, multilayers with the largest reflectance at a desired wavelength are here demonstrated to require nonsequential optimization when radiation is partially polarized. The thicknesses of multilayers with the largest possible reflectance at a desired wavelength can be calculated sequentially either for s- or p-polarized radiation or for normal incidence and any polarization. The equations that impose the condition of maximum reflectance in the general case of partial polarization do not allow for the simplification that is performed when radiation is s or p polarized, which implies that multilayer optimization for partially polarized radiation is not sequential. An example is given in which the importance of nonsequential optimization is displayed. In contrast to the case of s- or p-polarized radiation, when radiation is partially polarized extra maxima may be found within an optical path difference of much less than half a wavelength.