Abstract

The reflectance and transmittance of dielectric thin films at oblique angles of incidence have strong polarization effects. For some uses these effects are undesirable. In this paper a nonpolarizing beamsplitter design concept is shown, based on the fact that in a quarterwave stack at λ_o, two effective indices that obey the Brewster condition for the p-state affect only the spectral performance of the s-state at λ_o. When added to a quarterwave stack with a certain p-state transmittance, these layers can change the s-state transmittance to almost any desired value without affecting the p-state. This concept can be applied to a wide range of angles and transmittance values, using effective quarterwave layers of at lease three different materials.

© 1991 Optical Society of America