Interphase in plasma-deposited films on plastics: effect on the spectral properties of optical filters

The plasma-enhanced chemical vapor deposition of optical coatings on plasti c substrates leads to the formation of a physically thick (approximate to 5 0-100-nm) interfacial region (or interphase). We propose, based on our earl ier spectroellipsometric (in situ and ex situ) and spectrophotometric (ex s itu) studies, an optical model for the description of the interphase refrac tive-index profile n(z). We study in detail the effect of such an inter pha se on the spectral performance of various optical filters (antireflective V -coat, W-coat, achromatic W-coat, and minus filter). It is shown that consi dering the inhomogeneous n(z) profile in the design can improve the optical performance of some filters. (C) 2000 Optical Society of America.