In this paper we present the optical properties of heterocyclic azo dyes containing polymers thin films. From spectroscopic ellipsometry combined with transmittance measurements we estimated the absorption coefficients, refractive indices and optical energy band gaps of studied compounds. One can notice that the optical properties of azo dyes polymers strongly depend on the type of substitution in the azobenzene moiety. The different substitution pattern in azobenzene moiety leads to a change in the value of refractive index and red shifts in the absorption spectrum. We also found that different polymer systems (such as guest-host system or side-chain) result in changes of the optical properties (such as the values of refractive index, optical energy band gap) of azo dyes. (C) 2016 Elsevier B.V. All rights reserved.