Abstract: Polymethyl methacrylate (PMMA) and polyvinyl pyrrolidone (PVP) are deposited on Porous Silicon (PS) substrates by spin coating technique, to make PMMA/PS and PVP/PS junctions. The porosity of the PS samples was determined using the parameters obtained from SEM images by geometrical method. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. This porous silicon layer can be considered as sponge like structure. The refractive index of the PS samples as a function of porosity was determined by Effective Medium Approximation (EMA) methods. The influence of polymer fraction on porosity and refractive index of PS, were discussed. These results suggest that this nanocrystalline porous silicon could be a potential candidate for optical as well as optoelectronic device applications.