This paper presents an extensive literature review on the electrophysical properties of polymer films subjected to ion implantation. The aim of this work was also to study thin polyethylene terephthalate C22H8O4 films previously subjected to nickel ion implantation at various doses and currents using optical spectroscopy. The results obtained and the optical spectra, both transmission and reflection, are presented. A relationship was found between the increase in dose in these spectra and the decrease in the relative absorption coefficient. The possible manifestation of optical plasmon resonance is considered. The relative shift of the absorption edge observed in a series of spectra with increasing size of π-electron carbon clusters with increasing dose load is explained. This allows, by studying the relative change in optical characteristics, to determine how metal implantation into a polymer affects the change in its internal structure and properties.