The thesis presented by the researcher (Numan Salim Hashem), the study that is presented in this thesis, included the preparation of a copolymer, which is Poly(3HT-Co-Th) from the two monomers (hexylthiophene (3HT)) and thiophene ( Thiophene (Th)) using the polymerization method. Then, the copolymer was added to the polymer poly(methyl methacrylate) to obtain the mixed polymer, in order to study the optical, linear and nonlinear properties and electrical properties of the prepared mixed polymer, polymeric films were prepared, with different percentages of the polymer The co-polymer added to PMMA, using the casting method. The percentages of copolymer that were used are 0.033%, 0.040%, 0.046%, 0.053%, 0.060%. To include practical applications in the current study, polymeric films were prepared and used as optical sensors, and then their optical and electrical properties were studied. Optical sensor films samples were prepared by adding different percentages of polymer phenyl - C61 - butyric acid methyl ester (PCBM). ) to the copolymer Poly(3HT- Co-Th) is 5%, 9%, 13%, 17%, 20%. Two types of mixed polymer films were prepared with two different ratios of the copolymer added to the PMMA polymer, these two types are, Poly(3HT). - Co-Th)1- PMMA and Poly(3HT- Co-Th)2- PMMA The optical and electrical properties of these two types of mixed polymer have been studied.