Obtainment of Graded Index Preforms by Combined Frontal Co‐Polymerization of MMA and BzMA

Summary. A simple system to obtain preforms with graded refraction index (GI) is presented. Index profiles with cylindrical symmetry are developed by introduction of a uniform rod of Poly Methylmethacrylate (65%)‐co‐Benzilmethacrylate (35%) (Poly‐(MMA‐co‐BzMA)) during mass copolymerization of an 80% MMA – 20% BzMA solution of the same monomers. The obtained preforms present a gradual variation of the refraction index with approximate radial symmetry. Dripping of the central bar produces moderate variations of the index profile along the preform axis, but a large enough fraction of the obtained preforms have potential to produce graded index (GI) polymer optical fibers (POF) by subsequent drawing and to obtain flat polymeric lenses by slicing.