The polymer optical fiber has a high-purity concentric double-layer structure, a polymethylmethacrylate (called PMMA) core and a specially selected transparent fluoropolymer cladding. The refractive index of the cladding is lower than that of the core. The structure can effectively maintain the emitted light power.description:The polymer optical fiber has a high-purity concentric double-layer structure, a polymethylmethacrylate (called PMMA) core and a specially selected transparent fluoropolymer cladding. The refractive index of the cladding is lower than that of the core. The structure can effectively maintain the emitted light power.Application advantages1) Low transmission loss in the visible spectrum.2) Large core diameter and wide receiving angle.3) Excellent durability and reliability4) Large alignment tolerance of the connection