Method of manufacturing a graded-index plastics optical fiber

A method of manufacturing a graded-index plastics optical fiber whose refractive index varies continuously between its center and its periphery, said fiber being made from at least one polymer P and at least one compound M1 enabling refractive index to be varied, said method comprising:

• preparing two compositions of different refractive indices, the refractive index difference between the two compositions being not less than 5×10−3, each composition comprising at least the polymer P, and a “first” one of said compositions also having at least the compound M1, a cross-linking photo-initiator being present in at least one of said compositions;
• diffusing the two compositions into each other;
• and
• spinning said mixture so as to obtain a graded-index plastics optical fiber;
• wherein the polymer P and the compound M1 are selected in such a manner that:
• said polymer P is of molecular mass lying in the range 1000 to 20,000 and said compound M1 is of molecular mass lying in the range 100 to 1000;
• said compound M1 has at least on reactive functional group selected from the group consisting of vinyls and acrylates;
• the polymer P has at least one reactive functional group selected from the group consisting of vinyls and acrylates;
• and
• at least one of the two compounds P and M1 is at least mono-functional, the other of the two compounds P and M1 being at least bi-functional;
• wherein, prior to spinning, the two compositions are subjected to active mixing using at least one mixing means so as to obtain continuous variation in the refractive index of the optical fiber;
• and
• wherein spinning of the graded-index plastics optical fiber is followed by curing giving rinse to a cross-linked three-dimensional lattice.