Manufacturing method of a polymer GRIN lens using sulfonation

摘要

The present invention relates to a manufacturing method of a polymer GRIN lens which is used for focusing light in connections for example between two or more optical fibers and between an optical fiber and a light source in the optical communication field. The manufacturing method of a GRIN lens according to the present invention utilizes a characteristic of polystyrene that its refractive-index is decreased by sulfonation. The method includes polymerizing a sphere or rod made of a directional monomer that is capable of sulfonating like a styrene, together with a cross-linking agent, and a polymerization initiator; swelling the polymerized cross-linked polymer by using a predetermined solvent; and sulfonating the swollen cross-linked polymer using a sulfuric acid. Accordingly, the present method can be easily controlled to obtain the desired refractive-index distribution since the refractive-index distribution is determined by the diffusion of the sulfuric acid as a sulfonation.