Formation of Radial Refractive Index Gradient in Multi- layer Polymer Fiber by Multi-Coating Method

摘要

An innovative multi-layer coating method has been studied for preparation of gradient refractive index (GRIN) lens. This preparation method employs a polymer optical fiber (POF) as a core fiber, which is subjected to a repeated process alternating peripheral coating with fixation. Polymer solutions were coated in descending order of refractive index in order to establish a refractive index (RI) distribution. The coating behavior of polymer solutions of different RIs on the periphery of the core fiber was studied. The coating thickness was dependent on the capillary number, and could be controlled by changing the composition of polymer solution. The refractive index distribution was formed in radial direction in the fiber. However, the distribution was a little irregular, and it is necessary to clarify the mechanism for the formation of the RI distribution.