Tomographic study of polymer bridges between two optical fibers for telecommunication applications

In this paper we present the tomographic studies of refractive index distribution in polymer bridges between two optical fibers. Detailed refractive index maps are needed in order to improve the technological process of manufacturing of those bridges and to achieve lower return losses. At first the technological process of bridges fabrication through photopolymerization is presented. The interferometric measurements of reference fibers used to produce those bridges and two series of microbridges are performed in visible (632.8 nm) and infrared (1550 nm) experimental systems. The relations between vis and IR results are determined, which allows for performing tomographic measurements in more accurate conditions secured in visible spectrum. The experimentally obtained refractive index distributions in microbridges are used for modeling the insertion and return losses, which are compared with the real losses obtained for the produced microbridges. This knowledge will be used for better understanding of the manufacturing process and its further optimization.