Tomographic and numerical studies of polymer bridges between two optical fibers for telecommunication applications

We present the tomographic study of the refractive index distribution in polymer bridges between two optical fibers. Detailed refractive index maps are needed in order to improve the technological process for manufacturing those bridges and to achieve a lower return loss. At first, the technological process of the fabrication of bridges through photopolymerization is presented. The interferometric measurements of reference fibers used to produce those bridges and two series of microbridges are performed experimentally in the visible (VIS; 632.8 nm) and infrared (IR; 1550 nm) wavelength regions. The relation between the VIS and IR results is determined, which allows performing tomographic measurements in more accurate conditions in the VIS spectrum. The experimentally obtained refractive index distributions in the microbridges are used for modeling the insertion and return losses, which are compared with the real loss obtained for the produced microbridges. This knowledge will be used for better understanding the manufacturing process and its further optimization. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)