Polymer optical bridges for efficient splicing of optical fibers

摘要

In this work we present application of opto-numerical methodology for improvement of functional parameters of polymer optical bridges working as splices between two optical fibers. Optical bridges are formed by means of photopolymerization with light emerging from one fiber and coupled into the second axially-aligned fiber, therefore creating a stable mechanical connection. To fully determine and improve properties of this kind of microstructures, experimental methods are combined with numerical modeling. The parameters describing functionality of the polymer optical bridges are optical losses (insertion and return), which determine the usability of those elements as optical fiber splices. These parameters are the function of such features as: refractive index distribution, geometry of the microstructure and the wavelength of propagating light. To analyze the relation of those features on the functional parameters of the studied microstructures, the experimental results are compared to the ones obtained with simulations. Numerical modeling of aforementioned optical bridges is performed by means of the finite-difference time-domain method, which allows analysis of the electromagnetic field propagating through the microstructure. Experimental methods consist of optical diffraction tomography, which is used in order to obtain full three-dimensional refractive index distribution of optical bridge, and measurements of optical losses. Implementation of the proposed methodology in iterative procedure allows to optimize the fabrication procedure in order to produce efficient and reliable optical splices with desired functional parameters — insertion loss at the level 0.2 dB and return loss below -60 dB.