Tomographic analyses and numerical simulations of optical fiber end microcomponents for determining their functional parameters

Michał Dudek

Abstract

The main goal of this work was to develop a hybrid experimental-numerical methodology to optimize fabrication process of polymer microcomponents (microtips and optical bridges) manufactured at the end face of optical fiber, in order to achieve selected functional parameters of these elements. To achieve this goal an experimental method of optical phase tomography was used in order to obtain full 3D refractive index distributions of studied elements, while numerical modeling was performed by means of the finite-difference time-domain method (FDTD). The parameters describing functionality of the aforementioned polymer microstructures were for microtips - distribution of a output beam and optical losses for optical bridges. These parameters are the function of such features as: 3D distribution of refractive index, a geometry of microelements and the wavelength of light propagating in the microelements. To analyze the relation of those features with the functional parameters of the studied microstructures, the experimental results had been compared to the ones obtained with simulations. Implementation of the proposed methodology in iterative procedure allowed to optimize the fabrication process in order to obtain the aforementioned functional properties. Additionally, in order to perform the tomographic measurements in workshop and production conditions a new compact tomographic system with low sensitivity to environmental changes was designed and built. Also an all-purpose software was developed with possibility of measurement control, phase and tomographic analysis and visualization of tomographic data. The proposed hybrid methodology allowed to finally obtain the selected functionality parameters both in polymer microtips and optical bridges. The final results confirmed the applicability of this methodology, which combined with the novel tomographic system may in future be utilized directly at the production line and could lead to further improvement of the fabrication process of microtips and microbridges.