Structural evolution of fused optic-fiber components: Numerical simulations and experimental study

A variety of optical components are fabricated by the so called "Heat and Pull" technique in which optical fibers are fused and tapered. A numerical model simulating the temporal and spatial material distribution in such components is presented and validated by comparison with experimental results. Over the years, numerous models and tools have been developed to simulate the optical behavior of fused fiber-optic components. While these models are well established, their predictions depend on accurate knowledge of the component's physical structure and its refractive index distribution. Unfortunately, no such generic simulation tools are readily available. The need of a high fidelity structural simulation tool for such components is further emphasized in complex systems, which are difficult to fabricate and are optically sensitive to small structural variation. In view of the above, we developed a novel numerical methodology based on Immersed Boundary (IB) Method specifically designed to simulate flows in the presence of complex geometries and moving boundaries. In the present formulation pressure and interface curvature are implicitly embedded into the system of incompressible Navier-Stokes equations as distributed Lagrange multipliers. The developed methodology is currently capable to simulate two phase flows in two dimensions and is also adapted to solve quasi-3D evolutions. For validation, the simulation output is compared to the cross-sectional material distribution of a real component fabricated at our lab. The developed model, as well as the experimental results and the comprehensive analysis predicting the structure of symmetric and non-symmetric optic fiber components are presented and discussed.