Modeling the growth of a polymer microtip on an optical fiber end

Abstract

Manufacturing end-of-fiber optical components able to realize optical functions ranging from a simple lens to more complex functions such as mode selective components is a decisive but a priori complex task owing to the fiber core dimensions. Effective low cost methods allowing to grow polymer components by free-radical photopolymerization using the light coming out of the fiber have recently been reported. A novel phenomenological model of the photopolymerization process underlying is here given and used to simulate the polymer component growth in a three dimensional time-resolved manner. The simulations results are thus used to understand and optimize the component growth conditions, focusing particularly on the role of oxygen either present in the atmosphere or dissolved in the solution.

Finite element formulation for self-writing of polymer optical fiber sensors

“…The last two phenomena that have been seen experimentally, but have not been explicitly incorporated into this code are tapering and necking (focusing and refocusing of the wave as it is guided along the cured polymer [10]) effects on the written waveguide. It was discussed in section 2.2 that it was difficult to get uniform waveguides due to the change in index of refraction and density changes which can cause tapering and necking effects as demonstrated by [18,10,22,20]. This model does not explicitly show the effects of necking, however, if the model geometry were longer it is possible that the tapering effects could lead to necking.…”

“…After the early works of Monro et al, more emphasis was placed on numerical modeling and simulation of the photopolymerization and self-writing processes. For example, a series of three papers looked at writing a polymer micro-tip on the end of silica fibers [10,17,18].…”

“…Beginning with an empirical approach, this set of studies built up experimental research on tip growth and then developed a model based on the beam propagation method in two [10] and three dimensions [17,18]. These studies also looked at the effects of oxygen on the photopolymerization process and found that higher concentrations of oxygen hindered the reaction and either caused a delay in polymerization or did not allow the reaction to initiate if the concentration was too high.…”

Technology of Polymer Microtips’ Manufacturing on the Ends of Multi-Mode Optical Fibers

“…In this mixture, Eosin Y disodium salt and methyldiethanolamine (MDEA) were used as sensitizer and co-initiator, respectively. Eosin Y is photosensitive in the spectral range from 450 nm to 550 nm and allows use of the trigger photopolymerization process for the used VIS light source [15]. Both above-mentioned chemical compounds were purchased from Sigma-Aldrich.…”

Polymer-Tipped Optical Fibers

“…This effect can lead to nodes in the formed tip with a geometry that can be predicted numerically by an iterative beam propagation method in a medium with a time varying refractive index [8,12]. Figure 2 shows that the tip's radius of curvature (ROC), systematically checked by scanning electron microscopy (SEM), can be controlled by adjustment of the exposure time.…”