Optonumerical method for improving functional parameters of polymer microtips

Abstract

We proposed an optonumerical method that supports the optimization of the fabrication process of polymer microtips manufactured at the ends of optical fibers. The optimization was aimed at obtaining the functional parameter of microtips—the output beam distribution in the far-field diffraction region. This parameter depends on refractive index distribution within the microtip and its geometrical properties, which are determined by the optical power distribution of the actinic light and the exposition time during the photopolymerization process. The proposed method constitutes a convenient feedback loop for modification of the fabrication parameters. A single cycle of the proposed scheme includes numerical simulations and measurements of the functional parameter, tomographic measurements, and modifications of the fabrication process. We proposed utilization of the measured values of three-dimensional refractive index distribution of microtips as input data for the finite-difference time-domain simulations. It was proven that the iterative process leads to controlled modification of the technology parameters and finally to obtaining the desired functional parameter of fabricated microtips.