Analysis of radiation scattering by a periodic structure of microcavities in a multimode optical waveguide

Subject of study. Optical radiation scattered by a periodic structure of microcavities formed in a planar optical waveguide simulating a 62.5/125 µm multimode fiber is investigated. Aim of study. This work aims to determine the power distribution of optical radiation scattered by a periodic structure of bullet-shaped microcavities on the lateral surface of a planar waveguide based on mathematical modeling, to develop a method for assessing the efficiency of scattering elements, and to determine the values of the geometric parameters of the microcavity structure that yield the highest uniformity of scattered radiation. Method. Mathematical modeling of radiation scattering by a periodic structure is carried out using the COMSOL Multiphysics package. The model allows variation of the size and relative arrangement of the microcavities. Main results. The power distribution of scattered radiation at a wavelength of 1310 nm from the lateral surface of the waveguide is obtained. The results demonstrate that both the size and relative arrangement of the microcavities have a significant effect on the power distribution of scattered radiation. A method for estimating the uniformity of the scattered power distribution along the waveguide is proposed. Practical significance. The results are applicable to multimode optical fibers incorporating periodic microcavity structures for scattering laser radiation. Such fibers can serve as radiation sources for medical applications. Periodic structures can be used as sensing elements for fiber-optic sensors. The results are relevant to the development of diffusers with highly uniform scattered radiation patterns.