Efficient Modeling of Tapered Photonic Structures

Tapered optical structures play a crucial role in modern photonic systems because of their ability to efficiently couple, mode convert and multiplex light. Modeling such structures is challenging since, as the region of interest shrinks, there is a significant loss of numerical resolution. In this study, we present a novel approach to model tapered structures by introducing the taper reference frame. The key idea is to render the tapered refractive index profile constant within this frame. By working in the tapered reference frame, we eliminate the need for recalculating or resizing the refractive index distribution, which reduces computational overhead. Most importantly, unlike traditional methods, our approach maintains high numerical resolution in the region of interest, which is critical for capturing intricate features and subtle variations in the structure’s behavior. We validate our method by comparing our numerical simulations with analytical solutions in tapered GRIN media. We applied our model to the analysis of photonic lanterns — intricate tapered fiber optic devices. Our results demonstrate vastly improved accuracy and computational efficiency compared to existing approaches. The proposed tapered reference frame technique enables major advancements in the design and optimization of optical devices across various applications.