Transformation-optics modeling of 3D-printed freeform waveguides

Abstract

Multi-photon lithography allows to complement planar photonic integrated circuits (PIC) by in-situ 3D-printed freeform waveguide structures. However, design and optimization of such freeform waveguides using time-domain Maxwell's equations solvers often requires comparatively large computational volumes, within which the structure of interest only occupies a small fraction, thus leading to poor computational efficiency. In this paper, we present a solver-independent transformation-optics-(TO-) based technique that allows to greatly reduce the computational effort related to modeling of 3D freeform waveguides. The concept relies on transforming freeform waveguides with curved trajectories into equivalent waveguide structures with modified material properties but geometrically straight trajectories, that can be efficiently fit into rather small cuboid-shaped computational volumes. We demonstrate the viability of the technique and benchmark its performance using a series of different freeform waveguides, achieving a reduction of the simulation time by a factor of 3-6 with a significant potential for further improvement. We also fabricate and experimentally test the simulated waveguides by 3D-printing on a silicon photonic chip, and we find good agreement between the simulated and the measured transmission at $\lambda =1550\text{ nm}$.

arXiv comment23 pages, 8 figures

References in corpus (7)

• Deep Learning with Coherent Nanophotonic Circuits
• Ultrafast optical ranging using microresonator soliton frequency combs
• Illusion optics: The optical transformation of an object into another object
• Hybrid integration of silicon photonics circuits and InP lasers by photonic wire bonding
• Three dimensional waveguide-interconnects for scalable integration of photonic neural networks
• Silicon-plasmonic integrated circuits for terahertz signal generation and coherent detection
• Hybrid 2D/3D photonic integration for non-planar circuit topologies