Photonic topological insulators have emerged as an exciting new platform for backscatter-free waveguiding even in the presence of defects, with applications in robust long-range energy and quantum information transfer, spectroscopy and sensing, chiral quantum optics, and optoelectronics. We demonstrate a design for spin-Hall photonic topological insulators with remarkably low refractive index contrast, enabling the synthesis of photonic topological waveguides from polymeric materials for the first time. Our design is compatible with additive manufacturing methods, including fused filament fabrication for microwave frequencies, and constitutes the first demonstration of a 3D printed all-dielectric photonic topological insulator. We combine rapid device fabrication through 3D printing with high-speed FDTD simulation to quantify topological protection of transmission through “omega” shaped bent topological waveguides and find that one corner in the waveguide is 3-5 times more robust to disorder than the other. This dichotomy, a new empirical design rule for ℤ2 topological insulator devices, is shown to originate in the fundamental system symmetries and is illustrated via the distributions of Poynting vectors that describe energy flow through the waveguide. Taken together, our demonstration of 3D printed polymeric spin-Hall photonic topological insulators paired with quantification of robustness to disorder at bent topological interfaces provides a rapid, flexible scheme for engineering high-performance topological photonic devices across multiple frequency regimes from microwave to THz, to visible.
Supporting Information for: 3D Printed Polymer Photonic Topological Insulators and their Robustness to Fabrication Disorder
Figure S1: Geometry, band structure and experimental and FDTD transmission spectra for the topologically trivial compressed lattice. Figure S2: Identification of common features in low-transmission bent topological waveguide designs. Table S1: Slicing parameters for fused filament fabrication of photonic topological insulators. Figure S3: Procedure for quantifying the extent of disorder at the corners in a bent topological waveguide. Figure S4: Assessing robustness to disorder at each corner in a taller bent topological waveguide with more unit cells included in the diagonal. Figure S5: Simulated forward and backward transmission through a bent topological waveguide to verify reciprocity. Figure S6: Photographs of the parallel plate waveguide apparatus.