With the explosion of interest in photonic topological insulators, there has been an unfortunate lack of progress on implementing these devices in practical settings. They offer surprising features of robustness to defects and high field enhancement, but in almost every paper you will see the chosen excitation boiling down to a small dipole blasting energy. Not only is this clunky and aggravating in the lab (fancy near field scans take time!), but also makes these demonstrations more about confirming their theory of operation than a demonstration of something useful to an engineer or designer.

In the hopes of pushing these new devices towards adoption in industry and other practical settings, my colleagues and I have been exploring various strategies towards integrating PTI technology with standard microwave equipment. We currently have a method of transitioning from a classical 50 ohm microstrip quasi-TEM wave to a metallic spin-type PTI based on a duality principle, with associated losses of ~2.1%. This and future designs illustrate that such PTIs are a viable platform for highly robust waveguiding at microwave bands, and can be analyzed with standard tools.

Associated Publications

1. R. J. Davis, D. J. Bisharat, and D. F. Sievenpiper, “Classical-to-topological transmission line couplers,” Appl. Phys. Lett., vol. 118, no. 13, p. 131102, Mar. 2021, doi: 10.1063/5.0041055. (arxiv) Editor's Pick

2. S. Singh, R. J. Davis, D. J. Bisharat, J. Lee, S. M. Kandil, E. Wen, X. Yang, Y. Zhou, P. R. Bandaru, and D. F. Sievenpiper, “Advances in metasurfaces: topology, chirality, patterning, and time modulation,” , pp. 2–14, 2021, doi: 10.1109/MAP.2021.3127541.

3. R. J. Davis, D. J. Bisharat, and D. F. Sievenpiper, “Efficient Transition from a Traditional Planar Transmission Line to a Topological Line Wave,” in 2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, Jul. 2020, pp. 757–758, doi: 10.1109/IEEECONF35879.2020.9329833.