@article {30043, title = {Topological extraordinary optical transmission}, journal = {Phys. Rev. Research}, volume = {4}, year = {2022}, pages = {L032011}, abstract = {Τhe incumbent technology for bringing light to the nanoscale, the near-field scanning optical microscope, has notoriously small throughput efficiencies of the order of\ 104\ -105, or less. We report on a\ broadband, topological, unidirectionally guiding structure, not requiring adiabatic tapering and, in principle, enabling near-perfect (\~{}100\%) optical transmission through an unstructured single arbitrarily subdiffraction slit at its end. Specifically, for a slit width of just\ λeff/72(λ0/138)\ the attained normalized transmission coefficient reaches a value of\ 1.52, while for a unidirectional-only (nontopological) device the normalized transmission through a\ λeff/21(\~{}λ0/107)\ slit reaches\ 1.14; both limited only by inherent material losses, and with zero reflection from the slit. The associated, under ideal (ultralow-loss) conditions, near-perfect optical extraordinary transmission has implications, among diverse areas in wave physics and engineering, for high-efficiency, maximum-throughput nanoscopes and heat-assisted magnetic recording devices.}, url = {https://doi.org/10.1103/PhysRevResearch.4.L032011}, author = {BASKOURELOS, K. and O. Tsilipakos and Stefa{\'n}ski, T. and S. F. Galata and Economou, E. and M. Kafesaki and K. L. Tsakmakidis} }