All-optical analog to electromagnetically induced transparency based on higher-order topological states

摘要

In this paper, we investigate a topologically nontrivial kagome lattice and some special higher-order corner states, which originate from next-nearest-neighbor interactions and evolve from the edge states, so that the coupling between these new corner states is more easily to be tuned in contrast to the conventional "zero-energy" corner state. By introducing this topologically nontrivial kagome lattice with a zigzag perfect-electric-conductor boundary into a conventional photonic crystal waveguide system, and using a simple method to precisely control the coupling between the corner states and the waveguide, an all-optical analog of electromagnetically induced transparency with topological protection is achieved for the first time, to the best of our knowledge. These results may expand our understanding of the higher-order corner modes in a more general framework, and find applications in the fields of light delay, narrowband filter, and on-chip optical signal processing.

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