Abstract

Compared to conventional periodic nanostructures such as photonic crystals, topological photonic systems require more precise fabrication techniques due to the need to place multiple dielectrics at appropriate positions within a unit cell, and this becomes particularly remarkable in the optical communication band. In this paper, observing photonic band structures by using hyperspectral Fourier image spectroscopy, we quantitatively discuss the fabrication accuracy of typical topological photonic systems in which triangle nanoholes were arranged in a deformed honeycomb lattice with ${{\rm C}_{6{\rm v}}}$ symmetry. Here the size and corner radius of triangle nanoholes were precisely controlled using shape correction electron beam lithography. The results showed that the fabrication error must be controlled to below ${\sim}{10}\;{\rm nm}$ for the size and ${\sim}{30}\;{\rm nm}$ for the corner radius, in order to achieve the desired topological edge state that occurs at the interface between two photonic structures different in topology.

© 2022 Optica Publishing Group

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