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arXiv · 2404.02494

Wide-mode-area slow light waveguides in valley photonic crystal heterostructures

Chengkun Zhang·Yasutomo Ota·Satoshi Iwamoto
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Abstract

We designed slow-light waveguides with a wide mode area based on slab-type valley photonic crystal (VPhC) heterostructures which are composed of a graphene-like PhC sandwiched by two topologically distinct VPhCs. The group velocity of the topological guided mode hosted in a VPhC heterostructure can be slowed down by shifting the VPhC lattice toward the graphene-like PhC at the domain interfaces. Simultaneously, the mode width of the slow-light topological guided mode can be widened by increasing the size of the graphene-like PhC domain. We found that employing the graphene-like structure at the center domain is crucial for realizing a topological single-guided mode in such heterostructures. Furthermore, the impact of random fluctuations in air-hole size in the graphene-like domain was numerically investigated. Our simulation results demonstrate that the transmittance for the slow-light states can be kept high as far as the size fluctuation is small although it drops faster than that for fast-light states when the disorder level increases. The designed wide-mode-area slow-light waveguides are based on hole-based PhCs, offering novel on-chip applications of topological waveguides.

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Chengkun Zhang, Yasutomo Ota, Satoshi Iwamoto. 2024-04-03. Wide-mode-area slow light waveguides in valley photonic crystal heterostructures. https://arxiv.org/abs/2404.02494

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