Topologically enabled ultrahigh-Q guided resonances robust to out-of-plane scattering

By Jicheng Jin, Xuefan Yin, Liangfu Ni, Marin Soljačić, B. Zhen, Chao Peng. Nature, 2018

612 citations recorded by the source corpus.

Because of their ability to confine light, optical resonators1–3 are of great importance to science and technology, but their performance is often limited by out-of-plane-scattering losses caused by inevitable fabrication imperfections4,5. Here we theoretically propose and experimentally demonstrate a class of guided resonances in photonic crystal slabs, in which out-of-plane-scattering losses are strongly suppressed by their topological nature. These resonances arise when multiple bound states in the continuum—each carrying a topological charge6—merge in momentum space and enhance the quality factors Q of all nearby resonances in the same band. Using such resonances in the telecommunication regime, we experimentally achieve quality factors as high as 4.9 × 105—12 times higher than those obtained with standard designs—and this enhancement remains robust for all of our samples. Our work paves the way for future explorations of topological photonics in systems with open boundary conditions and for their application to the improvement of optoelectronic devices in photonic integrated circuits. Bound states in the continuum are merged in momentum space by varying the periodicity of the photonic crystal lattice, giving high-quality-factor guided resonances that are robust to out-of-plane scattering.

View Paper: https://www.semanticscholar.org/paper/568021846f70f4d7c2027c057e39ce66b8bd4312

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1. T. Ozawa
2. H. Price
3. Alexander B. Khanikaev
4. A. Amo
5. Andrea Alù
6. Y. Chong
7. Yihao Yang
8. Meng Kang

Citations in the corpus

• Nonradiating photonics with resonant dielectric nanostructures (2019, background): “Based on these findings, topologically enabled ultra-highQ resonances were proposed [71] arising when multiple BICs merge in the momentum space, with a measured Q factor of 5 × 105.”
• Roadmap on topological photonics (2022, methodology): “For PhC slab, the full-wave coupled-wave-theory can be a promising framework since it analytically depicts the radiation and energy band simultaneously [142, 143], thus enabling the investigation of the topology of both.”
• Multipolar origin of bound states in the continuum (2019, result): “Similar effect was observed in [21] for the photonic crystal slab.”
• Applications of bound states in the continuum in photonics (2023, background): “To overcome this challenge, multiple off-Γ BICs can be simultaneously tuned to the vicinity of symmetry-protected BICs to suppress out-of-plane radiation over a broader wavevector range 99 .”