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arXiv · 2206.02486

Ultra-narrowband terahertz circular dichroism driven by planar metasurface supporting chiral quasi bound states in continuum

Jitao Li·Zhen Yue·Jie Li·Chenglong Zheng·Dingyu Yang·Silei Wang·Mengyao Li·Yating Zhang·Jianquan Yao
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Abstract

Terahertz (THz) chirality pursues customizable manipulation from narrowband to broadband. While conventional THz chirality is restricted by non-negligible linewidth and unable to handle narrowband well. Recently, the concept "quasi bound states in continuum" (quasi-BIC) is introduced to optics resonance system whose the quality factor can be extremely high with the ultra-low radiative loss, thus providing a conceptual feasibility for wave control with ultra-narrow linewidth. Herein, we construct quasi-BIC in a planar all-silicon THz metasurface with in-plane C2 and mirror symmetries breaking. Such system not only exposes the symmetry-protected BIC, but also exposes the parameter-tuned BIC assigned to single resonance type. An extremely narrow linewidth (below 0.06 GHz) with high quality factor (104 level) is obtained at quasi-BIC frequency, which achieves the ultra-narrowband THz chirality.

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Jitao Li, Zhen Yue, Jie Li, Chenglong Zheng, Dingyu Yang, Silei Wang, Mengyao Li, Yating Zhang, Jianquan Yao. 2022-06-06. Ultra-narrowband terahertz circular dichroism driven by planar metasurface supporting chiral quasi bound states in continuum. https://doi.org/10.1016/j.optlastec.2023.109173

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