Optical Bound States in Continuum in MoS<sub>2</sub>-Based Metasurface for Directional Light Emission.

Muhammad, Naseer; Chen, Yang; Qiu, Cheng-Wei; Wang, Guo Ping · Nano Lett · 2021

basic_science · Level V

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Abstract

High quality factor (<i>Q</i>-factor) and strong field localization in nanostructures is a newly emerged direction in nanophotonics. The bound states in the continuum (BIC) have been investigated in nanoparticles with infinite <i>Q</i>-factor. We report BIC in molybdenum disulfide (MoS<sub>2</sub>) based Mie nanoresonator suspended in air. The ultrathin nanodisk supports symmetry protected BIC, and the quasi-BIC (<i>q</i>-BIC) are exploited by breaking the symmetry of the structure. The strongly localized modes in our MoS<sub>2</sub>-based nanodisk sustain a similar magnetic field profile before and after symmetry breaking, unlike what has been previously reported in silicon-based structures. Strong directional emission is observed in BIC regime from a hybrid configuration with a resonator placed on the stacked metal-dielectric layers, which transform BIC to <i>q</i>-BIC and exploit highly directional light. The structure persists emission with small variations in normalized intensity at distorted symmetry. The giant <i>Q</i>-factor in <i>q</i>-BIC is highly desired for biosensing and optical filters.