Dual high-Q bound states in the continuum based Fano resonances in bulk WS2 meta-lattice

Abstract Bound states in the continuum (BICs) play a promising role in enhancing light–matter interaction with a high quality (Q) factor in transition metal dichalcogenides (TMDCs). In this work, a structured meta-lattice of bulk tungsten disulfide (WS2), a well-known material of TMDCs, with double high-Q resonances governed by quasi-BIC is presented. Two types of quasi-BIC are exploited simultaneously by rotational and longitudinal asymmetries of WS2 rods, acting as the meta-atoms. These Fano line shaped quasi-BIC resonances have a very high quality factor of 1.6×104 with a reasonable asymmetric parameter of 1%. Although, tuning the asymmetric parameter changes the linewidth of the resonances and the resulting Q-factor, for all values of these parameters the amplitude of reflection remains constant at one. In addition to exploring and analysing two quasi-BICs, strong coupling between exciton and quasi-BICs is illustrated with Rabi splitting of 116.6meV and 54.2meV for rotational and longitudinal asymmetries, respectively. These findings show promise for the development of high-Q photonic devices and applications in polaritonics.