All-dielectric metasurfaces enabled by quasi-BIC for high-Q near-perfect light absorption

All-dielectric metasurface (ADM) absorbers driven by quasi-bound states in the continuum (BIC) are critical for high-performance optoelectronic devices due to their ability to offer high Q-factor absorption. However, these all- dielectric metasurfaces usually require the aid of degenerate critical coupling schemes or back-metal reflective layers to achieve high absorption, which often suffers from limitations such as sensitive geometrical parameters, ohmic losses, and low Q-factors. This work presents an ADM for high-Q near-perfect light absorption, which consists of double Si nanorods and SiO2/Ta2O5 multilayers. By breaking the symmetry of the length of the Si nanorods, this ADM can excite a single quasi-BIC resonance corresponding to the electric dipole. Without introducing a metal layer, we realize the highly asymmetric coupling of quasi-BIC by only 6 layers of SiO2/Ta2O5 films. It is theoretically and numerically demonstrated that the quasi-BIC has more than 98% absorption at 943.68 nm and a Q-factor as high as 2842. In addition, the ADM exhibits excellent tolerance to geometrical parameters while ensuring high absorption performance. Our results provide new ideas for the design of all-dielectric perfect absorbers with large tolerances and high Q-factors and also open up new possibilities for optical filtering, optical sensing, and photon detection devices. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.