Quasi-BIC induced coherent perfect absorption from anisotropic dimer metasurfaces

We propose an anisotropic dimer metasurface to achieve coherent perfect absorption (CPA) through quasi-bound states in the continuum (quasi-BIC) with distinct mechanisms under different polarized illuminations. Specifically, the metasurface achieves a CPA band, induced by the quasi-BIC resonance generated by the obliquely incident x-polarized wave. Additionally, the metasurface supports quasi-BIC resonance for y-polarized waves due to the asymmetry from the structural perturbations, facilitating another separate CPA band. Our findings pave the way for advanced control over coherent absorption and the development of multifunctional absorber systems tailored for various polarized electromagnetic waves, and applications as illustrated for the perfect optical switches.