Broadband variable beamsplitter made of a subwavelength-thick metamaterial

We propose and validate a method for designing a broadband variable beamsplitter using a metamaterial with subwavelength thickness. Through theoretical analysis and numerical simulations, we demonstrate that the reflectance-to-transmittance ratio of a single-layer resonant metamaterial at its resonance frequency can be controlled by varying the spatial arrangement of the constituent meta-atoms, without altering their individual structures. Building on this theory, we further conjecture a method for achieving a frequency-independent reflectance-to-transmittance ratio across a broad spectral range. Numerical results confirm that a metamaterial with subwavelength thickness can be engineered to function as a broadband variable beamsplitter using the proposed approach. These findings contribute to the advancement of techniques for splitting and combining electromagnetic waves in compact systems.