Quad-channel independent wavefront encoding with dual-band multitasking metasurface.

Achieving multiple electromagnetic (EM) functionalities on a shared aperture in dual frequency bands is crucial for many applications; however, existing dual-band metasurfaces are affected by limited channels or narrow bandwidths. Herein, we propose a reflective coding metasurface that empowers four independent EM functionalities in quad-polarization channels in two wide frequency bands. By integrating quasi-I-shaped and cross-shaped metastructures, the meta-atom can feature independent phase modulation for two orthogonally linear and two decoupled circular polarizations at low and high frequencies, respectively. To validate the proposed metasurface, a multifunctional metadevice is designed that integrates beam deflection, diffuse scattering, and vortex beam generation. Both experimental and simulation results indicate distinct wavefront tailoring in each channel. The proposed multi-functional metasurface with low cross-talk and independent phase modulation depending on frequencies and polarizations may unlock the metasurfaces' potentials for complete wavefront control in EM function integration, multiple channel communication, polarization optics, etc.