Frequency-dependent electromagnetic beam manipulation with dual-polarized wideband metagrating at extreme-angle incidence

Recent advances in extraordinary optical diffraction metagratings have enabled electrically-thin sheets capable of wavefront shaping with near-unity efficiency, providing unprecedented opportunities for controlling large-angle wave scattering in photonics and spectroscopy. However, current metagrating has mostly suffered from limits on the polarization and bandwidth for extreme-angle wavefront transformation, remaining as a basic obstacle for developing metagrating devices and their applicability for energy control in different polarization and frequency channels. Utilizing the orthogonally embedded grating method, a dual-polarized metagrating beam deflector is reported for high-efficiency scattering manipulation over a wide band. Exemplary cases of electromagnetic retroreflection and frequency-dependent beam scanning with a large angular range at a particular extreme-angle incidence are implemented at microwave frequencies. Due to the attractive features of simple geometry, extreme wavefront transformation, and dual polarization, the proposed metagratings offer possibilities for many practical applications, such as polarization and frequency division multiplexing wireless communications, remote sensing, etc.