Terahertz All-Dielectric Magnetic Mirror Metasurfaces

We demonstrate an all-dielectric metasurface operating in the terahertz band that is capable of engineering a reflected beam's spatial properties with high efficiency. The metasurface is formed from an array of silicon cube resonators which simultaneously support electric and magnetic dipolar Mie resonances. By controlling the interference between these modes, the amplitude and phase of a reflected wave can be arbitrarily controlled over a subwavelength area. We demonstrate the flexibility and utility of this metasurface by optimizing the surface to produce several reflected beam types including vortex and Bessel beams; the latter being useful for diffraction-free point-to-point terahertz communications. Additionally, we show theoretically and experimentally how the metasurface can produce an all-dielectric magnetic mirror in the terahertz band.