Terahertz metalens for manipulating focal point and imaging

Lenses accessing multiple focal spots with polarization rotatable functionality or focal spot with extended focal depth is naturally challenging. We propose and experimentally demonstrate an approach to realizing terahertz multi-foci metalens with polarization-rotated focal points. Terahertz polarization-dependent imaging is realized by the multi-foci metalens. Furthermore, we propose and approach to design terahertz metalens with simultaneous extended focal depth and polarization insensitivity. As a proof-of-concept, longitudinal high-tolerance imaging is demonstrated by the metalens.