Resonance-domain diffractive lens for the terahertz region.

Diffractive optics has long served as the basis of spectroscopic measurements of materials. Operation in the resonance domain further allows these elements to achieve high efficiency and polarization control. An effective grating theory is a practical tool for modeling such optics, and here we extend use of this theory to the terahertz region, experimentally demonstrating an all-dielectric binary off-axis diffractive lens. We achieve a high-efficiency, polarization-independent optic that both focuses and disperses terahertz light, suggesting potential applications in pharmaceutical, security, and semiconductor imaging.