Subsurface nanoimaging by THz pulse near-field microscopy

Combined with THz time-domain spectroscopy, THz near-field microscopy based on an atomic force microscope is a technique that, while challenging to implement, is invaluable for probing low-energy light-matter interactions of solid-state and biomolecular nanostructures, which are usually embedded in background media. Here, we experimentally demonstrate a broadband THz pulse near-field microscope that provides subsurface nanoimaging with a nearly frequency-independent lateral resolution of 90 nm, corresponding to -X/3300 at 1 THz.