Highly sensitive surface plasmon terahertz imaging with planar plasmonic crystals.

We report on the operation of a highly sensitive terahertz imaging system relying on a planar metallic plasmonic crystal as a terahertz surface plasmon resonant (THz-SPR) sensor. The terahertz imaging is based on the resonantly enhanced transmission phenomenon of a periodically perforated metal film. The detection sensitivity and the imaging contrast for small amounts of substance are considerably better than those of the conventional terahertz transmission imaging without a THz-SPR sensor. As a demonstration, a high contrast image of a fingerprint recorded on a thin film can be achieved by using this system.