Imaging of terahertz fields and responses

In recent years it has become possible to generate terahertz-frequency (THz) fields that are strong enough to induce nonlinear responses in ordinary molecules and materials. Part of the development of THz technology and nonlinear spectroscopy has relied on optical imaging of THz field profiles and their time and position-dependent evolution. A THz "polaritonics" platform enables extensive control over THz fields that are generated; integration of functional elements such as bandgap structures and metamaterial devices; optical imaging of the THz near and far fields with subcycle temporal and subwavelength spatial resolution; and exploitation of the results for nonlinear spectroscopy.